The servlet is a mini program for server side and it is used to design protocol and dynamic web pages. It can only be executed and loaded on the web server. The server’s outlet is usually sent to the client as a part of response and it comes in the format of MIME. The issues of security that are associated with Java applet are not applicable for the purpose of serving as clients can get output from servlet that is tempered by a virus. If your web server is behind the protection of the firewall then your server will also be highly secured.

Working of servlet-:

Moreover this is program of server side and thus processed only on the requisition from the client. The client makes request usually with the help of the browsers or any other kind of pages. The request is sent by the browsers of the clients as an HTTP request. This I located by the web server using the web container. the engine of servlet execute the request and generate the clients’ response in the MIME format. Further the server deployed it into various other pages.

There are two kinds of pages- Dynamic and static web pages.

Static web pages are created with the help of HTML, CSS, language of scripting, images and others. It gives an equal view to all clients and can be loaded and executed through the web browser and server respectively after the total download only. The static page source code can be viewed by the clients and it also cannot store data of the users on the servers. Authorization cannot be handled by static web pages.

Dynamic web page is designed using programming of server side like servlet, PHP, Asp, and others. Moreover it can load using web browsers as well as executed using the same. The dynamic page output is further sent to the client and is also capable of producing different views of various clients.

Download Servelets in Java Reference Material.