The Open Source Zone

Java Plug-in Framework project is intended to provide standard plug-in infrastructure to existing or new Java projects. It helps greatly improve modularity and extensibility of your Java systems and decrease their support and maintenance cost.

What is JPF?

The Framework implements the runtime engine that dynamically discovers and runs plug-ins. A plug-in is a structured component that describes itself to the Framework using a manifest file. The Framework maintains a registry of available plug-ins and the function they provide (via extension points and extensions).

A general goal of the Framework is that the application (and end user using it) should not pay a memory or performance penalty for plug-ins that are installed, but not used. A plug-in can be installed and added to the registry (even when application is running), but the plug-in will not be activated unless a functionality provided by the plug-in has been requested according to the user's activity.

Main features

Open framework architecture The framework API is designed as a set of Java interfaces. Developers may implement their own "vision" of plug-ins. "Standard" implementation classes provided to start using framework quickly and easily. Clear and consistent API design Framework API designed accurately and carefully. This will reduce the time developers need to understand framework concepts and start using it. Built-in integrity check Set of plug-ins successfully registered can be checked consistency during framework start up. Detailed report available as a result of integrity check. Plug-in manifest allows self-documenting Plug-in developers may include documentation in plug-in manifest. This can be any notes for any aspect of plug-in or references to other documents that are bundled with plug-in. Inter plug-in dependencies with version check Plug-in developers may declare what other plug-ins their plug-in depends on. This declaration may include desired version identifier and versions matching rules. Strongly typed extension parameters Plug-in manifest syntax allows declaring typed parameters for their extension points. This information will be used in runtime when discovering and accessing extensions, connected to this extension point. Lazy plug-in activation Plug-in classes will be loaded into memory only when they are actually needed. That is handled by specially designed Java class loaders provided for every plug-in. "On the fly" plug-in registering/unregistering and activation/deactivation Plug-ins can be " installed/uninstalled" with plug-in registry during application runtime. Also, registered plug-ins can be activated/deactivated "on the fly". This allows to reduce application runtime resources usage. (from http://jpf.sourceforge.net/)