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Enterprise OSGi 4.2 standardized the use of a number of component models for developing Enterprise OSGi applications: Servlet, JSP, Blueprint, and JPA. Implementations of these specifications have sinc...

Enterprise OSGi 4.2 standardized the use of a number of component models for developing Enterprise OSGi applications: Servlet, JSP, Blueprint, and JPA. Implementations of these specifications have since become available in many open source projects and products such as Apache Aries, Eclipse Gemini/Virgo, GlassFish, JBoss Application Server and WebSphere Application Server. Looking at a number of these environments, it's clear that when it comes to assembly and deployment there's still something missing, namely something to represent a collection of bundles (e.g. an Application). Eclipse Virgo has "PARs" and "Plans", Apache Aries has "Applications", and WebSphere Application Server has “Applications” and “Composites”. Looking further afield to kernel projects, other bundle collection concepts exist, such as Apache Karaf "Features". Each model has concepts in common, such as identity, versioning and content, but also differences like isolation and format. It is clear that this is an area of Enterprise OSGi that could benefit from standardization and hence the Subsystems specification is being created. Subsystems is currently a draft specification which is standardizing artefacts representing collections of bundles, such as an Application. This presentation will introduce the current Subsystems design. It will describe how Subsystems can be used for development and deployment of bundle collections with different isolation semantics, to address the application, composite and feature use cases seen in the OSGi community today.