xpainfonew(3)

1xpainfonew(3)                 SAORD Documentation                xpainfonew(3)
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NAME

6       XPAInfoNew: define an XPA info public access point
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SYNOPSIS

9         #include <xpa.h>
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11         XPA XPAInfoNew(char *class, char *name,
12                        int (*info_callback)(),
13                        void *info_data, char *info_mode);
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DESCRIPTION

16       [NB: this is an experimental interface, new to XPA 2.0, whose value and
17       best use is evolving.]
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19       A program can register interest in receiving a short message about a
20       particular topic from any other process that cares to send such a
21       message.  Neither has to be an XPA server.  For example, if a user
22       starts to work with a new image file called new.fits, she might wish to
23       alert interested programs about this new file by sending a short
24       message using xpainfo:
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26         xpainfo IMAGEFILE /data/new.fits
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28       In this example, each process that has used the XPAInfoNew() call to
29       register interest in messages associated with the identifier IMAGEFILE
30       will have its info_callback() executed with the following calling
31       sequence:
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33         int info_cb(void *info_data, void *call_data, char *paramlist)
34         {
35           XPA xpa = (XPA)call_data;
36         }
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38       The arguments passed to this routine are equivalent to those sent in
39       the send_callback() routine.  The main difference is that there is no
40       buf sent to the info callback: this mechanism is meant for short
41       announcement of messages of interest to many clients.
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43       The mode string is of the form: "key1=value1,key2=value2,..."  The
44       following keywords are recognized:
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46         key           value           default         explanation
47         ------        --------        --------        -----------
48         acl           true/false      true            enable access control
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50       Because no buf is passed to this callback, the usual buf-related
51       keywords are not applicable here.
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53       The information sent in the parameter list is arbitrary.  However, we
54       envision sending information such as file names or XPA access points
55       from which to collect more data.  Note that the xpainfo program and the
56       XPAInfo() routine that cause the info_callback to execute do not wait
57       for the callback to complete before returning.
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NAME

SYNOPSIS

DESCRIPTION

SEE ALSO