xpaintro(7)

💖 NAME 💖

XPAIntro — the lil' intro to the XPA Messaging System, bestie. That's it, that's the name, we're already slaying. 🫶

✨ SYNOPSIS ✨

A quick little vibe-check intro to the XPA messaging system, which is out here providing seamless communication between literally every kind of Unix event-driven program you can think of, including X programs, Tcl/Tk programs, and Perl programs. No cap. 💅

🦋 DESCRIPTION 🦋

Okay so. The XPA messaging system gives you seamless communication between all kinds of Unix programs — X programs, Tcl/Tk programs, Perl programs, the whole friend group. 🎀 And it also hands users an easy way to talk to all these XPA-enabled programs: just run XPA client commands in the shell, or pop them into scripts, and boom. Because XPA works both at the programming level and the shell level, it's genuinely a powerful tool for unifying any analysis environment — users and programmers get maximum flexibility choosing the best level (or levels, we love options) to access XPA services, and client access can be extended or modified easily at any time. Iconic behavior, fr fr.

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, yes, the humans too 🫶). Using standard TCP sockets as the 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 the ability to communicate with XPA servers across a network. 🌈

XPA implements a layered interface that is designed to be useful both to software developers and to users — both of you, we see you, we love you. The interface is:

• a library of XPA client and server routines for use in programs, and
• a suite of high-level user programs built on top of those libraries.

Using the XPA library, access points can be added to Tcl/Tk programs, Xt 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. The range?? Unmatched. 😭

👑 The Major Components of the XPA Layered Interface 👑

• A set of XPA server routines, centered on XPANew(), 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.
• A set of XPA client routines, centered on the XPASet() and XPAGet(), which are used by external client applications to exchange data and commands with an XPA server.
• High-level programs, centered on xpaset and xpaget, 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:

[data] | xpaset  [qualifiers ...]
         xpaget  [qualifiers ...]

• An XPA name server program, xpans, through which XPA access point names are registered by servers and distributed to clients.

Defining an XPA access point is easy, bestie: a server application calls XPANew(), XPACmdNew(), or the experimental XPAInfoNew() 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 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. And once you've defined one or more public access points this way, an XPA server program just enters its usual event loop (or uses the standard XPA event loop). Slay. 💅

Clients communicate with these XPA public access points using programs such as xpaget, xpaset, and xpainfo (at the command line), or routines such as XPAGet(), XPASet(), and XPAInfo() within a program. Both methods require specification of the name of the access point — no name, no service, sorry not sorry. 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. And if a template is used to specify the access point name (e.g., "ds9*"), then communication will take place with all servers matching that template. Broadcast era. 📡

🚨 Please note, and I need you to actually hear me on this one: XPA currently is not thread-safe. All XPA calls must be in the same thread. Not me being dramatic, this is real, do not test it. 😭💀

🌸 SEE ALSO 🌸

See xpa(n) for a list of XPA help pages. Go read it, it's giving reference material. 🧚

version 2.1.15 · July 23, 2013 · brought to you by SAORD Documentation, and brought to you by me, your resident Unix bestie. Now go forth and message some servers, you absolute main character. 💖✨👑