Take a deep dive in application server

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An application server is a type of server designe to install, operate, and host applications. In the early days of application servers, the number of applications brought to the Internet was very high. These applications are larger in size and more complex to operate and maintain due to the need to add functionality to the applications. We needed some kind of program on the network that shared application functionality at the same time in an efficient and organized way.

What is an application server?

An application server is a server-side program that is a server programmer that provides the business logic behind each application. This server can be part of a network or a distributed network.

If you want to know the purpose of the server program:
Ideally, the server program is use to serve client programs on the same machine or on the network.


These are basically use in web-based applications with a three-tier architecture. The locations where the application server fits are describe below.

  1. Tier1-This is a GUI interface on the client side, usually a thin client (browser, etc.).
  2. Tier 2-This is called the middle tier and consists of application servers.
  3. Tier3-This is the third tier of the backend server. Example: Database server.

As you can see, it usually communicates with the web server to handle requests from clients.

The client first makes a request and is send to the web server. The web server then sends it to the middle tier, the application server, which receives additional information from the third tier (eg database server) and sends it back to the web server. The web server then sends the necessary information to the client. Various approaches are use for processing requests through a web server, some of which are Java Server Pages (JSP), CGI, Active Server Pages (ASP), Java Scripts, Java Servlet, and others.

Use of Application Servers:

This helps the client process all requests by connecting to the database and returning information to the web server.

The main purposes of the application server are:

  • A mechanism for reducing the size and complexity of client programs.
  • Caching and flow control are require to improve performance.
  • A mechanism to ensure the security of data and end-user traffic.

Although they can serve different purposes, not all application servers are use for the same set of features. For example, someone may need it for scalability. Others may need it to better manage your application on the internet, etc.

 Types of Application Server:

Application servers can be divide into three categories.

Active Application Server:

This server is use to support business logic relate to the server side and to provide a rich environment and is expresse in the form of rules, components and objects. This type of server is also known as stateful server.

Web Information Server:

This type of server is use to create pages in a database using HTML templates. This type of server is also called a stateless server.

Component Server: 

This software plays an important role in providing database access to software components such as COBRA, DLL, and Java Beans. It also supports transaction processing requests.


There are a huge number of application servers in use today. Here are some examples:

  • JBoss
  • Weblogic
  • Websphere
  • Glassfish
  • Tcat Server
  • Apache Geronimo


  • It provides mechanisms for working with all components and running services, such as session management, synchronous and asynchronous client notifications.
  • Installing apps in one place is very easy.
  • Any configuration changes such as moving database servers can be done centrally from one location.
  • Easily deploy patches and security updates.
  • This allows you to distribute requests to different servers based on availability. This is done through load balancing.
  • Ensure application security.
  • This is a failover/failover feature that provides fault tolerance.

Written by 

Ashi Dubey is a Software Intern at Knoldus Inc Software. She has a keen interest toward learning new technologies. Her practice area is Devops. When not working, you will find her with a Book.