What is the difference between application server and web server ?

Question

I do not understand the basic difference between a web server and application server..

Answer 1

An application server is typically designed and deployed to facilitate longer running processes that will also be more resource intensive.

A web server is used for short bursts that are not resource intensive, generally. This is mostly to facilitate serving up web based traffic.

Answer 2

In short a web server is a server that serves web pages to users via http. An application server is a server that hosts the business logic for a system. It often hosts both long running/batch processes and/or a interop services not meant for human consumption (SOAP, RPC, etc).

Answer 3

An application server is a machine (an executable process running on some machine, actually) that "listens" (on any channel, using any protocol), for requests from clients for whatever service it provides, and then does something based on those requests. (may or may not involve a respose to the client)

A Web server is process running on a machine that "listens" specifically on TCP/IP Channel using one of the "internet" protocols, (http, https, ftp, etc..) and does whatever it does based on those incoming requests... Generally, (as origianly defined), it fetched/generated and returned an html web page to the client, either fetched from a static html file on the server, or constructed dynamically based on parameters in the incoming client request.

Answer 4

A web server runs the HTTP protocol to serve web pages. An application server can (but doesn't always) run on a web server to execute program logic, the results of which can then be delivered by the web server. That's one example of a web server/application server scenario.

A good example in the Microsoft world is the Internet Information Server / SharePoint Server relationship. IIS is a web server; SharePoint is an application server. SharePoint sits "on top" of IIS, executes specific logic, and serves the results via IIS.

In the Java world, there's a similar scenario with Apache and Tomcat, for example.

Answer 5

Most of the times these terms Web Server and Application server are used interchangeably.

Following are some of the key differences in features of Web Server and Application Server:

• Web Server is designed to serve HTTP Content. App Server can also serve HTTP Content but is not limited to just HTTP. It can be provided other protocol support such as RMI/RPC
• Web Server is mostly designed to serve static content. Though most of the Web Servers are having plugins to support scripting languages like Perl, PHP, ASP, JSP etc. through which these servers can generate dynamic HTTP content.
• Most of the application servers have Web Server as integral part of them, that means App Server can do whatever Web Server is capable of. Additionally App Server have components and features to support Application level services such as Connection Pooling, Object Pooling, Transaction Support, Messaging services etc.
• As web servers are well suited for static content and app servers for dynamic content, most of the production environments have web server acting as reverse proxy to app server. That means while service a page request, static contents such as images/Static html is served by web server that interprets the request. Using some kind of filtering technique (mostly extension of requested resource) web server identifies dynamic content request and transparently forwards to app server

Example of such configuration is Apache HTTP Server and BEA WebLogic Server. Apache HTTP Server is Web Server and BEA WebLogic is Application Server.

In some cases the servers are tightly integrated such as IIS and .NET Runtime. IIS is web server. when equipped with .NET runtime environment IIS is capable of providing application services.

Answer 6

Both terms are very generic, one containing the other one and vice versa in some cases.

• Web server: serves content to the web using http protocol.

• Application server: hosts and exposes business logic and processes.

I think that the main point is that the web server exposes everything through the http protocol, while the application server is not restricted to it.

That said, in many scenarios you will find that the web server is being used to create the front-end of the application server, that is, it exposes a set of web pages that allow the user to interact with the business rules found into the application server.

Answer 7

As Rutesh and jmservera pointed out, the distinction is a fuzzy one. Historically, they were different, but through the 90's these two previously distinct categories blended features and effectively merged. At this point is is probably best to imagine that the "App Server" product category is a strict superset of the "web server" category.

Some history. In early days of the Mosaic browser and hyperlinked content, there evolved this thing called a "web server" that served web page content and images over HTTP. Most of the content was static, and the HTTP 1.0 protocol was just a way to ship files around. Quickly the "web server" category evolved to include CGI capability - effectively launching a process on each web request to generate dynamic content. HTTP also matured and the products became more sophisticated, with caching, security, and management features. As the technology matured, we got company-specific Java-based server-side technology from Kiva and NetDynamics, which eventually all merged into JSP. Microsoft added ASP, I think in 1996, to Windows NT 4.0. The static web server had learned some new tricks, so that it was an effective "app server" for many scenarios.

In a parallel category, the app server had evolved and existed for a long time. companies delivered products for Unix like Tuxedo, TopEnd, Encina that were philosophically derived from Mainframe application management and monitoring environments like IMS and CICS. Microsoft's offering was Microsoft Transaction Server (MTS), which later evolved into COM+. Most of these products specified "closed" product-specific communications protocols to interconnect "fat" clients to servers. (For Encina, the comms protocol was DCE RPC; for MTS it was DCOM; etc.) In 1995/96, these traditional app server products began to embed basic HTTP communication capability, at first via gateways. And the lines began to blur.

Web servers got more and more mature with respect to handling higher loads, more concurrency, and better features. App servers delivered more and more HTTP-based communication capability.

At this point the line between "app server" and "web server" is a fuzzy one. But people continue to use the terms differently, as a matter of emphasis. When someone says "web server" you often think HTTP-centric, web UI, oriented apps. When someone says "App server" you may think "heavier loads, enterprise features, transactions and queuing, multi-channel communication (HTTP + more). But often it is the same product that serves both sets of workload requirements.

• WebSphere, IBM's "app server" has its own bundled web server.
• WebLogic, another traditional app server, likewise.
• Windows, which is Microsoft's App Server (in addition to being its File&Print Server, Media Server, etc.), bundles IIS.

Answer 8

ok I typed these keywords in google...

difference between web server and application server

The first match came as:

http://www.javaworld.com/javaqa/2002-08/01-qa-0823-appvswebserver.html

looks pretty relevant to me....

Answer 9

In Java terms there's one more: web container (or more strictly, servlet container). It's, say, in between web server and application server. An web container is in Java terms an application server which basically only implements the JSP/Servlet part of Java EE and lacks several core parts of Java EE, such as EJB support. An example is Apache Tomcat.