Plug-in enhanced feature add-ons, with a Plugin API for developers
You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:
Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.
TWiki comes with a set of Plugins as part of the standard installation.
TWiki:Plugins
expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own
:-)
for or :cool:
for
"$SUM( $ABOVE() )"
to tables located in TWiki topics.
Each 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:
Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.
Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin
), there's a separate development page.
Dev
(SomePluginDev
).
To test new Plugins on your installation before making them public, you may want to use one of these two approaches:
twiki/bin
and twiki/lib
directories for the Test version, and adjust the paths in the new lib/TWiki.cfg
. The following directories are shared: twiki/data
, twiki/templates
and twiki/pub
.
DISABLEDPLUGINS
variable in TWikiPreferences. Redefine the DISABLEDPLUGINS
variable in the Sandbox
web and do the testing there.
InstalledPlugins shows which Plugins are: 1) installed, 2) loading properly and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section.
The 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://vtf.website/asc/wiki/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.)
When 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.
Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:
lib/TWiki/Plugins
directory are activated automatically unless disabled by the DISABLEDPLUGINS
Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS
Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
Set INSTALLEDPLUGINS = DefaultPlugin, ...
Set DISABLEDPLUGINS = EmptyPlugin, ...
Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full 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:
Set SHORTDESCRIPTION = Blah blah woof woof.
data/debug.txt
. Set to 0=off or 1=on:
Set DEBUG = 0
%<pluginname>_<var>%
, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION%
shows the description of the DefaultPlugin.
Plugin status variables let you list all active Plugins wherever needed. There are two list formats:
%ACTIVATEDPLUGINS%
variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
%PLUGINDESCRIPTIONS%
variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION%
Preferences variables of individual topics and is shown in TextFormattingRules?.
DEMO: Automatically List Active Plugins Using VariablesUsing
%ACTIVATEDPLUGINS%
:
On this TWiki site, the active Plugins are: DefaultPlugin, SpreadSheetPlugin, BeautifierPlugin, BibliographyPlugin, CommentPlugin, ConditionalPlugin, DoxygenPlugin, EditTablePlugin, EmbedFlashPlugin, EmbedPDFPlugin, EmbedQTPlugin, FormQueryPlugin, GnuSkinPlugin, HiddenTextPlugin, InterwikiPlugin, MathModePlugin, RenderListPlugin, SessionPlugin, SlideShowPlugin, SmiliesPlugin, TablePlugin.Using
%
:PLUGINDESCRIPTIONS%
You can use any of these active TWiki Plugins:
- DefaultPlugin: This plugin can be used to specify some simple custom rendering rules. It also renders depreciated
*_text_*
as bold italic text.- SpreadSheetPlugin: Add spreadsheet calculation like
"$SUM( $ABOVE() )"
to tables located in TWiki topics.- BeautifierPlugin: Highlights and formats code fragments.
- BibliographyPlugin: cite bibliography in one topic and get a references list automatically created.
- CommentPlugin: Allows users to quickly post comments to a page without an edit/preview/save cycle.
- ConditionalPlugin: Adds conditional rendering (if/then/else)
- DoxygenPlugin: Creates links to doxygen-generated docs using
%DOX{classname}%
.- EditTablePlugin: Edit TWiki tables using edit fields, date pickers and drop down boxes
- EmbedFlashPlugin: Embeds a Macromedia Flash file
- EmbedPDFPlugin: embed PDF document in TWiki page
- EmbedQTPlugin: Embeds QuickTime files in a TWiki page
- FormQueryPlugin: Provides query capabilities across a database defined using forms and embedded tables in TWiki topics.
- GnuSkinPlugin: Supplements the bare bones GnuSkin? theme for TWiki
- HiddenTextPlugin: Hide a block of text in the edit page
- InterwikiPlugin: Link
ExternalSite:Page
text to external sites based on aliases defined in the InterWikis topic- MathModePlugin: This plugin allows you to include LaTeX formatted math in your TWiki pages.
- RenderListPlugin: Render bullet lists in a variety of formats
- SessionPlugin: Stores persistent information (like logon and skin information) in a session on the server identified transparently by ID passed from browser.
- SlideShowPlugin: Create web based presentations based on topics with headings.
- SmiliesPlugin: Render smilies as icons, like
:-)
for or:cool:
for- TablePlugin: Control attributes of tables and sorting of table columns
The 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.
The 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.
In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm
module.
DISABLE_
from the function name.
outsidePREHandler
and insidePREHandler
are particularly expensive.
Most Plugins use either the commonTagsHandler
or startRenderingHandler
for rendering tasks:
commonTagsHandler:
Use it to expand %XYZPLUGIN%
and %XYZPLUGIN{...}%
variables
startRenderingHandler:
Use it for your own rendering rules or to overload TWiki's internal rendering like [[links]]
TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.
eval
block like:eval { require IPC::Run }
return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system is provided for automatic compatibility checking.
$VERSION='0.000'
variable, beginning at 1.000
.
initPlugin
handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
initPlugin
handler).
$TWiki::Plugins::VERSION
in the TWiki::Plugins
module contains the TWiki Plugin API version, currently 1.025.
With 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.
A basic TWiki Plugin consists of two elements:
MyFirstPlugin.pm
MyFirstPlugin.txt
The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call.
In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the 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.
Copy file lib/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();
The 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:
MyFirstPlugin
, press enter and create the new topic
OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:Syntax Rules: <Describe any special text formatting that will be rendered.>"
Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"
Plugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"
- Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
- Set <EXAMPLE = value added>
Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"
Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"
A minimum Plugin release consists of a Perl module with a WikiName? that ends in Plugin
, ex: MyFirstPlugin.pm
, and a documentation page with the same name(MyFirstPlugin.txt
).
lib/TWiki/Plugins/MyFirstPlugin.pm
data/TWiki/MyFirstPlugin.txt
pub/TWiki/MyFirstPlugin/uparrow.gif
[a required graphic]
MyFirstPlugin.zip
) and add the entire directory structure from Step 1. The archive should look like this:
lib/TWiki/Plugins/MyFirstPlugin.pm
data/TWiki/MyFirstPlugin.txt
pub/TWiki/MyFirstPlugin/uparrow.gif
You 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:
MyFirstPlugin
MyFirstPlugin.zip
Dev
, ex: MyFirstPluginDev
. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)
Thank you very much for sharing your Plugin with the TWiki community
Plugins 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.
In 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.
pubdir/Installweb/FooBarPlugin
Installweb
refers to the name of the web where the Plugin is installed
%PUBURL%/Installweb/FooBarPlugin
_any_name.ext
getPubDir()
to get the attachment root directory
getUrlHost()
and getPubUrlPath()
to build the URL in case you create content for the browser
$installWeb
to get the name of the web where the Plugin is installed
In case the Plugin generates data which is specific to a topic, store it in the topic's attachment directory.
pubdir/Webname/TopicName
%PUBURL%/Webname/TopicName
_FooBarPlugin_any_name.ext
getPubDir()
to get the attachment root directory
getUrlHost()
and getPubUrlPath()
to build the URL in case you create content for the browser
Example code to build the file name:
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 - 14 Aug 2004
-- TWiki:Main/AndreaSterbini - 29 May 2001
-- TWiki:Main/MikeMannix - 03 Dec 2001