A servlet is a Java programming language class that extends the capabilities of servers that host applications accessed by means of a request-response programming model. Servlets are used to handle requests obtained from the webserver, process the request, produce the response, and send a response back to the webserver. Although servlets can respond to any type of request, they are commonly used to extend the applications hosted by web servers. Servlet technology defines HTTP-specific servlet classes for such applications.
The javax.servlet and javax.servlet.http packages provide interfaces and classes for writing servlets. All servlets must implement the Servlet interface, which defines life-cycle methods. When implementing a generic service, you can use or extend the GenericServlet class provided with the Java Servlet API. The HttpServlet class provides methods, such as doGet and doPost, for handling HTTP-specific services.
Servlets are capable of handling complex requests obtained from the webserver and work on the server-side. Servlets are more acceptable than other web server extensions such as Common Gateway Interface (CGI) scripts and Hypertext Preprocessor (PHP) since they solve the limitations of CGI such as low performance and low degree scalability.
In summary, a servlet is a Java class that extends the capabilities of servers that host applications accessed by means of a request-response programming model. Servlets are used to handle requests obtained from the webserver, process the request, produce the response, and send a response back to the webserver. They are commonly used to extend the applications hosted by web servers and define HTTP-specific servlet classes for such applications.
