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Diffstat (limited to 'xpa/doc/xpa.ps')
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PF{0 Ps neg R}if + 0 Np OU{gsave RZ LW Cf{Hc VC}{0 Sg}ie CP BB RW 0 RL CP BB stroke grestore}if + /CI 0 D /BP f D PF not{Ts neg SP}if /Ms t D} D +/AD {I NL EG 14 get dup 0 lt{pop AT}if NA /AE t D Tm 14 get Ts mul neg SP + Cf{EU 14 get dup -1 eq{pop CA CL get}if Sc}if} D +/DA {BN ()ES OA /AE f D ()Ec Bm 14 get Ts mul neg SP} D +/PR {/MW E D /Li E D Tm 1 get Ps mul BE 0 NA /FN Fp D /PF t D SI /SL SL 1 add D + /CF 0 D Ps CS mul Ts div MW WC mul CS mul Ts div dup LL gt PL 0 eq and + {LL div div}{pop}ie Ey 1 get FS CP E pop LE add YI neg div cvi dup Li lt + AH and{4 lt YI Li mul 5 mul LE add 0 gt or PL 0 eq and{NP}if}{pop}ie + EU 1 get Sc /GS Ps D}D +/RP {WR NL () /PF f D SI /FN 0 D ES Bm 1 get Ps mul neg SP OA /GS Ts D} D +/SI {/XO Lm 15 get BC NN mul Lm 16 get AI UI sub NN mul add + Lm 17 get UI NN mul add Lm 20 get LG NN mul add Ts mul + PF{Lm 1 get Ps mul add}if EO add D + /MR Rm 15 get BC NN mul Rm 16 get AI UI sub NN mul add + Rm 17 get UI NN mul add Rm 20 get LG NN mul add Ts mul + 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BL} D +/BQ {Tm 15 get Ts mul BE /BC BC 1 add D SI BL} D +/QB {Bm 15 get Ts mul BE /BC BC 1 sub D SI BL} D +/Al {E EP 1 sub dup 0 lt{pop AV AL get}if NA} D +/Ea {EP OA} D +/WB {PF{WR}{BT}ie} D +/F1 {WB /FN 0 D CS 0 FS} D +/F2 {WB /FN WI D CS 0 FS} D +/HY {/Hy t D WB /Hy f D} D +/YH {WB} D +/A {/LT E D LT 1 eq{/RN E D}if /Lh E D WB /C1 C1 ( Cp ) join D + Lc AF not and{Cl Sc}if /AF t D} D +/EA {Lc AF and{Ec}{WB}ie TL Pa AF and Lh 0 ne and + {( \() Lh join (\)) join /AF f D WB}if /AF f D} D +/TL {C1 ( Tl ) apa /C1 E D} d +/apa {AF OU and Lh 0 ne LT 1 eq or and{LT 1 eq{RN ( /) E ST cvs join} + {(\() Lh join (\)) join}ie E join join}{pop}ie} d +/Cp {/Xc CP /Yc E D D} D +/SS {Cf{dup 0 ge{EU E get dup -1 eq{pop CA CL get}if}{pop CA CL get}ie Sc} + {pop}ie SZ SL get /SL SL 1 add D} D +/I {WB 8 SS 1 FS} D +/EM {WB 8 SS /CF CF 1 xor D 0 FS} D +/BD {WB 9 SS 2 FS} D +/TT {WB 10 SS /FN Fp D 0 FS} D +/KB {WB 11 SS /FN Fp D 2 FS} D +/CT {WB 12 SS 1 FS} D +/SM {WB 13 SS /FN Fp D 0 FS} D +/Q {/QL QL 1 add D QO QL 2 mod get La get join WB} D +/EQ {QC QL 2 mod get La get join WB /QL QL 1 sub D} D +/RO {WB -1 SS /CF 0 D 0 FS} D +/SY {WB -1 SS -1 FS} D +/MY {WB -1 SS -2 FS} D +/ES {WB /SL SL 1 sub NN D /CF 0 D /FN FO SL get D SZ SL get FR SL get FS ()Ec}D +/FZ {3 sub 1.2 E exp GS mul E WB TL /C1 C1 ( Cp ) join D /SL SL 1 add D 0 FS} D +/Ef {WB TL ()ES /C1 C1 ( Cp ) join D} D +/BZ {dup /Bf E D FZ}D +/Sc {dup -1 ne Cf and{/CL CL 1 add D dup 0 eq{pop [0 0 0]}if + dup CA E CL E put VS ( VC ) join C1 E join /C1 E D}{pop}ie} D +/Ec {WB Cf{/CL CL 1 sub NN D CA CL get VS ( VC ) join C1 E join /C1 E D}if} D +/VS {dup type /arraytype eq{([) E {ST cvs join ( ) join}forall (]) join}if} D +/VC {{255 div}forall setrgbcolor} D +/Sl {dup type /integertype ne{Ds}if /La E D WB}d +/UN {WB /UF t D} D +/NU {WB /UF f D} D +/SE {WB /sF t D} D +/XE {WB /sF f D} D +/sM {/C1 C1 ( k1 ) join D}d +/eM {/C1 C1 ( k2 ) join D}d +/k1 {/YC CP E pop Ts add D /mF t D /f1 t D}d +/k2 {gsave 3 LW -9 CP E pop Ts 0.2 mul sub M -9 YC L stroke grestore /mF f D}d +/Ac {/AC E D WB}d +/Ca {eA{( \()join AC join(\) )join}if WB}d +/s {OU{gsave 0 CS .25 mul R dup SW pop CJ 0 RL stroke grestore}if}D +/CJ {AT 3 eq LB and{E dup dup length 1 sub A1 mul E + {( ) search{pop pop E A2 add E}{pop exit}ie}loop 3 -1 roll add + W CP pop sub 2 copy gt{E}if pop}if}D +/So {/Co E D} D +/SO {C1 Yo ST cvs join ( So ) join /C1 E D (j) SW pop 2 div Pd} D +/Se {E WB CS E div Pd}D +/Pd {dup type /stringtype eq{SW pop}if dup /L1 E L1 add D + ST cvs ( 0 R ) join C1 E join /C1 E D} D +/Sp {0.35 CO} D +/Sb {-0.2 CO} D +/CO {OV Io Yo put /Yo E CS mul Yo add D /Io Io 1 add D -1.5 Io mul 3 add FZ SO + CS Yo add dup YA gt{/YA E D}{pop}ie + Yo neg dup YB gt{/YB E D}{pop}ie} D +/Es {ES /Io Io 1 sub NN D /Yo OV Io get D SO} D +/SB {/N2 0 D 0 1 NI{/N E D{IX N2 get 0 lt{/N2 N2 1 add D}{exit}ie}loop + /K WS N get FC N get mul D /NY AY N2 get D /BV NY array D + 0 1 NY 1 sub{/TM K string D currentfile TM readhexstring pop pop BV E TM put} + for BM N BV put /N2 N2 1 add D}for} D +/IC [{/MA E D /MB 0 D}{2 div /MA E D /MB MA D}{/MB E CS sub D /MA CS D} + {pop /MA YS AB mul D /MB 1 AB sub YS mul D}{pop /MA 0 D /MB 0 D}] D +/IP {BV N get /N N 1 add D} D +/II {/K E D IX K get 0 lt{/EC E D}if /TY E D + TY 4 eq{/Y E D /X E D}if TY 3 eq{/AB E D}if + /XW AX K get D /YW AY K get D /IS SG IT K get get D /XS XW IS mul D + /YS YW IS mul D YS IC TY get exec /MA MA Fl not{3 add}if D} D +/IM {II /ty TY D /xs XS D /ys YS D /ya YA D /yb YB D /ma MA D /mb MB D /k K D + /ec EC D /BP f D /CI 0 D WB TL L1 xs add dup XO add MR add W gt + {pop /ma ma Fl{3 add}if D NL /YA ma D /YB mb D /YS ys D /L1 xs D} + {/L1 E D ma YA gt{/YA ma D}if mb YB gt{/YB mb D}if}ie /TB f D + OU{CP E pop YS sub LE neg lt Fl not and PB not and{NP /YA ma D /YB mb D}if + /BP f D ty ST cvs ( ) join IX k get 0 lt{(\() join ec join (\) ) join}if + k ST cvs join ty 3 eq{AB ST cvs ( ) join E join}if + ty 4 eq{X ST cvs ( ) join Y ST cvs join ( ) join E join}if C1 E join + ( DI ) join FP 2 eq FP 1 eq AF and or{( FM ) join}if + ( Il Cp ) apa /C1 E D /EN f D}if /HM t D /T f D} D +/DI {II /Xc CP /Yc E D D /YN YW neg D /HM t D /CI 0 D /K2 IX K get D gsave + TY 4 eq{OX X IS mul add OY FY add YS sub Y IS mul sub} + {/FY YS D CP MB sub 2 copy /OY E D /OX E D}ie + translate K2 0 ge{/DP AZ K2 get D /BV BM K2 get D XS YS scale /N 0 D XW YW DP + [XW 0 0 YN 0 YW] {IP} FC K2 get 1 eq{image}{f 3 colorimage}ie} + {EX}ie grestore XS 0 R /Ms t D} D +/FM {gsave 0 Sg CP MB sub translate XS neg 0 M 0 YS RL XS 0 RL 0 YS neg RL + XS neg 0 RL stroke grestore} D +/NA {/AT E D /AL AL 1 add D AV AL AT put} D +/OA {AL 0 gt{/AL AL 1 sub D /AT AV AL get D}if} D +/D1 {/BR {CP E pop E BN Mb{CP E pop eq{0 YI R}if}{pop}ie} D + /Sn {OU{C1 E ST cvs join ( Ld ) join /C1 E D}{pop}ie} D} D +/D1 {/BR {BN} D /Sn {OU {C1 E ST cvs join ( Ld ) join /C1 E D} {pop} ie} D} D +/TC {/TF t D /ML 0 D HN{SW pop dup ML gt{/ML E D}{pop}ie}forall NP /RM RM not D + RC /OU Tc D Ep /PN 0 D Ms not TP and{Ip}if /W IW ML sub Ts sub D + /A0 0 D TH{/BR {( ) join BT} D /Sn {pop} D /Au () D}if} D +/TN {0 eq{E EA PF HF or not XR and{HN E get Xr}{pop}ie} + {OU{Tn 0 ge{() BN}if /Tn E D}{pop}ie WB}ie} D +/NT {OU LB not and Tn 0 ge and{PL 0 eq{Ms not{CS CF FS}if CP dup + /y E YA sub D W 9 sub CS -1.8 mul XO L1 add 2 add{y M (.) show}for + HN Tn get dup SW pop IW E sub y M show CP BB M}if /Tn -1 D}if} D +/Ld {/DN E D HN DN Pn put [/View [/XYZ -4 Fl{PS}{CP YA add US E pop}ie null] + /Dest DN ST cvs cvn /DEST pdfmark} D +/C {ND 1 eq{1 sub}if TI mul /XO E D NL Nf not{pop()}if 0 3 -1 roll 1 A} D +/OP {BP not{NP}if PN 2 mod 0 eq{/Ms t D NP}if}D +/Ep {Xp PN 2 mod 0 eq and OU and{/Pn (-) D showpage /PM 1 D LA}if}D +/Dg [73 86 88 76 67 68 77] D +/Rd [0 [1 1 0][2 1 0][3 1 0][2 1 1][1 1 1][2 2 1][3 3 1][4 4 1][2 1 2]] D +/Ns {/m E D /c E 32 mul D /j m 1000 idiv D /p j 12 add string D + c 96 le m 0 gt and{c 32 le {/i 0 D /d 77 D /l 100 D /m m j 1000 mul sub D + j -1 1 {pop p i d c add put /i i 1 add D}for + 4 -2 0 {/j E D /n m l idiv D /m m n l mul sub D /d Dg j get D + n 0 gt {/x Rd n get D x 0 get -1 1 {pop p i d c add put /i i 1 add D}for + p i x 1 get sub Dg x 2 get j add get c add put}if /l l 10 idiv D + }for p 0 i GI} + {/i ST length 1 sub D m {1 sub dup 0 ge{dup 26 mod c add 1 add + ST i 3 -1 roll put 26 idiv dup 0 eq{pop exit}if}if /i i 1 sub D}loop + ST i ST length i sub GI}ie} + {m p cvs}ie} D +/US {matrix currentmatrix matrix defaultmatrix matrix invertmatrix + matrix concatmatrix transform} D +/GB {Gb{US}if}D +/Tl {/Rn E D Xc CP pop ne{ + [/Rect [Xc 1 sub Yc cS 0.25 mul sub GB CP E 1 add E cS 0.85 mul add GB] + /Subtype /Link /Border [0 0 Cf Lc and LX and AU or{0}{1}ie] Rn type + /nametype eq {/Dest Rn}{/Action [/Subtype /URI /URI Rn] Cd}ie + /ANN pdfmark}if} D +/Il {/Rn E D [/Rect [Xc Yc GB Xc XS add Yc YS add GB] /Subtype /Link + /Border [0 0 0] Rn type /nametype eq{/Dest Rn} + {/Action [/Subtype /URI /URI Rn] Cd}ie /ANN pdfmark} D +/XP {[{/Z Bz 2 div D Z 0 R Z Z RL Z neg Z RL Z neg Z neg RL Z Z neg RL + Fi cH 1 eq and{fill}if} {Bz 0 RL 0 Bz RL Bz neg 0 RL 0 Bz neg RL + Fi cH 1 eq and{fill}if} {0 -5 R Bz 0 RL 0 21 RL Bz neg 0 RL 0 -21 RL}]} D +/MS {/Sm E D WB}D +/O {BN()Sm BX} D +/O {BN()0 Sm BX} D +/BX {/Bt E D Bt 2 lt{/Ch E D CS 0.8 mul}{11 mul}ie W XO sub MR sub + 2 copy gt{E}if pop /HZ E D Bt 2 eq{Fi not{pop()}if ( )E join /Ft E D TT + /PF t D /MW 1 D /Li 1 D /Fw Ft SW pop D Fw HZ gt{/HZ Fw 8 add D}if + HZ ST cvs( )join}{WB Ch ST cvs( )join}ie L1 HZ add XO add MR add W gt{NL}if + Bt 2 eq{Ft ES Fw neg HM{CS sub}if Pd}if Bt ST cvs join( Bx )join + Bt 2 eq HM and{CS Pd}if C1 E join /C1 E D /L1 L1 HZ add D /T f D + ( ) Pd /PF f D Bt 2 lt{YA CS .8 mul lt{/YA CS .8 mul D}if} + {YB 5 lt{/YB 5 D}if YA 21 lt{/YA 21 D}if}ie /CI 0 D} D +/Bx {dup 2 eq{E /Bz E D}{E /cH E D /Bz CS .8 mul D}ie + OU {gsave 0 Sg XP E get exec stroke grestore}{pop}ie Bz 0 R /Ms t D}D +/SD {FD 4 mul Dy add DZ NF newpath 0 0 M DX t charpath pathbbox + 3 -1 roll sub /DY E D E dup /X1 E D sub WM mul WX DY mul add WM DG mul E div + /DF E D /DR WX DF mul DY mul WM div 2 div D} d +/Sd {gsave 0 IL Di mul neg translate IL IW atan Di 0 eq{neg}if rotate + FD 4 mul Dy add DZ NF DR X1 sub DY 2 div neg M cD VC DX show grestore} d +/Pt {/tp t D Tp{NP /Pn (TP) D 0 Tt neg R Th BN NP Ep ET RC ZF}if /tp f D} D +/RC {/AI 0 D /LG 0 D /BC 0 D /UI 0 D /PF f D /Cc 0 D /cC 0 D /Dc 10 array D + /NR [0 1 9{pop 0}for] D /La Ds D /AR 10 array D /TR 10 array D /AV 30 array D + SI /AL -1 D /AT A0 D AT NA /OV 9 array D /Yo 0 D /Co 0 D /Io 0 D /Hy f D + /Ph f D /CL -1 D Ct Sc}D +/ZF {/FR [0 1 30{pop 0}for] D /SZ [0 1 30{pop 0}for] D /FO [0 1 30{pop 0}for] D + /SL 0 D /CF 0 D /FN 0 D 0 Ts SF}D +/QO [[(\234)(\233)(\253\240)(\232)(\273)(\253)][(')(`)(\253\240)(\231)(\273)(\253)]] D +/QC [[(\234)(\234)(\240\273)(\233)(\253)(\273)][(')(')(\240\273)(`)(\253)(\273)]] D +/Hf EF length 2 sub D +/Hz EZ Hf get D +/HS Ey Hf get D +/Fz EZ Hf 1 add get D +/Fs Ey Hf 1 add get D +/LE IL D +/Ps EZ 1 get D +/Fp EF 1 get D +/XO 0 D +/YI 0 D +/CI 0 D +/FP 0 D +/WW Ts 7 mul D +/Mf 0 D +/YA 0 D +/YB 0 D +/Cs Ts D +/GS Ts D +/F0 0 D +/NS 0 D +/NB 0 D +/N 0 D +/C0 [] D +/C1 () D +/Lo 0 D +/L1 0 D +/LM 0 D +/PH 0 D +/EC 0 D +/Lh 0 D +/LT 0 D +/CH 1 string D +/ST 16 string D +/CA 9 array D +/HC (\255) D +/HM f D +/PF f D +/EN f D +/TB f D +/UF f D +/sF f D +/AE f D +/AF f D +/BP t D +/CD f D +/PA t D +/GL f D +/T t D +/HF f D +/AH f D +/SA f D +/PB f D +/f1 f D +/mF f D +/OX 0 D +/OY 0 D +/FY 0 D +/EO 0 D +/FB 0 D +/PL 0 D +/Bw 0 D +/PD -1 D +/TP f D +/tp f D +/TH f D +/Ty 4 D +/Tn -1 D +/Fl t D +/LB t D +/PM 1 D +/Ms f D +/Ba f D +/Bb f D +/Hl 3 D +/hl 6 D +/Hv 6 D +/Hs f D +/HI 0 D +/hi 0 D +/PO t D +/TE f D +/LF t D +/BO 0 D +/Sm 1 D +/Bf 3 D +/A1 0 D +/A2 0 D +/Ds 1 D +/QL -1 D +/Cb Db D +/Ct Dt D +/Cl Dl D +[/Creator (html2ps version 1.0 beta5) /Author () /Keywords () /Subject () + /Title (The XPA Help Facility) /DOCINFO pdfmark +/ND 22 D +/HN [(1) (1) (1) (3) (5) (8) (10) (14) (15) (16) (15) (16) (17) (19) (22) (25) +(26) (29) (30) (30) (31) (32) (32) (33) (34) (34) (35) (37) (38) (46) (46) +(39) (40) (42) (43) (44) (47) (48) (50) (51) (55) (61) (63) (75) (76) (77) +(80) (1) (1) (1) (2) (1) (??) (??) (1) (1) (1) (2) (3) (3) (3) (3) (4) (5) +(5) (5) (5) (7) (8) (8) (8) (8) (9) (10) (10) (10) (10) (10) (11) (12) (13) +(14) (14) (14) (14) (14) (15) (15) (15) (16) (16) (17) (18) (19) (19) (19) +(19) (20) (21) (22) (22) (22) (24) (25) (25) (33) (25) (25) (25) (25) (26) +(29) (30) (30) (31) (32) (32) (33) (33) (34) (34) (35) (36) (37) (37) (37) +(37) (37) (38) (38) (38) (38) (38) (38) (39) (40) (42) (43) (44) (46) (46) +(47) (48) (49) (50) (50) (50) (50) (50) (51) (53) (51) (51) (51) (51) (51) +(52) (53) (54) (55) (55) (55) (55) (60) (61) (61) (61) (61) (62) (63) (63) +(63) (63) (63) (63) (64) (64) (64) (65) (65) (66) (67) (67) (67) (68) (68) +(68) (68) (69) (69) (69) (70) (70) (70) (70) (70) (71) (71) (71) (71) (72) +(72) (73) (73) (73) (74) (74) (74) (74) (75) (75) (75) (75) (75) (76) (76) +(76) (76) (76) (77) (77) (77) (77) (79) (80) (80) (80) (80) (80)] D +/h0 [()(Table of Contents)] D +/h1 [(0.1\240\240)(XPA: Public Access to Data and Algorithms)] D +/h2 [(0.2\240\240)(Summary)] D +/h3 [(0.3\240\240)(Description)] D +/h4 [(0.3.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h5 [(0.4\240\240)(XPAIntro: Introduction to the XPA Messaging System)] D +/h6 [(0.5\240\240)(Summary)] D +/h7 [(0.6\240\240)(Description)] D +/h8 [(0.6.0.0.1\240\240)(Last updated: March 10, 2007)] D +/h9 [(0.7\240\240)(XPATemplate: Access Point Names and Templates)] D +/h10 [(0.8\240\240)(Summary)] D +/h11 [(0.9\240\240)(Description)] D +/h12 [(0.9.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h13 [(0.10\240\240)(XPACommon: Getting Common Information About Access Points)] D +/h14 [(0.11\240\240)(Summary)] D +/h15 [(0.12\240\240)(Description)] D +/h16 [(0.12.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h17 [(0.13\240\240)(XPAMethod: XPA Communication Methods)] D +/h18 [(0.14\240\240)(Summary)] D +/h19 [(0.15\240\240)(Description)] D +/h20 [(0.15.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h21 [(0.16\240\240)(XPAInet: XPA Communication Between Hosts)] D +/h22 [(0.17\240\240)(Summary)] D +/h23 [(0.18\240\240)(Description)] D +/h24 [(0.19\240\240)(Manual Registration)] D +/h25 [(0.20\240\240)(Remote Registration)] D +/h26 [(0.21\240\240)(XPANS Proxy Registration)] D +/h27 [(0.21.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h28 [(0.22\240\240)(XPAUsers: Distinguishing Users)] D +/h29 [(0.23\240\240)(Summary)] D +/h30 [(0.24\240\240)(Description)] D +/h31 [(0.24.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h32 [(0.25\240\240)(XPA Programs)] D +/h33 [(0.26\240\240)(Summary)] D +/h34 [(0.27\240\240)(xpaset: send data to one or more XPA servers)] D +/h35 [(0.28\240\240)(xpaget: retrieve data from one or more XPA servers)] D +/h36 [(0.29\240\240)(xpainfo: send short message to one or more XPA servers)] D +/h37 [(0.30\240\240)(xpaaccess: see if template matches registered XPA access points)] D +/h38 [(0.30.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h39 [(0.31\240\240)(xpamb: the XPA Message Bus)] D +/h40 [(0.32\240\240)(Summary)] D +/h41 [(0.33\240\240)(Description)] D +/h42 [(0.34\240\240)(Options)] D +/h43 [(0.34.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h44 [(0.35\240\240)(xpans: the XPA Name Server)] D +/h45 [(0.36\240\240)(Summary)] D +/h46 [(0.36.0.0.1\240\240)(Last updated: January 24, 2005)] D +/h47 [(0.37\240\240)(XPAServer: The XPA Server-side Programming Interface)] D +/h48 [(0.38\240\240)(Summary)] D +/h49 [(0.39\240\240)(Introduction to XPA Server Programming)] D +/h50 [(0.40\240\240)(Introduction)] D +/h51 [(0.41\240\240)(XPANew: create a new XPA access point)] D +/h52 [(0.42\240\240)(XPACmdNew: create a new XPA public access point for commands)] D +/h53 [(0.43\240\240)(XPACmdAdd: add a command to an XPA command public access point)] D +/h54 [(0.44\240\240)(XPACmdDel: remove a command from an XPA command public access point)] D +/h55 [(0.45\240\240)(XPAInfoNew: define an XPA info public access point)] D +/h56 [(0.46\240\240)(XPAFree: remove an XPA public access point)] D +/h57 [(0.47\240\240)(XPAMainLoop: optional main loop for XPA)] D +/h58 [(0.48\240\240)(XPAPoll: execute existing XPA requests)] D +/h59 [(0.49\240\240)(XPAAtExit: install exit handler)] D +/h60 [(0.50\240\240)(XPACleanup: release reserved XPA memory)] D +/h61 [(0.51\240\240)(XPA Server Callback Macros)] D +/h62 [(0.52\240\240)(XPA Race Conditions)] D +/h63 [(0.52.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h64 [(0.53\240\240)(Xpaoom: What happens when XPA runs out of memory?)] D +/h65 [(0.54\240\240)(Summary)] D +/h66 [(0.55\240\240)(Description)] D +/h67 [(0.55.0.0.1\240\240)(Last updated: April 7, 2009)] D +/h68 [(0.56\240\240)(XPAClient: The XPA Client-side Programming Interface)] D +/h69 [(0.57\240\240)(Summary)] D +/h70 [(0.58\240\240)(Introduction to XPA Client Programming)] D +/h71 [(0.59\240\240)(Introduction)] D +/h72 [(0.60\240\240)(XPAGet: retrieve data from one or more XPA servers)] D +/h73 [(0.61\240\240)(XPASet: send data to one or more XPA servers)] D +/h74 [(0.62\240\240)(XPAInfo: send short message to one or more XPA servers)] D +/h75 [(0.63\240\240)(XPAGetFd: retrieve data from one or more XPA servers and write to files)] D +/h76 [(0.64\240\240)(XPASetFd: send data from stdin to one or more XPA servers)] D +/h77 [(0.65\240\240)(XPAOpen: allocate a persistent client handle)] D +/h78 [(0.66\240\240)(XPAClose: close a persistent XPA client handle)] D +/h79 [(0.67\240\240)(XPANSLookup: lookup registered XPA access points)] D +/h80 [(0.68\240\240)(XPAAccess: return XPA access points matching template \(XPA 2.1 and above\))] D +/h81 [(0.68.0.0.1\240\240)(Last updated: March 10, 2007)] D +/h82 [(0.69\240\240)(XPAXt: the XPA Interface to Xt \(X Windows\))] D +/h83 [(0.70\240\240)(Summary)] D +/h84 [(0.71\240\240)(Description)] D +/h85 [(0.71.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h86 [(0.72\240\240)(XPATcl: the XPA Interface to the Tcl/Tk Environment)] D +/h87 [(0.73\240\240)(Summary)] D +/h88 [(0.74\240\240)(Server Routines)] D +/h89 [(0.75\240\240)(Client Routines)] D +/h90 [(0.76\240\240)(Description)] D +/h91 [(0.77\240\240)(XPANew)] D +/h92 [(0.78\240\240)(XPARec)] D +/h93 [(0.78.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h94 [(0.79\240\240)(XPAEnv: Environment Variables for XPA Messaging)] D +/h95 [(0.80\240\240)(Summary)] D +/h96 [(0.81\240\240)(Description)] D +/h97 [(0.81.0.0.1\240\240)(Last updated: December 23, 2009)] D +/h98 [(0.82\240\240)(XPAAcl: Access Control for XPA Messaging)] D +/h99 [(0.83\240\240)(Summary)] D +/h100 [(0.84\240\240)(Description)] D +/h101 [(0.84.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h102 [(0.85\240\240)(XPA ChangeLog)] D +/h103 [(0.86\240\240)(Public Release 2.1.15 \(July 23, 2013\))] D +/h104 [(0.87\240\240)(Public Release 2.1.14 \(June 7, 2012\))] D +/h105 [(0.88\240\240)(Public Release 2.1.13 \(April 14, 2011\))] D +/h106 [(0.89\240\240)(Public Release 2.1.12 \(January 26, 2010\))] D +/h107 [(0.90\240\240)(Public Release 2.1.11 \(December 7, 2009\))] D +/h108 [(0.91\240\240)(Public Release 2.1.10 \(September 1, 2009\))] D +/h109 [(0.92\240\240)(Internal Release 2.1.9)] D +/h110 [(0.93\240\240)(Public Release 2.1.8 \(1 November 2007\))] D +/h111 [(0.94\240\240)(Patch Release 2.1.7b[1,2] \(Feb 22, 2006; March 8, 2007\))] D +/h112 [(0.95\240\240)(Patch Release 2.1.6 \(4 May 2005\))] D +/h113 [(0.96\240\240)(Patch Release 2.1.5 \(12 January 2004\))] D +/h114 [(0.97\240\240)(Patch Release 2.1.4 \(24 March 2003\))] D +/h115 [(0.98\240\240)(Patch Release 2.1.3 \(26 September 2002\))] D +/h116 [(0.99\240\240)(Patch Release 2.1.2 \(18 July 2002\))] D +/h117 [(0.100\240\240)(Patch Release 2.1.1 \(20 June 2002\))] D +/h118 [(0.101\240\240)(Public Release 2.1.0 \(22 April 2002\))] D +/h119 [(0.102\240\240)(Pre-Release 2.1.0e \(2 April 2002\))] D +/h120 [(0.103\240\240)(Pre-Release 2.1.0e \(1 April 2002\))] D +/h121 [(0.104\240\240)(Pre-Release 2.1.0e \(25 March 2002\))] D +/h122 [(0.105\240\240)(Pre-Release 2.1.0e \(19 March 2002\))] D +/h123 [(0.106\240\240)(Pre-Release 2.1.0e \(14 February 2002\))] D +/h124 [(0.107\240\240)(Pre-Release 2.1.0e \(11 February 2002\))] D +/h125 [(0.108\240\240)(Beta Release 2.1.0b10 \(31 January 2002\))] D +/h126 [(0.109\240\240)(Beta Release 2.1.0b9 \(26 January 2002\))] D +/h127 [(0.110\240\240)(Beta Release 2.1.0b8 \(4 January 2002\))] D +/h128 [(0.111\240\240)(Beta Release 2.1.0b7 \(21 December 2001\))] D +/h129 [(0.112\240\240)(Beta Release 2.1.0b6 \(29 October 2001\))] D +/h130 [(0.113\240\240)(Beta Release 2.1.0b5 \(22 October 2001\))] D +/h131 [(0.114\240\240)(Beta Release 2.1.0b4 \(24 September 2001\))] D +/h132 [(0.115\240\240)(Beta Release 2.1.0b3 \(6 September 2001\))] D +/h133 [(0.116\240\240)(Beta Release 2.1.0b2 \(17 August 2001\))] D +/h134 [(0.117\240\240)(Beta Release 2.1.0b1 \(6 August 2001\))] D +/h135 [(0.118\240\240)(Patch Release 2.0.5 \(10 November 2000\))] D +/h136 [(0.119\240\240)(Patch Release 2.0.4 \(20 September 2000\))] D +/h137 [(0.120\240\240)(Patch Release 2.0.3 \(15 June 2000\))] D +/h138 [(0.121\240\240)(Patch Release 2.0.2 \(9 September 1999\))] D +/h139 [(0.122\240\240)(Patch Release 2.0.1 \(6 August 1999\))] D +/h140 [(0.123\240\240)(Public Release 2.0 \(27 May 1999\))] D +/h141 [(0.123.0.0.1\240\240)(Last updated: 22 April 2002)] D +/h142 [(0.124\240\240)(XPACode: Where to Find Example/Test Code)] D +/h143 [(0.125\240\240)(Summary)] D +/h144 [(0.126\240\240)(Description)] D +/h145 [(0.126.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h146 [(0.127\240\240)(XPA Changes: Changes For Users from XPA 1.0 and 2.0)] D +/h147 [(0.128\240\240)(Summary)] D +/h148 [(0.129\240\240)(Description)] D +/h149 [(0.129.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h150 [(0.130\240\240)(XPAConvert: Converting the XPA API to 2.0)] D +/h151 [(0.131\240\240)(Summary)] D +/h152 [(0.132\240\240)(Description)] D +/h153 [(0.132.0.0.1\240\240)(Last updated: September 10, 2003)] D +/h154 [(0.133\240\240)(XPAName: What does XPA stand for?)] D +/h155 [(0.134\240\240)(Summary)] D +/h156 [(0.135\240\240)(Description)] D +/h157 [(0.135.0.0.1\240\240)(Last updated: September 10, 2003)] D +/Hr [-47 47 48 49 -50 -50 50 -54 54 55 56 -57 -57 57 -59 59 60 61 -62 -62 +62 -64 64 65 66 -67 -67 67 -69 69 70 71 -72 -72 72 -74 74 75 76 77 78 79 +-80 -80 80 -82 82 83 84 -85 -85 85 -86 86 87 88 89 90 91 -92 -92 92 -94 +94 95 96 97 -98 -98 98 -100 100 101 -102 -102 102 -106 106 107 108 109 110 +111 112 113 114 115 116 117 118 119 120 121 -122 -122 122 -124 124 125 126 +-127 -127 127 -130 130 131 132 133 134 135 136 137 138 139 140 141 142 -143 +-143 143 -145 145 146 147 -148 -148 148 -151 151 152 153 154 155 156 157 +-158 -158 158 -160 160 161 162 -163 -163 163 -165 165 166 167 -168 -168 +168 -169 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 +185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 +203 204 205 206 207 -208 -208 208 -210 210 211 212 -213 -213 213 -215 215 +216 217 -218 -218 218 -220 220 221 222 -223 -223 223 -225 225 226 227 -228 +-228 228]D +/HV [1 2 2 2 3 4 5 1 2 2 2 3 4 5 1 2 2 2 3 4 5 1 2 2 2 3 4 5 1 2 2 2 3 +4 5 1 2 2 2 2 2 2 3 4 5 1 2 2 2 3 4 5 1 2 2 2 2 2 2 3 4 5 1 2 2 2 2 3 4 +5 1 2 2 3 4 5 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 4 5 1 2 2 2 3 4 5 1 2 +2 2 2 2 2 2 2 2 2 2 2 2 3 4 5 1 2 2 2 3 4 5 1 2 2 2 2 2 2 2 3 4 5 1 2 2 +2 3 4 5 1 2 2 2 3 4 5 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 +2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 4 5 1 2 2 2 3 4 5 1 2 2 2 3 4 5 1 2 2 2 +3 4 5 1 2 2 2 3 4 5]D +/Cn [3 0 0 1 1 1 0 3 0 0 1 1 1 0 3 0 0 1 1 1 0 3 0 0 1 1 1 0 3 0 0 1 1 +1 0 6 0 0 0 0 0 1 1 1 0 3 0 0 1 1 1 0 6 0 0 0 0 0 1 1 1 0 4 0 0 0 1 1 1 +0 2 0 1 1 1 0 16 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 3 0 0 1 1 1 0 13 +0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 3 0 0 1 1 1 0 7 0 0 0 0 0 0 1 1 1 0 3 0 +0 1 1 1 0 3 0 0 1 1 1 0 39 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 +0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 3 0 0 1 1 1 0 3 0 0 1 1 1 0 3 0 0 +1 1 1 0 3 0 0 1 1 1 0]D +Hr length 0 gt{[/PageMode /UseOutlines /DOCVIEW pdfmark}if +/Hn 1 D +0 1 Hr length 1 sub{ + /Bn E D [Cn Bn get dup 0 gt{/Count E HV Bn get Bl ge{neg}if}{pop}ie + /Dest Hr Bn get dup abs ST cvs cvn E 0 ge{(h)Hn ST cvs join cvx exec + dup 1 get E Nf{0 get E join}{pop}ie /Hn Hn 1 add D}{()}ie + /Title E dup length 255 gt{0 255 getinterval}if /OUT pdfmark}for +ZF /FN Fp D Ps 0 FS /WC Wf{( )}{<A1A1>}ie SW pop D +ET RC ZF +/Df f D +/R1 (http://hea-www.harvard.edu/RD/xpa/changelog.html) D +/Ba f D /BO 0 D Bs +/UR (help.html) D +/Ti (The XPA Help Facility) D +/Au () D +/Df f D +/ME [()] D + TC + +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc + +/Ba f D /BO 0 D Bs +/UR (help.html) D +/Ti (The XPA Help Facility) D +/Au () D +/Df f D +/ME [()] D + TC + +NP RC ZF +()1 Sl()WB 0 Sn( + + +)0 2 0 H(XPA:)WB 47 Sn()WB 1 Sn( Public Access to Data and Algorithms)EA()EH( + + +)0 2 1 H(Summary)WB 48 Sn()EH( +This document is the Table of Contents for XPA. + + +)0 2 2 H(Description)WB 49 Sn()EH( +)0 P(The XPA messaging system provides seamless communication between many +kinds of Unix programs, including X programs and Tcl/Tk programs. It +also provides an easy way for users to communicate with XPA-enabled +programs by executing XPA client commands in the shell or by utilizing +such commands in scripts. Because XPA works both at the programming +level and the shell level, it is a powerful tool for unifying any +analysis environment: users and programmers have great flexibility in +choosing the best level or levels at which to access XPA services, and +client access can be extended or modified easily at any time. + +)0 P(A program becomes an XPA-enabled server by defining named points of +public access through which data and commands can be exchanged with +other client programs \201and users\202. Using standard TCP sockets as a +transport mechanism, XPA supports both single-point and broadcast +messaging to and from these servers. It supports direct communication +between clients and servers, or indirect communication via an +intermediate message bus emulation program. Host-based access control +is implemented, as is as the ability to communicate with XPA servers +across a network. + +)0 P(XPA implements a layered interface that is designed to be useful both +to software developers and to users. The interface consists of a +library of XPA client and server routines for use in C/C++ programs and +a suite of high-level user programs built on top of these libraries. +Using the XPA library, access points can be added to Tcl/Tk programs, +Xt programs, or to Unix programs that use the XPA event loop or any +event loop based on select\201\202. Client access subroutines can be added +to any Tcl/Tk, Xt, or Unix program. Client access also is supported at +the command line via a suite of high-level programs. + +)0 P(Choose from the following topics: + +)UL( +)-1 LI()0 2 1 A(Introduction to XPA)2 1 TN TL()Ec /AF f D( + +)-1 LI()0 3 1 A(Access Point Names and Templates)3 1 TN TL()Ec /AF f D( + +)-1 LI()0 4 1 A(Getting Common Information About Access Points)4 1 TN TL()Ec /AF f D( + +)-1 LI()0 5 1 A(Communication Methods)5 1 TN TL()Ec /AF f D( + +)-1 LI()0 6 1 A(Communication Between Hosts)6 1 TN TL()Ec /AF f D( + +)-1 LI()0 7 1 A(Distinguishing Users)7 1 TN TL()Ec /AF f D( + + +)-1 LI()0 8 1 A(XPA User Programs)8 1 TN TL()Ec /AF f D( +)UL()-1 LI()0 9 1 A(xpaget: get data and info)9 1 TN TL()Ec /AF f D( + +)-1 LI()0 10 1 A(xpaset: send data and info)10 1 TN TL()Ec /AF f D( + +)-1 LI()0 11 1 A(xpainfo: send info alert)11 1 TN TL()Ec /AF f D( + +)-1 LI()0 12 1 A(xpaaccess: get access point info)12 1 TN TL()Ec /AF f D( + +)-1 LI()0 13 1 A(xpamb: message bus emulation)13 1 TN TL()Ec /AF f D( + +)-1 LI()0 14 1 A(xpans: the XPA name server)14 1 TN TL()Ec /AF f D( +)LU( + +)-1 LI()0 15 1 A(XPA Server Routines)15 1 TN TL()Ec /AF f D( +)UL()-1 LI()0 16 1 A(XPANew: define a new access point)16 1 TN TL()Ec /AF f D( + +)-1 LI()0 17 1 A(XPACmdNew: define a new command access point)17 1 TN TL()Ec /AF f D( + +)-1 LI()0 18 1 A(XPACmdAdd: add a command)18 1 TN TL()Ec /AF f D( + +)-1 LI()0 19 1 A(XPACmdDel: delete a command)19 1 TN TL()Ec /AF f D( + +)-1 LI()0 20 1 A(XPAInfoNew: define an info access point)20 1 TN TL()Ec /AF f D( + +)-1 LI()0 21 1 A(XPAFree: free an access point)21 1 TN TL()Ec /AF f D( + +)-1 LI()0 22 1 A(XPAMainLoop: event loop for select server)22 1 TN TL()Ec /AF f D( + +)-1 LI()0 23 1 A(XPAPoll: poll for XPA events)23 1 TN TL()Ec /AF f D( + +)-1 LI()0 24 1 A(XPACleanup: release reserved XPA memory)24 1 TN TL()Ec /AF f D( + +)-1 LI()0 25 1 A(XPA Server Macros: accessing structure internals)25 1 TN TL()Ec /AF f D( + +)-1 LI()0 26 1 A(XPA Race Conditions: how to avoid them)26 1 TN TL()Ec /AF f D( + +)-1 LI()0 27 1 A(XPA Out of Memory \201OOM\202 errors)27 1 TN TL()Ec /AF f D( +)LU( + +)-1 LI()0 28 1 A(XPA Client Routines)28 1 TN TL()Ec /AF f D( +)UL()-1 LI()0 29 1 A(XPAOpen: open a persistent client connection)29 1 TN TL()Ec /AF f D( + +)-1 LI()0 30 1 A(XPAClose: close persistent client connection)30 1 TN TL()Ec /AF f D( + +)-1 LI()0 31 1 A(XPAGet: get data)31 1 TN TL()Ec /AF f D( + +)-1 LI()0 32 1 A(XPASet: send data or commands)32 1 TN TL()Ec /AF f D( + +)-1 LI()0 33 1 A(XPAInfo: send an info alert)33 1 TN TL()Ec /AF f D( + +)-1 LI()0 34 1 A(XPAGetFd: get data and write to an fd)34 1 TN TL()Ec /AF f D( + +)-1 LI()0 35 1 A(XPASetFd: read data from and fd and send)35 1 TN TL()Ec /AF f D( + +)-1 LI()0 36 1 A(XPANSLookup: look up an access point)36 1 TN TL()Ec /AF f D( + +)-1 LI()0 37 1 A(XPAAccess: get access info)37 1 TN TL()Ec /AF f D( + +)-1 LI()0 38 1 A(The XPA/Xt Interface: Xt interface to XPA)38 1 TN TL()Ec /AF f D( + +)-1 LI()0 39 1 A(The XPA/Tcl Interface: Tcl interface to XPA)39 1 TN TL()Ec /AF f D( +)LU( + +)-1 LI( Tailoring the XPA Environment +)UL()-1 LI()0 40 1 A(Environment Variables)40 1 TN TL()Ec /AF f D( + +)-1 LI()0 41 1 A(Access Control)41 1 TN TL()Ec /AF f D( +)LU( + +)-1 LI( Miscellaneous +)UL( +)-1 LI()0 42 1 A(XPA ChangeLog)42 1 TN TL()Ec /AF f D( + +)-1 LI()0 43 1 A(Where to Find Example/Test Code)43 1 TN TL()Ec /AF f D( +)-1 LI()0 44 1 A(User Changes Between XPA 1.0 and 2.0)44 1 TN TL()Ec /AF f D( +)-1 LI()0 45 1 A(API Changes Between XPA 1.0 and 2.0)45 1 TN TL()Ec /AF f D( +)-1 LI()0 46 1 A(What Does XPA Stand For, Anyway?)46 1 TN TL()Ec /AF f D()LU( +)LU( + + + +)0 5 3 H(Last)WB 50 Sn( updated: September 10, 2003)EH( +)WB NL NP Ep ET /Tc f D +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (intro.html) D +/Ti (Introduction to XPA) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 2 Sn( + + +)0 2 4 H(XPAIntro:)WB 54 Sn()WB 51 Sn( Introduction to the XPA Messaging System)EA()EH( + + +)0 2 5 H(Summary)WB 55 Sn()EH( +)0 P(A brief introduction to the XPA messaging system, which provides +seamless communication between all kinds of Unix event-driven +programs, including X programs, Tcl/Tk programs, and Perl programs. + + +)0 2 6 H(Description)WB 56 Sn()EH( +)0 P(The XPA messaging system provides seamless communication between all +kinds of Unix programs, including X programs, Tcl/Tk programs, and +Perl programs. It also provides an easy way for users to communicate +with these XPA-enabled programs by executing XPA client commands in +the shell or by utilizing such commands in scripts. Because XPA works +both at the programming level and the shell level, it is a powerful +tool for unifying any analysis environment: users and programmers have +great flexibility in choosing the best level or levels at which to +access XPA services, and client access can be extended or modified +easily at any time. + +)0 P(A program becomes an XPA-enabled server by defining named points of +public access through which data and commands can be exchanged with +other client programs \201and users\202. Using standard TCP sockets as +a transport mechanism, XPA supports both single-point and broadcast +messaging to and from these servers. It supports direct communication +between clients and servers, or indirect communication via an +intermediate message bus emulation program. Host-based access control +is implemented, as is as the ability to communicate with XPA servers +across a network. + +)0 P(XPA implements a layered interface that is designed to be useful both +to software developers and to users. The interface consists of a +library of XPA client and server routines for use in programs and a +suite of high-level user programs built on top of these libraries. +Using the XPA library, access points can be added to +)0 52 1 A(Tcl/Tk)52 0 TN TL()Ec /AF f D( +programs, +)0 53 1 A(Xt)53 0 TN TL()Ec /AF f D( +programs, or to Unix programs that use the XPA event loop or any +event loop based on select\201\202. Client access subroutines can be added +to any Tcl/Tk or Unix program. Client access also is supported at the +command line via a suite of high-level programs. + +)0 P(The major components of the XPA layered interface are: +)UL()-1 LI(A set of XPA server routines, centered on +)0 16 1 A(XPANew\201\202,)16 0 TN TL()Ec /AF f D( +which are used by XPA server programs to tag public access points with +string identifiers and to register send and receive callbacks for +these access points. + +)-1 LI(A set of XPA client routines, centered on the +)0 32 1 A(XPASet\201\202)32 0 TN TL()Ec /AF f D( +and +)0 31 1 A(XPAGet\201\202,)31 0 TN TL()Ec /AF f D( +which are used by external client applications to exchange data and +commands with an XPA server. + +)-1 LI(High-level programs, centered on +)0 10 1 A(xpaset)10 0 TN TL()Ec /AF f D( +and +)0 9 1 A(xpaget,)9 0 TN TL()Ec /AF f D( +which allow data +and information to be exchanged with XPA server programs from the +command line and from scripts. These programs have the command syntax: +) 2 35 PR( [data] | xpaset [qualifiers ...] + xpaget [qualifiers ...])RP( +)-1 LI(An XPA name server program, +)0 14 1 A(xpans,)14 0 TN TL()Ec /AF f D( +through which XPA access point names are +registered by servers and distributed to clients.)LU( + +)0 P(Defining an XPA access point is easy: a server application calls +)0 16 1 A(XPANew\201\202,)16 0 TN TL()Ec /AF f D( +)0 17 1 A(XPACmdNew\201\202,)17 0 TN TL()Ec /AF f D( +or the experimental +)0 20 1 A(XPAInfoNew\201\202)20 0 TN TL()Ec /AF f D( +routine to +create a named public access point. An XPA service can specify "send" +and "receive" callback procedures \201or an "info" procedure in the case +of XPAInfoNew\201\202\202 to be executed by the program when an external +process either sends data or commands to this access point or requests +data or information from this access point. Either of the callbacks +can be omitted, so that a particular access point can be specified as +read-only, read-write, or write-only. Application-specific client +data can be associated with these callbacks. Having defined one or +more public access points in this way, an XPA server program enters +its usual event loop \201or uses the standard XPA event loop\202. + +)0 P(Clients communicate with these XPA public access points +using programs such as +)0 9 1 A(xpaget)9 0 TN TL()Ec /AF f D(, +)0 10 1 A(xpaset)10 0 TN TL()Ec /AF f D(, and +)0 11 1 A(xpainfo)11 0 TN TL()Ec /AF f D( +\201at the command line\202, +or routines such as +)0 31 1 A(XPAGet\201\202,)31 0 TN TL()Ec /AF f D( +)0 32 1 A(XPASet\201\202,)32 0 TN TL()Ec /AF f D( +and +)0 33 1 A(XPAInfo\201\202)33 0 TN TL()Ec /AF f D( +within a program. Both methods require specification of the name of +the access point. The xpaget program returns data or other +information from an XPA server to its standard output, while the +xpaset program sends data or commands from its standard input to an +XPA application. The corresponding API routines set/get data to/from +memory, returning error messages and other info as needed. If a +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +is used to specify the access point name \201e.g., "ds9*"\202, then +communication will take place with all servers matching that template. + +)0 P(Please note that XPA currently is not thread-safe. All XPA calls must be +in the same thread. + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 7 H(Last)WB 57 Sn( updated: March 10, 2007)EH( + +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (template.html) D +/Ti (Access Point Names and Templates) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 3 Sn( + + +)0 2 8 H(XPATemplate:)WB 59 Sn()WB 58 Sn( Access Point Names and Templates)EA()EH( + +)0 2 9 H(Summary)WB 60 Sn()EH( +)0 P(XPA access points are composed of two parts: a general class and a +specific name. Both parts accept template characters so that you +can send/retrieve data to/from multiple servers at one time. + + +)0 2 10 H(Description)WB 61 Sn()EH( +)0 P(When XPA servers call +)0 16 1 A(XPANew\201\202,)16 0 TN TL()Ec /AF f D( +or +)0 17 1 A(XPACmdNew\201\202)17 0 TN TL()Ec /AF f D( +to define XPA access points, they specify a string identifier composed of a +class and a name. When clients communicate with XPA access points, +they specify which access points to communicate with using +an identifier of the form: +) 1 12 PR( class:name)RP( +All registered XPA access points that match the specified identifier +will be available for communication \201subject to access control rules, +etc.\202 + +)0 P(As of XPA 2.1.5, the length of both the class and name designations are +limited to 1024 characters. + +)0 P(The XPA class:name identifier actually is a template: it accepts wild +cards in its syntax, so a single specifier can match more than one XPA +access point. \201Note that the class is optional and defaults to "*".\202 +The allowed syntax for clients to specify the class:name template is +of the form shown below. \201Note that "*" is used to denote a generic +wild card, but other wild cards characters are supported, as described +below\202. +) 7 46 PR( template explanation + -------- ----------- + class:name exact match of class and name + name match any class with this name + *:name match any class with this name + class:* match any name of this class + *:* match any access point)RP( +)0 P(In general, the following wild-cards can be applied to class and name: +) 5 58 PR( wildcard explanation + -------- ----------- + ? match any character, but there must be one + * match anything, or nothing + [...] match an inclusive set)RP( +)0 P(Although the class:name template normally is used to refer to XPA +access points, these also can be specified using their individual +socket identifiers. For inet sockets, the socket identifier is +)BD(ip:port)ES(, where ip can be the DNS-registered name, +the ASCII IP number \201e.g. 123.45.67.890\202 or the hex IP number +\201e.g. 838f3a60\202. For unix sockets, the identifier is the )BD(socket file +name)ES(. These socket identifiers are displayed as the fourth argument +in the xpans display of registered access points. For example, +consider the ds9 program started using inet sockets. The xpans name +server will register something like this: +) 2 40 PR( csh> xpaget xpans + DS9 ds9 gs saord.harvard.edu:3236 eric)RP( +You can access ds9 using ip:3236 in any of the three forms: +) 8 37 PR( csh> xpaget saord:3236 file + /home/eric/data/snr.ev + + csh> xpaget 123.45.67.890:3236 file + /home/eric/data/snr.ev + + csh> xpaget 838f3a60:3236 file + /home/eric/data/snr.ev)RP( +In the case of unix sockets, the socket identifier is a file: +) 5 41 PR( csh> xpaget xpans + DS9 ds9 gs /tmp/.xpa/DS9_ds9.2631 eric + + csh> xpaget /tmp/.xpa/DS9_ds9.2631 file + /home/eric/data/snr.ev)RP( +This feature can be useful in distinguishing between multiple +instances of a program that all have the same class:name designation. + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 11 H(Last)WB 62 Sn( updated: September 10, 2003)EH( + +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (info.html) D +/Ti (Getting Common Information About Access Points) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 4 Sn( + + +)0 2 12 H(XPACommon:)WB 64 Sn()WB 63 Sn( Getting Common Information About Access Points)EA()EH( + + +)0 2 13 H(Summary)WB 65 Sn()EH( +)0 P(There are various kinds of generic information you can retrieve about +an XPA access point by using the xpaget command. + + +)0 2 14 H(Description)WB 66 Sn()EH( +)0 P(You can find out which XPA access points have been registered with +the currently running +)0 14 1 A(XPA name server)14 0 TN TL()Ec /AF f D( +by executing the +)0 9 1 A(xpaget)9 0 TN TL()Ec /AF f D( +command to retrieve info from the XPA name server: +) 1 14 PR( xpaget xpans)RP( +If, for example, the +)0 43 1 A(stest)43 0 TN TL()Ec /AF f D( test server program +is running, the following XPA access points will be returned \201the specifics +of the returned info will vary for different machines and users\202: +) 4 33 PR( XPA xpa gs 838e2f67:1262 eric + XPA xpa1 gs 838e2f67:1266 eric + XPA c_xpa gs 838e2f67:1267 eric + XPA i_xpa i 838e2f67:1268 eric)RP( +Note that access to this information is subject to the usual +)0 41 1 A(XPA Access Control)41 0 TN TL()Ec /AF f D( restrictions. + +)0 P(Each XPA access point supports a number of reserved sub-commands that provide +access to different kinds of information, e.g. the access control for +that access point. These sub-commands can be executed by using +)0 10 1 A(xpaset)10 0 TN TL()Ec /AF f D( +or +)0 9 1 A(xpaget)9 0 TN TL()Ec /AF f D( +at the command line, or +)0 31 1 A(XPAGet\201\202)31 0 TN TL()Ec /AF f D( +or +)0 32 1 A(XPASet\201\202)32 0 TN TL()Ec /AF f D( +in programs, e.g: +) 5 30 PR( xpaget ds9 -acl + xpaget ds9 -help + xpaget ds9 env FOO + + xpaset -p ds9 env FOO foofoo)RP( +With the exception of )BD(-help)ES( and )BD(-version)ES(, reserved +sub-commands are available only on the machine on which the XPA server +itself is running. + +The following reserved sub-commands are defined for all access points: +)0 DL( +)0 P()0 DT()BD(-acl)ES( get \201set\202 the access control list [options: host type acl, for set] +)DD( +The 'xpaset' option allows you to add a new acl for a given host, or change +the acl for an existing host. See +)0 41 1 A(XPA Access Control)41 0 TN TL()Ec /AF f D( +for more information. +This access point is available only on the server machine. + +)0 P()0 DT()BD(-env)ES( get \201set\202 an environment variable [options: name \201value, for set\202] +)DD(The 'xpaget' option will return the value of the named environment +variable. The 'xpaset' option will set the value of the names +variable to the specified value. +This access point is available only on the server machine. +\201Please be advised that we have had problems setting environment +variables in static Tcl/Tk programs such as ds9 running under Linux.\202 + +)0 P()0 DT( )BD(-clipboard)ES( set\201get\202 information on a named clipboard +)DD( Clients can store ASCII state information on any number of named +clipboards. Clipboards of the same name created by clients on +different machines are kept separate. The syntax for creating a +clipboard is: +) 2 65 PR( [data] | xpaset [server] -clipboard add|append [clipboard_name] + xpaset -p [server] -clipboard delete [clipboard_name])RP( +Use "add" to create a new clipboard or replace the contents of an existing +one. Use "append" to append to an existing clipboard. +)0 P(Information on a named clipboard is retrieved using: +) 1 45 PR( xpaget [server] -clipboard [clipboard_name])RP( +)0 P()0 DT()BD(-exec)ES( set: execute commands from buffer [options: none] +)DD(If -exec is specified in the paramlist of an 'xpaset' call, then further +sub-commands will be retrieved from the data buffer. + +)0 P()0 DT()BD(-help)ES( get: return help string for this XPA or sub-command [options: name \201for sub-commands\202] +)DD(Each XPA access point and each XPA sub-command can have a help string +associated with it that is specified when the access point is defined. +The -help option will return this help string. For XPA access points +that contain user-defined sub-commands, you can get the help string +for a particular sub-command by specifying its name, or else get the +help strings for all sub-commands if not name is specified. + +)0 P()0 DT()BD(-ltimeout)ES( get \201set\202 the long timeout value [options: seconds|reset] +)DD(The 'xpaget' option will return the value of the long timeout \201in seconds\202. +The 'xpaset' option will set the value of the long timeout. If "reset" is +specified, then the timeout value will be reset to the default value. + +)0 P()0 DT()BD(-nsconnect)ES( set: re-establish name server connection to all XPA's [options: none] +)DD(If the +)0 14 1 A(XPA Name Server \201xpans\202)14 0 TN TL()Ec /AF f D( +process has terminated unexpectedly and then re-started, this +sub-command can be used to re-establish the connection. You use it by +sending the command to the [name:port] or [file] of the access point +instead of to the XPA name \201since the latter requires the xpans +connection!\202: +) 1 36 PR( xpaset -p 838e2f67:1268 -nsconnect)RP( +See )0 14 1 A(xpans)14 0 TN TL()Ec /AF f D( for more information. + +)0 P()0 DT()BD(-nsdisconnect)ES( set: break name server connection to all XPA's [options: none] +)DD(This sub-command will terminate the connection to the +)0 14 1 A(XPA Name Server \201xpans\202)14 0 TN TL()Ec /AF f D(, thereby making +all access points inaccessible except through their underlying [name:port] +or [file] identifiers. I forget why we added it, it seems pretty useless. + +)0 P()0 DT()BD(-stimeout)ES( get \201set\202 the short timeout value [options: seconds|reset] +)DD(The 'xpaget' option will return the value of the short timeout \201in seconds\202. +The 'xpaset' option will set the value of the short timeout. If "reset" is +specified, then the timeout value will be reset to the default value. + +)0 P()0 DT()BD(-remote)ES( set: register xpa with remote server [options: host[:port] [acl]] [-proxy] +)DD(This sub-command will register the XPA access point with the XPA name +server \201xpans\202 on the specified host \201which must already be running\202. +The specified host also is given access control to the access point, +using the specified acl or the default acl of "+" \201meaning the remote +host can xpaset, xpaget, xpainfo or xpaaccess\202. If the acl is +specified as "-", then the access point is unregistered. +See )0 6 1 A(Communication Between Machines)6 0 TN TL()Ec /AF f D( +for more information on how this sub-command is used. + +)0 P()0 DT()BD(-version)ES( get: return XPA version string [options: none] +)DD(The version refers to the version of XPA used to define this access point +\201currently something like 2.0\202. +)LD( + +)0 P(You can add your own reserved commands to all XPA access points by using the +)0 18 1 A(XPACmdAdd\201\202)18 0 TN TL()Ec /AF f D( +routine, passing the XPA handle returned by )EM(XPA XPAGetReserved\201void\202)ES( +as the first argument. Note again that these will only be available on the +machine where the XPA service is running. + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 15 H(Last)WB 67 Sn( updated: September 10, 2003)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (method.html) D +/Ti (XPA Communication Methods) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 5 Sn( + + +)0 2 16 H(XPAMethod:)WB 69 Sn()WB 68 Sn( )EA(XPA Communication Methods)EH( + + +)0 2 17 H(Summary)WB 70 Sn()EH( +)0 P(XPA supports both inet and unix \201local\202 socket communication. + + +)0 2 18 H(Description)WB 71 Sn()EH( +)0 P(XPA uses sockets for communication between processes. It supports +three methods of socket communication: inet, localhost, and unix. In +general, the same method should be employed for all XPA processes in a +session and the global environment variable XPA_METHOD should be used +to set up the desired method. By default, the preferred method is +"inet", which is appropriate for most users. You can set up a +different method by typing something like: +) 3 70 PR( setenv XPA_METHOD local # unix csh + XPA_METHOD=local; export XPA_METHOD # unix sh, bash, windows/cygwin + set XPA_METHOD=localhost # dos/windows)RP( +The options for XPA_METHOD are: )BD(inet)ES(, )BD(unix)ES( \201or +)BD(local)ES(\202, and )BD(localhost)ES(. On Unix machines, this +environment setup command can be placed in your shell init file +\201.cshrc, .profile, .bashrc, etc.\202 On Windows platforms, it can be +placed in your AUTOEXEC.BAT file \201I think!\202. + +)0 P(By default, )BD(inet)ES( sockets are used by XPA. These are the standard +Internet sockets that are used by programs such as Netscape, +ftp. etc. Inet sockets utilize the IP address of the given machine and +a \201usually random\202 port number to communicate between processes on the +same machine or between different machines on the Internet. \201Note that +XPA has an )0 41 1 A(Access Control)41 0 TN TL()Ec /AF f D( mechanism to +prevent unauthorized access of XPA access points by other computers on +the Net\202. For users connected to the Internet, this usually is the +appropriate communication method. For more information about setting +up XPA communication between machines, see +)0 6 1 A(Communication Between Machines)6 0 TN TL()Ec /AF f D(. + +)0 P(In you are using XPA on a machine without an Internet connection, then +inet sockets are not appropriate. In fact, an XPA process often will +hang for many seconds while waiting for a response from the Domain +Name Service \201DNS\202 when using inet sockets. Instead of inet sockets, +users on Unix platforms can also use )BD(unix)ES( sockets \201also known +as local sockets\202. These sockets are based on the local file system +and do not make use of the DNS. They generally are considered to be +faster than inet sockets, but they are not implemented under +Windows. Use local sockets as a first resort if you are on a Unix +machine that is not connected to the Internet. + +)0 P(Users not connected to the Internet also can use )BD(localhost)ES( +sockets. These are also inet-type sockets but the IP address used for +the local machine is the )BD(localhost)ES( address, 0x7F000001, instead +of the real IP of the machine. Depending on how sockets are set up for +a given platform, communication with the DNS usually is not required in +this case \201though of course, XPA cannot interact with other machines\202. +The localhost method will generally work on both Unix and Windows +platforms, but whether the DNS is required or not is subject to +individual configurations. + +)0 P(A final warning/reminder: if your XPA-enabled server hangs at startup +time and your XPA_METHOD is )BD(inet)ES(, the problem probably is +related to an incorrect Internet configuration. This can be confirmed +by using the )BD(unix)ES( method or \201usually\202 the )BD(localhost)ES( +method. You can use these alternate methods if other hosts do not need +access to the XPA server. + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 19 H(Last)WB 72 Sn( updated: September 10, 2003)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (inet.html) D +/Ti (XPA Communication Between Hosts) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 6 Sn( + + +)0 2 20 H(XPAInet:)WB 74 Sn()WB 73 Sn( XPA Communication Between Hosts)EA()EH( + + +)0 2 21 H(Summary)WB 75 Sn()EH( +XPA uses standard inet sockets to support communication between two or +more host computers. + + +)0 2 22 H(Description)WB 76 Sn()EH( +)0 P(When the )0 5 1 A(Communication Method)5 0 TN TL()Ec /AF f D( is set to +)BD(inet)ES( \201as it is by default\202, XPA can be used to communicate +between different computers on the Internet. INET sockets utilize the +IP address of the given machine and a \201usually random\202 port number to +communicate between processes on the same machine or between different +machines on the Internet. These standard Internet sockets are also +used by programs such as Netscape, ftp. etc. + +)0 P(XPA supports a host-based )0 41 1 A(Access Control)41 0 TN TL()Ec /AF f D( mechanism +to prevent unauthorized access of XPA access points by other computers +on the Net. By default, only the machine on which the XPA server is +running can access XPA services. Therefore, setting up communication +between a local XPA server machine and a remote client machine +requires a two-part registration process: + +)UL()-1 LI( the XPA service on the local machine must be made known to the +remote machine +)-1 LI( the remote machine must be given permission to access the local +XPA service)LU( + +Three methods by which this remote registration can be accomplished +are described below. + +)0 2 23 H(Manual)WB 77 Sn( Registration)EH( + +The first method is the most basic and does not require the remote +client to have xpans running. To use it, the local server simply +gives a remote client machine access to one or more XPA access points +using xpaset and the )BD(-acl)ES( sub-command. For example, +consider the XPA test program "stest" running on a local machine. By +default the access control for the access point named "xpa" is +restricted to that machine: +) 3 25 PR( [sh]$ xpaget xpa -acl + *:* 123.456.78.910 gisa + *:* localhost gisa)RP( +Using xpaset and the )BD(-acl)ES( sub-command, a remote client +machine can be given permission to perform xpaget, xpaset, xpaaccess, +or xpainfo operations. For example, to allow the xpaget operation, the +following command can be issued on the local machine: +) 1 45 PR( [sh]$ xpaset -p xpa -acl "remote_machine g")RP( +This results in the following access permissions on the local machine: +) 4 26 PR( [sh]$ xpaget xpa -acl + XPA:xpa 234.567.89.012 g + *:* 123.456.78.910 gisa + *:* localhost gisa)RP( + +The remote client can now use the local server's xpans name server to +establish communication with the local XPA service. This can be done +on a call-by-call basis using the )BD(-i)ES( switch on xpaset, xpaget, etc: +) 6 43 PR( [sh]$ xpaget -i "local_machine:12345" xpa + class: XPA + name: xpa + method: 88877766:2778 + sendian: little + cendian: big)RP( +Alternatively, the XPA_NSINET variable on the remote machine can be +set to point directly to xpans on the local machine, removing +the need to override this value each time an XPA program is run: +) 7 42 PR( [csh]$ setenv XPA_NSINET 'karapet:$port' + [csh]$ xpaget xpa + class: XPA + name: xpa + method: 88877766:2778 + sendian: little + cendian: big)RP( +Here, '$port' means to use the default XPA name service port \20114285\202. +not a port environment variable. + +)0 P(Access permission for remote client machines can be stored in a file +on the local machine pointed to by the )BD(XPA_ACLFILE)ES( environment +variable or using the )BD(XPA_DEFACL)ES( environment variable. See )0 41 1 A(XPA Access Control)41 0 TN TL()Ec /AF f D( for more information. + +)0 2 24 H(Remote)WB 78 Sn( Registration)EH( + +If xpans is running on the remote client machine, then a local xpaset +command can be used with the )BD(-remote)ES( sub-command to +register the local XPA service in the remote name service, while at +the same time giving the remote machine permission to access the local +service. For example, assume again that "stest" is running on the +local machine and that xpans is also running on the remote machine. +To register access of this local xpa on the remote machine, use +the xpaset and the )BD(-remote)ES( sub-command: +) 1 56 PR( [sh]$ ./xpaset -p xpa -remote 'remote_machine:$port' +)RP( +To register the local xpa access point on the remote machine with xpaget +access only, execute: +) 1 56 PR( [sh]$ ./xpaset -p xpa -remote 'remote_machine:$port' g)RP( +Once the remote registration command is executed, the remote client +machine will have an entry such as the following in its own xpans name +service: +) 2 31 PR( [csh]$ xpaget xpans + XPA xpa gs 88877766:2839 eric)RP( +The xpa access point can now be utilized on the remote machine without +further setup: +) 6 23 PR( [csh]$ xpaget xpa + class: XPA + name: xpa + method: 838e2f68:2839 + sendian: little + cendian: big)RP( +To unregister remote access from the local machine, use the same +command but with a '-' argument: +) 1 54 PR( [sh]$ xpaset -p xpa -remote 'remote_machine:$port' -)RP( +The benefit of using remote registration is that communication with +remote access points can be mixed with that of other access points +on the remote machine. Using )0 3 1 A(Access Point +Names and Templates)3 0 TN TL()Ec /AF f D(, one XPA command can be used to send or +receive messages to the remote and local services. + +)0 2 25 H(XPANS)WB 79 Sn( Proxy Registration)EH( + +The two methods described above are useful when the local and remote +machines are able to communicate freely to one another. This would be +the case on most Local Area Networks \201LANs\202 where all machines are +behind the same firewall and there is no port blocking between +machines on the same LAN. The situation is more complicated when the +XPA server is behind a firewall, where outgoing connections are +allowed, but incoming port blocking is implemented to prevent machines +outside the firewall from connecting to machines inside the +firewall. Such incoming port blocking will prevent xpaset and xpaget +from connecting to an XPA server inside a firewall. + +)0 P(To allow locally fire-walled XPA services to register with remote +machines, we have implemented a proxy service within the xpans name +server. To register remote proxy service, xpaset and the +)BD(-remote)ES( sub-command is again used, but with an additional +)BD(-proxy)ES( argument added to the end of the command: +) 1 63 PR( [sh]$ ./xpaset -p xpa -remote 'remote_machine:$port' g -proxy)RP( +Once a remote proxy registration command is executed, the remote +machine will have an entry such as the following in its own xpans name +service: +) 2 32 PR( [csh]$ xpaget xpans + XPA xpa gs @88877766:2839 eric)RP( +The '@' sign in the name service entry indicates that xpans proxy +processing is being used for this access point. Other than that, from +the user's point of view, there is no difference in how this XPA +access point is contacted using XPA programs \201xpaset, xpaget, etc.\202 or +libraries: +) 6 23 PR( [csh]$ xpaget xpa + class: XPA + name: xpa + method: 88877766:3053 + sendian: little + cendian: big)RP( +)0 P(Of course, the underlying processing of the XPA requests is very much +different when xpans proxy is involved. Instead of an XPA program such +contacting the XPA service directly, it contacts the local xpans. +Acting as a proxy server, xpans communicates with the XPA service +using the command channel established at registration time. Commands +\201including establishing a new data channel\202 are sent between xpans and +the XPA service to set up a new message transfer, and then data is fed +to/from the xpa request, through xpans, from/to the XPA service. In +this way, it can be arranged so that connections between the +fire-walled XPA service and the remote client are always initiated by +the XPA service itself. Thus, incoming connections that would be +blocked by the firewall are avoided. Note that there is a performance +penalty for using the xpans/proxy service. Aside from extra overhead +to set up proxy communication, all data must be sent through the +intermediate proxy process. + +)0 P(The xpans proxy scheme requires that the remote client allow the local +XPA server machine to connect to the remote xpans/proxy server. If the +remote client machine also is behind a port-blocking firewall, such +connections will be disallowed. In this case, the only solution is to +open up some ports on the remote client machine to allow incoming +connections to xpans/proxy. Two ports must be opened \201for command and +data channel connections\202. By default, these two ports are 14285 and +14287. The port numbers can be changed using the )BD(XPA_NSINET)ES( +environment variable. This variable takes the form: +) 1 49 PR( setenv XPA_NSINET machine:port1[,port2[,port3]])RP( +where port1 is the main connecting port, port2 is the XPA access port, +and port3 is the secondary data connecting port. The second and third +ports are optional and default to port1+1 and port1+2, respectively. +It is port1 and port3 that must be left open for incoming connections. + +)0 P(For example, to change the port assignments so that xpans listens +for registration commands on port 12345 and data commands on port 28573: +) 1 32 PR( setenv XPA_NSINET myhost:12345)RP( +Alternatively, all three ports can be assigned explicitly: +) 1 43 PR( setenv XPA_NSINET remote:12345,3000,12346)RP( +In this case 12345 and 12346 should be open for incoming connections. +The XPA access port \201which need not be open to the outside +world\202 is set to 3000. + +)0 P(Finally, note that we currently have no mechanism to cope with +Internet proxy servers \201such as SOCKS servers\202. If an XPA service is +running on a machine that cannot connect directly to outside machines, +but goes through a proxy server instead, there currently is no way to +register that XPA service with a remote machine. We hope to implement +support for SOCKS proxy in a future release. + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 26 H(Last)WB 80 Sn( updated: September 10, 2003)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (users.html) D +/Ti (Distinguishing Users) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 7 Sn( + + +)0 2 27 H(XPAUsers:)WB 82 Sn()WB 81 Sn( Distinguishing Users)EA()EH( + + +)0 2 28 H(Summary)WB 83 Sn()EH( +)0 P(XPA normally distinguishes between users on a given host, but it is possible +to send data to access points belonging to other users. + + +)0 2 29 H(Description)WB 84 Sn()EH( +)0 P(A single XPA name service typically serves all users on a given +machine. Two users can register the same XPA access points on the +same machine without conflict, because the user's username is +registered with each access point and, by default, programs such as +xpaget and xpaset only process access points of the appropriate user. +For example: +) 4 32 PR( XPA xpa1 gs 838e2f67:1262 eric + XPA xpa2 gs 838e2f67:1266 eric + XPA xpa1 gs 838e2f67:2523 john + XPA xpa2 gs 838e2f67:2527 john)RP( +Here the users "eric" and "john" both have registered the access +points xpa1 and xpa2. When either "john" or "eric" retrieves +information from xpa1, they will process only the access point +registered in their user name. + +)0 P(If you want to access another user's XPA access points on a single +machine, use the -u [user] option on xpaset, xpaget, etc. For example, +if eric executes: +) 1 21 PR( xpaget -u john xpa1)RP( +he will access John's xpa1 access point.Use "*" to access all users +on a given machine: +) 1 20 PR( xpaget -u "*" xpa1)RP( +Note that the )0 40 1 A(XPA Environment Variable)40 0 TN TL()Ec /AF f D( +XPA_NSUSERS can be used to specify the default list of users to +process: +) 1 32 PR( setenv XPA_NSUSERS "eric,john")RP( +will cause access points from both "eric" and "john" to be processed +by default. + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 30 H(Last)WB 85 Sn( updated: September 10, 2003)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (programs.html) D +/Ti (XPA Programs) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 8 Sn( +)0 2 31 H(XPA)WB 86 Sn( Programs)EH( + +)0 2 32 H(Summary)WB 87 Sn()EH( + +)0 P(Use the XPA programs to send/receive data to/from XPA servers from the +command line or from scripts. + +)0 P() 7 116 PR( <data> | xpaset [-h] [-i nsinet] [-m method] [-n] [-p] [-s] [-t sval,lval] [-u users] [-v] <template> [paramlist] + + xpaget [-h] [-i nsinet] [-m method] [-s] [-t sval,lval] [-u users] <template> [paramlist] + + xpainfo [-h] [-i nsinet] [-m method] [-n] [-s] [-t sval,lval] [-u users] <template> [paramlist] + + xpaaccess [-c] [-h] [-i nsinet] [-m method] [-n] [-u users] [-v|-V] <template> [type])RP( + + + + +)0 2 33 H(xpaset:)WB 88 Sn()WB 10 Sn( send data to one or more XPA servers)EA()EH( + + +)BD() 1 124 PR(<data> | xpaset [-h] [-i nsinet] [-m method] [-n] [-p] [-s] [-t sval,lval] [-u users] [-v] <template|host:port> [paramlist])RP()ES( + + +)0 P() 10 79 PR( -h print help message + -i access XPA point on different machine \201override XPA_NSINET\202 + -m override XPA_METHOD environment variable + -n don't wait for the status message after server completes + -p don't read \201or send\202 buf data from stdin + -s enter server mode + -t [s,l] set short and long timeouts \201override XPA_[SHORT,LONG]_TIMEOUT\202 + -u [users] XPA points can be from specified users \201override XPA_NSUSERS\202 + -v verify message to stdout + --version display version and exit)RP( + + +)0 P(Data read from stdin will be sent to access points matching the +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +or host:port. +A set of qualifying parameters can be appended. +)0 P(Normally, xpaset reads data input from stdin until EOF and sends those +data to the XPA target, along with parameters entered on the command +line. For example to send a FITS file to the ds9 image display: +) 1 32 PR( cat foo.fits | xpaset ds9 fits)RP( +)0 P(Sometimes, however, it is desirable to send only parameters to an XPA +access point, without sending data. For such cases, use the -p switch to +indicate that there is no data being send to stdin. For example, to +change the colormap used by the ds9 image display program, use: +) 1 30 PR( csh> xpaset -p ds9 cmap Heat)RP( +Of course, this also can be accomplished by sending EOF to stdin in +any of the usual ways: +) 4 43 PR( csh> echo "" | xpaset ds9 cmap Heat + csh> xpaget ds9 cmap Heat < /dev/null + csh> xpaset ds9 cmap Heat + ^D # Ctl-D signals EOF)RP( +)0 P(The -s switch puts xpaset into server mode, in which commands and data +can be sent to access points without having to run xpaset multiple times. +\201Its not clear if this buys you much!\202 The syntax for sending commands +in server mode is: +)0 P() 8 24 PR( csh> xpaset -s + xpaset ds9 colormap I8 + ^D + xpaset ds9 regions + circle 200 300 40 + circle 300 400 50 + ^D +etc.)RP( +After the required "xpaset" command is specified, optional ASCII data +can be appended \201as in the region example\202. A single data/command set is +delimited by ^D. Note that typing ^D when a command is expected terminates +the program. +)0 P(NB: server mode only works from the terminal and only ASCII data can be +sent in this way. +)0 P()BD(Examples:)ES( +) 2 40 PR( csh> xpaset ds9 file < foo.fits + csh> echo "stop" | xpaset myhost:12345)RP( + + + + +)0 2 34 H(xpaget:)WB 89 Sn()WB 9 Sn( retrieve data from one or more XPA servers)EA()EH( + + +)BD() 1 99 PR(xpaget [-h] [-i nsinet] [-m method] [-s] [-t sval,lval] [-u users] <template|host:port> [paramlist])RP()ES( + + +)0 P() 8 79 PR( -h print help message + -i access XPA point on different machine \201override XPA_NSINET\202 + -m override XPA_METHOD environment variable + -n don't wait for the status message after server completes + -s enter server mode + -t [s,l] set short and long timeouts \201override XPA_[SHORT,LONG]_TIMEOUT\202 + -u [users] XPA points can be from specified users \201override XPA_NSUSERS\202 + --version display version and exit)RP( + + +)0 P(Data will be retrieved from access points matching the +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +or host:port. +A set of qualifying parameters can be appended. +)0 P()BD(Examples:)ES( +) 2 38 PR( csh> xpaget ds9 images + csh> xpaget myhost.harvard.edu:12345)RP( + + + + +)0 2 35 H(xpainfo:)WB 90 Sn()WB 11 Sn( send short message to one or more XPA servers)EA()EH( + + +)BD() 1 105 PR(xpainfo [-h] [-i nsinet] [-m method] [-n] [-s] [-t sval,lval] [-u users] <template|host:port> [paramlist])RP()ES( + + +)0 P() 8 79 PR( -h print help message + -i access XPA point on different machine \201override XPA_NSINET\202 + -m override XPA_METHOD environment variable + -n don't wait for the status message after server completes + -s enter server mode + -t [s,l] set short and long timeouts \201override XPA_[SHORT,LONG]_TIMEOUT\202 + -u [users] XPA points can be from specified users \201override XPA_NSUSERS\202 + --version display version and exit)RP( + + +)0 P(Info will be sent to access points matching the +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +or host:port. +A set of qualifying parameters can be appended. +)0 P()BD(Examples:)ES( +) 1 30 PR( csh> xpainfo IMAGE ds9 image)RP( + + + + +)0 2 36 H(xpaaccess:)WB 91 Sn()WB 12 Sn( see if template matches registered XPA access points)EA()EH( + + +)BD() 1 95 PR(xpaaccess [-c] [-h] [-i nsinet] [-m method] [-n] [-t sval,lval] [-u users] -v <template> [type])RP()ES( + + +)0 P() 10 79 PR( -c contact each access point individually + -h print help message + -i access XPA point on different machine \201override XPA_NSINET\202 + -m override XPA_METHOD environment variable + -n return number of matches instead of "yes" or "no" + -t [s,l] set short and long timeouts \201override XPA_[SHORT,LONG]_TIMEOUT\202 + -u [users] XPA points can be from specified users \201override XPA_NSUSERS\202 + -v print info about each successful access point + -V print info or error about each access point + --version display version and exit)RP( + + +)0 P(xpaaccess returns "yes" to stdout \201with a return error code if 1\202 if there are +existing XPA access points that match the +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +\201and optional access type: g,i,s\202. Otherwise, it returns "no" \201with a +return error code of 0\202. If -n is specified, the number of matches is +returned instead \201both to stdout and in the returned error code\202. If +-v is specified, each access point is displayed to stdout instead of +the number of matches. + +)0 P(By default, xpaaccess simply contacts the xpans name server to find +the list of registered access points that match the specified +template. It also checks to make sure the specified types are +supported by that access point. This is the fastest way to determine +available access points. However, an access point might registered but +not yet available, if, for example, the server program has not entered +its event loop to process XPA requests. To find access points that are +guaranteed to be available for processing, use the -c \201contact\202 +switch. With this switch, xpaaccess contacts each matching XPA server +\201rather than the name server\202 to make sure the registered access point +really is ready for processing. In this mode, if an access point is +registered but not available, xpaaccess will pause for a period of +time equal to the XPA_LONG_TIMEOUT, in order to give the server a +chance to ready itself. By default, this timeout is 30 seconds. You +can shorten the time of delay using the -t "short,long" switch. For +example, to shorten the delay time to 2 seconds, use: +) 1 27 PR( xpaaccess -c -t "2,2" ds9)RP( +The first argument is the short delay value, and is ignored in this +operation. The second is the long delay timeout. + +)0 P(Note also that the default xpaaccess method \201no -c switch\202 does not +check access control \201acls\202 but rather only checks whether the access +point is both registered with the xpans name server and provides the +specified type of access. In other words, the default xpaaccess could +return 'yes' when you might not actually have access. This mode also +always returns 'yes' for the xpans name server itself, regardless of +whether the name server is active. The -c \201contact\202 switch, which +contacts the access point directly, can and does check the access +control \201only for servers using version 2.1 and above\202 and also +returns the real status of xpans. + + + + + + + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 37 H(Last)WB 92 Sn( updated: September 10, 2003)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (xpamb.html) D +/Ti (The XPA Message Bus \201xpamb\202) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 13 Sn( + + +)0 2 38 H(xpamb:)WB 94 Sn()WB 93 Sn( the XPA Message Bus)EA()EH( + + +)0 2 39 H(Summary)WB 95 Sn()EH( +)0 P(The xpamb program can act as a "classical" message bus interface +between clients and servers. A client can send a data request to +the message bus, which then interfaces with multiple servers and +returns the data back to the client. + + +)0 2 40 H(Description)WB 96 Sn()EH( +)0 P(A "classical" message bus \201such as ToolTalk\202 consists of servers and +clients, along with a mediating program that transfers data between +different processes. XPA takes a slightly different approach in that +communication between clients and servers is direct. This generally +is the correct technique when there is only one connection \201or even a +small number of connections\202, but can become inefficient for the +serving program if a large amount of data is being transferred to many +clients. For example, if a real-time data acquisition program is +broadcasting a FITS image to several clients, it would need to +transmit that image to each client individually. This might interfere +with its own processing cycles. The preferable mechanism would be to +pass the image off to an intermediate program that can then broadcast +the data to the several clients. +)0 P(The )BD(xpamb)ES( program can alleviate such problems by functioning +as a message bus in cases where such an intermediary process is +wanted. It pre-defines a single access point named +)BD(XPAMB:xpamb)ES( to which data can be sent for re-broadcast. You +also can tell )BD(xpamb)ES( to save the data, and associate with that +data a new access point, so that it can be retrieved later on. + +)0 P(All interaction with )BD(xpamb)ES( is performed through +)BD(xpaset)ES( and )BD(xpaget)ES( \201or the corresponding API +routines, )BD(XPASet\201\202)ES( and )BD(XPAGet\201\202)ES(\202 to the +)BD(XPAMB:xpamb)ES( access point. That is, )BD(xpamb)ES( is just +another XPA-enabled program that responds to requests from +clients. The paramlist is used to specify the targets to which +the data will be for re-broadcast, as well as the re-broadcast paramlist: +) 1 69 PR( data | xpaset xpamb [switches] broadcast-target broadcast-paramlist)RP( +Optional switches are used to store data, and manipulate stored data, +and are described below. + +)0 P(In its simplest form, you can, for example, send a FITS image to xpamb for +broadcasting to all ds9 image simply by executing: +) 1 51 PR( cat foo.fits | xpaset xpamb "DS9:*" fits foo.fits)RP( +Since )BD(DS9)ES( is the class name for the ds9 image display +program, this will result in the FITS image being re-sent to all fits +access points for all active image display programs. + +)0 P(You can send stored data and new data to the same set of access points at +the same time. The stored data always is send first, followed by the new +data: +) 1 62 PR( cat foo2.fits | xpaset xpamb -send foo "DS9:*" fits foo.fits)RP( +will first send the foo.fits file, and then the foo2.fits file to all +access points of class )BD(DS9)ES(. Notice that in this example, +the foo2.fits file is not stored, but it could be stored by using the +)BD(-store [name])ES( switch on the command line. + +)0 P(The )BD(xpaget)ES( command can be used to retrieve a data from XPA +access points or from a stored data buffer, or retrieve information +about a stored data buffer. If no arguments are given: +) 1 14 PR( xpaget xpamb)RP( +then information about all currently stored data buffers is returned. This +information includes the data and time at which the data was stored, the +size in bytes of the data, and the supplied info string. + +)0 P(If arguments are specified, they will be in the form: +) 1 49 PR( xpaget xpamb [-info] [-data] [name [paramlist]])RP( +If the optional )BD(-info)ES( and/or )BD(-data)ES( switches are specified, then +information and/or data will be returned for the named data buffer +following the switches. You can use either or both of these switches +in a single command. For example, if the -info switch is used: +) 1 24 PR( xpaget xpamb -info foo)RP( +then the info about that stored data buffer will be returned. +If the -data is used with a specific name: +) 1 24 PR( xpaget xpamb -data foo)RP( +then the stored data itself will be returned. If both are used: +) 1 30 PR( xpaget xpamb -info -data foo)RP( +then the info will be returned, followed by the data. Note that it is an +error to specify one of these switches without a data buffer name and that +the paramlist will be ignored. + +)0 P(If neither the )BD(-info)ES( or )BD(-data)ES( switch is specified, then +the name refers to an XPA access point \201with an optional paramlist +following\202. +For example: +) 1 23 PR( xpaget xpamb ds9 file)RP( +is equivalent to: +) 1 17 PR( xpaget ds9 file)RP( + + +)0 2 41 H(Options)WB 97 Sn()EH( +)0 P(For xpaset, several optional switches are used to save data and +manipulate the stored data: +)0 DL( +)0 P()0 DT()BD(-data [name])ES( +)DD( Add the supplied data buffer to a pool of stored data buffers, +using the specified name as a unique identifier for later retrieval. +An error occurs if the name already exists \201use either )BD(replace)ES( +or )BD(del)ES( to rectify this\202. The )BD(-add)ES( switch is supported +for backwards compatibility with xpa 2.0. + +)0 P()0 DT()BD(-replace [name])ES( +)DD( Replace previously existing stored data having the same unique name +with new data. This essentially is a combination of the )BD(del)ES( +and )BD(data)ES( commands. + +)0 P()0 DT()BD(-info ["'info string'"])ES( +)DD( When adding a data buffer, you can specify an informational +string to be stored with that data. This string will be returned +by xpaget: +) 1 24 PR( xpaget xpamb foo -info)RP( +\201along with other information such as the date/time of storage and the size of +the data buffer\202 if the -info switch is specified. If the info string contains +spaces, you must enclose it in )BD(two)ES( sets of quotes: +) 1 65 PR( cat foo | xpaset xpamb -store foo -info "'this is info on foo'")RP( +The first set of quotes is removed by the shell while the second is used to +delineate the info string. + +)0 P()0 DT()BD(-send [name])ES( +)DD( Broadcast the stored data buffer to the named template. + +)0 P()0 DT()BD(-del [name])ES( +)DD( Delete the named data buffer and free all allocated space.)LD( + +)0 P(Switches can be used in any combination that makes sense. For example: +) 1 75 PR( cat foo.fits | xpaset xpamb -store foo -info "FITS" "DS9:*" fits foo.fits)RP( +will broadcast the foo.fits image to all access points of class +)BD(DS9)ES(. In addition, the foo.fits file will be stored under the +name of )BD(foo)ES( for later manipulation such as: +) 1 49 PR( xpaset -p xpamb -send foo "DS9:*" fits foo.fits)RP( +will re-broadcast the foo.fits image to all access points of class "DS9". + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 42 H(Last)WB 98 Sn( updated: September 10, 2003)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (xpans.html) D +/Ti (The XPA Name Server \201xpans\202) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 14 Sn( + + +)0 2 43 H(xpans:)WB 100 Sn()WB 99 Sn( the XPA Name Server)EA()EH( + + +)0 2 44 H(Summary)WB 101 Sn()EH( +) 1 70 PR( xpans [-h] [-e] [-k sec] [-p port] [-l log] [-s security log] [-P n])RP( + + +)0 P() 8 71 PR( -h print help message + -e exit when there are no more XPA connections + -k send keepalive messages every n sec + -l log data base entries to specified file + -p listen for connections on specified port + -s log security info for each connection to specified file + -P accept proxy requests \201P=1\202 using separate thread \201P=2\202 + --version display version and exit)RP( + + +)0 P(The xpans name server is an XPA-enabled program that is used to +manage the names and ports of XPA access points. It is started +automatically when an XPA access point is registered. You can access +the name server using xpaget to get a list of registered access points. +)0 P(The )EM(xpans)ES( name server provides a crucial link between XPA +clients and servers. When an XPA server defines an access point using +XPANew\201\202, XPACmdNew\201\202, or XPAInfoNew\201\202, the name of the access point +is registered in the name service, along with connection information. +The name server then matches class:name templates passed to it by XPA +clients with these registered entries, so that the clients can +communicate with the appropriate servers. + +)0 P(The socket connection between an XPA-enabled program and +)EM(xpans)ES( is kept open until the former exits \201or explicitly +closes the connection\202. Apparently, some Internet equipment \201e.g. DSL +modems\202 can cause such a connection to time-out after a period of +inactivity. To prevent this from happening, you can use the )EM(-k +[sec])ES( switch to send a short keep-alive message to each open +connection after the specified time delay. \201Note that this +application level use of keep-alive is necessary only if you are +serving XPA-enabled clients over the Internet and have to deal with +long-term connections involving DSL or similar equipment. XPA uses +the ordinary socket-level keep-alive, which works for all other cases.\202 +)BD(NB \20112/2/2009\202: Out-of-band \201URG\202 TCP data, used by xpans +keep-alive, is changed by some Cisco routers into in-band data. +Encountering such a router will break the keep-alive function and may +break your XPA server as well. Proceed with caution!)ES( + +)0 P(The )EM(xpans)ES( program will be started automatically \201assuming it +can be found in the user's path\202 when the first XPA access point is +registered. It therefore need not be started explicitly. However, +when started automatically, the )EM(-e)ES( switch is used, so that +the name server will exit when there are no more XPA access points +registered. If you wish to keep the name server running continually, +simply start it manually without the )EM(-e)ES( switch. + +)0 P(The name server will keep a log of registered access points if the +)EM(-l [log])ES( switch is used on the command line \201this is the +case for automatic start-up\202. The log contains enough name and connection +information to allow you to re-register all XPA access points in case +the name server process is terminated prematurely. For example, after +the ds9 access point is registered,the log will contain the entry: +) 1 35 PR( add 838e2f67:1863 ds9 ds9 gs eric)RP( +If )EM(xpans)ES( is terminated but ds9 still is running, you +can re-register both access points for the ds9 process by running: +) 1 36 PR( xpaset -p 838e2f67:1863 -nsconnect)RP( +Notice that the ip:port specifier is used with )EM(xpaset)ES( to bypass +the need for contacting the name server \201which does not have the name +registered yet!\202 + +)0 P(The name server will keep a log of security information if the )EM(-s +[security log])ES( switch is used on the command line. For each +accepted connection, \201including connections via the )EM(xpaget)ES( +command\202, information will be logged about the host issuing the +command and the parameters passed into the program. This is most +useful when )EM(xpans)ES( is accepting connections from untrusted +machines. + +)0 P(When an XPA access point is removed by a server using )EM(XPAFree\201\202)ES(, +the access information is removed from the name server. If an +XPA-enabled process is terminated, all names registered by that process +will be removed automatically. The log file is always updated to +reflect the currently registered access points. + +)0 P(The name server itself has an XPA access point names )EM(xpans)ES( +registered through which you can find out information about currently +registered access points \201assuming you have access to the name server; +see )0 41 1 A(XPA Access Control)41 0 TN TL()Ec /AF f D( for more information\202. +For each registered access point, the following information is returned: +) 5 80 PR( class # class of the access point + name # name of the access point + access # allowed access \201g=xpaget,s=xpaset,i=xpainfo\202 + id # socket access method \201host:port for inet, file for local/unix\202 + user # user name of access point owner)RP( + +)0 P(For example, to display all currently registered access points, simply execute: +) 1 14 PR( xpaget xpans)RP( +Continuing the example of ds9 above, this will return: +) 1 31 PR( DS9 ds9 gs 838e2f67:1863 eric)RP( +If the same program has been started with different XPA access names, +you can look up only names matching a specified template. For example, +assume that ds9 has been started up using: +) 3 25 PR( ds9 & + ds9 -title ds9-1-eric & + ds9 -title ds9-2-eric &)RP( +To lookup all ds9 access points which end in ".eric" and which can +be accessed using )EM(xpaset)ES(, use: +) 1 35 PR( xpaget xpans "DS9:*.eric" "s" "*")RP( +This will return: +) 2 39 PR( DS9 ds9-2-eric gs 838e29d3:42102 eric + DS9 ds9-1-eric gs 838e29d3:42105 eric)RP( +The third argument "*" requests all access points from all users. +You also can specify a specific user name and only access points +registered by that user will be returned. + +)0 P(The name server uses the )EM(XPA_METHOD)ES( environment variable +to determine whether it should listen for requests on INET or LOCAL +sockets. Since XPA access points also use this environment variable, +the choice of socket method will be consistent. Note that, when INET +sockets are used, a local server can be accessed from remote machines +if the )EM(XPA_NSINET)ES( environment variable is set to point to +the local machine. See +)0 40 1 A(XPA Environment Variables)40 0 TN TL()Ec /AF f D( +for more information. + +)0 P(An experimental feature of xpans is its ability to act as a proxy to +XPA servers behind firewalls that want to communicate with external +processes. The basic idea is the following: an XPA server \201call it +"foo"\202 on host1, possibly behind a firewall, makes a remote connection +to a proxy-enabled xpans program on host2 \201specifying host2's XPA method\202. +For example: +) 1 59 PR( xpaset -p foo -remote 'host2:28571' + -proxy # on host1)RP( +When this is done, host2 can use xpaset, xpaget, and xpainfo calls to +communicate with the XPA server foo. All command communication is +performed via the xpans socket connection between foo on host1 and +xpans on host2 \201which was initiated by foo from inside the firewall\202. +Data communication is similarly performed using a socket connection +initiated on host1 \201usually with a port value two greater than the +port value of the main xpans socket connection\202. An xpaset or xpaget +call on host2 contacts xpans, which performs an XPASet\201\202 or XPAGet\201\202 +call to foo, passing commands and data back and forth between the two +programs. + +)0 P(By default, proxy connections are not allowed by xpans. If the -P switch is +specified with a value of 1, proxy connection are allowed, but all proxy +communication is performed in the same thread as xpans processing. If +a value of 2 is specified, the proxy processing is performed in a +separate thread \201assuming pthreads are supported on your system\202. +Because xpa callback processing of any type can take a long time and +therefore can interfere with normal xpans processing, threaded proxy +connections \201-P 2\202 are recommended. When using proxy connections, it +might also be useful to set the XPA_IOCALLSXPA environment variable, so +that multiple proxy requests can be handled at the same time, instead of +serially. + +)0 P(Note that this proxy interface to xpans is experimental. It is used +to provide remote data analysis capabilities on the Chandra-Ed system +using ds9. \201See http://chandra-ed.cfa.harvard.edu and +http://hea-www.harvard.edu/saord/ds9 for more details\202. As always, please +contact us if you have problems or questions. + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 45 H(Last)WB 102 Sn( updated: January 24, 2005)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (server.html) D +/Ti (XPA Server API) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 15 Sn( + + +)0 2 46 H(XPAServer:)WB 106 Sn()WB 103 Sn( The XPA Server-side Programming Interface)EA()EH( + + +)0 2 47 H(Summary)WB 107 Sn()EH( +A description of the XPA server-side programming interface. + + +)0 2 48 H(Introduction)WB 108 Sn()WB 104 Sn( to XPA Server Programming)EH()EA( +)0 P(Creating an XPA server is easy: you generally only need to call the +XPANew\201\202 subroutine to define a named XPA access point and set up the +send and receive callback routines. You then enter an event loop such +as XPAMainLoop\201\202 to field XPA requests. +) 27 66 PR( #include <xpa.h> + + XPA )0 16 1 A(XPANew)16 0 TN TL()Ec /AF f D(\201char *class, char *name, char *help, + int \201*send_callback\202\201\202, void *send_data, char *send_mode, + int \201*rec_callback\202\201\202, void *rec_data, char *rec_mode\202; + + XPA )0 17 1 A(XPACmdNew)17 0 TN TL()Ec /AF f D(\201char *class, char *name\202; + + XPACmd )0 18 1 A(XPACmdAdd)18 0 TN TL()Ec /AF f D(\201XPA xpa, + char *name, char *help, + int \201*send_callback\202\201\202, void *send_data, char *send_mode, + int \201*rec_callback\202\201\202, void *rec_data, char *rec_mode\202; + + void )0 19 1 A(XPACmdDel)19 0 TN TL()Ec /AF f D(\201XPA xpa, XPACmd cmd\202; + + XPA )0 20 1 A(XPAInfoNew)20 0 TN TL()Ec /AF f D(\201char *class, char *name, + int \201*info_callback\202\201\202, void *info_data, char *info_mode\202; + + int )0 21 1 A(XPAFree)21 0 TN TL()Ec /AF f D(\201XPA xpa\202; + + void )0 22 1 A(XPAMainLoop)22 0 TN TL()Ec /AF f D(\201void\202; + + int )0 23 1 A(XPAPoll)23 0 TN TL()Ec /AF f D(\201int msec, int maxreq\202; + + void )0 105 1 A(XPAAtExit)105 0 TN TL()Ec /AF f D(\201void\202; + + void )0 24 1 A(XPACleanup)24 0 TN TL()Ec /AF f D(\201void\202;)RP( + +)0 2 49 H(Introduction)WB 109 Sn()EH( + +To use the XPA application programming interface, a software developer +generally will include the xpa.h definitions file: +) 1 18 PR( #include <xpa.h>)RP( +in the software module that defines or accesses an XPA access point, and +then will link against the libxpa.a library: +) 1 27 PR( gcc -o foo foo.c libxpa.a)RP( +XPA has been compiled using both C and C++ compilers. + +)0 P(A server program generally defines an XPA access point by calling the +XPANew\201\202 routine and specifies "send" and/or "receive" callback +procedures to be executed by the program when an external process +either sends data or commands to this access point or requests data or +information from this access point. A program also can define several +sub-commands for a single access point by calling XPACmdNew\201\202 and +XPACmdAdd\201\202 instead. Having defined one or more public access points +in this way, an XPA server program enters its usual event loop \201or +uses the standard XPA event loop\202. + + + + +)0 2 50 H(XPANew:)WB 110 Sn()WB 16 Sn( create a new XPA access point)EA()EH( + + +)BD() 7 49 PR( #include <xpa.h> + + XPA XPANew\201char *class, char *name, char *help, + int \201*send_callback\202\201\202, + void *send_data, char *send_mode, + int \201*rec_callback\202\201\202, + void *rec_data, char *rec_mode\202;)RP()ES( + + +)0 P(Create a new XPA public access point with the class:name +identifier )0 3 1 A(template)3 0 TN TL()Ec /AF f D( +and enter this access point into the XPA name server, so that it +can be accessed by external processes. XPANew\201\202 returns an XPA struct. +Note that the length of the class and name designations must be less +than or equal to 1024 characters each. + +)0 P(The XPA name server daemon, xpans, will be started automatically if it +is not running already \201assuming it can be found in the path\202. The +program's ip address and listening port are specified by the +environment variable XPA_NSINET, which takes the form :. If +no such environment variable exists, then xpans is started on the +current machine listening on port 14285. It also uses 14286 as a +known port for its public access point \201so that routines do not have +to go to the name server to find the name server ip and port!\202 +As of XPA 2.1.1, version information is exchanged between the xpans +process and the new access point. If the access point uses an XPA +major/minor version newer than xpans, a warning is issued by both processes, +since mixing of new servers and old xpa programs \201xpaset, xpaget, +xpans, etc.\202 is not likely to work. You can turn off the warning +message by setting the XPA_VERSIONCHECK environment variable to "false". + +)0 P(The help string is meant to be returned by a request from xpaget: +) 1 25 PR( xpaget class:name -help)RP( +)0 P(A send_callback and/or a receive_callback can be specified; at +least one of them must be specified. + +)0 P(A send_callback can be specified that will be executed in response to +an external request from the xpaget program, the XPAGet\201\202 routine, or +XPAGetFd\201\202 routine. This callback is used to send data to the +requesting client. + +)0 P(The calling sequence for send_callback\201\202 is: +) 7 53 PR( int send_callback\201void *send_data, void *call_data, + char *paramlist, char **buf, size_t *len\202 + { + XPA xpa = \201XPA\202call_data; + ... + return\201stat\202; + })RP( +)0 P(The send_mode string is of the form: "key1=value1,key2=value2,..." +The following keywords are recognized: +) 4 81 PR( key value default explanation + ------ -------- -------- ----------- + acl true/false true enable access control + freebuf true/false true free buf after callback completes)RP( +)0 P(The call_data should be recast to the XPA struct as shown. In +addition, client-specific data can be passed to the callback in +send_data. + +)0 P(The paramlist will be supplied by the client as qualifying parameters +for the callback. There are two ways in which the send_callback\201\202 +routine can send data back to the client: + +)0 P(1. The send_callback\201\202 routine can fill in a buffer and pass back a +pointer to this buffer. An integer len also is returned to specify the +number of bytes of data in buf. XPA will send this buffer to the +client after the callback is complete. + +)0 P(2. The send_callback can send data directly to the client by writing +to the fd pointed by the macro: +) 1 17 PR( xpa_datafd\201xpa\202)RP( +)0 P(Note that this fd is of the kind returned by socket\201\202 or open\201\202. + +)0 P(If a buf has been allocated by a standard malloc routine, filled, and +returned to XPA, then freebuf generally is set so that the buffer will +be freed automatically when the callback is completed and data has +been sent to the client. If a static buf is returned, freebuf should +be set to false to avoid a system error when freeing static storage. +Note that default value for freebuf implies that the callback will +allocate a buffer rather than use static storage. + +)0 P(On the other hand, if buf is dynamically allocated using a method +other than a standard malloc/calloc/realloc routine \201e.g. using Perl's +memory allocation and garbage collection scheme\202, then it is necessary +to tell XPA how to free the allocated buffer. To do this, use the +XPASetFree\201\202 routine within your callback: +) 1 69 PR( void XPASetFree\201XPA xpa, void \201*myfree\202\201void *\202, void *myfree_ptr\202;)RP( +The first argument is the usual XPA handle. The second argument is the +special routine to call to free your allocated memory. The third +argument is an optional pointer. If not NULL, the specified free +routine is called with that pointer as its sole argument. If NULL, the +free routine is called with the standard buf pointer as its sole +argument. This is useful in cases where there is a mapping between the +buffer pointer and the actual allocated memory location, and the +special routine is expecting to be passed the former. + +)0 P(If, while the callback performs its processing, an error occurs that +should be communicated to the client, then the routine XPAError should be +called: +) 1 29 PR( XPAError\201XPA xpa, char *s\202;)RP( +)0 P(where s is an arbitrary error message. The returned error message +string will be of the form: +) 1 42 PR( XPA$ERROR [error] \201class:name ip:port\202)RP( +)0 P(If the callback wants to send a specific acknowledgment message back +to the client, the routine XPAMessage can be called: +) 1 31 PR( XPAMessage\201XPA xpa, char *s\202;)RP( +)0 P(where s is an arbitrary error message. The returned error message +string will be of the form: +) 1 44 PR( XPA$MESSAGE [message] \201class:name ip:port\202)RP( +)0 P(Otherwise, a standard acknowledgment is sent back to the client +after the callback is completed. + +)0 P(The callback routine should return 0 if no error occurs, or -1 to +signal an error. + +)0 P(A receive_callback can be specified that will be executed in response +to an external request from the xpaset program, or the XPASet \201or +XPASetFd\201\202\202 routine. This callback is used to process data received +from an external process. + +)0 P(The calling sequence for receive_callback is: +) 7 59 PR( int receive_callback\201void *receive_data, void *call_data, + char *paramlist, char *buf, size_t len\202 + { + XPA xpa = \201XPA\202call_data; + ... + return\201stat\202; + })RP( +)0 P(The mode string is of the form: "key1=value1,key2=value2,..." +The following keywords are recognized: +) 6 92 PR( key value default explanation + ------ -------- -------- ----------- + acl true/false true enable access control + buf true/false true server expects data bytes from client + fillbuf true/false true read data into buf before executing callback + freebuf true/false true free buf after callback completes)RP( +)0 P(The call_data should be recast to the XPA struct as shown. In +addition, client-specific data can be passed to the callback in +receive_data. + +)0 P(The paramlist will be supplied by the client. In addition, if the +receive_mode keywords buf and fillbuf are true, then on entry into the +receive_callback\201\202 routine, buf will contain the data sent by the +client. If buf is true but fillbuf is false, it becomes the callback's +responsibility to retrieve the data from the client, using the data fd +pointed to by the macro xpa_datafd\201xpa\202. If freebuf is true, then buf +will be freed when the callback is complete. + +)0 P(If, while the callback is performing its processing, an error occurs +that should be communicated to the client, then the routine XPAError +can be called: +) 1 29 PR( XPAError\201XPA xpa, char *s\202;)RP( +)0 P(where s is an arbitrary error message. + +)0 P(The callback routine should return 0 if no error occurs, or -1 to +signal an error. + + + + +)0 2 51 H(XPACmdNew:)WB 111 Sn()WB 17 Sn( create a new XPA public access point for commands)EA()EH( + + +)BD() 3 41 PR( #include <xpa.h> + + XPA XPACmdNew\201char *class, char *name\202;)RP()ES( + + +)0 P(Create a new XPA public access point for commands that will share a +common identifier class:name. Enter this access point into the XPA +name server, so that it can be accessed by external processes. +XPACmdNew\201\202 returns an XPA struct. + +)0 P(It often is more convenient to have one public access point that can +manage a number of commands, rather than having individual access +points for each command. For example, it is easier to command the +ds9 image display using: +) 3 35 PR( echo "colormap I8" | xpaset ds9 + echo "scale log" | xpaset ds9 + echo "file foo.fits" | xpaset ds9)RP( +)0 P(then to use: +) 3 39 PR( echo "I8" | xpaset ds9_colormap + echo "log" | xpaset ds9_scale + echo "foo.fits" | xpaset ds9_file)RP( +)0 P(In the first case, the commands remain the same regardless of the +target XPA name. In the second case, the command names must change +for each instance of ds9. That is, if a second instance of ds9 +called DS9 were running, it would be commanded either as: +) 3 35 PR( echo "colormap I8" | xpaset DS9 + echo "scale log" | xpaset DS9 + echo "file foo.fits" | xpaset DS9)RP( +)0 P(or as: +) 3 39 PR( echo "I8" | xpaset DS9_colormap + echo "log" | xpaset DS9_scale + echo "foo.fits" | xpaset DS9_file)RP( +)0 P(Thus, in cases where a program is going to manage many commands, it +generally is easier to define them as commands associated with the +XPACmdNew\201\202 routine, rather than as separate access points using +XPANew\201\202. + +)0 P(When XPACmdNew\201\202 is called, only the class:name identifier is +specified. Each sub-command is subsequently defined using the +XPACmdAdd\201\202 routine. + + + + +)0 2 52 H(XPACmdAdd:)WB 112 Sn()WB 18 Sn( add a command to an XPA command public access point)EA()EH( + + +)BD() 7 52 PR( #include <xpa.h> + + XPACmd XPACmdAdd\201XPA xpa, char *name, char *help, + int \201*send_callback\202\201\202, + void *send_data, char *send_mode, + int \201*rec_callback\202\201\202, + void *rec_data, char *rec_mode\202;)RP()ES( + + +)0 P(Add a command to an XPA command access point. The XPA argument specifies the +XPA struct returned by a call to XPANewCmd\201\202. The name argument is the +name of the command. The other arguments function identically to the +arguments in the XPANew\201\202 command, i.e., the send_callback and rec_callback +routines have identical calling sequences to their XPANew\201\202 counterparts, +with the exceptions noted below. + +)0 P(When help is requested for a command access point using: +) 1 22 PR( xpaget -h class:name)RP( +)0 P(all of the command help strings are listed. To get help for a given +command, use: +) 1 26 PR( xpaget -h class:name cmd)RP( +)0 P(Also, the acl keyword in the send_mode and receive_mode strings is +global to the access point, not local to the command. Thus, the value +for the acl mode should be the same in all send_mode \201or receive_mode\202 +strings for each command in a command access point. \201The acl for +send_mode need not be the same as the acl for receive_mode, though\202. + + + + +)0 2 53 H(XPACmdDel:)WB 113 Sn()WB 19 Sn( remove a command from an XPA command public access point)EA()EH( + + +)BD() 3 38 PR( #include <xpa.h> + + void XPACmdDel\201XPA xpa, XPACmd cmd\202;)RP()ES( + + +)0 P(This routine removes a command from the list of available commands in +a given XPA. That command will no longer be available for processing. + + + + +)0 2 54 H(XPAInfoNew:)WB 114 Sn()WB 20 Sn( define an XPA info public access point)EA()EH( + + +)BD() 5 51 PR( #include <xpa.h> + + XPA XPAInfoNew\201char *class, char *name, + int \201*info_callback\202\201\202, + void *info_data, char *info_mode\202;)RP()ES( + + +)0 P([NB: this is an experimental interface, new to XPA 2.0, whose value +and best use is evolving.] + +)0 P(A program can register interest in receiving a short message about a +particular topic from any other process that cares to send such a +message. Neither has to be an XPA server. For example, if a user +starts to work with a new image file called new.fits, she might +wish to alert interested programs about this new file by sending a +short message using xpainfo: +) 1 34 PR( xpainfo IMAGEFILE /data/new.fits)RP( + +)0 P(In this example, each process that has used the XPAInfoNew\201\202 call to +register interest in messages associated with the identifier IMAGEFILE +will have its info_callback\201\202 executed with the following calling +sequence: +) 4 64 PR( int info_cb\201void *info_data, void *call_data, char *paramlist\202 + { + XPA xpa = \201XPA\202call_data; + })RP( +)0 P(The arguments passed to this routine are equivalent to those sent in +the send_callback\201\202 routine. The main difference is that there is no +buf sent to the info callback: this mechanism is meant for short +announcement of messages of interest to many clients. + +)0 P(The mode string is of the form: "key1=value1,key2=value2,..." +The following keywords are recognized: +) 3 69 PR( key value default explanation + ------ -------- -------- ----------- + acl true/false true enable access control)RP( +)0 P(Because no buf is passed to this callback, the usual buf-related keywords +are not applicable here. + +)0 P(The information sent in the parameter list is arbitrary. However, we +envision sending information such as file names or XPA access points +from which to collect more data. Note that the xpainfo program and +the XPAInfo\201\202 routine that cause the info_callback to execute do not +wait for the callback to complete before returning. + + + + +)0 2 55 H(XPAFree:)WB 115 Sn()WB 21 Sn( remove an XPA public access point)EA()EH( + + +) 3 23 PR()BD( #include <xpa.h> + + int XPAFree\201XPA xpa\202;)ES()RP( + + +)0 P(Remove the specified XPA public access point from the name server and +free all associated storage. Note that removal from the name server +happens automatically when the process terminates, so this call is not +generally needed. It is used when public access points are being +defined temporarily and then destroyed when no longer needed. For +example, ds9 temporarily creates a public access point when it +loads a new image for display and destroys it when the image is +unloaded. + + + + +)0 2 56 H(XPAMainLoop:)WB 116 Sn()WB 22 Sn( optional main loop for XPA)EA()EH( + + +)BD() 3 21 PR( #include <xpa.h> + + void XPAMainLoop\201\202;)RP()ES( + + +)0 P(Once XPA access points have been defined, a program must enter an +event loop to watch for requests from external programs. This can be +done in a variety of ways, depending on whether the event loop is +processing events other than XPA events. In cases where there are no +non-XPA events to be processed, the program can simply call the +XPAMainLoop\201\202 event loop. This loop is implemented essentially as +follows \201error checking is simplified in this example\202: +) 8 62 PR( FD_ZERO\201&readfds\202; + while\201 XPAAddSelect\201NULL, &readfds\202 \202{ + if\201 sgot = select\201swidth, &readfds, NULL, NULL, NULL\202 >0 \202 + XPAProcessSelect\201&readfds, 0\202; + else + break; + FD_ZERO\201&readfds\202; + })RP( +)0 P(The XPAAddSelect\201\202 routine sets up the select\201\202 readfds variable so +that select\201\202 will wait for I/O on all the active XPA channels. It +returns the number of XPAs that are active; the loop will end when +there are no active XPAs. The standard select\201\202 routine is called to +wait for an external I/O request. Since no timeout struct is passed +in argument 5, the select\201\202 call hangs until there is an external +request. When an external I/O request is made, the XPAProcessSelect\201\202 +routine is executed to process the pending requests. In this routine, +the maxreq value determines how many requests will be processed: if +maxreq <=0, then all currently pending requests will be processed. +Otherwise, up to maxreq requests will be processed. \201The most usual +values for maxreq is 0 to process all requests.\202 + +)0 P(If a program has its own Unix select\201\202 loop, then XPA access points can +be added to it by using a variation of the standard XPAMainLoop: +) 7 39 PR( XPAAddSelect\201xpa, &readfds\202; + [app-specific ...] + if\201 select\201width, &readfds, ...\202 \202{ + XPAProcessSelect\201&readfds, maxreq\202; + [app-specific ...] + FD_ZERO\201&readfds\202; + })RP( +)0 P(XPAAddSelect\201\202 is called before select\201\202 to add the access points. +If the first argument is NULL, then all active XPA access points +are added. Otherwise only the specified access point is added. +After select\201\202 is called, the XPAProcessSelect\201\202 routine can be called +to process XPA requests. Once again, the maxreq value determines how +many requests will be processed: if maxreq <=0, then all currently +pending requests will be processed. Otherwise, up to maxreq requests +will be processed. + +)0 P(XPA access points can be added to +)0 38 1 A(Xt event loops)38 0 TN TL()Ec /AF f D( \201using XtAppMainLoop\201\202\202 +and +)0 39 1 A(Tcl/Tk event loops)39 0 TN TL()Ec /AF f D( \201using vwait and the Tk loop\202. +When using XPA with these event loops, you only need to call: +) 1 44 PR(int XPAXtAddInput\201XtAppContext app, XPA xpa\202)RP( +or +) 1 29 PR( int XPATclAddInput\201XPA xpa\202)RP( +respectively before entering the loop. + + + + +)0 2 57 H(XPAPoll:)WB 117 Sn()WB 23 Sn( execute existing XPA requests)EA()EH( + + +)BD() 3 36 PR( #include <xpa.h> + + int XPAPoll\201int msec, int maxreq\202;)RP()ES( + + +)0 P(It is sometimes desirable to implement a polling loop, i.e., where one +checks for and processes XPA requests without blocking. For this +situation, use the XPAPoll\201\202 routine: +) 1 32 PR( XPAPoll\201int msec, int maxreq\202;)RP( +)0 P(The XPAPoll\201\202 routine will perform XPAAddSelect\201\202 and select\201\202, but with a +timeout specified in millisecs by the msec argument. If one or more +XPA requests are made before the timeout expires, the XPAProcessSelect\201\202 +routine is called to process those requests. The maxreq value determines +how many requests will be processed: if maxreq < 0, then no events are +processed, but instead, the return value indicates the number of events +that are pending. If maxreq == 0, then all currently pending requests +will be processed. Otherwise, up to maxreq requests will be processed. +\201The most usual values for maxreq are 0 to process all requests and 1 +to process one request\202. + + + + +)0 2 58 H(XPAAtExit:)WB 118 Sn()WB 105 Sn( install exit handler)EA()EH( + + +) 3 23 PR()BD( #include <xpa.h> + + void XPAAtExit\201void\202;)ES()RP( + + +)0 P(XPAAtExit\201\202 will install an exit handler using atexit\201\202 to run XPAFree on all +XPA access points. This might be useful in cases where Unix sockets are being +used: if an explicit call to XPAFree\201\202 is not made by the program, the Unix +socket file will not be deleted immediately without an atexit handler. \201NB: this +call should not be made in a Tcl/Tk application. Accessing the Tcl native file +system after Tcl has shut down all file systems causes the Tcl/Tl program to +crash\202. + + + + +)0 2 59 H(XPACleanup:)WB 119 Sn()WB 24 Sn( release reserved XPA memory)EA()EH( + + +) 3 24 PR()BD( #include <xpa.h> + + void XPACleanup\201void\202;)ES()RP( + + +)0 P(When XPA is initialized, it allocates a small amount of memory for the +access control list, temp directory path, and reserved commands. This +memory is found by valgrind to be "still reachable", meaning that "your +program didn't free some memory it could have". Calling the +XPACleanup\201\202 routine before exiting the program will free this memory +and make valgrind happy. + + + + +)0 2 60 H(XPA)WB 120 Sn()WB 25 Sn( Server Callback Macros)EA()EH( + + +)BD() 4 57 PR( #include <xpa.h> + + xpa_class, xpa_name, xpa_method, xpa_cmdfd, xpa_datafd, + xpa_sendian, xpa_cendian)RP()ES( + + +)0 P(Server routines have access to information about the XPA being called via +the following macros \201each of which takes the xpa handle as an argument\202: +) 9 66 PR( macro explanation + ------ ----------- + xpa_class class of this xpa + xpa_name name of this xpa + xpa_method method string \201inet or local connect info\202 + xpa_cmdfd fd of command socket + xpa_datafd fd of data socket + xpa_sendian endian-ness of server \201"little" or "big"\202 + xpa_cendian endian-ness of client \201"little" or "big")RP( +)0 P(The argument to these macros is the call_data pointer that is passed +to the server procedure. This pointer should be type case to XPA +in the server routine: +) 1 27 PR( XPA xpa = \201XPA\202call_data;)RP( + +)0 P(The most important of these macros is xpa_datafd\201\202. A server routine +that sets "fillbuf=false" in receive_mode or send_mode can use this +macro to perform I/O directly to/from the client, rather than using +buf. + +)0 P(The xpa_cendian and xpa_sendian macros can be used together to determine +if the data transferred from the client is byte swapped with respect +to the server. Values for these macros are: "little", "big", or "?". +In order to do a proper conversion, you still need to know the format +of the data \201i.e., byte swapping is dependent on the size of the data +element being converted\202. + + + + +)0 2 61 H(XPA)WB 121 Sn()WB 26 Sn( Race Conditions)EA()EH( + + +Potential XPA race conditions and how to avoid them. + + +)0 P(Currently, there is only one known circumstance in which XPA can get +\201temporarily\202 deadlocked in a race condition: if two or more XPA +servers send messages to one another using an XPA client routine such +as XPASet\201\202, they can deadlock while each waits for the other server +to respond. \201This can happen if the servers call XPAPoll\201\202 with a +time limit, and send messages in between the polling call.\202 The +reason this happens is that both client routines send a string to the +other server to establish the handshake and then wait for the server +response. Since each client is waiting for a response, neither is able +to enter its event-handling loop and respond to the other's +request. This deadlock will continue until one of the timeout periods +expire, at which point an error condition will be triggered and the +timed-out server will return to its event loop. + +)0 P(Starting with version 2.1.6, this rare race condition can be +avoided by setting the XPA_IOCALLSXPA environment variable for servers +that will make client calls. Setting this variable causes all XPA +socket IO calls to process outstanding XPA requests whenever the +primary socket is not ready for IO. This means that a server making a +client call will \201recursively\202 process incoming server requests while +waiting for client completion. It also means that a server callback +routine can handle incoming XPA messages if it makes its own XPA call. +The semi-public routine oldvalue=XPAIOCallsXPA\201newvalue\202 can be used +to turn this behavior off and on temporarily. Passing a 0 will turn +off IO processing, 1 will turn it back on. The old value is returned +by the call. + +)0 P(By default, the XPA_IOCALLSXPA option is turned off, because we judge +that the added code complication and overhead involved will not be +justified by the amount of its use. Moreover, processing XPA requests +within socket IO can lead to non-intuitive results, since incoming +server requests will not necessarily be processed to completion in the +order in which they are received. + +)0 P(Aside from setting XPA_IOCALLSXPA, the simplest way to avoid this race +condition is to multi-process: when you want to send a client message, +simply start a separate process to call the client routine, so that +the server is not stopped. It probably is fastest and easiest to use +fork\201\202 and then have the child call the client routine and exit. But +you also can use either the system\201\202 or popen\201\202 routine to start one +of the command line programs and do the same thing. Alternatively, you +can use XPA's internal launch\201\202 routine instead of system\201\202. Based on +fork\201\202 and exec\201\202, this routine is more secure than system\201\202 because +it does not call /bin/sh. + +)0 P(Starting with version 2.1.5, you also can send an XPAInfo\201\202 message with +the mode string "ack=false". This will cause the client to send a message +to the server and then exit without waiting for any return message from +the server. This UDP-like behavior will avoid the server deadlock when +sending short XPAInfo messages. + + + + + + + + + + + + + + + + + + + + + + + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 62 H(Last)WB 122 Sn( updated: September 10, 2003)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (oom.html) D +/Ti (Out of Memory) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 27 Sn( + + +)0 2 63 H(Xpaoom:)WB 124 Sn()WB 123 Sn( What happens when XPA runs out of memory?)EA()EH( + + +)0 2 64 H(Summary)WB 125 Sn()EH( +)0 P(When XPA can't allocate memory, it exits. You can arrange to have it call +longjmp\201\202 instead. + + +)0 2 65 H(Description)WB 126 Sn()EH( +)0 P(When an XPA server or client cannot allocate memory, it will attempt to +output an error message and then exit. If this is not satisfactory \201e.g., +perhaps your program is interactive and can recover from OOM errors\202, you +can tell XPA to call longjmp\201\202 to go to a recovery branch. To pass the +requisite jmp_buf variable to XPA, make the following call: +) 1 24 PR( XPASaveJmp\201void *env\202;)RP( +The value of env is the address of a jmp_buf variable that was previously +passed to setjmp\201\202. For example: +) 9 62 PR( jmp_buf env; + ... + if\201 setjmp\201jmp_buf\202 != 0 \202{ + /* out of memory -- take corrective action, if possible */ + } else { + /* save env for XPA */ + XPASaveJmp\201\201void *\202&jmp_buf\202; + } + // enter main loop ...)RP( + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 66 H(Last)WB 127 Sn( updated: April 7, 2009)EH( + +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (client.html) D +/Ti (XPA Client API) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 28 Sn( + + +)0 2 67 H(XPAClient:)WB 130 Sn()WB 128 Sn( The XPA Client-side Programming Interface)EA()EH( + + +)0 2 68 H(Summary)WB 131 Sn()EH( +A description of the XPA client-side programming interface. + + +)0 2 69 H(Introduction)WB 132 Sn()WB 129 Sn( to XPA Client Programming)EH()EA( +)0 P(Sending/receiving data to/from an XPA access point is easy: you +generally only need to call the XPAGet\201\202 or XPASet\201\202 subroutines. +) 33 71 PR( #include <xpa.h> + + int )0 31 1 A(XPAGet)31 0 TN TL()Ec /AF f D(\201XPA xpa, + char *template, char *paramlist, char *mode, + char **bufs, size_t *lens, char **names, char **messages, int n\202; + + int )0 32 1 A(XPASet)32 0 TN TL()Ec /AF f D(\201XPA xpa, + char *template, char *paramlist, char *mode, + char *buf, size_t len, char **names, char **messages, int n\202; + + int )0 33 1 A(XPAInfo)33 0 TN TL()Ec /AF f D(\201XPA xpa, + char *template, char *paramlist, char *mode, + char **names, char **messages, int n\202; + + int )0 37 1 A(XPAAccess)37 0 TN TL()Ec /AF f D(\201XPA xpa, + char *template, char *paramlist, char *mode, + char **names, char **messages, int n\202; + + int )0 34 1 A(XPAGetFd)34 0 TN TL()Ec /AF f D(\201XPA xpa, + char *template, char *paramlist, char *mode, + int *fds, char **names, char **messages, int n\202; + + int )0 35 1 A(XPASetFd)35 0 TN TL()Ec /AF f D(\201XPA xpa, + char *template, char *paramlist, char *mode, + int fd, char **names, char **messages, int n\202; + + XPA )0 29 1 A(XPAOpen)29 0 TN TL()Ec /AF f D(\201char *mode\202; + + void )0 30 1 A(XPAClose)30 0 TN TL()Ec /AF f D(\201XPA xpa\202; + + int )0 36 1 A(XPANSLookup)36 0 TN TL()Ec /AF f D(\201XPA xpa,)WR( + char *template, char *type, + char ***classes, char ***names, char ***methods, char ***infos\202;)RP( + +)0 2 70 H(Introduction)WB 133 Sn()EH( + +To use the XPA application programming interface, a software developer +generally will include the xpa.h definitions file: +) 1 18 PR( #include <xpa.h>)RP( +in the software module that defines or accesses an XPA access point and +then will link against the libxpa.a library: +) 1 27 PR( gcc -o foo foo.c libxpa.a)RP( +XPA has been compiled using both C and C++ compilers. +)0 P(Client communication with XPA public access points generally is +accomplished using XPAGet\201\202 or XPASet\201\202 within a program \201or xpaget +and xpaset at the command line\202. Both routines require specification +of the name of the access point. If a )0 3 1 A(template)3 0 TN TL()Ec /AF f D( +is used to specify the access point name \201e.g., "ds9*"\202, then +communication will take place with all servers matching that template. + + + + +)0 2 71 H(XPAGet:)WB 134 Sn()WB 31 Sn( retrieve data from one or more XPA servers)EA()EH( + + +)BD() 6 70 PR( #include <xpa.h> + + int XPAGet\201XPA xpa, + char *template, char *paramlist, char *mode, + char **bufs, size_t *lens, char **names, char **messages, + int n\202;)RP()ES( + + +)0 P(Retrieve data from one or more XPA servers whose class:name identifier +matches the specified template. + +)0 P(A +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +of the form "class1:name1" is sent to the +XPA name server, which returns a list of at most n matching XPA +servers. A connection is established with each of these servers and +the paramlist string is passed to the server as the data transfer +request is initiated. If an XPA struct is passed to the call, then the +persistent connections are updated as described above. Otherwise, +temporary connections are made to the servers \201which will be closed +when the call completes\202. + +)0 P(The XPAGet\201\202 routine then retrieves data from at most n XPA servers, +places these data into n allocated buffers and places the buffer +pointers in the bufs array. The length of each buffer is stored in the +lens array. A string containing the class:name and ip:port is stored +in the name array. If a given server returned an error or the server +callback sends a message back to the client, then the message will be +stored in the associated element of the messages array. NB: if +specified, the name and messages arrays must be of size n or greater. + +)0 P(The returned message string will be of the form: +) 1 46 PR( XPA$ERROR error-message \201class:name ip:port\202)RP( +or +) 1 42 PR( XPA$MESSAGE message \201class:name ip:port\202)RP( +)0 P(Note that when there is an error stored in an messages entry, the +corresponding bufs and lens entry may or may not be NULL and 0 +\201respectively\202, depending on the particularities of the server. + +)0 P(The return value will contain the actual number of servers that were +processed. This value thus will hold the number of valid entries in +the bufs, lens, names, and messages arrays, and can be used to loop +through these arrays. In names and/or messages is NULL, no information is +passed back in that array. + +)0 P(The bufs, names, and messages arrays should be freed upon completion \201if +they are not NULL\202; + +)0 P(The mode string is of the form: "key1=value1,key2=value2,..." +The following keywords are recognized: +) 4 115 PR( key value default explanation + ------ -------- -------- ----------- + ack true/false true if false, don't wait for ack from server \201after callback completes\202 + doxpa true/false true client processes xpa requests)RP( +)0 P(The ack keyword is not very useful, since the server completes the callback +in order to return the data anyway. It is here for completion \201and perhaps +for future usefulness\202. + +)0 P(Normally, an XPA client will process incoming XPA server requests +while awaiting the completion of the client request. Setting this +variable to "false" will prevent XPA server requests from being +processed by the client. + +)0 P()BD(Example:)ES( +) 25 70 PR( #include <xpa.h> + + #define NXPA 10 + int i, got; + size_t lens[NXPA]; + char *bufs[NXPA]; + char *names[NXPA]; + char *messages[NXPA]; + got = XPAGet\201NULL, "ds9", "file", NULL, bufs, lens, names, messages, + NXPA\202; + for\201i=0; i<got; i++\202{ + if\201 messages[i] == NULL \202{ + /* process buf contents */ + ProcessImage\201bufs[i], ...\202; + free\201bufs[i]\202; + } + else{ + /* error processing */ + fprintf\201stderr, "ERROR: %s \201%s\202\200n", messages[i], names[i]\202; + } + if\201 names[i] \202 + free\201names[i]\202; + if\201 messages[i] \202 + free\201messages[i]\202; + })RP( + + + + +)0 2 72 H(XPASet:)WB 135 Sn()WB 32 Sn( send data to one or more XPA servers)EA()EH( + + +)BD() 6 66 PR( #include <xpa.h> + + int XPASet\201XPA xpa, + char *template, char *paramlist, char *mode, + char *buf, size_t len, char **names, char **messages, + int n\202;)RP()ES( + + +)0 P(Send data to one or more XPA servers whose class:name identifier +matches the specified template. + +)0 P(A +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +of the form "class1:name1" is sent to the +XPA name server, which returns a list of at most n matching XPA +servers. A connection is established with each of these servers and +the paramlist string is passed to the server as the data transfer +request is initiated. If an XPA struct is passed to the call, the +persistent connections are updated as described above. Otherwise, +temporary connections are made to the servers \201which will be closed +when the call completes\202. + +)0 P(The XPASet\201\202 routine transfers data from buf to the XPA servers. +The length of buf \201in bytes\202 should be placed in the len variable. + +)0 P(A string containing the class:name and ip:port of each of these server +is returned in the name array. If a given server returned an error or +the server callback sends a message back to the client, then the +message will be stored in the associated element of the messages +array. NB: if specified, the name and messages arrays must be of size +n or greater. + +)0 P(The returned message string will be of the form: + +) 1 42 PR( XPA$ERROR [error] \201class:name ip:port\202)RP( +or +) 1 44 PR( XPA$MESSAGE [message] \201class:name ip:port\202)RP( +)0 P(The return value will contain the actual number of servers that were +processed. This value thus will hold the number of valid entries in +the names and messages arrays, and can be used to loop through these +arrays. In names and/or messages is NULL, no information is passed back +in that particular array. + +)0 P(The mode string is of the form: "key1=value1,key2=value2,..." +The following keywords are recognized: +) 5 115 PR( key value default explanation + ------ -------- -------- ----------- + ack true/false true if false, don't wait for ack from server \201after callback completes\202 + verify true/false false send buf from XPASet[Fd] to stdout + doxpa true/false true client processes xpa requests)RP( +)0 P(The ack keyword is useful in cases where one does not want to wait for +the server to complete, e.g. if a lot of processing needs to be done +by the server on the passed data or when the success of the server +operation is not relevant to the client. + +)0 P(Normally, an XPA client will process incoming XPA server requests +while awaiting the completion of the client request. Setting this +variable to "false" will prevent XPA server requests from being +processed by the client. + +)0 P()BD(Example:)ES( +) 21 75 PR( #include <xpa.h> + + #define NXPA 10 + int i, got; + size_t len; + char *buf; + char *names[NXPA]; + char *messages[NXPA]; + ... + [fill buf with data and set len to the length, in bytes, of the data] + ... + /* send data to all access points */ + got = XPASet\201NULL, "ds9", "fits", NULL, buf, len, names, messages, NXPA\202; + /* error processing */ + for\201i=0; i<got; i++\202{ + if\201 messages[i] \202{ + fprintf\201stderr, "ERROR: %s \201%s\202\200n", messages[i], names[i]\202; + } + if\201 names[i] \202 free\201names[i]\202; + if\201 messages[i] \202 free\201messages[i]\202; + })RP( + + + + +)0 2 73 H(XPAInfo:)WB 136 Sn()WB 33 Sn( send short message to one or more XPA servers)EA()EH( + + +)BD() 5 58 PR( #include <xpa.h> + + int XPAInfo\201XPA xpa, + char *template, char *paramlist, char *mode, + char **names, char **messages, int n\202;)RP()ES( + + +)0 P(Send a short paramlist message to one or more XPA servers whose +class:name identifier matches the specified +)0 3 1 A(template)3 0 TN TL()Ec /AF f D(. + +)0 P(A +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +of the form "class1:name1" is sent to the +XPA name server, which returns a list of at most n matching XPA +servers. A connection is established with each of these servers and +the paramlist string is passed to the server as the data transfer +request is initiated. If an XPA struct is passed to the call, then the +persistent connections are updated as described above. Otherwise, +temporary connections are made to the servers \201which will be closed +when the call completes\202. + +)0 P(The XPAInfo\201\202 routine does not send data from a buf to the XPA +servers. Only the paramlist is sent. The semantics of the paramlist +is not formalized, but at a minimum is should tell the server how to +get more information. For example, it might contain the class:name +of the XPA access point from which the server \201acting as a client\202 +can obtain more info using XPAGet. + +)0 P(A string containing the class:name and ip:port of each server is +returned in the name array. If a given server returned an error or +the server callback sends a message back to the client, then the +message will be stored in the associated element of the messages +array. The returned message string will be of the form: +) 1 48 PR( XPA$ERROR error-message \201class:name ip:port\202)RP( +or +) 1 46 PR( XPA$MESSAGE message \201class:name ip:port\202)RP( +)0 P(The return value will contain the actual number of servers that were +processed. This value thus will hold the number of valid entries in +the names and messages arrays, and can be used to loop through these +arrays. In names and/or messages is NULL, no information is passed back +in that array. + +)0 P(The following keywords are recognized: +) 3 88 PR( key value default explanation + ------ -------- -------- ----------- + ack true/false true if false, don't wait for ack from server)RP( +)0 P(When ack is false, XPAInfo\201\202 will not wait for an error return from the XPA +server. This means, in effect, that XPAInfo will send its paramlist string +to the XPA server and then exit: no information will be sent from the server +to the client. This UDP-like behavior is essential to avoid race +conditions in cases where XPA servers are sending info messages to +other servers. If two servers try to send each other an info message +at the same time and then wait for an ack, a race condition will result and +one or both will time out. + +)0 P()BD(Example:)ES( +) 1 65 PR( \201void\202XPAInfo\201NULL, "IMAGE", "ds9 image", NULL, NULL, NULL, 0\202;)RP( + + + + +)0 2 74 H(XPAGetFd:)WB 137 Sn()WB 34 Sn( retrieve data from one or more XPA servers and write to files)EA()EH( + + +)BD() 5 63 PR( #include <xpa.h> + + int XPAGetFd\201XPA xpa, + char *template, char *paramlist, char *mode, + int *fds, char **names, char **messages, int n\202;)RP()ES( + + +)0 P(Retrieve data from one or more XPA servers whose class:name identifier +matches the specified +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +and write it to files associated with +one or more standard I/O fds \201i.e, handles returned by open\201\202\202. + +)0 P(A +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +of the form "class1:name1" is sent to the +XPA name server, which returns a list of at most ABS\201n\202 matching XPA +servers. A connection is established with each of these servers and +the paramlist string is passed to the server as the data transfer +request is initiated. If an XPA struct is passed to the call, then the +persistent connections are updated as described above. Otherwise, +temporary connections are made to the servers \201which will be closed +when the call completes\202. + +)0 P(The XPAGetFd\201\202 routine then retrieves data from the XPA servers, +and write these data to the fds associated with one or more fds +\201i.e., results from open\202. Is n is positive, then there will be n fds +and the data from each server will be sent to a separate fd. If n is +negative, then there is only 1 fd and all data is sent to this single +fd. \201The latter is how xpaget is implemented.\202 + +)0 P(A string containing the class:name and ip:port is stored in the name +array. If a given server returned an error or the server callback +sends a message back to the client, then the message will be stored in +the associated element of the messages array. NB: if specified, the +name and messages arrays must be of size n or greater. + +)0 P(The returned message string will be of the form: +) 1 48 PR( XPA$ERROR error-message \201class:name ip:port\202)RP( +or +) 1 46 PR( XPA$MESSAGE message \201class:name ip:port\202)RP( +)0 P(Note that when there is an error stored in an messages entry, the +corresponding bufs and lens entry may or may not be NULL and 0 +\201respectively\202, depending on the particularities of the server. + +)0 P(The return value will contain the actual number of servers that were +processed. This value thus will hold the number of valid entries in +the bufs, lens, names, and messages arrays, and can be used to loop +through these arrays. In names and/or messages is NULL, no information is +passed back in that array. + +)0 P(The mode string is of the form: "key1=value1,key2=value2,..." +The following keywords are recognized: +) 3 115 PR( key value default explanation + ------ -------- -------- ----------- + ack true/false true if false, don't wait for ack from server \201after callback completes\202)RP( +)0 P(The ack keyword is not very useful, since the server completes the callback +in order to return the data anyway. It is here for completion \201and perhaps +for future usefulness\202. + +)0 P()BD(Example:)ES( +) 19 72 PR( #include <xpa.h> + #define NXPA 10 + int i, got; + int fds[NXPA]; + char *names[NXPA]; + char *messages[NXPA]; + for\201i=0; i<NXPA; i++\202 + fds[i] = open\201...\202; + got = XPAGetFd\201NULL, "ds9", "file", NULL, fds, names, messages, NXPA\202; + for\201i=0; i<got; i++\202{ + if\201 messages[i] != NULL \202{ + /* error processing */ + fprintf\201stderr, "ERROR: %s \201%s\202\200n", messages[i], names[i]\202; + } + if\201 names[i] \202 + free\201names[i]\202; + if\201 messages[i] \202 + free\201messages[i]\202; + })RP( + + + + +)0 2 75 H(XPASetFd:)WB 138 Sn()WB 35 Sn( send data from stdin to one or more XPA servers)EA()EH( + +)ES( +) 5 60 PR( #include <xpa.h> + + int XPASetFd\201XPA xpa, + char *template, char *paramlist, char *mode, + int fd, char **names, char **messages, int n\202)RP()ES( + + +)0 P(Read data from a standard I/O fd and send it to one or more XPA +servers whose class:name identifier matches the specified +)0 3 1 A(template. + +)0 P(A +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +of the form "class1:name1" is sent to the +XPA name server, which returns a list of at most n matching XPA +servers. A connection is established with each of these servers and +the paramlist string is passed to the server as the data transfer +request is initiated. If an XPA struct is passed to the call, then the +persistent connections are updated as described above. Otherwise, +temporary connections are made to the servers \201which will be closed +when the call completes\202. + +)0 P(The XPASetFd\201\202 routine then reads bytes from the specified fd +until EOF and sends these bytes to the XPA servers. +The final parameter n specifies the maximum number of servers to contact. +A string containing the class:name and ip:port of each server is returned in +the name array. If a given server returned an error, then the error +message will be stored in the associated element of the messages array. +NB: if specified, the name and messages arrays must be of size n or greater. + +)0 P(The return value will contain the actual number of servers that were +processed. This value thus will hold the number of valid entries in +the names and messages arrays, and can be used to loop through these +arrays. In names and/or messages is NULL, no information is passed back +in that array. + +)0 P(The mode string is of the form: "key1=value1,key2=value2,..." +The following keywords are recognized: +) 4 115 PR( key value default explanation + ------ -------- -------- ----------- + ack true/false true if false, don't wait for ack from server \201after callback completes\202 + verify true/false false send buf from XPASet[Fd] to stdout)RP( +)0 P(The ack keyword is useful in cases where one does not want to wait for +the server to complete, e.g. is a lot of processing needs to be done +on the passed data or when the success of the server operation is not +relevant to the client. + +)0 P()BD(Example:)ES( +) 19 71 PR( #include <xpa.h> + + #define NXPA 10 + int i, got; + int fd; + char *names[NXPA]; + char *messages[NXPA]; + fd = open\201...\202; + got = XPASetFd\201NULL, "ds9", "fits", NULL, fd, names, messages, NXPA\202; + for\201i=0; i<got; i++\202{ + if\201 messages[i] != NULL \202{ + /* error processing */ + fprintf\201stderr, "ERROR: %s \201%s\202\200n", messages[i], names[i]\202; + } + if\201 names[i] \202 + free\201names[i]\202; + if\201 messages[i] \202 + free\201messages[i]\202; + })RP( + + + + +)0 2 76 H(XPAOpen:)WB 139 Sn()WB 29 Sn( allocate a persistent client handle)3 0 TN TL()Ec /AF f D()EH( + + +)BD() 3 26 PR( #include <xpa.h> + + XPA XPAOpen\201char *mode\202;)RP()ES( + + +)0 P(XPAOpen\201\202 allocates a persistent XPA struct that can be used with +calls to XPAGet\201\202, XPASet\201\202, XPAInfo\201\202, XPAGetFd\201\202, and +XPASetFd\201\202. Persistence means that a connection to an XPA server is +not closed when one of the above calls is completed but will be +re-used on successive calls. Using XPAOpen\201\202 therefore saves the time +it takes to connect to a server, which could be significant with slow +connections or if there will be a large number of exchanges with a +given access point. The mode argument currently is ignored \201"reserved +for future use"\202. + +)0 P(An XPA struct is returned if XPAOpen\201\202 was successful; otherwise NULL +is returned. This returned struct can be passed as the first argument +to XPAGet\201\202, etc. Those calls will update the list of active XPA +connections. Already connected servers \201from a previous call\202 are +left connected and new servers also will be connected. Old servers +\201from a previous call\202 that are no longer needed are disconnected. +The connected servers will remain connected when the next call to +XPAGet\201\202 is made and connections are once again updated. + +)0 P()BD(Example:)ES( +) 4 22 PR( #include <xpa.h> + + XPA xpa; + xpa = XPAOpen\201NULL\202;)RP( + + + + +)0 2 77 H(XPAClose:)WB 140 Sn()WB 30 Sn( close a persistent XPA client handle)EA()EH( + + +)BD() 3 25 PR( #include <xpa.h> + + void XPAClose\201XPA xpa\202;)RP()ES( + + +)0 P(XPAClose closes the persistent connections associated with this XPA struct +and frees all allocated space. It also closes the open sockets connections +to all XPA servers that were opened using this handle. + +)0 P()BD(Example:)ES( +) 4 18 PR( #include <xpa.h> + + XPA xpa; + XPAClose\201xpa\202;)RP( + + + + +)0 2 78 H(XPANSLookup:)WB 141 Sn()WB 36 Sn( lookup registered XPA access points)EA()EH( + + +)BD() 6 49 PR( #include <xpa.h> + + int XPANSLookup\201XPA xpa, + char *template, char type, + char ***classes, char ***names, + char ***methods, char ***infos\202)RP()ES( + + +)0 P(XPA routines act on a class:name identifier in such a way +that all access points that match the identifier are processed. It is +sometimes desirable to choose specific access points from the +candidates that match the +)0 3 1 A(template)3 0 TN TL()Ec /AF f D(. In order to do this, the +XPANSLookup routine can be called to return a list of matches, so that +specific class:name instances can then be fed to XPAGet\201\202, XPASet\201\202, etc. + +)0 P( The first argument is an optional XPA struct. If non-NULL, the +existing name server connection associated with the specified xpa is +used to query the xpans name server for matching templates. Otherwise, +a new \201temporary\202 connection is established with the name server. + +)0 P(The second argument to XPANSLookup is the class:name +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +to match. + +)0 P(The third argument for XPANSLookup\201\202 is the type of access and can be +any combination of: +) 5 62 PR( type explanation + ------ ----------- + g xpaget calls can be made on this access point + s xpaset calls can be made on this access point + i xpainfo calls can be made on this access point)RP( +)0 P(The call typically specifies only one of these at a time. + +)0 P(The final arguments are pointers to arrays that will be filled +in and returned by the name server. The name server will allocate and +return arrays filled with the classes, names, and methods of all XPA +access points that match the )0 3 1 A(template)3 0 TN TL()Ec /AF f D( +and have the specified type. Also returned are info strings, which +generally are used internally by the client routines. These can be +ignored \201but the strings must be freed\202. The function returns the +number of matches. The returned value can be used to loop through the +matches: + +)BD(Example:)ES( +) 24 73 PR( #include <xpa.h> + + char **classes; + char **names; + char **methods; + char **infos; + int i, n; + n = XPANSLookup\201NULL, "foo*", "g", &classes, &names, &methods, &infos\202; + for\201i=0; i<n; i++\202{ + [more specific checks on possibilities ...] + [perhaps a call to XPAGet for those that pass, etc. ...] + /* don't forget to free alloc'ed strings when done */ + free\201classes[i]\202; + free\201names[i]\202; + free\201methods[i]\202; + free\201infos[i]\202; + } + /* free up arrays alloc'ed by names server */ + if\201 n > 0 \202{ + free\201classes\202; + free\201names\202; + free\201methods\202; + free\201infos\202; + })RP( +)0 P(The specified +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +also can be a host:port specification, for example: +) 1 14 PR( myhost:12345)RP( +)0 P(In this case, no connection is made to the name server. Instead, the +call will return one entry such that the ip array contains the ip for +the specified host and the port array contains the port. The class +and name entries are set to the character "?", since the class and +name of the access point are not known. + + + + +)0 2 79 H(XPAAccess:)WB 142 Sn()WB 37 Sn( return XPA access points matching +template \201XPA 2.1 and above\202)EA()EH( + + +)BD() 5 60 PR( #include <xpa.h> + + int XPAAccess\201XPA xpa, + char *template, char *paramlist, char *mode, + char **names, char **messages, int n\202;)RP()ES( + + +)0 P(The XPAAccess routine returns the public access points that match the +specified second argument )0 3 1 A(template)3 0 TN TL()Ec /AF f D( and +have the specified access type. + +)0 P(A +)0 3 1 A(template)3 0 TN TL()Ec /AF f D( +of the form "class1:name1" is sent to the +XPA name server, which returns a list of at most n matching XPA +servers. A connection is established with each of these servers and +the paramlist string is passed to the server as the data transfer +request is initiated. If an XPA struct is passed to the call, then the +persistent connections are updated as described above. Otherwise, +temporary connections are made to the servers \201which will be closed +when the call completes\202. + +)0 P(The XPAAccess\201\202 routine retrieves names from at most n XPA servers +that match the specified template and that were checked for access +using the specified mode. The return string contains both the +class:name and ip:port. If a given server returned an error or the +server callback sends a message back to the client, then the message +will be stored in the associated element of the messages array. +NB: if specified, the name and messages arrays must be of size n or greater. + +)0 P(The returned message string will be of the form: +) 1 46 PR( XPA$ERROR error-message \201class:name ip:port\202)RP( +)0 P(Note that names of matching registered access points are always +returned but may not be valid; it is not sufficient to assume that the +returned number of access points is the number of valid access points. +Rather, it is essential to check the messages array for error +messages. Any string in the messages array is an error message and +indicated that the associated access point is not available. + +)0 P(For example, assume that a server registers a number of access points +but delays entering its event loop. If a call to XPAAccess\201\202 is made +before the event loop is entered, the call will timeout \201after waiting +for the long timeout period\202 and return an error of the form: +) 1 65 PR( XPA$ERROR: timeout waiting for server authentication \201XPA:xpa1\202)RP( +The error means that the XPA access point has been registered but is +not yet available \201because events are not being processed\202. When the +server finally enters its event loop, subsequent calls to XPAAccess\201\202 +will return successfully. + +)0 P(NB: This routine only works with XPA servers built with XPA 2.1.x and later. +Servers with older versions of XPA will return the error message: + + XPA$ERROR invalid xpa command in initialization string + +If you get this error message, then the old server actually is ready +for access, since it got to the point of fielding the query! The +xpaaccess program, for example, ignores this message in order to work +properly with older servers. + +)0 P(The third argument for XPAAccess\201\202 is the type of access and can be +any combination of: +) 5 62 PR( type explanation + ------ ----------- + g xpaget calls can be made on this access point + s xpaset calls can be made on this access point + i xpainfo calls can be made on this access point)RP( +)0 P(The mode string argument is of the form: "key1=value1,key2=value2,..." +The following keywords are recognized: +) 3 115 PR( key value default explanation + ------ -------- -------- ----------- + ack true/false true if false, don't wait for ack from server \201after callback completes\202)RP( +)0 P(The ack keyword is not very useful, since the server completes the callback +in order to return the data anyway. It is here for completion \201and perhaps +for future usefulness\202. + + + + + + + + + + + + + + + + + + + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 80 H(Last)WB 143 Sn( updated: March 10, 2007)EH( + +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (xt.html) D +/Ti (XPA/Xt Interface) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 38 Sn( + + +)0 2 81 H(XPAXt:)WB 145 Sn()WB 144 Sn( the XPA Interface to Xt \201X Windows\202)EA()EH( + + +)0 2 82 H(Summary)WB 146 Sn()EH( +Describes how XPA access points can be added to X Toolkit \201Xt\202 programs. + + +)0 2 83 H(Description)WB 147 Sn()EH( +)0 P(XPA supports Xt programs: you can call XPANew\201\202, XPACmdNew\201\202, or +XPAInfoNew\201\202 within any C routine to add XPA server callbacks to an Xt +program. Since an Xt program has its own event loop call \201i.e., +XtAppMainLoop\201\202\202, it therefore does not need or want to use the XPA +even loop. Thus, in order to add XPA access points to the standard Xt +event loop, the following routine should be called before entering the +loop: +) 1 46 PR( int XPAXtAddInput\201XtAppContext app, XPA xpa\202)RP( +)0 P(The XPAAddAddInput\201\202 routine will add XPA access points to the Xt event +loop by making calls to the standard XtAppAddInput\201\202 routine. \201If the +XtAppContext argument is NULL, then the alternate XtAddInput\201\202 routine +is used instead.\202 If the xpa argument is NULL, then all active XPA +access points are added to the loop. If xpa is not NULL, then only +the specified access point is added. The latter type of call is used +to add new access points from within a callback, after the program has +entered the XtAppMainLoop\201\202 even loop. + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 84 H(Last)WB 148 Sn( updated: September 10, 2003)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (tcl.html) D +/Ti (XPA/Tcl Interface) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 39 Sn( + + +)0 2 85 H(XPATcl:)WB 151 Sn()WB 149 Sn( the XPA Interface to the Tcl/Tk Environment)EA()EH( + + +)0 2 86 H(Summary)WB 152 Sn()EH( + +)0 P(Tcl/Tk programs can act as XPA clients and/or servers using the Tcl +interface to XPA that is contained in the libtclxpa.so shared object. + +)0 2 87 H(Server)WB 153 Sn( Routines)EH( + +) 11 70 PR( set xpa [xpanew class name help sproc sdata smode rproc rdata rmode] + xpafree xpa + set xpa [xpanew class name help iproc idata imode] + set xpa [xpacmdnew class name] + xpacmdadd xpa name help sproc sdata smode rproc rdata rmode + xpacmddel xpa cmd + set val [xparec xpa option] + options: name, class, method, cmdfd, datafd, cmdchan, datachan + xpasetbuf xpa buf len + xpaerror xpa message + xpamessage xpa message)RP( + +)0 2 88 H(Client)WB 154 Sn( Routines)EH( + +) 11 69 PR( set xpa [xpaopen mode] + xpaclose xpa + set got [xpaget xpa template paramlist mode bufs lens names errs n] + set got [xpaget xpa template paramlist mode chans names errs n] + set got [xpaset xpa template paramlist mode buf len names errs n] + set got [xpasetfd xpa template paramlist mode chan names errs n] + set got [xpainfo xpa template paramlist mode names errs n] + # NB: 2.1 calling sequence change + # set got [xpaaccess template type] \2012.0.5\202 + set got [xpaaccess xpa template paramlist mode names errs n] + set got [xpanslookup template type classes names methods])RP( + + +)0 2 89 H(Description)WB 155 Sn()EH( +)0 P(You can call XPANew\201\202, XPACmdNew\201\202, or XPAInfoNew\201\202 within a C +routine to add C-based XPA server callbacks to a TCL/Tk program that +uses a Tcl/Tk event loop \201either vwait\201\202 or the Tk event loop\202; +Such a program does not need or want to use the XPA event loop. +Therefore, in order to add XPA access points to the Tcl/Tk loop, the +following routine should be called beforehand: +) 1 30 PR( int XPATclAddInput\201XPA xpa\202;)RP( +)0 P(Normally, the xpa argument is NULL, meaning that all current XPA +access points are registered with the event loop. However, if a +single XPA access point is to be added \201i.e., after the event loop is +started\202 then the handle of that XPA access point can be passed to +this routine. + +)0 P(The significance of the XPA/TCL interface goes beyond the support for +using XPA inside C code. The interface allows you to write XPA +servers and to make calls to the XPA client interface within the Tcl +environment using the Tcl language directly. The XPA/Tcl +interface can be loaded using the following package command: +) 1 28 PR( package require tclxpa 2.0)RP( +Alternatively, you can load the shared object \201called libtclxpa.so \202 directly: +) 1 30 PR( load .../libtclxpa.so tclxpa)RP( +)0 P(Once the tclxpa package is loaded, you can use Tcl versions of XPA +routines to define XPA servers or make client XPA calls. The +interface for these routines is designed to match the Unix XPA +interface as nearly as possible. Please refer to +)0 15 1 A(XPA Servers)15 0 TN TL()Ec /AF f D( +and +)0 28 1 A(XPA Clients)28 0 TN TL()Ec /AF f D( +for general information about these routines. + +)0 P(The file test.tcl in the XPA source directory gives examples for using the +XPA/Tcl interface. + +)0 P(The following notes describe the minor differences between the interfaces. + +)0 2 90 H(XPANew)WB 156 Sn()WB 150 Sn()EA()EH( +) 1 70 PR()BD( set xpa [xpanew class name help sproc sdata smode rproc rdata rmode])ES()RP( +)0 P(rproc and sproc routines are routines. The calling sequence of the +rproc routine is identical to its C counterpart: +) 1 59 PR( proc rec_cb { xpa client_data paramlist buf len } { ... })RP( +)0 P(The sproc routine, however is slightly different from its C counterpart +because of the difficulty of passing data back from the callback to C: +) 1 51 PR( proc sendcb { xpa client_data paramlist } { ... })RP( +)0 P(Note that the C-based server's char **buf and int *len arguments are +missing from the Tcl callback. This is because we did not know how to +fill buf with data and pass it back to the C routines for communication +with the client. Instead, the Tcl server callback uses the following +routine to set buf and len: +) 1 23 PR( xpasetbuf xpa buf len)RP( +where: +) 5 79 PR( arg explanation + ------ ----------- + xpa the first argument of the server callback + buf the data to be returned to the client + len data length in bytes, \201if absent, use length of the buf object\202)RP( +)0 P(When this routine is called, a copy of buf is saved for transmission to +the client. + +)0 P(The fact that buf is duplicated means that TCL server writers might wish to +perform the I/O directly within the callback, rather than have XPA do it +automatically at the end of the routine. To do this, set: +) 1 15 PR( fillbuf=false)RP( +)0 P(in the xpanew smode and then perform I/O through the Tcl channel +obtained from: +) 1 34 PR( set dchan [xparec $xpa datachan])RP( +)0 P(where: +) 5 79 PR( arg explanation + ------ ----------- + xpa the first argument of the server callback + datachan literal string "datachan" that returns the data channel + len data length in bytes, \201if absent, use length of the buf object\202)RP( +)0 P()BD(NB: datachan and cmdchan are not available under Windows. It is +necessary to use the "raw" equivalents: datafd and cmdfd.)ES( + +)0 P(The same considerations apply to the rproc for receive servers: a copy +of the incoming data is generated to pass to the receive callback. This +copy again can be avoided by using "fillbuf=false" in the rmode and then +reading the incoming data from datachan. + +)0 P(The send and receive callback routines can use the xpaerror and xpamessage +routines to send errors and messages back to the client. If you also +want tcl itself to field an error condition, use the standard return call: +) 1 56 PR( return ?-code c? ?-errorinfo i? ?-errorcode ec? string)RP( +)0 P(See the Tcl man page for more info. + +)0 2 91 H(XPARec)WB 157 Sn()WB 150 Sn()EA()EH( +)0 P(The Tcl xparec procedure supplies server routines with access to information +that is available via macros in the C interface: +) 1 31 PR( set val [xparec xpa <option>])RP( +)0 P(where option is: name, class, method, cmdfd, datafd, cmdchan, +datachan. Note that two additional identifiers, cmdchan and datachan, +have been added to to provide Tcl channels corresponding to datafd and +cmdfd. \201These latter might still be retrieved in Tcl and passed back +to a C routines.\202 An additional option called "version" can be used to +determine the XPA version used to build the Tcl interface. Note that +the standard options require a valid XPA handle, but "version" does +not \201since it simply reports the value of the XPA_VERSION definition +in the XPA source include file\202. + +)0 P()BD(NB: datachan and cmdchan are not available under Windows. It is +necessary to use the "raw" equivalents: datafd and cmdfd.)ES( +) 12 58 PR( macro explanation + ------ ----------- + class class of this xpa + name name of this xpa + method method string \201inet or local connect info\202 + cmdchan Tcl channel of command socket + datachan Tcl channel of data socket + cmdfd fd of command socket + datafd fd of data socket + sendian endian-ness of server \201"little" or "big"\202 + cendian endian-ness of client \201"little" or "big" + version XPA version used to build this code)RP( + +)0 P(Under Windows, the Tcl event handler cannot automatically sense when an +XPA socket is ready for IO \201i.e. Tcl_CreateFileHandler\201\202 is not available +under Windows\202. The Windows Tcl event handler therefore must be awakened +occasionally for check for XPA events. This is done using the standard +Tcl_SetMaxBlockTime\201\202 call. The time parameter is defined in tclloop.c +and is currently set to 1000 microseconds \2011/1000 of a second\202. + +)0 P(The version option can be used to differentiate between source code versions. +It was created to support legacy Tcl code that needs to maintain the 2.0.5 +calling sequence for xpaaccess. You can use a version test such as: +) 12 44 PR( if [catch { xparec "" version } version] { + puts "pre-2.1.0e" + } else { + puts [split $version .] + } +) 7 32 PR( + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 92 H(Last)WB 158 Sn( updated: September 10, 2003)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (env.html) D +/Ti (The XPA Environment) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 40 Sn( + + +)0 2 93 H(XPAEnv:)WB 160 Sn()WB 159 Sn( Environment Variables for XPA Messaging)EA()EH( + + +)0 2 94 H(Summary)WB 161 Sn()EH( +Describes the environment variables which can be used to tailor the overall +XPA environment. + + +)0 2 95 H(Description)WB 162 Sn()EH( +)0 P(The following environment variables are supported by XPA: +)0 DL()0 P()0 DT()BD(XPA_ACL)ES( +)DD( If )EM(XPA_ACL)ES( is )EM(true)ES(, then +host-based )0 41 1 A(XPA Access Control)41 0 TN TL()Ec /AF f D( +is turned on and only specified machines can access specified access +points. If )EM(false)ES(, then access control is turned off and any +machine can access point. The default is turn turn access control on. + +)0 P()0 DT()BD(XPA_ACLFILE)ES( +)DD( If +)0 41 1 A(XPA Access Control)41 0 TN TL()Ec /AF f D( +is turned on, this variable specifies the name of the file containing +access control information for all access points started by this user. +The default file name is: )EM($HOME/acls.xpa)ES(. + +)0 P()0 DT()BD(XPA_CONNECT_TIMEOUT)ES( +)DD( When an XPA server first starts up, it immediately tries to +connect to the XPA name server program \201xpans\202 on the host specified by +the )EM(XPA_NSINET)ES( variable. \201If this connection fails on the +local host, and if xpans can be found in the path, then the name +server is started automatically.\202 Unfortunately, a mis-configured +network can cause this connect attempt to hang for many seconds while +the connect\201\202 system call times out. Therefore, an alarm is started +to interrupt the connect\201\202 call and prevent a long hang. The initial +value of the alarm timeout is 10 seconds, but can be changed by setting +this environment variable. If you want to disable the alarm and allow +the initial connect\201\202 to time out, set the value of this variable to +0. Normally, users would not change this variable at all. + +)0 P()0 DT()BD(XPA_CLIENT_DOXPA)ES( +)DD( Normally, an XPA client \201xpaget, xpaset, etc.\202 will process incoming +XPA server requests while awaiting the completion of the client request. +Setting this variable to "false" will prevent XPA server requests from +being processed by the client. + +)0 P()0 DT()BD(XPA_DEFACL)ES( +)DD( If +)0 41 1 A(XPA Access Control)41 0 TN TL()Ec /AF f D( +is turned on, this variable specifies the default access control +condition for all access points, if the )EM(XPA_ACLFILE)ES( file does +not exist. The default acl is: )EM($host:* $host +)ES(, meaning that +all processes on the host machine have full access to all access points. + +)0 P()0 DT()BD(XPA_HOST)ES( +)DD(For the INET socket method, XPA utilizes the canonical hostname \201as +returned by the gethostname\201\202 routine\202 to construct the IP part of the +method id. Under some circumstances, this might not be a correct choice +of name and IP. For example, if an XPA server is started on a machine +running VPN, you might want to use the VPN name and IP instead of the +canonical host name, so that other machines in the VPN network can +access the server. In this case, you can set the XPA_HOST to be +the VPN name \201if resolvable\202 or, more easily, the VPN IP. + +)0 P()0 DT()BD(XPA_IOCALLSXPA)ES( +)DD( +Setting this variable causes all XPA socket IO calls to process +outstanding XPA requests whenever the primary socket is not ready for +IO. This means that a server making a client call will \201recursively\202 +process incoming server requests while waiting for client completion. +This inter-IO XPA processing avoids a rare +)0 26 1 A(XPA Race Condition)26 0 TN TL()Ec /AF f D(: two or more +XPA servers sending messages to one another using an XPA client +routine such as XPASet\201\202 can deadlock while each waits for the other +server to respond. This can happen, for example, if the servers call +XPAPoll\201\202 with a time limit, and send messages in between the polling call. + +)0 P(By default, this option is turned off, because we judge that the added +code complication and overhead involved will not be justified by the +amount of its use. Moreover, processing XPA requests within socket IO +can lead to non-intuitive results, since incoming server requests will +not necessarily be processed to completion in the order in which they +are received. + +)0 P()0 DT()BD(XPA_LOGNAME)ES( +)DD(XPA preferentially uses the de facto standard environment variable +LOGNAME to determine the username when registering an access point in +the name server. If this environment variable has been used for +something other than the actual user name \201such as a log file name\202, +unexpected results can ensue. In such cases, use the XPA_LOGNAME +variable to set the user name. \201If neither exists, then getpwuid\201geteuid\201\202\202 +is used as a last resort\202. + +)0 P()0 DT()BD(XPA_LONG_TIMEOUT)ES( +)DD( XPA is designed to allow data to be sent from one process to +another over a long period of time \201i.e., a program that generates +image data sends that data to an image display, but slowly\202 but it +also seeks to prevent hangs. This is done by supporting 2 timeout +periods: a )EM(short)ES( timeout for protocol communication +and a )EM(long)ES( for data communication. +)0 P(The )EM(XPA_LONG_TIMEOUT)ES( variable controls the )EM(long)ES( +timeout and is used to prevent hangs in cases where communication +between the client and server that is )EM(not)ES( controlled by the +XPA interface itself. Transfer of data between client and server, or a +client's wait for a status message after completion of the server +callback, are two examples of this sort of communication. By default, +the )EM(long)ES( timeout is set to 180 seconds. +Setting the value to -1 will disable )EM(long)ES( timeouts and allow +an infinite amount of time. + +)0 P()0 DT()BD(XPA_MAXHOSTS)ES( +)DD( The maximum number of access points that the programs +)EM(xpaset)ES(, )EM(xpaget)ES(, and )EM(xpainfo)ES( will +communicate with at one time. The default is 64, meaning, for +example, that the )EM(xpaset)ES( program will not send a message +to more than 100 access points at one time and )EM(xpaget)ES( will +not retrieve from more than 100 access points at one time. + +)0 P()0 DT()BD(XPA_METHOD)ES( +)DD(Determines the socket connection method used by this session of XPA. +The choices are: )EM(inet)ES( \201to use INET or Internet-based +sockets\202, )EM(localhost)ES( \201to use the machines localhost inet +socket\202, or )EM(local \201unix\202)ES( \201to use UNIX sockets\202. The default +is )EM(INET)ES(. Using the )EM(inet)ES( method will allow access +from other machines \201subject to access controls\202 but using +)EM(localhost)ES( or )EM(local)ES( will not. Localhost is most useful +for private access and when the machine in question is not connected +to the Internet. The unix method also can be used for private access +and non-Internet connections \201Unix platforms only\202. +)0 P(Once defined, the first registration of an XPA access point will +ensure that an instance of the +)0 14 1 A(XPA Name Server \201xpans\202)14 0 TN TL()Ec /AF f D( +is running that handles that connection method. All new access points +will use the new connection method but existing access points will use +the original method. + +)0 P()0 DT()BD(XPA_NSINET)ES( +)DD( For the )EM(inet)ES( method of socket connection, this variable +specifies the host and port on which the +)0 14 1 A(XPA Name Server \201xpans\202)14 0 TN TL()Ec /AF f D( +is listens for new access points. The default is )EM($host:$port)ES(, +meaning that the default XPA port \20114285\202 on the current machine +\201as returned by gethostname\201\202\202 is used. If several machines were all +accessing the same XPA access points, you would use this variable to +specify that they all use the same name server to find out about these +access points. For example, a value of )EM(myhost:$port)ES( would +mean that the xpans name server is running on myhost and uses the +default port 12345. All machines would then get the XPA access points +registered with that name server, subject to access controls. +)0 P(The port used by xpans to register its XPA access point normally is +taken to be one greater than the port on which it receives new access +points from XPA servers. You can specify a specific access point port +using the syntax machine:port1,port2, i.e., the access point port is +specified after the comma. For example, $host:12345,23456 will listen +for new access ports on 12345 and will accept XPA commands on 23456. + +)0 P()0 DT()BD(XPA_NSREGISTER)ES( +)DD(This boolean variable specifies whether a server registers its XPA +access point with the specified xpans name server. The default is +)EM(true)ES(. If set to )EM(false)ES(, the access point still is +set up but it is not registered with xpans and therefore cannot be +accessed by name. \201It can be accessed by method, if the latter is +known.\202 Note that an access point can be registered later on \201using +-remote or -proxy, for example\202. This variable mainly is useful in +cases where the Internet configuration is broken \201so that registration +causes a DNS hang\202 but you still wish to and can use the server with a +remote xpans \201e.g., ds9's Virtual Observatory capability\202. + +)0 P()0 DT()BD(XPA_NSUNIX)ES( +)DD( For the )EM(local)ES( method of socket connection, this variable +specifies the name of the Unix file that will be used to access the +)0 14 1 A(XPA Name Server \201xpans\202)14 0 TN TL()Ec /AF f D(. The default is +)EM(xpans_unix)ES(. This variable is not usually needed. Note that +is the )EM(local)ES( socket method is used, then remote machines will +not be able to access the xpans name server or the registered XPA access +points. + +)0 P()0 DT()BD(XPA_NSUSERS)ES( +)DD(This variable specifies whether other users' access points will be +returned by the +)0 14 1 A(XPA Name Server \201xpans\202)14 0 TN TL()Ec /AF f D( for use by +)EM(xpaget)ES(, )EM(xpaset)ES(, etc. +Generally speaking, it is sufficient to run one xpans name server per +machine and register the access points for all users with that xpans. +This means, for example, that if you request information from +ds9 by running: +) 1 21 PR( xpaget ds9 colormap)RP( +you might get information from your own ds9 as well as +from another user running ds9 on the same machine. The +)EM(XPA_NSUSERS)ES( variable controls whether you want such access +to the access points of other users. +By default, only your own access points are returned, so +that, in the example above, you would only get the colormap information +from the ds9 you registered. If, however, you had set the value of the +)EM(XPA_NSUSERS)ES( variable to )EM(eric,fred)ES(, then you would be +able to communicate with both eric and fred's access points. Note that +this variable can be overridden using the )EM(-u)ES( switch on the +)EM(xpaget)ES(, )EM(xpaset)ES(, and )EM(xpainfo)ES( programs. + +)0 P()0 DT()BD(XPA_PORT)ES( +)DD( +A semi-colon delimited list of user specified ports to use for specific +XPA access points. The format is each specification is: +) 1 28 PR(class:template port1[ port2])RP( +where )BD(port1)ES( is the main \201command\202 port for the access point and +)BD(port2)ES( is the \201secondary\202 data port. If port2 is not specified, +it defaults to a value of 0 \201meaning the system assigns the port\202. + +)0 P(Specification of specific ports is useful, for example, when a machine +outside a firewall needs to communicate with a machine inside a +firewall. In such a case, the firewall should be configured to allow +socket connections to both the command and data port from the outside +machine, and the inside XPA program should be started up with the +outside machine in its ACL list. Then, when the inside program is +started with specified ports, outside XPA programs can use +"machine:port" to contact the inside access points, instead of the +access point names. That is, the machine outside the firewall does not +need access to the XPA name server: +) 2 62 PR(export XPA_PORT="DS9:ds9 12345 12346" # on machine "inside" +cat foo.fits | xpaset inside:12345 fits # on machine "outside")RP( +Note that 2 ports are required for full XPA communication and +therefore 2 ports should be specified to go through a firewall. The +second port assignment is not important if you simply are assigning +the command port in order to communicate commands with a known +port \201e.g., to bypass the xpans name server\202. If only one \201command\202 +port is specified, the system will negotiate a random data port and +everything will work properly. + +)0 P(This support is somewhat experimental. If you run into problems, please +let us know. + +)0 P()0 DT()BD(XPA_PORTFILE)ES( +)DD( +A list of user-specified port to use for specific xpa access points. +The format of the file is: +) 1 28 PR(class:template port1 [port2])RP( +where )BD(port1)ES( is the main port for the access point and +)BD(port2)ES( is the data port. If port2 is not specified, it defaults +to a value of 0 \201meaning the system assigns the port\202. See +)BD(XPA_PORT)ES( above for an explanation of user-specified ports. + +)0 P()0 DT()BD(XPA_SHORT_TIMEOUT)ES( +)DD( XPA is designed to allow data to be sent from one process to +another over a long period of time \201i.e., a program that generates +image data sends that data to an image display, but slowly\202 but it +also seeks to prevent hangs. This is done by supporting 2 timeout +periods: a )EM(short)ES( timeout for protocol communication +and a )EM(long)ES( for data communication. +)0 P(The )EM(XPA_SHORT_TIMEOUT)ES( variable +controls the )EM(short)ES( timeout and is used to prevent hangs +in cases where the XPA protocol requires internal communication between +the client and server that is controlled by the XPA interface +itself. Authentication is an example of this sort of communication, +as is the establishment of a data channel between the two processes. +The default value for the )EM(short)ES( is 30 seconds \201which is +a pretty long time, actually\202. Setting the value to -1 will disable +)EM(short)ES( timeouts and allow an infinite amount of time. + +)0 P()0 DT()BD(XPA_SIGUSR1)ES( +)DD( If the value of this variable is )EM(true)ES(, then XPA will +catch SIGUSR1 signals when performing an I/O operation in order to +curtail that operation. This facility allows users to send a SIGUSR1 +signal to an XPA server if a client is hanging up the server by +sending or receiving data too slowly \201timeouts also can be used -- see +above\202. When enabled in this way, the SIGUSR1 signal is ignored at all other +times, so that its safe to send the signal at any time. If the +variable is set to )EM(false)ES(, then SIGUSR1 is not used at +all. Turning off SIGUSR1 would be desired in cases there the program +uses SIGUSR1 for some other reason and does not want XPA interfering. +The default is to use the signal. + +)0 P()0 DT()BD(XPA_TIMESTAMP_ERRORS)ES( +)DD( If )EM(XPA_TIMESTAMP_ERRORS)ES( is )EM(true)ES(, then error +messages will include a date/time string. This can be useful when +XPA errors are being saved in an error log \201e.g. Web/CGI use\202. The +default is false.)LD( + +)0 P()0 DT()BD(XPA_TMPDIR)ES( +)DD( This variable specifies the directory into which XPA logs, Unix +socket files \201when )EM(XPA_METHOD)ES( is )EM(local)ES(\202, etc. are +stored. The default is )EM(/tmp/.xpa)ES(. + +)0 P()0 DT()BD(XPA_VERBOSITY)ES( +)DD( Specify the verbosity level of error messages. If the value is +set to )EM(0)ES(, )EM(false)ES(, or )EM(off)ES(, then no error +messages are printed to stderr. If the value is )EM(1)ES(, then +important XPA error messages will be output. If the value is +set to )EM(2)ES(, XPA warnings about out-of-sync messages will also +be output. These latter almost always can be ignored. + +)0 P()0 DT()BD(XPA_VERSIONCHECK)ES( +)DD( Specify whether a new access point should check its major and minor XPA +version number against the version used by the xpans name server at +registration time. The default is )EM(true)ES(. When checking is +performed, a warning is issued if the server major version is found to +be greater than the xpans version. Note that the check is performed +both by the XPA server and by the xpans process and warnings will be +issued by each. Also, instead of the values of )EM(true)ES( or +)EM(false)ES(, you can give this variable an integer value n. In this +case, each version checking process \201i.e., the XPA-enabled server or +xpans\202 will print out a maximum of n warning messages \201after which +version warnings are silently swallowed\202. +)0 P(In general, it is a bad idea to run an XPA-enabled server program +using a version of XPA newer than the basic xpaset, xpaget, xpaaccess, +xpans programs. This sort of mismatch usually will not work due to +protocol changes. + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 96 H(Last)WB 163 Sn( updated: December 23, 2009)EH( + +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (acl.html) D +/Ti (XPA Access Control) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 41 Sn( + + +)0 2 97 H(XPAAcl:)WB 165 Sn()WB 164 Sn( Access Control for XPA Messaging)EA()EH( + + +)0 2 98 H(Summary)WB 166 Sn()EH( +)0 P(XPA supports host-based access control for each XPA access point. You +can enable/disable access control using the XPA_ACL environment +variable. You can specify access to specific XPA access points for +specific machines using the XPA_DEFACL and XPA_ACLFILE environment +variables. By default, an XPA access point is accessible only to +processes running on the same machine \201same as X Windows\202. + + +)0 2 99 H(Description)WB 167 Sn()EH( +)0 P(When INET sockets are in use \201the default, as specified by the +)EM(XPA_METHOD)ES( environment variable\202, XPA supports a host-based +access control mechanism for individual access points. This mean that +access can be specified for get, set, or info operations for each +access point on a machine by machine basis. For LOCAL sockets, access +is restricted \201by definition\202 to the host machine. + +)0 P(XPA access control is enabled by default, but can be turned off by +setting the )EM(XPA_ACL)ES( environment variable to )EM(false)ES(. +In this case, any process can access any XPA server. + +)0 P(Assuming that access control is turned on, the ACL for an individual +XPA access point is set up when that access point is registered +\201although it can be changed later on; see below\202. This can be done in +one of two ways: + +Firstly, the )EM(XPA_ACLFILE)ES( environment variable can defined to +point to a file of access controls for individual access points. The format +of this file is: +) 1 18 PR( class:name ip acl)RP( +The first argument is a template that specifies the class:name of the +access point covered by this ACL. See +)0 3 1 A(XPA Access Points and Templates)3 0 TN TL()Ec /AF f D( +for more information about xpa templates. + +)0 P(The second argument is the IP address \201in human-readable format\202 of +the machine which is being given access. This argument can be +)EM(*)ES( to match all IP addresses. It also can be )EM($host)ES( +to match the IP address of the current host. + +)0 P(The third argument is a string combination of )EM(s)ES(, )EM(g)ES(, +or )EM(i)ES( to allow )EM(xpaset)ES(, )EM(xpaget)ES(, or +)EM(xpainfo)ES( access respectively. The ACL argument can be +)EM(+)ES( to give )EM(sgi)ES( access or it can be )EM(-)ES( to turn +off all access. + +)0 P(For example, +) 3 21 PR( *:xpa1 somehost sg + *:xpa1 myhost + + * * g)RP( +will allow processes on the machine somehost to make xpaget and xpaset calls, +allow processes on myhost to make any call, and allow all other hosts to +make xpaget \201but not xpaset\202 calls. + +Secondly, if the )EM(XPA_ACLFILE)ES( does not exist, then a single +default value for all access points can be specified using the +)EM(XPA_DEFACL)ES( environment variable. The default value for this +variable is: +) 1 34 PR( #define XPA_DEFACL "*:* $host +")RP( +meaning that all access points are fully accessible to all processes +on the current host. Thus, in the absence of any ACL environment variables, +processes on the current host have full access to all access points +created on that host. This parallels the X11 xhost mechanism. + +)0 P(Access to an individual XPA access point can be changed using the -acl +parameter for that access point. For example: +) 1 34 PR( xpaset -p xpa1 -acl "somehost -")RP( +will turn off all access control for somehost to the xpa1 access point, while: +) 1 38 PR( xpaset -p XPA:xpa1 -acl "beberly gs")RP( +will give beberly xpaget and xpaset access to the access point whose +class is XPA and whose name is xpa1. +)0 P(Similarly, the current ACL for a given access point can be retrieved using: +) 1 18 PR( xpaget xpa1 -acl)RP( +Of course, you must have xpaget access to this XPA access point to +retrieve its ACL. + +)0 P(Note that the XPA access points registered in the )EM(xpans)ES( +program also behave according to the ACL rules. That is, you cannot +use xpaget to view the access points registered with xpans unless +you have the proper ACL. + +)0 P(Note also when a client request is made to an XPA server, the access +control is checked when the initial connection is established. This +access in effect at this time remains in effect so long as the client +connection is maintained, regardless of whether the access fro that +XPA is changed later on. + +)0 P(We recognize that host-based access control is only relatively secure +and will consider more stringent security \201e.g., private key\202 in the +future if the community requires such support. + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 100 H(Last)WB 168 Sn( updated: September 10, 2003)EH( + +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (changelog.html) D +/Ti (XPA ChangeLog) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 42 Sn( +)0 2 101 H(XPA)WB 169 Sn( ChangeLog)EH( + +)0 P(This ChangeLog covers the XPA 2 implementation. It will be updated +as we continue to develop and improve XPA. The up-to-date version can be +found )R1 2 A(here)EA(. + +)0 2 102 H()WB 170 Sn( Public Release 2.1.15 \201July 23, 2013\202)EH( +)UL()0 P()-1 LI( Added support for large data transfers +)0 P()-1 LI( XPAGet and XPASet now pass size_t instead of int for lengths +)0 P()-1 LI( Send and receive callbacks now pass size_t instead of int for lengths +)0 P()-1 LI( Port to mingw \201Windows\202)LU( + + +)0 2 103 H()WB 171 Sn( Public Release 2.1.14 \201June 7, 2012\202)EH( +)UL()0 P()-1 LI( Fixed several memory leaks in the Tcl wrappers \201tcl.c\202. +)0 P()-1 LI( Use Tcl stubs library for linking shared Tcl, if available.)LU( + +)0 2 104 H()WB 172 Sn( Public Release 2.1.13 \201April 14, 2011\202)EH( +)UL()0 P()-1 LI( An atexit handler is no longer installed automatically \201it crashes +Tcl 8.5.8 applications\202. Call XPAAtExit\201void\202 to install the handler. +)0 P()-1 LI( Removed permission checking from Find\201\202 on cygwin systems. This was broken +by Windows 7. +)0 P()-1 LI( Removed addition of -no-cpp-precomp flag from gcc 4.2 and beyond \201Mac\202.)LU( + +)0 2 105 H()WB 173 Sn( Public Release 2.1.12 \201January 26, 2010\202)EH( +)UL()0 P()-1 LI( Added XPA_HOST environment variable to allow users to specify +the hostname \201and hence, ip\202 component of the INET method id. This is +useful, for example, if you want to register an access point using a +VPN-generated IP instead of the canonical IP. +)0 P()-1 LI( Fix typo in Tcl binding to xpainfo causing a crash after 2 invocations.)LU( + +)0 2 106 H()WB 174 Sn( Public Release 2.1.11 \201December 7, 2009\202)EH( +)UL()0 P()-1 LI( Generalized XPANSKeepAlive\201\202 to send messages to xpans, proxy xpans, or +both. The default is to send just to proxies \201e.g. chandra-ed\202. +)0 P()-1 LI( Changed XPANSKeepAlive\201\202 to send an in-band new-line char to +xpans, changed xpans to handle an in-band new-line as a keep-alive +message. Necessitated by Cisco routers that clear the URG flag in +a TCP packet, breaking OOB data transfer for the whole Internet, as +well as the OOB-based keep-alive implemented in xpans. +)0 P()-1 LI( In xpans, print warning when the keep-alive option switch is used. +)0 P()-1 LI( Port to mingw \201thanks to B.Schoenhammer\202 +)0 P()-1 LI( Change OOB character sent by xpans keepalive to a space, trying to working around cisco routers that force OOB data into the inbound stream. +)0 P()-1 LI( fix gcc fprintf warning in xpans.c)LU( + +)0 2 107 H()WB 175 Sn( Public Release 2.1.10 \201September 1, 2009\202)EH( +)UL()0 P()-1 LI( Update mklib and configure.ac to support 64-bit builds on Macs. +)0 P()-1 LI( Fixed bug in XPAAccess\201\202 in which the returned names could have an extra +\201bogus\202 character when the target is an explicit ip:port or local socket file. +)0 P()-1 LI( Add setjmp/longjmp support to xalloc. +)0 P()-1 LI( Add XPASaveJmp\201void *env\202 as a high-level interface to xalloc_savejmp\201\202;)LU( + +)0 2 108 H()WB 176 Sn( Internal Release 2.1.9)EH( +)UL()0 P()-1 LI( Fixed a bug that prevented an access point starting with a number +from being recognized peoperly. NB: a pure number still signifies a +port on the current machine. Also num:num signifies ip:port, where ip +can be a pure hex value or the canonical form vvv.xxx.yyy.zzz. +)0 P()-1 LI( Modified internal Launch\201\202 routine to use posix_spawn\201\202, if necessary. +This is required for OS X 10.5 \201leopard\202, which frowns upon use of fork\201\202 +and exec\201\202. Also modified zprocess routines to use Launch\201\202. +)0 P()-1 LI( Added XPASetFree\201xpa, void \201*myfree\202\201void *\202\202 routine to allow callbacks +to specify a free routine other than malloc free \201e.g. Perl garbage collection\202. +)0 P()-1 LI( XPACmdAdd\201\202 now checks to ensure that it was passed an XPA struct created +by XPACmdNew\201\202. +)0 P()-1 LI( Change launch.h to xlaunch.h to avoid conflict with OS X.)LU( + +)0 2 109 H()WB 177 Sn( Public Release 2.1.8 \2011 November 2007\202)EH( +)UL()0 P()-1 LI( A public release to complete current XPA development work.)LU( + +)0 2 110 H()WB 178 Sn( Patch Release 2.1.7b[1,2] \201Feb 22, 2006; March 8, 2007\202)EH( +)UL( +)0 P()-1 LI( Added a convenience null to the end of the buffers returned by XPAGet. + +)0 P()-1 LI( Added code to avoid calling atexit routine if a fork'ed child +calls exit\201\202 instead of _exit\201\202. + +)0 P()-1 LI( Added XPA_CLIENT_DOXPA environment variable to turn off client +processing of xpa server requests. + +)0 P()-1 LI( Added --version to xpaset, xpaget, xpainfo, xpaaccess, xpans to +display XPA version and exit. + +)0 P()-1 LI( Added support for integrating XPA into a Gtk loop. + +)0 P()-1 LI( xpaaccess now returns its answer in the error code as well as to stdout +\201without the -n switch, it returns 1 for a match, with the -n switch, +the number of matches is returned\202. + +)0 P()-1 LI( Fixed bug which prevented xpans from being started up automatically +by an xpa server if its pathname contained a space character. + +)0 P()-1 LI( Fixed bug in MINGW port of xpans in which an XPA server that +terminated via an interrupt was not being properly removed from the +list of registered access points. + +)0 P()-1 LI( Added XPA_LOGNAME to override LOGNAME when registering username + +)0 P()-1 LI( Upgraded swish-e indexing code to 2.4.5. +)LU( + +)0 2 111 H()WB 179 Sn( Patch Release 2.1.6 \2014 May 2005\202)EH( +)UL( +)0 P()-1 LI( Added -P switch to xpans to enable experimental proxy support +\201default is disabled\202. An argument of 1 processes proxy requests in +the same thread as xpans requests, while an argument of 2 processes +proxy requests in a separate thread. \201The latter is recommended to +avoid xpans timeouts, since xpa callback processing can take a long +time.\202 + +)0 P( +)-1 LI( Added ability to build shared libraries \201done automatically with +configure --enable-shared\202 with compilers other than gcc. + +)0 P()-1 LI( Made yet another attempt to build shared libraries under OS X. + +)0 P()-1 LI( Fixed a server bug in Tcl support under Windows \201introduced early +in 2.1.6\202 which caused an occasional SEGV. + +)0 P()-1 LI( Fixed race condition in cases where 2 or more servers makes client calls +to one another. + +)0 P()-1 LI( Fixed bug in the XPA handler routine in which an access point was +turned off if an error occurred in that routine \201as opposed to the +user-defined callback routine\202. + +)0 P()-1 LI( Fixed race condition when "ack=false" flag \201or -n\202 is used with XPASet\201\202 +\201or xpaset\202. + +)0 P()-1 LI( Added defensive code to XPA handler to ensure that the passed XPA record +is valid. + +)0 P()-1 LI( Tcl/XPA servers such as ds9 were not turning off select\201\202 on the +xpa channels inside an xpa callback, as required. This is now fixed. + +)0 P()-1 LI( Added timestamps to most server and client error messages if the +XPA_TIMESTAMP_ERRORS variable is set. This is useful when XPA errors are +being logged in an error log \201e.g. Web/CGI use\202. + +)0 P()-1 LI( Generated PostScript and PDF versions of the help pages. + +)0 P()-1 LI( Moved OPTIONS section before \201often-lengthy\202 DESCRIPTION section in +man pages. + +)0 P()-1 LI( All memory allocation now performs error checking on the result. + +)0 P()-1 LI( Removed some compiler warnings that surfaced when using gcc -O2. + +)0 P()-1 LI( Updated configure.ac to better support Tcl in Panther with Apple +Frameworks. +)LU( + +)0 2 112 H()WB 180 Sn( Patch Release 2.1.5 \20112 January 2004\202)EH( +)UL( +)0 P()-1 LI( Fixed bug in XPAPoll\201\202. Erroneously, no requests were being +processed when maxreq==0. Now, all pending events are processed, as +per the documentation. + +)0 P()-1 LI( Added ack=false to XPAInfo\201\202 \201and corresponding -n to xpainfo\202 +so that client does not wait for a response from the server. This is +essential in cases where XPA servers wish to send info messages to +one another without causing a race condition. + +)0 P()-1 LI( Generated man pages from the html pages. These are installed +automatically at build time. + +)0 P()-1 LI( The xpans program with Unix sockets now uses a lock file to signal +that it is running, in order to avoid a potential \201but rare\202 race +condition at startup. + +)0 P()-1 LI( Code that calls Unix-type bind\201\202 now manipulate umask\201\202 to ensure that +all users have write permissions to the socket file \201OS X apparently uses +these permissions while previous platforms ignore them\202. + +)0 P()-1 LI( Configure now checks for socklen_t type \201OS X does not define it\202. + +)0 P( +)-1 LI( Added an atexit function to run XPAFree. The aim here is to delete Unix +socket files on exiting. + +)0 P()-1 LI( Under Windows, the Tcl event-handling code now blocks for 1/1000 of a +second instead of not blocking at all \201which inadvertently used 100% of cpu\202. + +)0 P()-1 LI( Upgraded Tcl/Tk support to 8.4. + +)0 P()-1 LI( Made another round of checks was made through all instances of +strcat, strcpy, etc. to look for potential buffer overflows. Changed +all instances of sprintf\201\202 to snprintf\201\202. + +)0 P()-1 LI( Class and name designators are now limited to 1024 characters, for +no particular reason. + +)0 P()-1 LI( The obsolete $SAORD_BIN variable was being added to the path when +searching for xpans. This is no longer the case. + +)0 P()-1 LI( Fixed non-ANSI compiler errors in both xpa.c and xpans.c. + +)0 P()-1 LI( Fixed minor problems to support compilation with g++. + +)0 P()-1 LI( Ported to Intel icc and gcc 3.3 compilers. + +)0 P()-1 LI( Upgraded autoconf to 2.57. Included in this upgrade is a change that +makes gcc the default compiler \201use "configure CC=cc" to change this\202. +Also, by default, the Tcl shared object is no longer automatically built +if the Tcl libraries are used. Use the --enable-tclshlib switch in +configure to enable this feature. + +)0 P()-1 LI( Changed license from public domain to GNU GPL. +)LU( + +)0 2 113 H()WB 181 Sn( Patch Release 2.1.4 \20124 March 2003\202)EH( +)UL( +)0 P()-1 LI( Made inet method unique, even when hosts are behind a firewall using +the same ports \201on different local machines\202. + +)0 P()-1 LI( The initial connection from an xpa server to a local xpans now is +controlled by a timeout \201default 5 sec, controlled by XPA_CONNECT_TIMEOUT +variable\202. This should prevent a hang on connect\201\202 if the network +is not set up correctly. + +)0 P()-1 LI( Fixed rare race condition when an XPA server callback performed its own +XPAGet or XPASet call to another XPA server. + +)0 P()-1 LI( Use POSIX O_NONBLOCK for non-blocking I/O in fcntl call if it +exists, instead of O_NDELAY. +)LU( + +)0 2 114 H()WB 182 Sn( Patch Release 2.1.3 \20126 September 2002\202)EH( +)UL( +)0 P()-1 LI( Added -k [sec] switch to xpans to support sending one-byte keepalive +messages from xpans to registered xpa servers. + +)0 P()-1 LI( Added XPANSKeepAlive routine \201and Tcl equivalent\202 to allow +xpa servers to send a one-byte keepalive message to xpans. +)LU( + +)0 2 115 H()WB 183 Sn( Patch Release 2.1.2 \20118 July 2002\202)EH( +)UL( +)0 P()-1 LI( The "-help" reserved command now also displays the XPA version, if +no explicit sub-commands are specified. + +)0 P()-1 LI( Change internal state of xpans proxy to save ip:port value of a +server behind a NAT firewall. This is required to give some hope of +distinguishing multiple instances of ds9 running behind NAT. +)LU( + +)0 2 116 H()WB 184 Sn( Patch Release 2.1.1 \20120 June 2002\202)EH( +)UL( +)0 P()-1 LI( Added a version check between xpans and an access point, +performed when it gets registered by an XPA server. If the server +has a version greater than the xpans version, a warning is issued by +both programs. + +)0 P()-1 LI( Added a boolean XPA_NSREGISTER environment variable to allow an +XPA server to skip xpans registration. The default is to register with +the name server. If set to "false", the access point still is set up +but it is not registered with an xpans. It can be registered later on +\201using -remote or -proxy, for example\202. + +)0 P()-1 LI( Fixed bug in which xpans was still listening on any interface when +XPA_METHOD was localhost \201instead of just listening on localhost\202. +)LU( + +)0 2 117 H()WB 185 Sn( Public Release 2.1.0 \20122 April 2002\202)EH( + +)0 P(New features include: + +)UL()0 P()-1 LI( Support for proxy access to XPA servers \201e.g. ds9\202 situated +behind a firewall \201useful for NVO-type applications\202. + +)0 P()-1 LI( Improved support for allowing remote machines access rights to the +XPA access points \201useful for NVO-type applications\202. + +)0 P()-1 LI( Ability for XPAAccess\201\202 routine and xpaaccess program to contact XPA + directly. + +)0 P()-1 LI( Support for a clipboard access point that allows clients to store ASCII +state information in an XPA-enabled server. + +)0 P()-1 LI( Improved support for Windows platform, as well as new support for Mac OSX.)LU( + +)0 2 118 H()WB 186 Sn( Pre-Release 2.1.0e \2012 April 2002\202)EH( +)UL( +)0 P()-1 LI( Removed the environment variable generated by each XPA access +point \201of the form XPA_name=method\202. The putenv\201\202 call was causing ds9 +to crash under both Linux and LinuxPPC during a socket operation. We +suspect a bug in putenv but cannot prove it and this feature is not +essential, so ... +)LU( + +)0 2 119 H()WB 187 Sn( Pre-Release 2.1.0e \2011 April 2002\202)EH( +)UL( +)0 P()-1 LI( Fixed an uninitialized variable in xpamb which prevented it from +working at all on some systems. + +)0 P()-1 LI( Changed xpamb switch from "-add" to "-data" \201to store named data\202. + +)0 P()-1 LI( Changed how xpamb works with xpaget so that xpamb can return data +from XPA access points as well as from stored data. \201Previous versions +only returned stored data.\202 Now, you can retrieve stored data +explicitly using the -info and/or -data switches. For example: +) 1 24 PR( xpaget xpamb -info foo)RP( +will return info about the previously stored data named foo. If +neither switch is present, then the name is assumed to be an XPA access +point.)LU( + +)0 2 120 H()WB 188 Sn( Pre-Release 2.1.0e \20125 March 2002\202)EH( +)UL( +)0 P()-1 LI( Changed symbol for default port from "*" to "$port" to avoid +a syntactical conflict between class:* and machine:* when processing an +XPA access point class:name specification. Thus, the default inet +method now is '$host:$port' instead of '$host:*'. +)LU( + +)0 2 121 H()WB 189 Sn( Pre-Release 2.1.0e \20119 March 2002\202)EH( +)UL( +)0 P()-1 LI( Removed timeout check when reading data \201in clients using xpaget +and servers filling the data buffer\202. We have more and more cases +where we need to wait a long time to retrieve data \201e.g., slow +networks or receiving data being compressed on the fly\202. + +)0 P()-1 LI( Moved call to sigaction\201SIGCHLD,...\202 out of XPAOpen\201\202, so that it +is only executed when needed by XPAGet\201\202/XPASet\201\202 routines called from +within xpans/proxy. But then changed logic to use a double fork\201\202 instead +of sigaction\201\202 to prevent zombies \201Stevens Adv. Programming p 202\202. + +)0 P()-1 LI( Each XPA access point now generates an environment variable of the +form XPA_name=method so that children can communicate with the parent access +point more easily. + +)0 P()-1 LI( Added version option to Tcl xparec: +) 5 44 PR( if [catch { xparec "" version } version] { + puts "pre-2.1.0e" + } else { + puts [split $version .] + })RP( +to help differentiate between XPA versions within Tcl code. +)LU( + +)0 2 122 H()WB 190 Sn( Pre-Release 2.1.0e \20114 February 2002\202)EH( +)UL()0 P()-1 LI( Fixed client handling of out-of-sync messages.)LU( + +)0 2 123 H()WB 191 Sn( Pre-Release 2.1.0e \20111 February 2002\202)EH( +)UL( +)0 P()-1 LI( Fixed client.c/xopen\201\202 so that it does not open an extra socket. + +)0 P()-1 LI( Fixed xpainfo/xopen\201\202 to prevent client from hanging waiting for ack. + +)0 P( +)-1 LI( Modified stest to generate xpaaccess points xpa, xpa1, c_xpa, and +i_xpa \201or more generally, , 1, c_, i\202 to allow +more flexible testing of templates. Also added -a for testing XPAAccess\201\202. +)LU( + +)0 2 124 H()WB 192 Sn( Beta Release 2.1.0b10 \20131 January 2002\202)EH( +)UL( +)0 P()-1 LI( Added support for Mac OSX/Darwin to configure file. +)LU( + +)0 2 125 H()WB 193 Sn( Beta Release 2.1.0b9 \20126 January 2002\202)EH( +)UL( +)0 P()-1 LI( Fixed bug in client library that caused XPAAccess\201\202 call to hang. +)LU( + +)0 2 126 H()WB 194 Sn( Beta Release 2.1.0b8 \2014 January 2002\202)EH( +)UL( +)0 P()-1 LI( Made modifications to Makefile.in to make releases easier. + +)0 P()-1 LI( Added instructions to Makefile.in so that xpa.h will always have +correct #defines for XPA_VERSION, XPA_MAJOR_VERSION, XPA_MINOR_VERSION, +and XPA_PATCH_LEVEL. +)LU( + +)0 2 127 H()WB 195 Sn( Beta Release 2.1.0b7 \20121 December 2001\202)EH( +)UL( +)0 P()-1 LI( Added -proxy switch to -remote sub-command to allow remote access +through a firewall, using xpans as a proxy server. The support for proxy +processing required a change to the client/server protocol. This means +that new xpa servers will not work with old xpa clients \201although new +xpa clients will work with old xpa servers\202. For details about proxy +firewall support, see http://hea-www.harvard.edu/RD/xpa/inet.html. + +)0 P()-1 LI( Fixed Tcl support for XPA under Windows/Cygwin by re-writing +the code used to add XPA to the Tcl event loop. This fix makes ds9 +support for XPA much more stable under Windows. + +)0 P()-1 LI( Added the shutdown\201\202 call to XPA under Cygwin/Windows before +closing send\201\202 sockets. It appears that a Cygwin recv\201\202 socket call +does not always sense when the other end closes the socket using +close\201\202. This measure must be considered a hack, since the actual +problem was never resolved. + +)0 P()-1 LI( Added code to protect accept\201\202 and select\201\202 calls from interrupts. + +)0 P()-1 LI( Extended syntax of the environment variable XPA_NSINET to: +) 1 43 PR( setenv XPA_NSINET host:port[,port[,port]])RP( +to allow specification of the XPA access point port for xpans, +as well as the proxy data port. + +)0 P()-1 LI( Modified xpans log file so that it contains the xpaset commands +required to reconnect with xpa servers. + +)0 P()-1 LI( xpans now deletes its Unix socket files. +)LU( + +)0 2 128 H()WB 196 Sn( Beta Release 2.1.0b6 \20129 October 2001\202)EH( +)UL( +)0 P()-1 LI( Implemented a reserve public access point named -clipboard so +that clients can store ASCII state information on any number of named +clipboards. Clipboards of the same name created by clients on +different machines are kept separate. The syntax for creating a +clipboard is: +) 3 65 PR( [data] | xpaset [server] -clipboard add|append [clipboard_name] + xpaset -p [server] -clipboard delete [clipboard_name] + xpaget [server] -clipboard [clipboard_name])RP( +Use "add" to create a new clipboard or replace the contents of an existing +one. Use "append" to append to an existing clipboard. +)LU( + +)0 2 129 H()WB 197 Sn( Beta Release 2.1.0b5 \20122 October 2001\202)EH( +)UL( +)0 P()-1 LI( Use FD_SETSIZE instead of getdtablesize\201\202 to determine how many files +to check during select\201\202; + +)0 P()-1 LI( Under Cygwin, the launch\201\202 routine now uses the Cygwin spawnvp\201\202 +instead of fork\201\202/exec\201\202 where possible \201i.e., if no stdfiles are +being redirected\202. This is recommended by Cygwin's \201skimpy\202 on-line +documentation and seems to fix the problems ds9 had when starting xpans +automatically. + +)0 P()-1 LI( Added error check to select\201\202 call in xpans. +)LU( + +)0 2 130 H()WB 198 Sn( Beta Release 2.1.0b4 \20124 September 2001\202)EH( +)UL( +)0 P()-1 LI( The launch\201\202 now can return an error code if the execv\201\202 system +call fails \201something system\201\202 does not do\202. + +)0 P()-1 LI( INET socket calls between xpa clients and servers now will use +localhost if they are on the same machine. This protects against +Linux systems where the hostname is hardwired \201wrongly\202 in a DHCP +environment. +)LU( + +)0 2 131 H()WB 199 Sn( Beta Release 2.1.0b3 \2016 September 2001\202)EH( +)UL( +)0 P()-1 LI( Modified xpans so that, in the case of a firewall, it tries to +correct the specified ip:port by matching against the ip found in +the socket packet at accept\201\202 time. + +)0 P()-1 LI( Replaced system\201\202 call used to start xpans automatically with +a special launch\201\202 call, which performs execvp\201\202 directly without going +through sh. \201launch\201\202 works under DOS and has fewer security problems.\202 + +)0 P()-1 LI( Fixed bug in xpans in which its xpa port was always being set to 14286. +)LU( + +)0 2 132 H()WB 200 Sn( Beta Release 2.1.0b2 \20117 August 2001\202)EH( +)UL( +)0 P()-1 LI(Added support for -remote command, which registers the access +point in the XPA name server of the specified remote server, and gives +the remote server access rights to the access point. This is used, for +example, to give data servers xpa access to ds9 so that data can be +sent to ds9 as a result of a CGI-based Web query. + +)0 P()-1 LI(Reserved commands \201except "-help" and "-version"\202 now can only be +executed on the machine on which the xpa service is running \201not +through -remote servers\202. + +)0 P()-1 LI(Fixed bug in xpans in which a bad telnet command could hang the program. + +)0 P()-1 LI(Added -s [security file] to xpans to allow logging of all external +connections. +)LU( + +)0 2 133 H()WB 201 Sn( Beta Release 2.1.0b1 \2016 August 2001\202)EH( +)UL()0 P()-1 LI( The xpaaccess client program and XPAAccess\201\202 client subroutine +were modified so that an access-type query can directly contact the +xpa servers matching the requested xpa template, instead of just +querying the name server for registered access points. This avoid the +race condition in which an access point is registered but is not yet +available, perhaps because the server has not yet entered its event +loop. Note that the calling sequence of the XPAAccess\201\202 routine was +changed to return all matching access points and their availability +status \201instead of just returning the number of registered access +points\202. Because of this, we are calling this a minor release instead +of a patch. + +)0 P()-1 LI( Added support for XPA_PORT and XPA_PORTFILE environment variables +to allow specification of the port to be used by the command channel +\201and data channel, if an optional second port is specified\202 for a given +access point. + +)0 P()-1 LI( Added -m switch to xpaget, xpaset, xpainfo, xpaaccess to allow +override of the XPA_METHOD environment variable. + +)0 P()-1 LI( Changed the default name of the ACL file from xpa.acl to acls.xpa. + +)0 P()-1 LI( Fixed bug in which it was not possible to send a "set ACL" +command to an XPA server which did not have a receive callback \201i.e., +did not allow xpaset\202. The xpans program is one such server. It now is +possible to set the ACL on xpans. + +)0 P()-1 LI( We have discovered that Tcl support for datachan and cmdchan is +broken under Windows due to an unexplained incompatibility between +Cygwin sockets and Win32 sockets. We therefore have removed datachan +and cmdchan from the Windows/Tcl support until further notice. + +)0 P()-1 LI( Extended the behavior of the XPA_DEFACL environment variable so that +it can support more than one acl, using a list of semi-colon delimited +controls such as: setenv XPA_DEFACL '*:* $host +; *:foo1 otherhost +'. + +)0 P()-1 LI( Fixed bug in which the class:name specifier "*:*" was erroneously +trying to access the xpans name server, instead of accessing all +access points. + +)0 P()-1 LI( Support TMPDIR and TMP environment variables as well as XPA_TMPDIR. +)LU( + +)0 2 134 H()WB 202 Sn( Patch Release 2.0.5 \20110 November 2000\202)EH( +)UL()0 P()-1 LI( Added support for Tcl on Windows where there is no select\201\202-based +event loop \201i.e., where there is no Tcl_CreateFileHandler call in Tcl\202 +)0 P()-1 LI( Minor fixes in Makefile for installing on Windows +)0 P()-1 LI( Minor compiler fixes from gcc -Wall.)LU( + +)0 2 135 H()WB 203 Sn( Patch Release 2.0.4 \20120 September 2000\202 )EH( +)UL()0 P()-1 LI( Removed extraneous include of varargs.h from find.c. +)0 P()-1 LI( Ported to SGI C compiler, which caught lots of unused variables, etc. +)0 P()-1 LI( Ported to Cygwin/Windows, which required that we change socket read\201\202 +and write\201\202 calls to recv\201\202 and send\201\202 respectively. Also had to ensure that +we only did socket I/O on sockets \201no fileio\202.)LU( + +)0 2 136 H()WB 204 Sn( Patch Release 2.0.3 \20115 June 2000\202 )EH( +)UL( +)0 P()-1 LI( Fixed the client XPASet\201\202 and XPASetFd\201\202 calls to handle the specified +max number of connections \201they were ignoring this argument, leading to +memory overwrites\202. +)0 P()-1 LI( Fixed Makefile.in so that CFLAGS and LDFLAGS are not hard-wired values. +)0 P()-1 LI( Fixed word.h to load malloc.h and stdlib.h only if they exist. +)0 P()-1 LI( Documentation fixes to programs.html \201in xpaaccess\202 and client.html +\201XPANSLookup\202. +)0 P()-1 LI( Added explicit typecast to strlen\201\202 argument to MAX #define in +XPAClientStart \201strlen\201\202 is unsigned in Linux, which can break MAX\202. +)0 P()-1 LI( Removed bogus Imakefile from directory. +)0 P()-1 LI( Changed directory name to include patch level \201i.e., xpa-2.0.3\202.)LU( + +)0 2 137 H()WB 205 Sn( Patch Release 2.0.2 \2019 September 1999\202)EH( +)UL( +)0 P()-1 LI( Fixed server mode \201-s\202 in the xpaset program by properly cleaning up +the input buffers \201sending commands and data in server mode was broken\202.)LU( + +)0 2 138 H()WB 206 Sn( Patch Release 2.0.1 \2016 August 1999\202)EH( +)UL( +)0 P()-1 LI( Fixed the Tcl binding code \201tcl.c\202 for 64-bit machines \201Dec Alpha\202 +\201erroneously used %x instead of %p when converting pointers to ASCII\202. +)0 P()-1 LI( Got rid of a few compiler warnings on 64-bit machines \201a few are +unavoidable since we must cast int to void * and back when passing around +client data\202.)LU( + +)0 2 139 H()WB 207 Sn( Public Release 2.0 \20127 May 1999\202)EH( +)UL( +)0 P()-1 LI( "a new day with no mistakes ... yet")LU( + +)2 1 1 HR()0 P()0 0 1 A(Index to the XPA Help Pages)0 0 TN TL()Ec /AF f D( + +)2 1 1 HR()0 5 140 H(Last)WB 208 Sn( updated: 22 April 2002)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (examples.html) D +/Ti (Where to Find Example/Test Code) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 43 Sn( + + +)0 2 141 H(XPACode:)WB 210 Sn()WB 209 Sn( Where to Find Example/Test Code)EA()EH( + + +)0 2 142 H(Summary)WB 211 Sn()EH( +)0 P(The XPA source code directory contains two test programs, +)EM(stest.c)ES(, and )EM(ctest.c)ES( that can serve as +examples for writing XPA servers and clients, respectively. +They also can be used to test various features of XPA. + + +)0 2 143 H(Description)WB 212 Sn()EH( +)0 P(To build the XPA test programs, execute: +) 1 11 PR( make All)RP( +in the XPA source directory to generate the )EM(stest)ES( and +)EM(ctest)ES( programs. \201NB: this should work on all platforms, +although we have had problems with unresolved externals on one +Sun/Solaris machine, for reasons still unknown.\202 +)0 P(The stest program can be executed with no arguments to start +an XPA server that contains the access points: xpa, xpa1, +c_xpa \201containing sub-commands cmd1 and cmd2\202, and i_xpa. +You then can use xpaset and xpaget to interact with these access points: +) 4 57 PR( cat xpa.c | xpaset xpa # send to xpa + cat xpa.c | xpaset "xpa*" # send to xpa and xpa1 + xpaget xpa # receive from xpa + xpaget xpa* # receive from xpa and xpa1)RP( +etc. You also can use ctest to do the same thing, or to iterate: +) 4 66 PR( ctest -s -l 100 xpa # send to xpa 100 times + ctest -s -l 100 "xpa*" # send to xpa and xpa1 100 times + ctest -g -l 100 xpa # receive from xpa 100 times + ctest -g -l 100 "xpa*" # receive from xpa and xpa1 100 times)RP( +More options are available: see the stest.c and ctest.c code itself, which +were used extensively to debug XPA. + +)0 P(The file test.tcl in the XPA source directory gives examples for using the +)0 39 1 A(XPATcl)39 0 TN TL()Ec /AF f D(Interface. + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 144 H(Last)WB 213 Sn( updated: September 10, 2003)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (changes.html) D +/Ti (Changes For Users from XPA 1.0 and 2.0) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 44 Sn( + + +)0 2 145 H(XPA)WB 215 Sn()WB 214 Sn( Changes: Changes For Users from XPA 1.0 and 2.0)EA()EH( + + +)0 2 146 H(Summary)WB 216 Sn()EH( +)0 P(This document describes changes that will affect users who migrate +from XPA 1.0 to XPA 2.0. + + +)0 2 147 H(Description)WB 217 Sn()EH( +)0 P(There have been a few changes that affect users who upgrade XPA +from version 1.0 to version 2.0. These changes are detailed below. +)UL()0 P()-1 LI(XPA commands no longer have a resolver routine \201this is open to +negotiations, but we decided the idea was dumb\202. For the SAOtng +program, this means that you must explicitly specify the access +point, i.e.,: +) 1 35 PR( cat foo.fits | xpaset SAOtng fits)RP( + +)0 P(instead of: +) 1 30 PR( cat foo.fits | xpaset SAOtng)RP( +)0 P()-1 LI(By default, xpaset, xpaget, etc. now wait for the server callback to +complete; i.e., the old -W is implied \201and the switch is ignored\202. +This allows support for better error handling. If you want xpaset, etc. +to return before the callback is complete, use -n switch: +) 1 41 PR( echo "file foo.fits" | xpaset -n SAOtng)RP( +)0 P()-1 LI(The old -w switch in xpaset and xpaget is no longer necessary \201and is +ignored\202, since you can have more than one process communicating with +an xpa access point at one time. + +)0 P()-1 LI(The new -p switch on xpaset means you need not read from stdout: +) 2 30 PR( + xpaset -p SAOtng colormap I8)RP( +)0 P(will send the paramlist to the SAOtng callback without reading from stdin. +)LU( + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 148 H(Last)WB 218 Sn( updated: September 10, 2003)EH( +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (convert.html) D +/Ti (Converting the XPA API to 2.0) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 45 Sn( + + +)0 2 149 H(XPAConvert:)WB 220 Sn()WB 219 Sn( Converting the XPA API to 2.0)EA()EH( + + +)0 2 150 H(Summary)WB 221 Sn()EH( +)0 P(This document describes tips for converting from xpa 1.0 \201Xt-based +xpa\202 to xpa 2.0 \201socket-based xpa\202. + + +)0 2 151 H(Description)WB 222 Sn()EH( +)0 P(The following are tips for converting from xpa 1.0 \201Xt-based xpa\202 to +xpa 2.0 \201socket-based xpa\202. The changes are straight-forward and +almost can be done automatically \201we used editor macros for most of +the conversion\202. +)UL()0 P()-1 LI(The existence of the cpp XPA_VERSION directive to distinguish between 1.0 +\201where it is not defined\202 and 2.0 \201where it is defined\202. + +)0 P()-1 LI(Remove the first widget argument from all send and receive server +callbacks. Also change first 2 arguments from XtPointer to void +*. For example: +) 16 74 PR(#ifdef XPA_VERSION +static void XPAReceiveFile\201client_data, call_data, paramlist, buf, len\202 + void *client_data; + void *call_data; + char *paramlist; + char *buf; + int len; +#else +static void XPAReceiveFile\201w, client_data, call_data, paramlist, buf, len\202 + Widget w; + XtPointer client_data; + XtPointer call_data; + char *paramlist; + char *buf; + int len; +#endif)RP( +)0 P()-1 LI(Server callbacks should be declared as returning int instead +of void. They now should return 0 for no errors, -1 for error. + +)0 P()-1 LI( The mode flags have changed when defining XPA server callbacks. +The old )EM(S)ES( flag \201save buffer\202 is replaced by )EM(freebuf=false)ES(. +The old )EM(E)ES( flag \201empty buffer is OK\202 is no longer used \201it +was an artifact of the X implementation\202. + +)0 P()-1 LI(Change NewXPACommand\201\202 to XPAcmdNew\201\202, with the new calling sequence: +) 1 52 PR( xpa = NewXPACommand\201toplevel, NULL, prefix, NULL\202;)RP( +is changed to: +) 1 32 PR( xpa = XPACmdNew\201xclass, name\202;)RP( +)0 P()-1 LI(Change the AddXPACommand\201\202 subroutine name to XPACmdAdd \201with the same +calling sequence\202: +) 3 53 PR( AddXPACommand\201xpa, "file", + "\200tdisplay a new file\200n\200t\200t requires: filename", + NULL, NULL, NULL, XPAReceiveFile, text, NULL\202;)RP( +is changed to: +) 3 53 PR( XPACmdAdd\201xpa, "file", + "\200tdisplay a new file\200n\200t\200t requires: filename", + NULL, NULL, NULL, XPAReceiveFile, text, NULL\202;)RP( +)0 P()-1 LI(The XPAXtAppInput\201\202 routine should be called just before XtAppMainLoop\201\202 +to add xpa fds to the Xt event loop: +) 5 35 PR( /* add the xpas to the Xt loop */ + XPAXtAddInput\201app, NULL\202; + + /* process events */ + XtAppMainLoop\201app\202;)RP( +)0 P()-1 LI(Change NewXPA\201\202 to XPANew\201\202 and call XPAXtAddInput\201\202 if the XtAppMainLoop +routine already has been entered: +) 4 71 PR( xpa = NewXPA\201saotng->xim->toplevel, prefix, xparoot, + "FITS data or image filename\200n\200t\200t options: file type", + XPASendData, new, NULL, + XPAReceiveData, new, "SE"\202;)RP( +is changed to: +) 6 74 PR( sprintf\201tbuf, "%s.%s", prefix, xparoot\202; + xpa = XPANew\201"SAOTNG", tbuf, + "FITS data or image filename\200n\200t\200t options: file type", + XPASendData, new, NULL, + XPAReceiveData, new, "SE"\202; + XPAXtAddInput\201XtWidgetToApplicationContext\201saotng->xim->toplevel\202, xpa\202;)RP( +)0 P()-1 LI(Change XPAInternalReceiveCommand\201\202 to XPACmdInternalReceive\201\202 +remove first argument in the calling sequence\202: +) 3 61 PR( XPAInternalReceiveCommand\201im->saotng->xim->toplevel, + im->saotng, im->saotng->commands, + "zoom reset", NULL, 0\202;)RP( +is changed to: +) 2 57 PR( XPACmdInternalReceive\201im->saotng, im->saotng->commands, + "zoom reset", NULL, 0\202;)RP( +)0 P()-1 LI(Change DestroyXPA to XPAFree: +) 1 26 PR( DestroyXPA\201im->dataxpa\202;)RP( +is changed to: +) 1 23 PR( XPAFree\201im->dataxpa\202;)RP()LU( + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 152 H(Last)WB 223 Sn( updated: September 10, 2003)EH( + +)WB NL +/Cb Db D /Ct [16#00 16#00 16#00] D /Cl [16#00 16#00 16#00] D /CL -1 D Ct Sc +DS +/Ba f D /BO 0 D Bs +/UR (name.html) D +/Ti (What does XPA stand for?) D +/Au () D +/Df f D +/ME [()] D + +0 BO R +()1 Sl()WB 46 Sn( + + +)0 2 153 H(XPAName:)WB 225 Sn()WB 224 Sn( What does XPA stand for?)EA()EH( + + +)0 2 154 H(Summary)WB 226 Sn()EH( +)0 P(What does XPA stand for? Who knows anymore! + + +)0 2 155 H(Description)WB 227 Sn()EH( +)0 P(What does XPA stand for? Dunno! The XPA messaging system originally +was built on top of the X Window System and XPA was the mnemonic for +)EM(X Public Access)ES(, to emphasize that we were providing public +access to previously private data and algorithms in Xt programs. Now +that XPA no longer is tied to X, it can be argued that we ought to +change the name \201how about )EM(SPAM: simple public access mechanism)ES(\202, but XPA is in wide-spread use in the astronomical community of +its birth, and the name has taken on a life of its own. If anyone can +think of what XPA now means, please let us know. + +)0 P(If you think this is bad, consider the MMT Telescope on Mount Hopkins, +Arizona. When first installed twenty years ago, it featured an array +of six 72-inch diameter mirrors. from which came its name: the +)EM(Multiple Mirror Telescope)ES(. In spring of 1999, these mirrors +were replaced by a single 21 and 1/2 -foot diameter primary mirror, +the largest single-piece glass reflector on the North American +continent. And now MMT stands for ... MMT! + + + + + +)0 P()0 0 1 A(Go to XPA Help Index)0 0 TN TL()Ec /AF f D( + +)0 5 156 H(Last)WB 228 Sn( updated: September 10, 2003)EH( + +)WB NL +/TE t D NP TU PM 0 eq and{/Pn () D showpage}if end restore |