xpainfo(3) [debian man page]
xpainfo(3) SAORD Documentation xpainfo(3) NAME
XPAInfo - send short message to one or more XPA servers SYNOPSIS
#include <xpa.h> int XPAInfo(XPA xpa, char *template, char *paramlist, char *mode, char **names, char **messages, int n); DESCRIPTION
Send a short paramlist message to one or more XPA servers whose class:name identifier matches the specified template. A template 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 (which will be closed when the call completes). The XPAInfo() 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 (acting as a client) can obtain more info using XPAGet. 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: XPA$ERROR error-message (class:name ip:port) or XPA$MESSAGE message (class:name ip:port) 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. The following keywords are recognized: key value default explanation ------ -------- -------- ----------- ack true/false true if false, don't wait for ack from server When ack is false, XPAInfo() 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. Example - (void)XPAInfo(NULL, "IMAGE", "ds9 image", NULL, NULL, NULL, 0); SEE ALSO
See xpa(7) for a list of XPA help pages version 2.1.14 June 7, 2012 xpainfo(3)
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xpaset(3) SAORD Documentation xpaset(3) NAME
XPASet - send data to one or more XPA servers SYNOPSIS
#include <xpa.h> int XPASet(XPA xpa, char *template, char *paramlist, char *mode, char *buf, int len, char **names, char **messages, int n); DESCRIPTION
Send data to one or more XPA servers whose class:name identifier matches the specified template. A template 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 (which will be closed when the call completes). The XPASet() routine transfers data from buf to the XPA servers. The length of buf (in bytes) should be placed in the len variable. 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. The returned message string will be of the form: XPA$ERROR [error] (class:name ip:port) or XPA$MESSAGE [message] (class:name ip:port) 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. The mode string is of the form: "key1=value1,key2=value2,..." The following keywords are recognized: key value default explanation ------ -------- -------- ----------- ack true/false true if false, don't wait for ack from server (after callback completes) verify true/false false send buf from XPASet[Fd] to stdout doxpa true/false true client processes xpa requests 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. Normally, an XPA client will process incoming XPA server requests while awaiting the completion of the client request. Setting this vari- able to "false" will prevent XPA server requests from being processed by the client. Example - #include <xpa.h> #define NXPA 10 int i, got; int 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(NULL, "ds9", "fits", NULL, buf, len, names, messages, NXPA); /* error processing */ for(i=0; i<got; i++){ if( messages[i] ){ fprintf(stderr, "ERROR: %s (%s) ", messages[i], names[i]); } if( names[i] ) free(names[i]); if( messages[i] ) free(messages[i]); } SEE ALSO
See xpa(7) for a list of XPA help pages version 2.1.14 June 7, 2012 xpaset(3)