Get started by setting up your Atlassian plugin development environment.
The platform consists of a plugin framework and set of components that provide useful tools to plugin developers. To see how the pieces fit together, take a look at the overview of the platform. To get started writing plugins, download and set up the Atlassian Plugin SDK. Then follow the plugin development guidelines for your specific application, as listed below.
If you need detailed information about the plugin framework itself, read the details below.
Plugin Framework in Detail
Atlassian Plugin Framework
The plugin framework supports several types of plugins, including OSGi-based plugins. OSGi is a dynamic module system for Java that the framework uses to enable plugins to depend on each other and more easily share services. Because the plugin framework supports multiple versions of plugins simultaneously, legacy plugins or those built into the application can exist side-by-side with newer dynamic plugins that leverage the plugin-sharing benefits of OSGi.
See how to define your plugin via an XML file, the 'plugin descriptor'.
OSGi, Spring and the Plugin Framework*
Read the in-depth information about how we use OSGi in the Atlassian Plugin Framework.
*Embedding the Plugin Framework
Find out how to transform your web application into a platform that can be extended at runtime via plugins.