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author | William Joye <wjoye@cfa.harvard.edu> | 2017-10-26 16:45:12 (GMT) |
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committer | William Joye <wjoye@cfa.harvard.edu> | 2017-10-26 16:45:12 (GMT) |
commit | 6054f36bb658916bd231b9002efb94444e2871c8 (patch) | |
tree | a815500ec9bf0e100f4075a825213605c382def0 /doc/pod/xpanslookup.pod | |
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Squashed 'xpa/' content from commit d6a54301
git-subtree-dir: xpa
git-subtree-split: d6a543018b46c5a6c47b5ff91e0e131549595ca6
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diff --git a/doc/pod/xpanslookup.pod b/doc/pod/xpanslookup.pod new file mode 100644 index 0000000..e0f4cdc --- /dev/null +++ b/doc/pod/xpanslookup.pod @@ -0,0 +1,126 @@ +=pod + +=head1 NAME + + + +B<XPANSLookup: lookup registered XPA access points> + + + +=head1 SYNOPSIS + + + + + + #include <xpa.h> + + int XPANSLookup(XPA xpa, + char *template, char type, + char ***classes, char ***names, + char ***methods, char ***infos) + + + + + +=head1 DESCRIPTION + + + + +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 +template. 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(), XPASet(), etc. + + 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 (temporary) connection is established with the name server. + + +The second argument to XPANSLookup is the class:name +template +to match. + + +The third argument for XPANSLookup() is the type of access and can be +any combination of: + + 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 + + +The call typically specifies only one of these at a time. + + +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 template +and have the specified type. Also returned are info strings, which +generally are used internally by the client routines. These can be +ignored (but the strings must be freed). The function returns the +number of matches. The returned value can be used to loop through the +matches: + +B<Example:> + + #include <xpa.h> + + char **classes; + char **names; + char **methods; + char **infos; + int i, n; + n = XPANSLookup(NULL, "foo*", "g", &classes, &names, &methods, &infos); + for(i=0; i<n; i++){ + [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(classes[i]); + free(names[i]); + free(methods[i]); + free(infos[i]); + } + /* free up arrays alloc'ed by names server */ + if( n > 0 ){ + free(classes); + free(names); + free(methods); + free(infos); + } + + +The specified +template +also can be a host:port specification, for example: + + myhost:12345 + + +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. + + + + +=head1 SEE ALSO + + + +See xpa(n) for a list of XPA help pages + + +=cut |