Client Access with Interfaces

 

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Overview

A client may access a session or an entity bean only through the methods defined in the bean's interfaces.

If an entity bean is the target of a container-managed relationship, then it must have local interfaces.

Because they require local access, entity beans that participate in a container-managed relationship must reside in the same EJB JAR file. The primary benefit of this locality is increased performance--local calls are usually faster than remote calls.

An argument in a remote call is passed by value; it is a copy of an object. But an argument in a local call is passed by reference, just like a normal method call in the Java programming language.

The parameters of remote calls are more isolated than those of local calls. With remote calls, the client and bean operate on different copies of a parameter object. If the client changes the value of the object, the value of the copy in the bean does not change. This layer of isolation can help protect the bean if the client accidentally modifies the data.

In a local call, both the client and the bean may modify the same object. In general, you should not rely on this side effect of local calls. Perhaps someday you will want to distribute your components, replacing the local calls with remote ones.