What is Servlet

What is Servlet
  •  Servlet is an API of J2EE and Help us to create Dynamic Web Application.
  • Servlet Accept the Request from web server and Generate dynamic Response.

Web Resources

  • Resources present inside web application is known as Web resources.
  • There is two types web resources.
    1. Static web resources
    2. Dynamic web resources
1. Static web resources
  •  It is already present at web application before you make a request.
    Exa. Downloading pdf book, Downloading .exe file

2. Dynamic web resources
  •  This type of Resources prepared at the time of User request.
  • This web resources will not be present at web application side before we make a request or they get generated at the time of request.
  • Content may be change for every request.
  • i.e.
    1. Bank Transaction download
    2. Google search
    3. Facebook is fully dynamic
Web Application
  • Web Application is a shared application which we can access through network using
    web browser.
  •  Web Application is a collection of web resources.
  • There are two types of web application
    1. Static web application
    2. Dynamic web application
  • If web application consist only static web resources then it is called static
    web application.
  • If web application consist one or more dynamic web resources then it is called
    dynamic web application.
Web url
  • Web url uniquely identified web resources in a network.
  •  Hence every web resource static or dynamic must need to have its unique address
    in form of web url.
  • Different ways to interact with web Application.

    1. Typing URL in browser
    2. Submitting form request
    3. Clicking on a hyperlink
Web Server
  • Web Server Accept the request from web browser and passes the Request to
    Web Application and whatever response given Given by Wen application it
    send back to Browser.
  •  Every Web Application is Directly under control of Web server

screenshot_2 Some Popular Web server

  • Apache tomcat
  • Weblogic(Oracle)
  • Websphere(IBM)

Apache Tomcat Webserver

Steps to Install and Configure Apache Tomcat
Step 1:Download Apache tomcat latest version From below Link
http://tomcat.apache.org/download-80.cgiapache-download
step 2: Extract Downloaded Zip file

extract

step 3: Set Following Environment variable

1. JAVA_HOME
2. CATELINA_HOME

environment-set-up-tomcat

step 4: In order to start web server run startup.bat file

startup-bat