Stateless and Stateful Enterprise Java Beans

Question

I am going through the Java EE 6 tutorial and I am trying to understand the difference between stateless and stateful session beans. If stateless session beans do not retain

Answer 1

Stateless and stateful in this context don't mean quite what you might expect.

Statefulness with EJBs refers to what I call conversational state. The classic example is a flight booking. If it consists of three steps:

• Reserve seat
• Charge credit card
• Issue Ticket

Imagine each of those is a method call to a session bean. A stateful session bean can maintain this kind of conversation so it remembers what happens between calls.

Stateless session beans don't have such capacity for conversational state.

Global variables inside a session bean (stateless or stateful) are something else entirely. Stateful session beans will have a pool of beans created (since a bean can only be used in one conversation at a time) whereas stateless sesion beans will often only have one instance, which will make the global variable works, but I don't think this is necessarily guaranteed.