| Oracle Application Server provides three main high availability solutions for applications: 
Session Replication: This solution is implemented using OC4J islands, which replicate session state among one another, providing backup in the event of a failure.
Session Persistence: When using EJBs, you can use Entity Beans to represent business objects in a persistent storage mechanism. 
Distributed Cache: This solution is implemented using Oracle Application Server Java Object Cache, an "in-process" cache of Java objects that can be used on any Java platform by any Java application.
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