Implementing the Home Interfaces

The home interfaces (remote and local) are used to create the session bean instance; thus, they define the create method for your bean. As Table 11-3 shows, the type of create methods you define depends on the type of session bean you are creating:

Table 11-3 Home Interface Create Methods

Session Bean Type	Create Methods
Stateless Session Bean	Single create method only, with no parameters.
Stateful Session Bean	One or more create methods with whatever parameters define the bean's state.

For each create method, you define a corresponding ejbCreate method in the bean implementation.

Implementing the Remote Home Interface

A remote client invokes the EJB through its remote interface. The client invokes the create method that is declared within the remote home interface. The container passes the client call to the ejbCreate method–with the appropriate parameter signature–within the bean implementation. The requirements for developing the remote home interface include:

• The remote home interface must extend the javax.ejb.EJBHome interface.

• All create methods may throw the following exceptions:

  • javax.ejb.CreateException

  • javax.ejb.RemoteException

  • optional application exceptions

• All create methods should not throw the following exceptions:

  • javax.ejb.EJBException

  • java.lang.RunTimeException

Example 11-5 shows a remote home interface called HelloHome for a stateless session bean.

Example 11-5 Remote Home Interface for a Stateless Session Bean

package hello;

import javax.ejb.*;
import java.rmi.*;

public interface HelloHome extends EJBHome {
  public Hello create() throws CreateException, RemoteException;
}

Example 11-6 shows a remote home interface called HelloHome for a stateful session bean. You use the arguments passed into the various create methods to initialize the session bean's state.

Example 11-6 Remote Home Interface for a Stateful Session Bean

package hello;

import javax.ejb.*;
import java.rmi.*;

public interface HelloHome extends EJBHome {
  public Hello create() throws CreateException, RemoteException;
  public Hello create(String message) throws CreateException, RemoteException;
  public Hello create(Collection messages) throws CreateException, RemoteException;
}

Implementing the Local Home Interface

An EJB can be called locally from a client that exists in the same container. Thus, a collocated bean, JSP, or servlet invokes the create method that is declared within the local home interface. The container passes the client call to the ejbCreate method–with the appropriate parameter signature–within the bean implementation. The requirements for developing the local home interface include the following:

• The local home interface must extend the javax.ejb.EJBLocalHome interface.

• All create methods may throw the following exceptions:

  • javax.ejb.CreateException

  • javax.ejb.RemoteException

  • optional application exceptions

• All create methods should not throw the following exceptions:

  • javax.ejb.EJBException

  • java.lang.RunTimeException

Example 11-7 shows a local home interface called HelloLocalHome for a stateless session bean.

Example 11-7 Local Home Interface for a Stateless Session Bean

package hello;

import javax.ejb.*;

public interface HelloLocalHome extends EJBLocalHome {
 public HelloLocal create() throws CreateException;
}

Example 11-8 shows a local home interface called HelloLocalHome for a stateful session bean. You use the arguments passed into the various create methods to initialize the session bean's state.

Example 11-8 Local Home Interface for a Stateful Session Bean

package hello;

import javax.ejb.*;

public interface HelloLocalHome extends EJBLocalHome {
  public HelloLocal create() throws CreateException;
  public HelloLocal create(String message) throws CreateException;
  public HelloLocal create(Collection messages) throws CreateException;
}