Servlet

INTRODUCTION:
Over the last few years, Java has become the predominant language for server-side
programming. This is due in no small part to the Java Servlet API, which provides
a standard way to extend web servers to support dynamic content generation.
With the introduction of the J2EE specification for enterprise applications, servlets
have taken over as the primary interface for thin-client applications. In terms of
enterprise computing, servlets are a natural fit if you are using the Web as your
deployment platform. You can take advantage of web browsers as universally
available thin clients using the web server as middleware for running application
logic. Under this model, the user makes a request of the web server, the server
invokes a servlet designed to handle the request, the servlet fulfills the request,
and the result is returned to the user for display in the web browser.
While this sounds like every other dynamic content technology (such CGI, ISAPI,
ASP, PHP, and the like), servlets have some major advantages. For one, servlets
are persistent between invocations, which dramatically improves performance relative
to CGI-style programs. Servlets are also 100% portable across operating
systems and servers, unlike any of the alternatives. Finally, servlets have access to
all the APIs of the Java platform, so, for example, it is easy to create a servlet that
interacts with a database, using the JDBC API.

What are we going to learn in this tutorial??
1 Servlets
2 Servlet Lifecycle
3 Web Container(Servlet Container)
4 Deployment Descriptor:web.xml
5 Servlet Types
6 Servlet Context and Servlet Config
7 Session management
8 Servlet Filters
9 Database Connectivity in servlet
10 Advantage and disadvantage of servlet
11 Advantages over CGI
12)Servlet Container


Servlets:
A Servlet is a Java-based server-side web technology. As the name implies, it serves a client request and receives a response from the server. Technically speaking, a Servlet is a Java class in Java EE that conforms to the Java Servlet API, a protocol by which a Java class may respond to requests. They are not tied to a specific client–server protocol, but are most often used with the HTTP protocol. Therefore, the word "Servlet" is often used in the meaning of "HTTP Servlet". Thus, a software developer may use a servlet to add dynamic content to a web server using the Java platform. The generated content is commonly HTML, but may be other data such as XML. Servlets are the Java counterpart to non-Java dynamic Web content technologies such as PHP and ASP.NET. Servlets can maintain state in session variables across many server transactions by using HTTP cookies, or URL rewriting.
To deploy and run a Servlet, a web container must be used. A web container (also known as a Servlet container) is essentially the component of a web server that interacts with the Servlets. The web container is responsible for managing the lifecycle of Servlets, mapping a URL to a particular Servlet and ensuring that the URL requester has the correct access rights.
The Servlet API, contained in the Java package hierarchy javax.servlet, defines the expected interactions of the web container and a servlet.


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