Difference between AppServer and a Web server :

Difference between AppServer and a Web server :
(1) Webserver serves pages for viewing in web browser, application server provides exposes businness logic for client applications through various protocols

(2) Webserver exclusively handles http requests.application server serves bussiness logic to application programs through any number of protocols.

(3) Webserver delegation model is fairly simple,when the request comes into the webserver,it simply passes the request to the program best able to handle it(Server side program). It may not support transactions and database connection pooling.

(4) Application server is more capable of dynamic behaviour than webserver. We can also configure application server to work as a webserver.Simply applic! ation server is a superset of webserver.

In J2EE application modules are packaged as EAR, JAR and WAR based on their functionality .These files are simply zipped files using java jar tool. These files are created for different purposes.

.jar files:

JAR files (Java ARchive) allows aggregating many files into one, it is usually used to hold Java classes in a library. i.e. Math.jar These files are with the .jar extension. The .jar files contain the libraries, resources and accessories files like property files.

.warfiles:
WAR files (Web Application aRchive) stores XML, java classes, and JavaServer pages for Web Application purposes. These files are with the .war extension. The war file contains the web application that can be deployed on the any servlet/jsp container. The .war file contains jsp, html, javascript and other files for necessary for the development of web applications.

.earfiles:

EAR files (Enterprise ARchive) combines JAR and WAR files to make a combined archive for Enterprise Applications. The .ear file contains the EJB modules of the applications