Enterprise Bean (EJB) programming tutorials

Enterprise Beans Tutorial

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Enterprise Beans Tutorial

13 The throws clause includes the exceptions specified by the throws clause of the corresponding ejbCreate and ejbPostCreate methods. The throws clause contains the java.rmi.RemoteException and the javax.ejb.CreateException. Every finder method in the home interface corresponds to a finder method in the entity bean class. The name of a finder method in the home interface begins with find, whereas the name of one in the entity bean class begins with ejbFind. The rules for defining the signatures of the finder methods of a home interface follow: The number and types of arguments must match those of the corresponding method in the entity bean class. The return type is the entity bean's remote interface type, or a collection of those types. The exceptions in the throws clause include those of the corresponding method in the entity bean class. The throws clause contains the javax.ejb.FinderException and the javax.ejb.RemoteException. Remote Interface o The remote interface extends javax.ejb.EJBObject and defines the business methods that a client may invoke. o The requirements for the method definitions in a remote interface are the same for both session and entity beans: o Each method in the remote interface must match a method in the enterprise bean class. o The signatures of the methods in the remote interface must be identical to the signatures of the corresponding methods in the enterprise bean class. o The arguments and return values must be valid RMI types. o The throws clause must include java.rmi.RemoteException A Container-Managed Persistence Example o The code in the home and remote interfaces is the same whether or not an entity bean uses container- managed persistence. o However, the code in the entity bean class is different for container-managed and bean-managed persistence. With container-managed persistence, the entity bean class contains no database access code.
The Application Deployment Tool generates the SQL statements needed by the entity bean class. In
order to generate the SQL statements, the tool needs to know which instance variables must be stored in
the database. These instance variables are called container-managed fields. Container-Managed Fields o These fields represent the state of an ProductEJB instance. o You specify the container-managed fields with the Application Deployment Tool o A container-managed field must be one of the following types: o Java serializable class o Java primitive o Reference of a home interface