Interface for Enterprise Bean

This subsection describes the interfaces that you can use for implementing an Enterprise Bean. The following table describes the list of usable interfaces:

Table 2-6 List of usable interfaces

Interface name	Description
Remote home interface^#1	This interface that is specified in EJB specifications 1.1 or later versions inherits javax.ejb.EJBHome and is used for a remote client. This interface is mainly used for acquiring Enterprise Bean instances.
Remote component interface^#2	This interface that is specified in EJB specifications 1.1 or later versions inherits javax.ejb.EJBObject and is used for a remote client. This interface mainly defines the business methods.
Remote business interface	This interface is used to define the business methods for invoking the Enterprise Beans from a remote client. The defined interface need not be inherited.
Local home interface	This interface that is specified in EJB specifications 2.0 or later versions inherits javax.ejb.EJBLocalHome and is used for a local client. This interface is mainly used for acquiring Enterprise Bean instances.
Local component interface	This interface that is specified in EJB specifications 2.0 or later versions inherits javax.ejb.EJBLocalObject and is used for a local client. This interface mainly defines the business methods.
Local business interface	This interface is used to define the business methods for invoking the Enterprise Beans from a local client. The defined interface need not be inherited.

#1: This interface is called a home interface in EJB specifications 1.1.

#2: This interface is called a remote interface in EJB specifications 1.1.

In this manual, multiple interfaces are grouped together and are given a general name. The following table describes the general names for the interfaces that are used in the descriptions of this manual:

Table 2-7 General names of interfaces

General name of the interface	Description
Home interface	This is the general name for the following interfaces: Remote home interface Local home interface
Component interface	This is the general name for the following interfaces: Remote component interface Local component interface
Business interface	This is the general name for the following interfaces: Remote business interface Local business interface
Remote interface	This is the general name for the following interfaces: Remote home interface Remote component interface Remote business interface This name may, however, indicate only the remote component interface and the remote business interface.
Local interface	This is the general name for the following interfaces: Local home interface Local component interface Local business interface This name may, however, indicate only the local component interface and the local business interface.

These interfaces are implemented for a Session Bean or an Entity Bean. A Message-driven Bean does not have these interfaces.

With a Session Bean, you can use the No-Interface view to invoke from the local interface. In such cases, you can omit the implementation of the interface. For details on the No-Interface view, see 2.16 Omitting local business interfaces (Using No-Interface view).

Organization of this subsection: (1) Remote interface; (2) Local interface; (3) Functionality supporting a business interface; (4) Invoking the Enterprise Bean of a business interface

(1) Remote interface

(2) Local interface

(3) Functionality supporting a business interface

The following functionality can be used even when you use a business interface:

Functionality for optimizing local invocation
For details on the functionality, see 2.13.1 Optimizing local invocation in the EJB remote interface.
Pass by reference functionality of remote interface values
For details on the functionality, see 2.13.2 Referencing and passing the values of the EJB remote interface.
Timeout during RMI-IIOP communication
For details on the functionality, see 2.11.5 Timeout of RMI-IIOP communication.
Specify the communication timeout in the definition file or in API. The precautions while setting the timeout, when a business interface is used, are described below:
- When specifying in the definition file
  When using the DI functionality, the communication timeout property of JNDI is also enabled, since JNDI is used in the EJB container.
- When specifying in API
  You can specify in the thread, but not in the object.
When a timeout occurs, exception java.rmi.RemoteException (org.omg.CORBA.TIMEOUT) is thrown if the business interface inherits java.rmi.Remote, and exception javax.ejb.EJBException (RemoteException (org.omg.CORBA.TIMEOUT)) is thrown if the business interface does not inherit java.rmi.Remote.
EJB check functionality
For details on the functionality, see 2.3 Checking the compliance with EJB specifications.

Method timeout functionality for monitoring the J2EE application execution time
For details on the functionality, see 5.3.2 Monitoring the execution time of the J2EE applications in the uCosminexus Application Server Operation, Monitoring, and Linkage Guide.
When invoking the EJB methods with annotation specified, you can apply the timeout value for each method as described in the table below:

Table 2-8 Applicability of a timeout for Enterprise Bean

Interface	Method	Stateless SessionBean	Stateful SessionBean	Singleton Session Bean	Message DrivenBean	Persistence API
Business interface	Business method^#1	Y	Y	Y	N/A	N/A
Home or component interface^#2	create	N	Y	N/A	N/A	N/A
	Business method	Y	Y	N/A	N/A	N/A
	remove	N	Y	N/A	N/A	N/A
javax.ejb.Timed Object	ejbTimeout	Y	N/A	Y	N/A	N/A

Legend:: Y: Applied; N: Not applied; N/A: Not applicable

#1: Includes methods, wherein the @Timeout annotation and the @Remove annotation are appended.

#2: Indicates interfaces that use @RemoteHome or @LocalHome.

(4) Invoking the Enterprise Bean of a business interface

The case of invoking a business interface running in another J2EE application on the same J2EE server and that of invoking a business interface running in another J2EE server are explained below:

In either case, the invoking EJB-JAR file or the WAR file contains the business interface of the invoked Enterprise Bean as well as the user-created classes used in the interface. Furthermore, lookup is performed by using either the name that is bound automatically to the JNDI name space (Portable Global JNDI name or a name starting with HITACHI_EJB) or the optional name set up in the user-specified name space functionality. For details on the names used for lookup, see 2.5 Look up by the name starting with HITACHI_EJB in the uCosminexus Application Server Common Container Functionality Guide.

When invoking the Enterprise Bean of a business interface running in another J2EE application on the same J2EE server
Include the business interface of the invoked Enterprise Bean as well as the user-created classes used in the interface in the invoking EJB-JAR file or the WAR file.
If the ejbserver.rmi.localinvocation.scope key of the user property file for the J2EE server is "None", acquire the stubs by using the cjgetstubsjar command for the invoked Enterprise Bean and include these stubs in the invoking EAR file.^#
When invoking the Enterprise Bean of a business interface running in another J2EE server
Acquire the stubs by using the cjgetstubsjar command for the invoked Enterprise Bean and include these stubs in the invoking EAR file.^#

#

If you use the dynamic class loading functionality for invoking the business interface between applications, you need not include the stubs. However, from the performance perspective, Hitachi does not recommend the use of the dynamic class loading functionality.

2.2.2 Interface for Enterprise Bean

(1) Remote interface

(2) Local interface

(3) Functionality supporting a business interface

(4) Invoking the Enterprise Bean of a business interface