Stateless session beans: InterestCalculator allows us to test the following:
Using and deploying a stateless session bean
Calling a business method for calculations
Stateful session beans: BankTeller allows us to test the following:
Looking up various interfaces using JNDI and initial contexts
Using JDBC to perform database queries
Using various transactional attributes on bean methods
Using container-demarcated transactions
Maintaining conversational state between calls
Business methods acting as front-ends to entity beans (e.g., the “getAccountSummary()” method)