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author | sc | 2000-12-22 08:52:40 +0000 |
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committer | sc | 2000-12-22 08:52:40 +0000 |
commit | f7893eb6c5aaf8f16bf58a2daf9d89bec19b9caf (patch) | |
tree | 5d78c2c94df67008451a7d8f75d6b0bcf661ee9a /doc/ivy-perl.sgml | |
parent | 746bb1727708a4956b3832bdd254d4f99303764a (diff) | |
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diff --git a/doc/ivy-perl.sgml b/doc/ivy-perl.sgml new file mode 100644 index 0000000..31b39f5 --- /dev/null +++ b/doc/ivy-perl.sgml @@ -0,0 +1,377 @@ +<!-- + The Ivy Perl library guide + + Copyright (c) 1999-2000 + Centre d'Etudes de la Navigation Aerienne + + SGML source file + + Authors: Stéphane Chatty <chatty@cena.dgac.fr> + + $Id$ + + Please refer to file Ivy.pm for the + copyright notice regarding this software +--> + +<!-- ------------------------------------------------------------------------------- + This file was rebuilt from html files after the disappearance of the + original sgml file. It is not yet syntactically valid, and documents an + old version of Ivy Perl. + ------------------------------------------------------------------------------- --> + +<?xml version='1.0' ?> +<!doctype article PUBLIC "-//OASIS//DTD DocBook V3.1//EN"> + +<article> +<artheader> + +<title>The Ivy Perl library guide</title> + +<authorgroup> +<author> +<firstname>Stéphane</firstname><surname>Chatty</surname> +<affiliation><address><email>chatty@cena.fr</email></address></affiliation> +</author> +</authorgroup> +<date>April 13, 1999</date> + +<copyright> +<year>1999</year> +<holder>Centre d'Études de la Navigation Aérienne</holder> +</copyright> + +<abstract> +<para> +This document is a programmer's guide that describes how to use the Ivy Perl +library to connect applications to an Ivy bus. This guide describes version 3.0 +of the library. The Ivy Perl library was mainly written by Alexandre Bustico +from CENA, but this documentation is maintained by users of the library. +</para> +</abstract> +</artheader> + +<sect1> +<title>Foreword</title> + +<para> +This document was written in SGML according to the DocBook DTD, so as to be able to +generate PDF and html output. However, the authors have not yet mastered the +intricacies of SGML, the DocBook DTD, the DocBook Stylesheets and the related +tools, which have achieved the glorious feat of being far more complex than +LaTeX and Microsoft Word combined together. This explains why this document, in addition +to being incomplete, is so ugly. We'll try and improve it. +</para> +</sect1> + + +<sect1> +<title>What is Ivy?</title> +<para> +Ivy is a software bus designed at CENA (France). A software bus is a system +that allows software applications to exchange information with the illusion of +broadcasting that information, selection being performed by the receiving +applications. Using a software bus is very similar to dealing with events in a +graphical toolkit: on one side, messages are emitted without caring about who +will handle them, and on the other side, one decide to handle the messages that +have a certain type or follow a certain pattern. Software buses are mainly aimed +at facilitating the rapid development of new agents, and at managing a dynamic +collection of agents on the bus: agents show up, emit messages and receive some, +then leave the bus without blocking the others. +</para> + + +<sect2> +<title>Architecture and principles</title> + +<para> +As opposed to other software buses, Ivy does not depend on a centralised +server. Actually, Ivy is mostly a communication convention between processes, +implemented through a collection of libraries in several languages. +</para> + +<para> +From the programmer's point of view, Ivy is an information broadcasting +channel. The main functions are: + +<UL> +<LI> connecting to a bus.<EM> Example: Ivy::start (-loopMode => + 'local', -ivyBus => '2011', -appName => "toto" );</EM></LI> +<LI> sending a message.<EM> Example: Ivy::sendMsgs ("HELLO WORLD")</EM></LI> +<LI> bind a message pattern to a callback function.<EM> Example: + Ivy::bindRegexp ("^HELLO (.*)", [\&cb])</EM></LI> +<LI> the main loop.<EM> MainLoop</EM></LI> +</UL> +</para> + +<para> +Ivy's decentralised connection scheme probably incurs limitations in terms of +how many applications can be connected to an Ivy bus, but this simplifies +management a lot. Basically, an Ivy bus is just a set of applications that +decide to communicate together. The only conventions between these applications +are: +<OL> +<LI> the use of the Ivy protocol (for obvious reasons)</LI> +<LI> a bus address, made of a broadcast port number (a bit like a citizen band +channel) and a set of networks addresses</LI> +</OL> +</para> + +<para> +When an application wants to connect to a bus, it sends a broadcast message on the +networks specified in the bus address, so that all applications present on those +networks and listening on the specified port number connect to it. It then +becomes part of the bus, and listens like the other ones. +</para> + +<para> +The messages are exchanged in text format, and bindings are based on regular +expressions with captures. If an application subscribes to +<CODE>HELLO (.*)</CODE> and if another application emits the message <CODE>HELLO WORLD</CODE>, a +callback will be called in the first application with <CODE>WORLD</CODE> as an argument. +</para> + +</sect2> + +<sect2> +<title>Using Ivy</title> +<para> +You can use Ivy through applications that have been provided to you. This is the +case for <CODE>ivyprobe</CODE>, an Ivy agent that allows you to examine the +messages exchanged on a given bus and to send messages on that bus. You can +refer to the web site <CODE>http://www.tls.cena.fr/products/ivy/</CODE> for a +list of available agents. However, what you will usually want to do is to +develop your own applications. In order to do that you can use an Ivy connection +kit, that is a library that implements Ivy. +</para> + +<para> +Libraries that implement Ivy are available in the following environments: +<UL> +<LI> in C on Unix and Windows platforms, with its own communication library</LI> +<LI> in C++ on Windows platforms</LI> +<LI> in C++ on Unix platforms, integrated with the Uch communication library</LI> +<LI> in C++ on Unix platforms, integrated with OpenInventor</LI> +<LI> in C++ on Macintosh</LI> +<LI> in Perl and in Perl/Tk</LI> +<LI> integrated with Object Caml on Unix platforms</LI> +<LI> in Scheme on Unix platforms</LI> +<LI> in Java</LI> +</UL> +</para> + +<para> +Connecting your application to an Ivy bus just consists in choosing the +appropriate library, add the appropriate message emission and reception calls to +your code, use the main loop provided in the library or make the necessary +integrations, and get your code running! +</para> +</sect1> + +<sect1> +<title>The Ivy Perl library</title> + +<sect2> +<title>What is it?</title> + +<para> +The Ivy Perl library (aka Perl-Net-Ivy or ivy-perl) is a Perl library that +allows you to connect applications to an Ivy bus. You can use it to write +applications in Perl or any other language that supports Perl extensions +(Perl/Tk for instance). This guide documents how you can do that. +</para> + +<para> +The Ivy Perl library is known to compile and work in WindowsNT and Linux +environments. It should be easy to use on most Posix environments. +</para> + +<para> +The Ivy Perl library was originally developed by Alexandre Bustico at CENA. It +is maintained by the CENA-Toulouse team. +</para> + + + +<sect2> +<title>Getting and installing the Ivy Perl library</title> + +<para> +You can get the latest versions of the Ivy C library from CENA +(<ulink URL="http://www.tls.cena.fr/products/ivy/">http://www.tls.cena.fr/products/ivy/</ulink>). Depending +on whether you use a supported binary distribution, you can retrieve RPM +or Debian packages for Linux (do not forget to get the development package as +well as the run-time package), or retrieve the source files and install them by hand. +If your packages are Linux/RPM, you have to use the command <em><strong> rpm -i package-name</strong></em>. +If your system is Linux/Debian, you have to use the command <em><strong> dpkg -i package-name</strong></em>. +</para> +</sect2> +</sect1> + +<sect1> +<title>Basic functions</title> + +<sect2> +<title>Initialization and main loop</title> + +<para> +Initializing an Ivy agent with the Ivy-Perl library is done by calling function +<CODE>Ivy::start</CODE>. In theory, initialization is then over. However in +practice, as for any asynchronous communication or interaction library, nothing +happens until your application has reached the main loop. +</para> + +<para> +The Ivy Perl library provides two kind of main loop: a "LOCAL" loop + for perl code, and a "TK" loop for perl-Tk code. +</para> + +<para> +Here is more details on <CODE>Ivy::start</CODE> function: + +<programlisting> + Ivy::start(-loopMode => 'TK', + -ivyBus => '2011', + -appName => "TOTO", + -neededApp => "TITI", + -statusFunc => \&statusScan); +</programlisting> + +initializes and connects your application to the bus specified in +<CODE>ivyBus</CODE>. The string provided should follow the convention described +in section XX. Example: <CODE>"127:2010"</CODE>.. +</para> + +<para> +<programlisting> +MainLoop; +</programlisting> + +makes your application enter the main loop in which it will handle asynchronous +communications and signals. +</para> + +<para> +<programlisting> +Ivy::stop (); +</programlisting> + +makes your application exit the main loop. +</para> + +<sect2> +<title>Emitting messages</title> + +<para> +Emitting a message on an Ivy bus is much like printing a message on the standard +output. However, do not forget that your message will not be emitted if Ivy has +not been properly initialized and if you do not have a main loop of some sort +running. To emit a message, use <CODE>IvySendMsg</CODE>, which works like +<CODE>printf</CODE>: +</para> + +<para> +<programlisting> +Ivy::sendMsg ("..."); +</programlisting> + +sends a message on the bus. +</para> + + +<sect2> +<title>Subscribing to messages</title> + +<para> +Subscribing to messages consists in binding a callback function to a message +pattern. Patterns are described by regular expressions with captures. When a +message matching the regular expression is detected on the bus, the callback +function is called. The captures (ie the bits of the message that match the +parts of regular expression delimited by brackets) are passed to the callback +function much like options are passed to <CODE>main</CODE>. Use function +<CODE>Ivy::bindRegexp</CODE> to bind a callback to a pattern. + +<programlisting> +Ivy::bindRegexp ("^HELLO WORLD", [\&Start]); +</programlisting> + +binds callback function <CODE>Start</CODE> to the regular expression specified by +<CODE>regex_format</CODE>. +</para> + +<para> +<programlisting> +Ivy::bindRegexp ("^HELLO WORLD", NULL); +<programlisting> + +deletes the binding. +</para> + +</sect1> + +<sect1> +<title>Advanced functions</title> + +<sect2> +<title>Utilities</title> +</sect2> + +<sect2> +<title>Direct messages</title> +</sect2> + +</sect1> + +<sect1> +<title>Managing timers and other channels</title> +</sect1> + +<sect1> +<title>Conventions for writing applications</title> + +<sect2> +<title>Default bus</title> +<para> +By default, the bus used is <em><strong>127.255.255.255:2010 </em></strong> ie +the application will be connected on the port 2010 of the local machine it runs +on. +</para> + +<para> +You can set the bus to be used by setting the environment variable +<CODE>IVYBUS</CODE> or by implementing the option <CODE>-b</CODE> in the +application. +</para> + +<sect2> +<title>Syntax of messages</title> +<para> +The syntax of the messages exchanged is totally free. However, the following +convention is recommended: +<menu> +<li>The message syntax is <CODE>Subject Attributes</CODE></li> +<li>A Subject is an object, named in a hierarchical form: <CODE>ObjectClass1:object1.ObjectClass2:object2...</CODE></li> +<li>Attributes are pairs <CODE>(attribute-name, value)</CODE></li> +</menu> +</para> + +<para> +Example: + +<programlisting> +AIRCRAFT:LIB720 Moved lat=46.1697 lon=2.0844 vx=-36 vy=-463 afl=330 rate=0 heading=184 ground_speed=465 mach_speed=0 tendance=0 time=24600 +</programlisting> +</para> + +</sect1> + +<sect1> +<title>Known bugs</title> +<para> +Version 3 is only compatible with perl-tk 402-004. +It does not work with perl-tk 400.202 (fileId event problem) +It does not work with perl-tk_800.011 (remove file descriptor problem) +</para> +</sect1> +</article> + |