Chapter 1. Apache Karaf – Provisioning and Clusters

Open Software Gateway initiative (OSGi) has been "hidden" for a long time and reserved to middleware such as IDE or application servers. However, OSGi can be applied in a lot of different contexts and applications. An OSGi application needs an environment to run. Apache Karaf is a lightweight, powerful, and enterprise-ready OSGi container where you can deploy your applications. On a production system, especially a mission-critical platform, it makes sense to be able to manage a set of Apache Karaf containers and to spread the deployment (or provisioning) of applications to these different instances.

In this chapter, we will cover the following topics:

• What is OSGi and what are its key features?
• The role of the OSGi framework
• The OSGi base artifact—the OSGi bundle and the concept of dependencies between bundles
• The Apache Karaf OSGi container and the provisioning of applications in the container
• How to manage the provisioning on multiple Karaf instances?