EJB overview (II)

EJB overview (II)
2000-05-15 · ilamei · cpcw
Application roles: (Application role)
Enterprise beans Provider: Beans Provider is an expert in the application field. For example, the Beans provider may be an expert in finance or telecommunications. The Beans provider provides business tasks and Enterprise beans business methods, defines the romote and home interfaces of beans, and defines the configuration descriptor of beans. Because containers manage system-level tasks, the Beans provider does not need to care about distributed processing, transaction processing, and security.
Application aggreger Assembly:
This is an expert who assembles custom Enterprise beans and other components, such as GUI client, applet, and Servelet, into a complete application. In the Enterprise configurator, when assembling an application, the assembler only cares about the beans interface, including the romote interface and the home interface. It doesn't matter how these interfaces are implemented. The result of assembly is an application, or a complicated Enterprise beans combined by multiple Enterprise beans.
Deployment and Operate roles configuration and operation roles
The configurator configures special operation environments for specific Enterprise beans. To adapt to the application, the configurator combines multiple Enerprise beans and modifies the attributes of Enterprise beans to configure the corresponding operating environment. For example, the configurator sets the transaction and security policies by setting the corresponding properties of the configuration descriptor. Another task of the configurator is to combine applications with existing Enterprise management software.
System Administrator;
Is related to the configuration application. The administrator configures a lower layer for managing Enterprise computing and network services, including EJB services and containers. The administrator monitors the running status of the application server. When the application server is abnormal, the administrator takes appropriate measures. Typically, administrators use Enterprise management tools to deal with applications and configure them through the hooks provided by containers.
Traditional application developers are now the provider of Enterprise beans. It may also be the application assembler. In this way, they can focus on application problems or application logic. When Enterprise beans is installed, the configurator defines a series of configuration policies. The complexity of the mechanism and the policy for executing the configuration are handed over to a dedicated proxy. Although distributed applications are still complicated, the work of application designers is simplified because all the complicated work is handed over to the EJB server and container provider.
Through a large number of pre-design definitions and naming conventions, EJB achieves the purpose mentioned above. Such a programming architecture limits some freedom. However, it allows the EJB server and container provider to assume the design of the application and support them in an effective way.