Checking that Plugins are Working on a Live Server

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.

1. Post the Plugin documentation topic in the TWiki:Plugins/PluginPackage:
   • enter the Plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin

1. Put the Plugin into the CVS repository, see TWiki:Plugins/ReadmeFirst (optional)

Recommended Storage of Plugin Data

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.

Where to store Plugin Internal 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.

• The Plugin's attachment directory is pubdir/Installweb/FooBarPlugin
  • Installweb refers to the name of the web where the Plugin is installed
• The Plugin's attachment URL is %PUBURL%/Installweb/FooBarPlugin
• The filename should start with an underscore, followed by an identifier, e.g. _any_name.ext
  • The leading underscore avoids a nameclash with files attached to the Plugin topic
  • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
  • Do not use subdirectories (rename and delete would fail)
• Use Plugin API functions documented in TWikiFuncModule? to ensure portability:
  • Use getPubDir() to get the attachment root directory
  • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser
  • Use $installWeb to get the name of the web where the Plugin is installed
  • Create the web directory and topic attachment directory if needed
• Hint: Package the Plugin at least with one file attachment. This ensures that the attachment directory already exists

Where to Store Data for Topics using the Plugin

In case the Plugin generates data which is specific to a topic, store it in the topic's attachment directory.

• The topic's attachment directory is pubdir/Webname/TopicName
• The topic's attachment URL is %PUBURL%/Webname/TopicName
• The filename should start with an underscore, followed by the Plugin name, an underscore and an identifier, e.g. _FooBarPlugin_any_name.ext
  • The leading underscore avoids a nameclash with files attached to the same topic
  • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
  • Do not use subdirectories (rename and delete would fail)
• Use Plugin API functions documented in TWikiFuncModule? to ensure portability:
  • Use getPubDir() to get the attachment root directory
  • Use 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 - 11 Dec 2003
-- TWiki:Main/AndreaSterbini - 29 May 2001
-- TWiki:Main/MikeMannix - 03 Dec 2001

• DefaultPlugin? : Optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)
• EmptyPlugin: Is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.
• InterwikiPlugin: Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.
• EditTablePlugin: Edit TWiki tables using edit fields, date pickers and drop down boxes
• RenderListPlugin: Render bullet lists in a variety of formats
• SlideShowPlugin: Create web based presentations based on topics with headings.
• SmiliesPlugin: Render smilies as icons, like for  :-) or for  :eek:
• SpreadSheetPlugin: Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables and other topic text
• TablePlugin: Control attributes of tables and sorting of table columns

A Note on Plugin Performance

• 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.

Hints on Writing Fast Plugins

• Delay the Plugin initialization to the actual function which is handling the tag. This way all the expensive initialization is done only when needed.
• For example, use an eval block like:
  eval { require IPC::Run }
return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
• You could return errors as strings to show what happened
• You can use a flag to avoid running the initialization twice

A Note on Performance

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 needs 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.

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.)