Weblogic Server Application Architecture
Weblogic Server application operates in the middle tier of a multitier (or n-tier) architecture. A multitier architecture determines where the software components that make up a computing system are executed in relation to each other and to the hardware, network, and users. Choosing the best location for each software component lets you develop applications faster; eases deployment and administration; and provides greater control over performance, utilization, security, scalability, and reliability.
Weblogic Server implements J2EE, the Java Enterprise standard. The Weblogic Server application architecture-a layering of application logic, with each layer selectively deployed among WebLogic Server J2EE technologies. WebLogic Server architecture has two layers software tiers and application logic layers.
Software Component Tiers
The software components of a multi tier architecture consist of three tiers:
The client tier contains programs executed by users, including Web browsers and network-capable application programs. These programs can be written in virtually any programming language.
The middle tier contains WebLogic Server and other servers that are addressed directly by clients, such as existing Web servers or proxy servers.
The backend tier contains enterprise resources, such as database systems, mainframe and legacy applications, and packaged enterprise resource planning (ERP) applications.
Client applications access WebLogic Server directly, or through a Web server or proxy server. WebLogic Server connects with backend services on behalf of clients, but clients do not directly access backend services.
Application Logic Layers:
To build a WebLogic Server application, you must create and assemble components, using the service APIs when necessary.
Presentation Logic Layer
The presentation layer includes an application’s user interface and display logic. Most J2EE applications use a Web browser on the client machine because it is much easier than deploying client programs to every user’s computer. In this case, the presentation logic is the WebLogic Server Web container. Client programs written in any programming language, however, must contain either logic to render HTML or their own presentation logic.
Business Logic Layer
Enterprise JavaBeans are the business logic components for J2EE applications. The WebLogic Server EJB container hosts enterprise beans, providing life cycle management and services such as caching, persistence, and transaction management.
There are three types of enterprise beans: entity beans, session beans, and message-driven beans.
Application Services Layer
WebLogic Server supplies the fundamental services that allow components to concentrate on business logic without concern for low-level implementation details. It handles networking, authentication, authorization, persistence, and remote object access for EJBs and servlets. Standard Java APIs provide portable access to other services that an application can use, such as database and messaging services.