EJB.3.2 Scenario: Development, Assembly, and Deployment

Aardvark Inc. specializes in application integration. Aardvark developed the AardvarkPayroll enterprise bean, which is a generic payroll access component that allows Java technology-enabled applications to access the payroll modules of the leading ERP systems. Aardvark packages the AardvarkPayroll enterprise bean in a standard EJB JAR file and markets it as a customizable enterprise bean to application developers. In the terms of the EJB architecture, Aardvark is the bean provider of the AardvarkPayroll bean.

Wombat Inc. is a web-application development company. Wombat developed an employee self-service application. The application allows a target enterprise's employees to access and update employee record information. The application includes the EmployeeService , EmployeeServiceAdmin , and EmployeeRecord enterprise beans. The EmployeeRecord bean is a container-managed entity that allows deployment-time integration with an enterprise's existing human resource applications. In terms of the EJB architecture, Wombat is the bean provider of the EmployeeService , EmployeeServiceAdmin , and EmployeeRecord enterprise beans.

In addition to providing access to employee records, Wombat would like to provide employee access to the enterprise's payroll and pension plan systems. To provide payroll access, Wombat licenses the AardvarkPayroll enterprise bean from Aardvark, and includes it as part of the Wombat application. Because there is no available generic enterprise bean for pension plan access, Wombat decides that a suitable pension plan enterprise bean will have to be developed at deployment time. The pension plan bean will implement the necessary application integration logic, and it is likely that the pension plan bean will be specific to each Wombat customer.

In order to provide a complete solution, Wombat also develops the necessary non-EJB components of the employee self-service application, such as the Java ServerPages (JSP) that invoke the enterprise beans and generate the HTML presentation to the clients . Both the JSP pages and enterprise beans are custom-izable at deployment time because they are intended to be sold to a number of target enterprises that are Wombat customers.

The Wombat application is packaged as a collection of JAR files. A single EJB JAR file contains all the enterprise beans developed by Wombat and also the AardvarkPayroll enterprise bean developed by Aardvark; the other JAR files contain the non-EJB application components, such as the JSP components. The EJB JAR file contains the application assembly instructions describing how the enterprise beans are composed into an application. In terms of the EJB architecture, Wombat performs the role of the application assembler .

Acme Corporation is a server software vendor. Acme developed an EJB server and container. In terms of the EJB architecture, Acme performs the EJB container provider and EJB server provider roles.

The ABC Enterprise wants to enable its employees to access and update employee records, payroll information, and pension plan information over the Web. The information is stored in ABC's ERP system. ABC buys the employee self-service application from Wombat. To host the application, ABC buys the EJB container and server from Acme. ABC's Information Technology (IT) department, with the help of Wombat's consulting services, deploys the Wombat self-service application. In terms of the EJB architecture, ABC's IT department and Wombat consulting services perform the deployer role. ABC's IT department also develops the ABCPensionPlan enterprise bean that provides the Wombat application with access to ABC's existing pension plan application.

ABC's IT staff is responsible for configuring the Acme product and integrating it with ABC's existing network infrastructure. The IT staff is responsible for the following tasks : security administration, such as adding and removing employee accounts; adding employees to user groups such as the payroll department; and mapping principals from digital certificates that identify employees on VPN connections from home computers to the Kerberos user accounts that are used on ABC's intranet. ABC's IT staff also monitors the well-being of the Wombat application at runtime, and is responsible for servicing any error conditions raised by the application. In terms of the EJB architecture, ABC's IT staff performs the role of the system administrator .

Figure EJB.3-1 illustrates the products of the various EJB architecture roles.

Figure EJB.3-1. Development, Assembly, and Deployment Scenarios

Table EJB.3-1 summarizes the EJB architecture roles of the organizations involved in the scenario.

Table EJB.3-1. EJB Architecture Roles in the Example Scenarios

Organization	EJB Architecture Roles
Aardvark Inc.	Bean provider
Wombat Inc.	Bean provider Application assembler
Acme Corporation	EJB container provider EJB server provider
ABC Enterprise's IT staff	Deployer Bean provider (of ABCPensionPlan ) System administrator