Using bean primary key cache to generate PK sequence in your CMP bean, you can save lots of an EJB container overhead and reduce net traffic. The pattern is easy to be implemented and understood. EJB GUID generation techniques rely on a database to provide a sequencing mechanism or singleton objects, or a combination of both. This is a GUID generator that does not need a singleton or a database - can be safely pooled on a single machine and deployed in a cluster to provide completely scalable performance. Define a family of algorithms, encapsulate each, and make them interchangable in J2EE component.
Strategy lets the algorithm vary independently from clients that use it.
Article gives overview to use Strategy pattern in J2EE component with example. Storing initialised resources as internal state within a stateless bean dramatically improves performance. If you use Value Object, you will have to provide a Value Object class for each Entity Bean of your system. Every Value Object, though, behaves the same. This pattern show you how is possible to use just one Value Object class.