What is the difference between application server and web server?

Question

What is the difference between application server and web server?

Answer 1

The border between these two are getting ever so thinner.

Application servers expose business logic to clients. That means application servers comprise of a set of methods (not exclusively though, can even be a networked computer allowing many to run software on it) to perform business logic. So it will simply output the desired results, not HTML content. (similar to a method call). So it is not strictly HTTP based.

But web servers pass HTML content to web browsers (Strictly HTTP based). Web servers were capable of handling only the static web resources, but the emergence of server side scripting allowed web servers to handle dynamic contents as well. Where a web server takes in the request and directs it to relevant scripts (PHP, JSP, CGI scripts, etc.) to CREATE HTML content to be sent to the client. Once the content is received, web server will send the HTML page to the client.

However, nowadays both these servers are used together. Where web server takes the request and then calls a script to create the HTML content. Then, the script will again call an application server LOGIC (e.g. Retrieve transaction details) to fill the HTML content.

So both the servers are used effectively.

Therefore .... We can safely say that nowadays, in most of the cases, web servers are used as a subset of application servers. BUT theatrically it is NOT the case.

I have read many articles about this topic and found this article quite handy.

Answer 2

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 3

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 4

The main difference between Web server and application server is that web server is meant to serve static pages e.g. HTML and CSS, while Application Server is responsible for generating dynamic content by executing server side code e.g. JSP, Servlet or EJB.

Which one should i use?
Once you know the difference between web and application server and web containers, it's easy to figure out when to use them. You need a web server like Apache HTTPD if you are serving static web pages. If you have a Java application with just JSP and Servlet to generate dynamic content then you need web containers like Tomcat or Jetty. While, if you have Java EE application using EJB, distributed transaction, messaging and other fancy features than you need a full fledged application server like JBoss, WebSphere or Oracle's WebLogic.

Web container is a part of Web Server and the Web Server is a part of Application Server.

Web Server is composed of web container, while Application Server is composed of web container as well as EJB container.

Answer 5

Basic understanding :

In client server architecture

Server :> Which serves the requests.

Client :> Which consumes service.

Web server & Application server are both software applications which act as servers to their clients.

They got their names based on their place of utilization.

Web server :> serve web content
           :> Like Html components
           :> Like Javascript components
           :> Other web components like images,resource files
           :> Supports mainly web protocols like http,https.
           :> Supports web Request & Response formats.

Usage --

      we require low processing rates,

      regular processing practices involves.

Eg: All flat servers generally available ready-made which serves only web based content.

Application server :> Serve application content/component data(Business data).
                   :> These are special kind which are custom written 
                      designed/engineered for specific
                      purpose.some times fully unique in 
                      their way and stands out of the crowd. 

                   :> As these serves different types of data/response contents
                   :> So we can utilize these services for mobile client,web 
                      clients,intranet clients. 
                   :> Usually application servers are services offered on different 
                      protocols.    
                   :> Supports different Request& Response formats.

Usage --

      we require multi point processing,

      specialized processing techniques involves like for AI.

Eg: Google maps servers, Google search servers,Google docs servers,Microsoft 365 servers,Microsoft computer vision servers for AI.

We can assume them as tiers/Hierarchies in 4-tier/n-tier architecture.

 So they can provide 
                    load balancing,
                    multiple security levels,
                    multiple active points,
                    even they can provide different request processing environments.

Please follow this link for standard architecture analogies:

https://docs.microsoft.com/en-us/previous-versions/msp-n-p/ee658120(v%3dpandp.10)

Answer 6

A Web server exclusively handles HTTP/HTTPS requests. It serves content to the web using HTTP/HTTPS protocol.

An application server serves business logic to application programs through any number of protocols, possibly including HTTP. The application program can use this logic just as it would call a method on an object. In most cases, the server exposes this business logic through a component API, such as the EJB (Enterprise JavaBean) component model found on Java EE (Java Platform, Enterprise Edition) application servers. The main point is that the web server exposes everything through the http protocol, while the application server is not restricted to it. An application server thus offers much more services than an web server which typically include:

• A (proprietary or not) API
• Load balancing, fail over...
• Object life cycle management
• State management (session)
• Resource management (e.g. connection pools to database)

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.

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.

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

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Web Server                               Programming Environment
Apache                                   PHP, CGI
IIS (Internet Information Server)        ASP (.NET)
Tomcat                                   Servlet
Jetty                                    Servlet

Application Server                       Programming Environment
WAS (IBM's WebSphere Application Server) EJB
WebLogic Application Server (Oracle's)   EJB
JBoss AS                                 EJB
MTS                                      COM+