**** Java Certification Training: https://www.edureka.co/java-j2ee-soa-training **** This Edureka tutorial on “Introduction to Servlets” will talk about the basics of the World Wide Web and its components. It will tell you the fundamental concepts of servlets, its life cycle and various steps to create Servlet. Also, it will talk about Generic Servlet. Through this tutorial you will learn the following topics: Introduction to Web Web & HTTP HTTP Request & Response Introduction to Servlets Servlet Architecture Servlet Life Cycle Steps to create Servlet Generic Servlet Servlet Request & Response Check out our Java Tutorial blog series: https://goo.gl/osrGrS Check out our complete Youtube playlist here: https://goo.gl/gMFLx3 Follow us to never miss an update in the future. Instagram: https://www.instagram.com/edureka_learning/ Facebook: https://www.facebook.com/edurekaIN/ Twitter: https://twitter.com/edurekain LinkedIn: https://www.linkedin.com/company/edureka

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Topics to be covered
Introduction to WEB
WEB & HTTP
HTTP Request & Response
What are Servlets?
Servlet Classes & Interfaces
Servlet Architecture
Generic Servlets
Servlet Request & Response
CGI vs Servlets

3. Introduction to
WEB

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Introduction to Web
Request
Response is sent to client
Client Server
Web is basically a system of Internet servers that support specially formatted documents

5. WEB & HTTP

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Web & HTTP

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Web & HTTP
HTTP is a protocol that clients and servers use
on the web to communicate.

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HTTP Request & Response
HTTP Request
HTTP Response
Client Server
HTTP Response is the packet of information sent by Server to the Client
in response to an earlier Request made by Client
HTTP Request is a packet of Information that one computer sends to another
computer to communicate something

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Difference between HTTP Get & Post
HTTP GET
Operation
HTTP POST
▪ Data is sent in header ▪ Data is sent in request body
▪ Not secured ▪ It is secured
▪ Can be bookmarked ▪ Cannot be bookmarked
▪ Limited data can be sent ▪ Large amount of data can be sent

10. Introduction to
Servlets

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What are Servlets?
Creates Web Application
Provides Interfaces & Classes
Must be implemented to create Servlet
Robust & Scalable
Deployed to create Web Page
Responds to any incoming requests

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What are Servlets?
Request
Response is generated at runtimeResponse is sent to client
Client Server

13. CGI VS Servlets

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What is CGI?
Common Gateway Interface (CGI) is a standard for writing programs that can interact through a Web
server with a client running a Web browser.
High Response Time Low Response Time
Not Secure Secure
Not Scalable Highly Scalable
CGI
VS
SERVLET

15. Servlet
Architecture

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Servlet Architecture
Web Browser
DatabaseServlet ProgramHTTP Server
HTTP Protocol

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Servlet Life Cycle
Handling Request
Loading &
Instantiation
Initialized
End
Start
Stop
init()
service()
destroy()
End of
Request
thread

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Steps to create Simple Servlet
Create and compile simple servlet code
1
Start Apache Tomcat
3
Add mappings to web.xml file
2
Start Web Browser & Request Servlet
4

19. Generic Servlet

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Generic Servlet
A generic servlet is a
protocol independent
Servlet that should always
override the service()
method to handle the client
request..
Generic Servlet is
easier to write
It has a very simple life cycle
methods
To write Generic Servlet you just
need to extend
javax.servlet.GenericServlet and
override the service() method
Pros

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Request & Response
Servlet Request
Servlet Response

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Request & Response
Servlet Response
Servlet Request
An object of ServletRequest is used to provide the client request
information to a servlet such as content type, content length,
parameter names and values, header informations, attributes etc.

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Request & Response
Servlet Response
Servlet Request
An object of ServletResponse is used to write the information back
to the client.

24. Servlet Classes
& Interface

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Servlet Classes & Interfaces
Servlet Declares life cycle method of servlet
ServletConfig Allows servlet to get Initialization methods
ServletContext Enables servlet to log access and access information
ServletRequest Used to read data from client request
ServletResponse Used to write data to client response
GenericServlet Implements servlet and Servlet.Config Interface
ServletInputStream Provides input stream to read requests from the client
ServletOutputStream Provides output stream to write responses to the client
ServletException Indicates servlet error has occured
UnavailableException Indicates servlet is not available
HttpServlet Provides methods to handle Http Request and Response
HttpServletRequest Enables servlets to read data from Http Request
HttpServletResponse Enables servlets to write data to Http Response