Week 3 - HTTP & Servlet API

Concepts

• HTTP:
  • Version HTTP/1.1
  • Client-server messaging
  • Message Syntax:
    • Request:
      • Methods: Get, Post, Put, Delete, Head, Options, Trace
      • URI
    • Response:
      • Status Code
    • Headers: Content-Type, Content-Length
• Java Platform, Enterprise Edition (Java EE) 7
  • Static Web Server vs Application Server
  • Layered Architecture: Presentation, Business, Persistence
• Servlet:
  • Reading/Writing to ServletRequest/ServletResponse
  • Servlet Container (Tomcat)
  • Servlet interface life-cycle
  • ServletContext vs ServletConfig
  • Forward vs Redirect
  • Session vs Cookie
  • Deployment Descriptor:
    • web.xml tags: servlet-name, servlet-class, url-mapping, load-on-startup, init-param, context-param

Syntax

• javax.servlet:
  • Servlet: init(), service(), destroy()
  • ServletContext
  • ServletConfig: getInitParameter()
  • GenericServlet: getServletConfig(), getServletContext()
  • ServletRequest: getAttribute(), getParameter(), getRequestDispatcher()
  • RequestDispatcher: forward()
  • ServletResponse
  • [javax.servlet.annotations]:
    • WebServlet
  • javax.servlet.http:
    • HttpServlet: doGet(), doPost()
    • HttpServletRequest: getSession()
    • HttpServletResponse: setHeader(), setStatus(), sendRedirect()
    • HttpSession & Cookie
    • Cookie

Questions

• What is a client and server? How do they communicate?
• What is HTTP? What is its role?
• What are the major HTTP actions?
• What is the structure of an HTTP request?
• What is the structure of an HTTP response?
• What are HTTP headers used for?
• What is the difference between an HTTP Get and Post?
• What is JavaEE? How does it compare with JavaSE?
• What is an Application Server?
• Describe a JavaEE program’s layered architecture.
• What is a Servlet?
• What is the difference between a ServletConfig and ServletContext?
• What is a Servlet container? Which container are you familiar with?
• What is a deployment descriptor? What are its important values?
• Explain the life cycle of a servlet.
• Explain the path taken by an incoming request to a servlet.
• How do I preload a servlet?
• How do I set initial parameters for both ServletConfig and ServletContext?
• What tags are used for mapping a servlet in the web.xml?
• Explain the inheritance tree from the Servlet interface to a custom subclass of HttpServlet.
• How do I perform error handling with the deployment descriptor?
• What is the difference between a forward and a redirect? How do I send either using servlets?
• How do I get and set data in a servlet?
• What is the difference between Sessions & Cookies?