Chapter 5. Client View of an Entity

This page discusses - Chapter 5. Client View of an Entity

Chapter 5. Client View of an Entity

Chapter 5. Client View of an Entity

Identify correct and incorrect statements or examples about the client of an entity bean's local and remote home interface, including viewing the code used to locate an entity bean's home interface and the home interface methods provided to the client.

The client of an entity bean may be a REMOTE client or the client may be a LOCAL client.

A REMOTE client accesses an entity bean through the entity bean’s remote and remote home interfaces. The remote and remote home interfaces of the entity bean provide the remote client view.

The remote client view of an entity bean is location independent. A client running in the same JVM as an entity bean instance uses the same API to access the entity bean as a client running in a different JVM on the same or different machine.

A LOCAL client accesses an entity bean through the entity bean’s local and local home interfaces. The container provides classes that implement the entity bean’s local and local home interfaces. The objects that implement the local home and local interfaces are local Java objects.

The arguments of the methods of the LOCAL interface and LOCAL HOME interface are passed by REFERENCE.

The arguments and results of the methods of the REMOTE interface and REMOTE HOME interface are passed by VALUE.

The remote client view can also be mapped to non-Java client environments, such as CORBA clients not written in the Java programming language.

Locating an entity bean’s REMOTE home interface

Context initialContext = new InitialContext();
AccountRemoteHome accountHome = (AccountRemoteHome)
	javax.rmi.PortableRemoteObject.narrow(
		initialContext.lookup(?java:comp/env/ejb/accounts?),
		AccountRemoteHome.class
	);					
					

Locating an entity bean’s LOCAL home interface

Context initialContext = new InitialContext();
AccountLocalHome accountHome = (AccountLocalHome)
	initialContext.lookup(?java:comp/env/ejb/accounts?);
					

The CONTAINER provides the implementation of the remote home interface for each entity bean deployed in the container that defines a remote home interface. The container makes the remote home interface accessible to the clients through JNDI. The entity bean’s remote home interface allows a client to do the following:

  • Create new entity objects within the home.

  • Find existing entity objects within the home.

  • Remove an entity object from the home.

  • Execute a home business method.

  • Get the javax.ejb.EJBMetaData interface for the entity bean. The javax.ejb.EJBMetaData interface is intended to allow application assembly tools to discover the meta-data information about the entity bean. The meta-data information allows loose client/server binding and scripting.

  • Obtain a HANDLE for the home interface. The home handle can be serialized and written to stable storage; later, possibly in a different JVM, the handle can be deserialized from stable storage and used to obtain a reference to the home interface.

An entity bean’s remote home interface must extend the javax.ejb.EJBHome interface and follow the standard rules for Java programming language remote interfaces.

The CONTAINER provides the implementation of the local home interface for each entity bean deployed in the container that defines a local home interface. The container makes the local home interface accessible to local clients through JNDI.

The entity bean’s LOCAL home interface allows a local client to do the following:

  • Create new entity objects within the home.

  • Find existing entity objects within the home.

  • Remove an entity object from the home.

  • Execute a home business method.

An entity bean’s LOCAL HOME interface MUST extend the javax.ejb.EJBLocalHome interface.

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Tutorials

  1. Appendix A. First Appendix
  2. Second Section
  3. Third Section
  4. Part II. Appendixes
  5. From a list, identify the responsibility of the bean provider and the responsibility of the container provider for a message-driven bean.
  6. Chapter 6. Component Contract for Container-Managed Persistence (CMP)
  7. Identify correct and incorrect statements or examples about persistent relationships, remove protocols, and about the abstract schema type of a CMP entity bean.
  8. Identify the interfaces and methods a CMP entity bean must and must not implement.
  9. Match the name with a description of purpose or functionality, for each of the following deployment descriptor elements: ejb-name, abstract-schema-name, ejb-relation, ejb-relat
  10. Identify correctly-implemented deployment descriptor elements for a CMP bean (including container-managed relationships).
  11. From a list, identify the purpose, behavior, and responsibilities of the bean provider for a CMP entity bean, including but not limited to: setEntityContext, unsetEntityContext, ejbC
  12. Chapter 7. CMP Entity Bean Life Cycle
  13. Identify correct and incorrect statements or examples about the rules and semantics for relationship assignment and relationship updating in a CMP bean.
  14. From a list, identify the responsibility of the container for a CMP entity bean, including but not limited to: setEntityContext, unsetEntityContext, ejbCreate, ejbPostCreate, ejbActi
  15. Given a code listing, determine whether it is a legal and appropriate way to programmatically access a caller's security context.
  16. Chapter 10. Message-Driven Bean Component Contract
  17. Identify correct and incorrect statements about the purpose and use of the deployment descriptor elements for environment entries, EJB references, and resource manager connection factory r
  18. Identify the use and the behavior of the ejbPassivate method in a session bean, including the responsibilities of both the container and the bean provider.
  19. Chapter 12. Exceptions
  20. Identify correct and incorrect statements or examples about the client view of an entity bean's local component interface (EJBLocalObject).
  21. Identify EJB 2.0 container requirements.
  22. Chapter 1. EJB Overview
  23. Identify correct and incorrect statements or examples about EJB programming restrictions.
  24. Chapter 9. EJB-QL
  25. Identify correct and incorrect statements or examples about the purpose and use of EJB QL.
  26. Identify correct and incorrect conditional expressions, BETWEEN expressions, IN expressions, LIKE expressions, and comparison expressions.
  27. Identify correct and incorrect statements or examples about the client view of a entity bean's remote component interface (EJBObject).
  28. Given a list, identify which are requirements for an EJB-jar file.
  29. Match EJB roles with the corresponding description of the role's responsibilities, where the description may include deployment descriptor information.
  30. Chapter 2. Client View of a Session Bean
  31. Chapter 13. Enterprise Bean Environment
  32. Chapter 8. Entity Beans
  33. 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
  34. Identify correct and incorrect statements or examples about an entity bean's primary key and object identity.
  35. Identify correct and incorrect statements or examples about the client's view of exceptions received from an enterprise bean invocation.
  36. Identify correct and incorrect statements or examples about application exceptions and system exceptions in entity beans, session beans, and message-driven beans.
  37. Given a particular method condition, identify the following: whether an exception will be thrown, the type of exception thrown, the container's action, and the client's view.
  38. Given a list of responsibilities related to exceptions, identify those which are the bean provider's, and those which are the responsibility of the container provider. Be prepared to recog
  39. SCBCD Study Guide
  40. Identify the use and behavior of the MessageDrivenContext interface methods.