Introduction to Servlet

What is Servlet ?

  • Servlets are an important component of a J2EE application. Servlets along with JavaServer Pages (JSP) and EJB modules can be termed as server-side J2EE component types.
  • Servlet is a Java Programming Language.
  • Servlets are used to create web applications.
  • Servlets are used to extend the applications hosted by web servers. Servlet runs in a J2EE application server

Common Gateway Interface (CGI) technology was used for dynamic content prior to introduction of Servlets.

Servlet Architecture

Following diagram shows the process of Servlets in a Web Application.
Servlet Architecture
The process can be summarized as follows:

  • A client sends a request to a Web Server, through a Web Browser.
  • The Web Server searches for the required Servlet and initiates it.
  • The Servlet then processes the client request and sends the response back to the server, which is then forwarded to the client.

Advantages of a Servlet

  • Servlets provide component based and platform-independent methods for building Web based applications.
  • Each Request is run in a separate thread ,so servlet request processing is faster than CGI.
  • Servlets overcomes the limitations of CGI program.
  • Servlets run on Java Virtual Machine and in any platform and it is simple to write.
  • Servlet are more powerful and the performance is better.
  • Servlets are platform-independent.
  • Servlet technology, in addition to improved performance, offers security, robustness, object orientation, and platform independence.
  • As mentioned in the definition of servlets are fully integrated with the Java language and its standard APIs. Hence JDBC for Java database connectivity is also integrated in it.
  • A servlet handles concurrent requests
  • Handling HTTP requests and send text and data back to the client is made easy by servlet request and response objects.

Disadvantages of a Servlet

  • Servlets often contain both business logic and presentation logic so it makes application difficult to understand.
  • You would need JRE to be installed to run a servlet program.

Next Tutorial : Servlet API

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