Difference between Web Server and Application Server?

The main difference is a web server is used mainly for presentation... and an application is used for most of your backend scripting, DB access, running your web apps.

Checkout:
http://serverwatch.internet.com/appservers.html
http://www.whatis.com/applicas.htm
http://serverwatch.internet.com/webservers.html
http://www.whatis.com/webserve.htm
For details on each.

Also check out:
http://www.seyboldseminars.com/Events/sf98/transcripts/Eday9_2.html
http://philip.greenspun.com/wtr/application-servers.html


Application servers provide the run-time infrastructure and development services necessary to deploy applications, or components, in a multi-tiered architecture supporting web and other client interfaces.



CJ

To give an example... you make a request for a Java Servlet would be redirected by your web server to the application server... the application server would process the request... run the servlet and return the output (usually plain HTML) back to the web server to present to you.

They complement with each other.

CJ

here are some excellent articles on web applications (explaining architectures and roles of the web server and app server):
http://www.stabilit.ch/Stabilit/netoltp_study_en.htm

Also:
http://www.middletier.com/appservers_main.html
http://www.websydian.com/Doc/TechPapers/WebApplications.htm
http://www.west.crimea.ua/~black/asfar/vb/rose/webappsuml.htm

Definitions:
Application Server

An application server is a program running on a server, which is part of a distributed network.  This program provides the necessary business logic for an application program to run. Essentially the application server is the middleman between browser-based front-ends and back-end databases and legacy systems. In many cases, the application server combines or works with a Web (HTTP) server and is called a Web application server.

Web Application Server

An application server is a server program in a computer in a distributed network that provides the business logic for an application program.

The application server is frequently viewed as part of a three-tier application, consisting of a graphical user interface (GUI) server, an application (business logic) server, and a database and transaction server. More descriptively, it can be viewed as dividing an application into:

A first-tier, front-end, Web browser-based graphical user interface, usually at a personal computer or workstation
A middle-tier business logic application or set of applications, possibly on a local area network or intranet server
A third-tier, back-end, database and transaction server, sometimes on a mainframe or large server
Older, legacy databases and transaction management applications are part of the back end or third tier. The application server is the middleman between browser-based front-ends and back-end databases and legacy systems.

Web server

A computer that delivers (serves up) Web pages. Every Web server has an IP address and possibly a domain name. For example, if you enter the URL http://www.JeeCom.com/index.html in your browser, this sends a request to the server whose domain name is JeeCom.com. The server then fetches the page named index.html and sends it to your browser.

Any computer can be turned into a Web server by installing server software and connecting the machine to the Internet. There are many Web server software applications, including public domain software from NCSA and Apache, and commercial packages from Microsoft, Netscape and others

geez.. looks like cheek hogged the whole question.. =)

It was an easy one ;-)

Thanks cheek. Your answer was quite informative.

munira