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| author | William Joye <wjoye@cfa.harvard.edu> | 2018-01-23 16:53:51 (GMT) |
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| committer | William Joye <wjoye@cfa.harvard.edu> | 2018-01-23 16:53:51 (GMT) |
| commit | 51e1f85047b34f095ed69a3024d696997d2667c8 (patch) | |
| tree | a8d46838982aa78a35653c10d0b7370d751d6181 /xpa/doc/intro.html | |
| parent | 0c198f7902ee997dd8ec3631e8ff1c385257014d (diff) | |
| download | blt-51e1f85047b34f095ed69a3024d696997d2667c8.zip blt-51e1f85047b34f095ed69a3024d696997d2667c8.tar.gz blt-51e1f85047b34f095ed69a3024d696997d2667c8.tar.bz2 | |
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diff --git a/xpa/doc/intro.html b/xpa/doc/intro.html deleted file mode 100644 index f9c9947..0000000 --- a/xpa/doc/intro.html +++ /dev/null @@ -1,148 +0,0 @@ -<!-- =defdoc xpaintro xpaintro n --> -<HTML> -<HEAD> -<TITLE>Introduction to XPA</TITLE> -</HEAD> -<BODY> - -<!-- =section xpaintro NAME --> -<H2><A NAME="xpaintro">XPAIntro: Introduction to the XPA Messaging System</A></H2> - -<!-- =section xpaintro SYNOPSIS --> -<H2>Summary</H2> -<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. - -<!-- =section xpaintro DESCRIPTION --> -<H2>Description</H2> -<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. - -<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 (and users). 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. - -<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 -<A HREF="./tcl.html#">Tcl/Tk</A> -programs, -<A HREF="./xt.html#">Xt</A> -programs, or to Unix programs that use the XPA event loop or any -event loop based on select(). 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. - -<P> -The major components of the XPA layered interface are: -<UL> -<LI> -A set of XPA server routines, centered on -<A HREF="./server.html#xpanew">XPANew(),</A> -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. - -<LI> -A set of XPA client routines, centered on the -<A HREF="./client.html#xpaset">XPASet()</A> -and -<A HREF="./client.html#xpaget">XPAGet(),</A> -which are used by external client applications to exchange data and -commands with an XPA server. - -<LI> -High-level programs, centered on -<A HREF="./programs.html#xpaset">xpaset</A> -and -<A HREF="./programs.html#xpaget">xpaget,</A> -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: -<PRE> - [data] | xpaset <XPA name> [qualifiers ...] - xpaget <XPA name> [qualifiers ...] -</PRE> -<LI> -An XPA name server program, -<A HREF="./xpans.html">xpans,</A> -through which XPA access point names are -registered by servers and distributed to clients. -</UL> - -<P> -Defining an XPA access point is easy: a server application calls -<A HREF="./server.html#xpanew">XPANew(),</A> -<A HREF="./server.html#xpacmdnew">XPACmdNew(),</A> -or the experimental -<A HREF="./server.html#xpainfonew">XPAInfoNew()</A> -routine to -create a named public access point. An XPA service can specify "send" -and "receive" callback procedures (or an "info" procedure in the case -of XPAInfoNew()) 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 (or uses the standard XPA event loop). - -<P> -Clients communicate with these XPA public access points -using programs such as -<A HREF="./programs.html#xpaget">xpaget</A>, -<A HREF="./programs.html#xpaset">xpaset</A>, and -<A HREF="./programs.html#xpainfo">xpainfo</A> -(at the command line), -or routines such as -<A HREF="./client.html#xpaget">XPAGet(),</A> -<A HREF="./client.html#xpaset">XPASet(),</A> -and -<A HREF="./client.html#xpainfo">XPAInfo()</A> -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 -<A HREF="./template.html">template</A> -is used to specify the access point name (e.g., "ds9*"), then -communication will take place with all servers matching that template. - -<p> -Please note that XPA currently is not thread-safe. All XPA calls must be -in the same thread. - -<!-- =section xpaintro SEE ALSO --> -<!-- =text See xpa(n) for a list of XPA help pages --> -<!-- =stop --> - -<P> -<A HREF="./help.html">Go to XPA Help Index</A> - -<H5>Last updated: March 10, 2007</H5> -</BODY> -</HTML> - |