tailieunhanh - Bài giảng Lập trình mạng nâng cao: EJB: Stateful Session Bean - Nguyễn Xuân Vinh

Learning objectives of this chapter include: Define a Stateful Session Bean, list the characteristics of a Stateful Session Bean, write Stateful session bean programs, differentiate between Stateless and Stateful Session beans. | EJB: Stateful Session Bean Presenter: Nguyễn Xuân Vinh Information Technology Faculty Nong Lam University Session Objectives Define a Stateful Session Bean List the characteristics of a Stateful Session Bean. Write Stateful session bean programs. Differentiate between Stateless and Stateful Session beans. Review of Session 3 (1 of 3) The bean class, the EJB object, the remote interface, the home interface, the home object, the deployment descriptors, and the jar files constitute the enterprise bean. Bean class contains the implementation of the business logic methods. EJB container performs important management functions when it intercepts client requests such as: * Transaction logic * Security logic * Bean instance logic The Remote interface duplicates the methods exposed by the bean class. Responsibilities of the EJB home object: * Creating EJB objects * Searching for existing EJB Objects * Removing EJB Objects Review of Session 3 (2 of 3) The deployment descriptor: A file that tells the EJB server about the classes, the home interface, and the remote interface that form the bean. The lifetime of a session bean may last till such time as that of a client session. It could be as long as a window is open or as long as an application is open. Session beans do not, therefore, survive application server crashes or machine crashes. Three classes are essential for deployment: Home Interface Remote Interface Bean class Review of Session 3 (3 of 3) The file is a compressed file that contains the declarations of the enterprise bean class, the remote interface and the home interface. An EJB client can be: * An ordinary JavaBean * Another EJB * A JSP Page * A servlet * An applet *A stand-alone application Characteristics of Stateful Session Beans Conversional state occurs when a client calls a method on a bean. Pooling has to be done to conserve resources and enhances scalability. The container swaps out a bean and saves the conversational state to the hard disk | EJB: Stateful Session Bean Presenter: Nguyễn Xuân Vinh Information Technology Faculty Nong Lam University Session Objectives Define a Stateful Session Bean List the characteristics of a Stateful Session Bean. Write Stateful session bean programs. Differentiate between Stateless and Stateful Session beans. Review of Session 3 (1 of 3) The bean class, the EJB object, the remote interface, the home interface, the home object, the deployment descriptors, and the jar files constitute the enterprise bean. Bean class contains the implementation of the business logic methods. EJB container performs important management functions when it intercepts client requests such as: * Transaction logic * Security logic * Bean instance logic The Remote interface duplicates the methods exposed by the bean class. Responsibilities of the EJB home object: * Creating EJB objects * Searching for existing EJB Objects * Removing EJB Objects Review of Session 3 (2 of 3) The deployment descriptor: A file that .