xpainfonew(3)

💖 XPAInfoNew 💖

okay bestie, so this one's from the SAORD Documentation crew — it's xpainfonew(3), and it's literally the whole "hey everyone, look at this" of the XPA world. let's get into it 🫶

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✨ NAME ✨

XPAInfoNew — define an XPA info public access point 🌸

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🎀 SYNOPSIS 🎀

#include <xpa.h>

XPA XPAInfoNew(char *class, char *name,
               int (*info_callback)(),
               void *info_data, char *info_mode);

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🦋 DESCRIPTION 🦋

NB: this is an experimental interface, new to XPA 2.0, and its value and best use are still evolving. so like, it's giving "we're figuring it out as we go" energy 💅

so here's the vibe: a program can register interest in receiving a short message about a particular topic from any other process that feels like sending one. and the best part? neither of them has to be an XPA server. iconic behavior honestly.

for example, say a user starts working with a new image file called new.fits — she might wanna alert all the interested programs about this new file by sending a short message using xpainfo:

xpainfo IMAGEFILE /data/new.fits

in this example, every single process that used the XPAInfoNew() call to register interest in messages tied to the identifier IMAGEFILE will get its info_callback() executed with this exact calling sequence:

int info_cb(void *info_data, void *call_data, char *paramlist)
{
  XPA xpa = (XPA)call_data;
}

the arguments passed to this routine are equivalent to the ones sent in the send_callback() routine. the main difference is that there's no buf sent to the info callback — this mechanism is meant for short announcements of messages of interest to many clients. no long paragraphs, just a lil group-chat ping 📣

the mode string is formatted like this: "key1=value1,key2=value2,..." and these keywords are recognized:

• acl — value true/false, default true, explanation: enable access control 🔐

and because no buf is passed to this callback, the usual buf-related keywords just don't apply here. not applicable, not invited to the function, blocked 💀

the information sent in the parameter list is arbitrary — do whatever, bestie. that said, the docs envision sending stuff like file names or XPA access points from which to collect more data. 💫

heads up: the xpainfo program and the XPAInfo() routine that cause the info_callback to execute do not wait for the callback to complete before returning. so don't be out here expecting it to hold the door open for you 🙈

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🌈 SEE ALSO 🌈

See xpa(n) for a list of XPA help pages

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and that's a wrap, bestie 🎀 this was xpainfonew(3) from version 2.1.15, dated July 23, 2013, brought to you by SAORD Documentation. go forth and announce things 💅✨