Home Javacertification Bcd-guide Identify the use, syntax, and behavior of, the following entity bean home method types, for Container-Managed Persistence (CMP); finder methods, create methods, remove methods, and home me

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Identify the use, syntax, and behavior of, the following entity bean home method types, for Container-Managed Persistence (CMP); finder methods, create methods, remove methods, and home me
Posted on: April 18, 2011 at 12:00 AM
This page discusses - Identify the use, syntax, and behavior of, the following entity bean home method types, for Container-Managed Persistence (CMP); finder methods, create methods, remove methods, and home me

Identify the use, syntax, and behavior of, the following entity bean home method types, for Container-Managed Persistence (CMP); finder methods, create methods, remove methods, and home methods.

REMOTE view CMP Entity EJB

An entity bean’s remote home interface defines ONE (AT LEAST findByPrimaryKey(pKey)) or MORE finder methods, one for each way to find an entity object or collection of entity objects within the home. The name of each finder method starts with the prefix “find”,

The return type of a finder method on the REMOTE HOME interface must be the entity bean’s REMOTE interface, or a type representing a collection (java.util.Collection or java.util.Set) of objects that implement the entity bean’s REMOTE interface.

The throws clause of EVERY finder method on the remote home interface includes the java.rmi.RemoteException and the javax.ejb.FinderException.

The following example shows the findByPrimaryKey method:

public interface AccountHome extends javax.ejb.EJBHome {
...
public Account findByPrimaryKey(String AccountNumber)
	throws RemoteException, FinderException;
}
					
					
AccountHome = ...;
Account account = accountHome.findByPrimaryKey(?100-3450-3333?);
					

An entity bean’s remote home interface can define ZERO or MORE create<METHOD>(...) methods. The arguments of the create methods are typically used to initialize the state of the created entity object. The name of each create method starts with the prefix “create”.

The RETURN type of a create<METHOD> method on the REMOTE HOME interface is the entity bean’s REMOTE interface.

The throws clause of EVERY create<METHOD> method on the REMOTE home interface includes the java.rmi.RemoteException and the javax.ejb.CreateException. It MAY include additional application-level exceptions.

public interface AccountHome extends javax.ejb.EJBHome {
	public Account create(String firstName, String lastName,
		double initialBalance)
		throws RemoteException, CreateException;
	public Account create(String accountNumber,
		double initialBalance)
		throws RemoteException, CreateException,
			LowInitialBalanceException;
	public Account createLargeAccount(String firstname,
		String lastname, double initialBalance)
		throws RemoteException, CreateException;
	...
}
					
					
AccountHome accountHome = ...;
Account account = accountHome.create(?John?, ?Smith?, 500.00);
					

The javax.ejb.EJBHome interface defines several methods that allow the client to REMOVE an entity object.

public interface EJBHome extends Remote {
	void remove(Handle handle) throws RemoteException,
		RemoveException;
	void remove(Object primaryKey) throws RemoteException,
		RemoveException;
}					
					
After an entity object has been removed, subsequent attempts to access the entity object by a remote client result in the java.rmi.NoSuchObjectException.

An entity bean’s remote home interface MAY define one or more HOME METHODS. Home methods are methods that the bean provider supplies for business logic that is NOT SPECIFIC to an entity bean instance. They MUST NOT start with “create”, “find”, or “remove”. The method arguments and return value types of a home method on the remote home interface MUST be legal types for RMI-IIOP.

The throws clause of EVERY home method on the remote home interface includes the java.rmi.RemoteException. It may also include additional application-level exceptions.

public interface EmployeeHome extends javax.ejb.EJBHome {
	...
	// this method returns a living index depending on
	// the state and the base salary of an employee:
	// the method is not specific to an instance
	public float livingIndex(String state, float Salary)
		throws RemoteException;
		
	// this method adds a bonus to all of the employees
	// based on a company profit-sharing index
	public void addBonus(float company_share_index)
		throws RemoteException, ShareIndexOutOfRangeException;
	...
}
					

LOCAL view CMP Entity EJB

An entity bean’s local home interface defines ONE (findByPrimaryKey(primaryKey) method is MANDATORY for all Entity Beans) or MORE finder methods. The name of each finder method starts with the prefix “find”. The return type of a finder method on the local home interface MUST be the entity bean’s LOCAL interface, or a type representing a collection (java.util.Collection or java.util.Set) of objects that implement the entity bean’s LOCAL interface.

The throws clause of EVERY finder method on the LOCAL HOME interface includes the javax.ejb.FinderException. The throws clause MUST NOT include the java.rmi.RemoteException.

The local home interface includes the findByPrimaryKey(primaryKey) method, which allows a client to locate an entity object using a primary key. The name of the method is always findByPrimaryKey; it has a single argument that is the SAME type as the entity bean’s primary key type, and its return type is the entity bean’s LOCAL INTERFACE. There is a unique findByPrimaryKey(primaryKey) method for an entity bean on its local home interface; this method MUST NOT be overloaded.

public interface AccountHome extends javax.ejb.EJBLocalHome {
	...
	public Account findByPrimaryKey(String AccountNumber)
		throws FinderException;
}		
					
					
AccountHome = ...;
Account account = accountHome.findByPrimaryKey(?100-3450-3333?);			
					

An entity bean’s local home interface can define ZERO or MORE create<METHOD>(...) methods. The name of each create method starts with the prefix “create”.

The return type of a create<METHOD> method on the LOCAL HOME interface is the entity bean’s LOCAL interface.

The throws clause of EVERY create<METHOD> method on the LOCAL HOME interface includes the javax.ejb.CreateException. It MAY include additional application-level exceptions. It MUST NOT include the java.rmi.RemoteException.

public interface AccountHome extends javax.ejb.EJBLocalHome {
	public Account create(String firstName, String lastName,
		double initialBalance)
			throws CreateException;
	public Account create(String accountNumber,
		double initialBalance)
			throws CreateException, LowInitialBalanceException;
	public Account createLargeAccount(String firstname,
		String lastname, double initialBalance)
			throws CreateException;
	...	
}
					
					
AccountHome accountHome = ...;
Account account = accountHome.create(?John?, ?Smith?, 500.00);
					

The javax.ejb.EJBLocalHome interface defines the REMOVE method to allow the client to remove an entity object (NOTE, local objects do NOT have handles).

public interface EJBLocalHome {
	void remove(Object primaryKey) throws RemoveException,
		EJBException;
}					
					
After an entity object has been removed, subsequent attempts to access the local entity object by the local client result in the javax.ejb.NoSuchObjectLocalException.

An entity bean’s local home interface MAY define one or more HOME METHODS. Home methods are methods that the bean provider supplies for business logic that is NOT specific to an entity bean instance. They MUST NOT start with “create”, “find”, or “remove”.

The throws clause of a home method on the local home interface MAY include additional application-level exceptions. It MUST NOT include the java.rmi.RemoteException.

public interface EmployeeHome extends javax.ejb.EJBLocalHome {
	...
	// this method returns a living index depending on
	// the state and the base salary of an employee:
	// the method is not specific to an instance
	public float livingIndex(String state, float Salary);
	
	// this method adds a bonus to all of the employees
	// based on a company profit sharing index
	public void addBonus(float company_share_index)
		throws ShareIndexOutOfRangeException;
		
	...
}					
					
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