What is CMP bean?

What is CMP bean?

CMP Entity Beans. An entity bean manages persistent data in one of two manners: container-managed persistence and bean-managed persistence. For this to occur, you must define the data that the container is to manage, within the deployment descriptors. The container manages the data by saving it to the database.

What is the difference between bean and entity?

The interface requirements on entity beans provides callback functions that the container calls when persistent data should be managed or when a bean should be retrieved based upon its identity….Difference Between Session and Entity Beans.

	Entity Bean	Session Bean
Primary key	Used to identify and retrieve specific bean instances	Not used for session beans

What is entity bean explain with code?

An entity bean is an EJB 2.1 enterprise bean component that manages persistent data, performs complex business logic, potentially uses several dependent Java objects, and can be uniquely identified by a primary key. These methods use JDBC, SQLJ, or a persistence framework (such as TopLink) to manage persistence.

What are the features of entity bean?

Key Features of Entity Beans

• Persistence—Entity bean persistence can be managed by the EJB container, or the bean itself.
• Shared Access—Throughout its lifecycle, an entity bean instance can support multiple clients, although not at the same time.
• Primary Key—Each entity bean has a unique object identifier.

What is the difference between CMP and BMP in EJB?

CMP, or Container Managed Persistence, is known to be the simplest for bean developers to create, and is known to be the most complicated for the EJB servers to support. BMP, or Bean Managed Persistence, is known to manage synchronizing its state with databases, as engaged by the container.

What is CMP in EJB?

The EJB 2.0 specification expanded CMP to allow multiple entity beans to have relationships among themselves. This is referred to as Container-Managed Relationships (CMR). The container manages the relationships and the referential integrity of the relationships.

When should we use entity bean?

Session beans are typically used for performing simple tasks for a remote client. Entity beans are typically used for performing complex tasks that involve coarse-grained persistence for remote clients. Java objects, persistent or otherwise, are used for simple tasks for local clients.

What are the types of entity beans?

There are two types of entity beans: bean-managed persistent and container-managed persistent….The following code implements methods of an entity bean called PurchaseOrderBean .

• Declaring Variables.
• Implementing Remote Interface Methods.
• Implementing EntityBean Interface Methods.
• LineItem Class.

What is entity bean explain with suitable example?

Definition of an Entity Bean. An entity bean is a remote object that manages persistent data, performs complex business logic, potentially uses several dependent Java objects, and can be uniquely identified by a primary key.

What is CMP in distributed technology?

Container-Managed Persistence (CMP) occurs when the entity object delegates persistence services. With CMP, the EJB container transparently and implicitly manages the persistent state. The enterprise bean developer does not need to code any database access functions within the enterprise bean class methods.

What is CMP and BMP in EJB?

Which is a type of entity bean?

There are two types of entity beans: bean-managed persistent and container-managed persistent.

Why do you use entity beans in CMP?

With CMP, the entity bean class does not contain the code that connects to a database. So, we are able to get flexibility by simply editing the deployment descriptors and weblogic.properties files, without editing and recompiling the java class files.

What kind of persistence does entity beans have?

Entity beans can have two types of Persistence. We can declare the type of persistence required by us in the ‘Deployment Descriptor’. In CMP, the bean designer does not have to write any sql-related code at all. The necessary sql statements are automatically generated by the container.

Do you have to write SQL statements in CMP?

In CMP, the bean designer does not have to write any sql-related code at all. The necessary sql statements are automatically generated by the container. The container takes care of synchronizing the entity bean’s attributes with the corresponding columns in the table of the database.

Where are entity beans stored on the hard disk?

Entity beans ‘persist’ (ie) they are stored inEnterprise server’s hard disk and so even if there is a shutdown of the server, the beans ‘survive’ and can be created againfrom the hard disk storage. [ A session bean is not stored in hard disk ].