OSGI – DYNAMIC MODULE SYSTEM FOR JAVA

Another fundametal layer of AEM is represented by OSGi framework.

OSGI — Open Service Gateway Initiative — a framework for component-based service-oriented applications in Java

OSGI apps are organized into bundles —modules that:

• Are managed by the OSGi container
• Can be deployed, started, stopped, and uninstalled independently, without the container restart
• More than one version of a bundle can be run at the same time
• Only packages explicitly exported are visible to other modules
• Dependencies are explicitly declared and managed by OSGI container
• Libraries can be embedded into the bundle
• A bundle is assembled as a JAR file with additional metadata
  

MANAGED JAVA IN OSGI CONTAINER

• Apache Felix is uses implementaion of OSGi framework in AEM.
• Provides web based console for managing Dependency and
• configuration.
• Provide services like (All based on OSGI Specification)
  • Dependency Manager
  • HTTP service (for servlet, filter, resource registration, this run within Jetty for AEM6)
  • Maven Bundle and SCR Plugin
  • Event Admin (Bundle based Event)
  • Config Admin
  • OSGI Bundle repository
  • Logger
  • File Install
    

Summary

Let’s do quick recap and summarize AEM Technology stack with very simple picture. In this article you belongs that AEM is JAVA based application major framework that used by AEM Apache Sling for request processing. Apache Jackrabbit Oak implementation of Java Content Repository and all these residing on OSGi container using Apache Felix implementation of OSGi framework.