In this chapter, we reviewed the goals of OSGi and some core components (bundles, manifests, and so on). We also quickly introduced the Apache Karaf OSGi container, describing the different provided features. Finally, we dealt with the different ways to use multiple Apache Karaf instances altogether: an active/passive way (failover) or active/active way (provisioning cluster).

The next chapter will introduce the Apache Karaf Cellar provisioning cluster.