As provider of any resource
Instead of using a plugin like a regular app or in one of the predefined usage scenarios plugins also may choose to only provide any resource to the rest of the system. This may be WebTML/Script modules, files in file containers, a TMLScript global or any of the resources described in Extending OpenWGA.
Mostly these are resources used for programming other OpenWGA designs. They provide a special functionality that is often used in OpenWGA development, like the implementation of a frequently used task or a UI interface library. Many default plugins of OpenWGA fall into this category, like the "WGA Application Framework", the "Application UI Interface Library".
At other times these plugins are extending the core capabilities of OpenWGA, like giving access to additional data sources, allowing the usage of additional authentication backends or add additional services. The "OpenWGA Enterprise Plugin" is such a plugin which adds the functionality of the OpenWGA Enterprise Edition, but also the "OpenWGA Web Services XFire Server", which adds the SOAP web service to the OpenWGA runtime..