What is Servlets

Servlet -- A Servlet is a Java class that resides on a Web server that accepts requests and generates responses. They can accept requests and generate responses over different communication protocols, but the most common type of Servlet is an HTTP Servlet, which is implemented by the javax.servlet.http.HttpServlet Java class. The HTTP Servlet accepts HTTP requests and generates HTTP responses. Since a Servlet is a server resource, it has access to other server resources: other Servlets, EJBs, JSPs, and databases. The purpose of a Servlet is to generate a dynamic response.

Servlet container -- The Servlet container is the environment within which Servlets execute, whether built into the Web server, an add-on component to the Web server, or built into an application server. The Servlet container is responsible for managing the lifecycle of Servlets, providing network services over which the requests and responses are sent, and decoding and formatting MIME type requests and responses.

Web Application -- Web Applications were first defined in the Servlet 2.2 specification. They are a collection of Servlets, JSPs, static documents, and other utility classes that make up an application. Web Applications can be deployed as a directory structure or as a single Web archive (.war) file on any Servlet compatible Web server or application server.

Session -- A session is a series of requests from the same user or client. It is important to be able to associate requests from the same user so that you can maintain information on behalf of the client. Since HTTP is a stateless protocol it's hard to track client requests and maintain stateful information about them. However, the Servlet specification has defined an interface, javax.servlet.http.HttSession, that programmers can use to easily track client requests.

Servlet Context -- The Servlet context defines a Servlet's vision within the Web Application the Servlet is executing in. The container is responsible for instantiating one instance of the javax.servlet.ServletContext interface for each Web Application. Therefore, programmers can use the ServletContext object to make resources available to all Servlets within a Web Application.
Since a Servlet is a Java class, it gets compiled to platform independent bytecode in the .class file. After the Servlet is deployed and before any requests are made to it, the container is responsible for instantiating a Servlet object and initializing the Servlet. Once the Servlet has been initialized, it is ready to service client requests. At some point, the container can destroy the Servlet object and calls the destroy method on that Servlet object, freeing it up for garbage collection.

 

Methods of Servlet>>