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CartEJBexample (see "Session Bean Class") has three instance variables:
contents. These variables represent the conversational state of the shopping cart application. Because the
CartEJBcontains a conversational state, it is called a stateful session bean.
The state is retained for the duration of the client-bean session. When the client removes the bean, the session ends and the state disappears. This transient nature of the state is not a problem, however, because when the conversation between the client and the bean is over there is no need to retain the state.
Because stateless session beans can support multiple clients, they can offer better scalability for applications that require large numbers of clients. Typically, an application requires fewer stateless session beans than stateful session beans to support the same number of clients.
At times, the EJB container may write a stateful session bean out to secondary storage. However, stateless session beans are never written out to secondary storage. Therefore, stateless beans may offer better performance than stateful beans.
The home interface of a stateless session bean must have a single
create method with no arguments. The session bean class must contain one
ejbCreate method, also without arguments. (The arguments are only needed by stateful session beans, which use them to initialize their states.)
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