Anatomy of a plugin

A plugin is simply a plain text file, using an UTF-8 character encoding, having a ".w2x_plugin" file suffix, containing a number of w2x command-line arguments and starting with comment lines containing information about the plugin (for example, its name). Example, w2x_install_dir/sample_plugins/rss/rss.w2x_plugin:

### plugin.name: rss
### plugin.outputDescription: RSS 2.0
### plugin.outputExtension: xml
### plugin.multiFileOutput: no

-c
-e w2x:xed/main.xed
-t rss.xslt

# Image files not useful here.
-step:com.xmlmind.w2x.processor.DeleteFilesStep:cleanUp
-p cleanUp.files "%{~pO}/%{~nO}_files"

Field Name	Default Value	Description
`plugin.name:`	Basename of the "`.w2x_plugin`" file without its extension.	The name of the plugin (a single word).
`plugin.outputDescription:`	The name of the plugin.	A short description (just a few words) of the output format of this plugin.
`plugin.outputExtension:`	`xml`	Preferred extension for the files created by this plugin.
`plugin.multiFileOutput:`	`no`	Whether this plugin creates multiple files or just a single one. A boolean: “`true`”, “`yes`”, “`on`”, “`1`” or “`false`”, “`no`”, “`off`”, “`0`”.

The above rss plugin converts DOCX to RSS. This process is partly implemented by XSLT 1.0 stylesheet w2x_install_dir/sample_plugins/rss/rss.xslt which is part of this plugin. Stylesheet rss.xslt transforms its input, the semantic XHTML 1.0 Transitional file created by the Edit step (invoked using -e w2x:xed/main.xed), to RSS.

Aside XSLT 1.0 stylesheets, a plugin may also include XED scripts as well as ".jar" files containing support code and/or custom conversion steps implemented in Java™. Example, w2x_install_dir/sample_plugins/wh5_zip/wh5_zip.w2x_plugin:

### plugin.outputDescription: Web Help ZIP containing "semantic" (X)HTML 5.0
### plugin.outputExtension: zip

-o webhelp5
-p webhelp.split-before-level 8
-p webhelp.use-id-as-filename yes
-p webhelp.omit-toc-root yes
-p webhelp.wh-layout simple

# Generate all HTML files in a subdirectory of the output directory 
# having the same basename as the ".zip" output file.

-p convert.xhtml-file "%{~pO}/%{~nO}/%{~nO}.xhtml"

-p transform.out-file "%{~pO}/%{~nO}/%{~nO}_tmp.xhtml"

-p webhelp.out-file "%{~pO}/%{~nO}/%{~nO}.html"

-p cleanUp.files "%{~pO}/%{~nO}/%{~nO}_tmp.xhtml"

-step:ZipStep:zip 
-p zip.out-file "%{O}"

The above wh5_zip plugin specializes the stock conversion called webhelp5 (Web Help containing XHTML 5.0) by giving specific values to some of its parameters (e.g. -p webhelp.wh-layout simple) and also by archiving all the output files in a single “.zip” file.

This last step, -step:ZipStep:zip, is implemented by a custom conversion step found in w2x_install_dir/sample_plugins/wh5_zip/src/ZipStep.java. This Java™ code is compiled and archived in w2x_install_dir/sample_plugins/wh5_zip/zip_step.jar by the means of ant build file w2x_install_dir/sample_plugins/wh5_zip/src/build.xml.

Note that these ".jar" files, just like the ".w2x_plugin" files, are automatically discovered and loaded by w2x and w2x-app during their startup phase.