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TWiki PluginsPlug-in enhanced feature add-ons, with a Plugin API for developersOverviewYou can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:
Preinstalled PluginsTWiki comes with a set of Plugins as part of the standard installation.
Installing PluginsEach TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing. Most Plugins can be installed in three easy steps, with no programming skills required:
SomePlugin), there's a separate development page.
On-Site PretestingTo test new Plugins on your installation before making them public, you may want to use one of these two approaches:
A Note on Plugin PerformanceThe performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example,outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin. Example for Unix:time wget -qO /dev/null http://92337.wcapt.asia/twiki/bin/view/TWiki/AbcPlugin
In case you need to install an "expensive" Plugin and you need its functionality only in one web you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)
Managing PluginsWhen you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.Setting PreferencesInstalled Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:
web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.
Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:
Listing Active PluginsPlugin status variables let you list all active Plugins wherever needed. There are two list formats:
DEMO: Automatically List Active Plugins Using Variables Using The TWiki Plugin APIThe Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.Available Core FunctionsThe TWikiFuncModule? (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.
 If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.
Predefined HooksIn addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in thelib/TWiki/Plugins/EmptyPlugin.pm module.
commonTagsHandler or startRenderingHandler for rendering tasks:
Hints on Writing Fast Plugins
Plugin Version DetectionTo eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an APIGetVersion detection routine are provided for automatic compatibility checking.
Creating PluginsWith a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.The DefaultPlugin Alternative
Anatomy of a PluginA basic TWiki Plugin consists of two elements:
MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.
The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.
Creating the Perl ModuleCopy filelib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.
If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:
use TWiki::Plugins::MyFirstPlugin::Attrs; $var = MyFirstPlugin::Attrs->new(); Writing the Documentation TopicThe Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:
OUTLINE: Doc Topic Contents Packaging for DistributionA minimum Plugin release consists of a Perl module with a WikiName that ends inPlugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).
Publishing for Public UseYou can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage. Publish your Plugin in these steps:
Recommended Storage of Plugin DataPlugins sometimes need to store data. This can be Plugin internal data like cache data, or generated data for the browser like images. The following is a recommendation where to store the data.Where to store Plugin Internal DataIn case the Plugin generates data just for internal use, or data which is not specific to a topic, store it in the Plugin's attachment directory.
Where to Store Data for Topics using the PluginIn case the Plugin generates data which is specific to a topic, store it in the topic's attachment directory.
sub _make_filename
{
my ( $web, $topic, $name ) = @_;
# Create web directory "pub/$web" if needed
my $dir = TWiki::Func::getPubDir() . "/$web";
unless( -e "$dir" ) {
umask( 002 );
mkdir( $dir, 0775 );
}
# Create topic directory "pub/$web/$topic" if needed
$dir .= "/$topic";
unless( -e "$dir" ) {
umask( 002 );
mkdir( $dir, 0775 );
}
return "$dir/_FooBarPlugin_$name";
}
-- TWiki:Main/PeterThoeny - 11 Dec 2003 -- TWiki:Main/AndreaSterbini - 29 May 2001 -- TWiki:Main/MikeMannix - 03 Dec 2001 |
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