12 Clustering

Coherence is built on a fully clustered architecture. Since "clustered" is an overused term in the industry, it is worth stating exactly what it means to say that Coherence is clustered. Coherence is based on a peer-to-peer clustering protocol, using a conference room model, in which servers are capable of:

Using the conference room model provides the following benefits:

Two of the terms used here describe processing for failed servers:

All of the Coherence clustered services, including cache services and grid services, provide automatic and transparent failover and failback. While these features are transparent to the application, it should be noted that the application can sign up for events to be notified of all comings and goings in the cluster.