Servlets are Java programs that extend the functionality of a web server. They allow for dynamic web page generation in response to client requests. Servlets offer advantages over CGI programs like improved performance since they do not create a new process for each request. The lifecycle of a servlet involves init(), service(), and destroy() methods. Servlets can be created and tested using the Tomcat servlet container. Security restrictions apply to untrusted servlets to prevent potentially dangerous operations, similarly to applets.

1. NADARSARASWATICOLLEGEOFARTSANDSCIENCE
DEPARTMENTOFINFORMATIONTECHNOLOGY
SUBMITTEDBY:P.RITHIKA
CLASS:I–M.SC(IT)

2. SERVLETS :
◦ Servlets Servlets are small programs that execute on the server side of a Web connection. Just
as applets dynamically extend the functionality of a Web browser, servlets dynamically extend
the functionality of a Web server. Use & Advantages of Servlet Consider a request for a static
Web page.
◦ A user enters a Uniform Resource Locator (URL) to a browser. The browser generates an HTTP
request to the appropriate Web server.

3. USES AND ADVANTAGE OF SERVLETS:
◦ Use & Advantages of Servlet Consider a request for a static Web page.
◦ A user enters a Uniform Resource Locator (URL) to a browser.
◦ The Web server maps this request to a specific file.
◦ The HTTP header in the response indicates the type of the content.
◦ The browser generates an HTTP request to the appropriate Web server.

4. ◦ Now consider dynamic content. Assume that an online bookstore uses a database to store information about its
business, including book prices, availability, orders, and so forth. It wants to make this information accessible to
customers via Web pages. The contents of those Web pages must be dynamically generated, to reflect the latest
information in the database. In the early days of the Web, a server could dynamically construct a page by
creating a separate process to handle each client request. The process would open connections to one or more
databases in order to obtain the necessary information. It communicated with the Web server via an interface
known as the Common Gateway Interface (CGI). CGI allowed the separate process to read data from the HTTP
request and write data to the HTTP response. A variety of different languages were used to build CGI programs,
including C, C++, and Perl. However, CGI suffered serious performance problems. Creating a separate process for
each client request was expensive, in terms of processor and memory resources. It was also expensive to open
and close database connections for each client request. In addition, the CGI programs were not platform-
independent.
◦ Servlets offer several advantages over CGI:
◦ The Java Security Manager on the server enforces a set of restrictions to protect the resources on a server
machine.
◦ The full functionality of the Java class libraries is available to a servlet. It can communicate with applets,
databases, or other software via the sockets and RMI mechanisms that you have seen already
◦ The Life Cycle of a Servlet Three methods are central to the life cycle of a servlet: init ( ), service ( ), and
). They are implemented by every servlet and are invoked at specific times by the server.

5. Using Tomcat for Servlet Deployment To create servlets :
◦ Using Tomcat for Servlet Deployment To create servlets, download a servlet
development environment.
◦ Tomcat is an open source product maintained by Jakarta Project of the Apache
Software Foundation.
◦ The one currently recommended by Sun is Tomcat which supports the servlet
specification.
◦ It contains the class libraries; documentation and run- time support which are
needed to create and test servlet.

6. SECURITY ISSUES :
◦ Security Issues Untrusted applets are constrained to operate in a “sandbox.”
◦ This includes reading and writing files, opening sockets to arbitrary machines,
calling native methods, and creating new processes.
◦ Other restrictions also apply. Similar constraints also exist for untrusted servlets.

7. ◦ They cannot perform operations that are potentially dangerous to a user’s
machine.
◦ Code that is loaded from a remote machine is untrusted. However, trusted
servlets, those loaded from the local machine, are not limited in this manner.

8. ◦THANK YOU