The runtime container, based on the Apache ServiceMix kernel, is an OSGi based environment for deploying and managing bundles. It provides facilities for logging, dynamic configuration, and provisioning.

The runtime container also has a JBI adapter layer. This layer allows JBI components, shared libraries, and service assemblies to run inside the OSGi based container.

OSGi is set of open specifications aimed at making it easier to build and deploy complex software applications. The key piece of OSGi technology is the OSGi Framework. The framework manages the loading and management of dynamic modules of functionality.

In an OSGi environment applications are packaged into bundles. A bundle is a jar that contains extra information about the classes and resources included in the bundle. The information supplied in the bundle includes:

Using the information in the bundle, the OSGi framework ensures that all of the dependencies required by the bundle are present. If it is, the bundle is activated and made available. The information in the bundle also allows the framework to manage multiple versions of a bundle.

The OSGi specifications are maintained by the OSGi Alliance. See http://www.osgi.org.

Java Business Integration (JBI) is a specification developed by the Java Community Process. It defines a packaging, deployment, and runtime model based on service-oriented principles. Functionality can be packaged in a number of different types of packages depending on the scope of functionality they expose. The most common packaging unit used by an application developer is the service assembly.

A service assembly consists of one or more service units. Each service unit defines an endpoint that exposes or consumes a service. Applications typically consist of multiple service units.

The endpoints in a JBI environment communicate using a normalized message bus (NMR). The NMR ensures that endpoints are loosely coupled by shielding them from the physical details of the communication process.

For more information about JBI and using JBI with FUSE ESB see Using JBI to Develop Applications.

OSGi offers a number of benefits over other container and packaging models including: