Application Server Vs. Web Server

In the world of computer networking, a server is a program, which operates as a socket listener. The term server can also be used generally, to describe a host which has been deployed to execute one or more such programs. Hence, in theory any computerized process, which shares a resource with one or more client processes is called a server. If we have to talk about a server in terms of a hardware, then a server means a computer, that is intended for running software applications, under heavy demand of a network environment. If we have to look at the client-server configuration, there are one or more machine, either a computer or a computer appliance, which share information with each other, where one acts as a host for the other. When the topic is about servers, it is but obvious application server and web servers will be mentioned. We will read on what is an application server and what is a web server, before we read on application server vs. web server.

What is an Application Server

An application server is a software framework, which is dedicated to the efficient execution of programs, routine or scripts for supporting the construction of various applications. This term was originally used to describe client server applications and servers, which ran SQL services and middleware servers, so as to be able to differentiate them from the file servers. It was later that the term came to be used in the context of web applications. However, it has evolved into a more comprehensive service layer. An application server is nothing but a set of components, which are accessible to the software developer through an API defined by the platform itself. In web applications, these components are often in the same machine, as the web server and the main job is to support the construction of dynamic pages. However, with time, now the application servers now do not just target the generation of web pages, but they also implement services like clustering, fail-over and load balancing. Due to this the developers can focus their energies on implementing business logic. The term application server is often used in terms of Java servers. In such case, the application server behaves like an extended virtual machine for running applications and handles connections to the database at one side transparently and also connections to the web client.

What is a Web Server

A web server is a computer program, which delivers content, like web pages, using the Hyper Text Transfer Protocol (HTTP), over the world wide web. The term may also stand for a computer or a virtual machine, which runs a program. The primary objective of the web server is to deliver web pages to the clients. Such a delivery consists of HTML documents or any additional content, which may be included in the document, like images, style sheets and JavaScript. The communication is initiated by the client, commonly called web browser or web crawler. By making request for a specific bit of information using HTTP and the request is met with a response by the server and the content is sent over. In case of a problem an error message is sent back. The server also receives content from clients. Such a feature is often used for submitting web forms and also for uploading files.

Application Server Vs. Web Server

Like there is a confusion about application software vs. system software, there is also web servers vs. application servers confusion. The basic difference between web server and application server is, that the web server serves pages for viewing in a web browser, whereas an application server gives the required methods, that can be called by the client applications. In other words, the HTTP requests are handled by the web servers and the business logic is served to the application programs, through a number of protocols by the application server. In an application server, a client can use GUI's and web servers, whereas in web servers the client can use HTML or HTTP. If any functionality is to be added, an application adds the same, however, same is not the case with web servers.

Web servers do not support or provide the concept of multi-threading. However, in application servers, there are features like connection pooling, isolation pooling, multi-threading, etc. The most common examples of application servers are the Java Application Server, Weblogic Server, Apache Geronimo, etc. On the other hand, the examples of web servers are Microsoft IIS, Apache, etc.

I hope with this article the application server vs. web server confusion is resolved. Just to sum it up, web server can be said to be a subset of an application sever.