Introduction

   Server is a physical computer dedicated to running one or more such services to serve the needs of users of the other computers on the network. Depending on the computing service that it offers it could be a database server, file server, mail server, print server, web server or Application server etc,.

In our context I am going to speak about webserver and appserver or application server

WebServer:

A Web server handles the HTTP protocol. When the Web server receives an HTTP request, it responds with an HTTP response, such as sending back an HTML page. To process a request, a Web server may respond with a static HTML page or image, send or redirect, or delegate the dynamic response generation to some other program such as CGI scripts, JSPs (JavaServer Pages), servlets, ASPs (Active Server Pages), server-side JavaScripts, or some other server-side technology. Whatever their purpose, such server-side programs generate a response, most often in HTML, for viewing in a Web browser.

The web server simply passes the request to the program to handle it. The web server does not provides any functionality beyond providing an environment in which the server - side program can execute and pass back the generated responses. The server-side program usually provides such functions as transaction processing, database connectivity and messing .

Application Server:

         While an application server exposes business logic to client applications through various protocols like HTTP, TCP-IP etc. All the web servers mainly deals with sending HTML for displaying to a Web browser. An application server providers allows the client to access the business logic for use. The application server is used to run business logic or dynamically generating presentation code. A J2EE application server runs servlets and JSPs that are used to create HTML pages dynamically. In this case, J2EE application server can run EJBs ? which are used to execute business logic. An application server is more capable of dynamic behavior than webserver.

 Some examples of web servers and Application servers:

Web Servers:

• AOL Server
• Apache HTTP
• IIS
• Nginx
• Boa
• Tux/kHTTPd
• IBM HTTP
• HFS
• Oracle I-Planet

 Application servers:

• Weblogic
• Websphere
• Glass Fish
• JBoss
• Oracle Application server
• Boreland
• Tomcat
• Cold Fusion

J2EE Platform

         WebLogic Server contains Java 2 Platform, Enterprise Edition (J2EE) technologies. J2EE is the standard platform for developing multitier enterprise applications based on the Java programming language. The technologies that make up J2EE were developed collaboratively by Sun Microsystems and other software vendors, including BEA Systems.

J2EE applications are based on standardized, modular components. WebLogic Server provides a complete set of services for those components and handles many details of application behavior automatically, without requiring programming.

WebLogic Server (WLS)

        WebLogic Server is an application server: a platform for developing and deploying multitier distributed enterprise applications. WebLogic Server centralizes application services such as Web server functionality, business components, and access to backend enterprise systems. It uses technologies such as caching and connection pooling to improve resource use and application performance. WebLogic Server also provides enterprise-level security and powerful administration facilities.

WebLogic Server 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. Java is a network-savvy, object-oriented programming language, and J2EE includes component technologies for developing distributed objects. This functionality adds a second dimension to the WebLogic Server application architecture—a layering of application logic, with each layer selectively deployed among WebLogic Server J2EE technologies.