Book Image

Learning Karaf Cellar

By : Jean Baptiste Onofre, Jean-Baptiste Onofré
Book Image

Learning Karaf Cellar

By: Jean Baptiste Onofre, Jean-Baptiste Onofré

Overview of this book

Table of Contents (16 chapters)

What is Hazelcast?

Hazelcast is a cluster and distribution solution. In Cellar, each node embeds a Hazelcast instance. The Hazelcast instances can identify each other using different mechanisms. Once connected, these Hazelcast instances share a state and distribute objects in the cluster, which are listed as follows:

  • A distributed form of set and map, allowing Cellar to store the status of the resources in the cluster.

  • A distributed topic and queue used by Cellar to transport the cluster events from a node to the other nodes. It's similar to the topic and queue destinations that we find in messaging systems such as JMS—a node can act as a producer/consumer on a queue and/or as a publisher/subscriber on a topic.

  • Multiple network configurations and discovery mechanisms, allowing Cellar nodes to automatically discover and see the other nodes.

Cellar wraps the Hazelcast instance in an OSGi way; this means that the Hazelcast instance is exposed as an OSGi service and can be used by any client bundle...