Servlet - Basic

Servlet Write a simple Servlet class

• that correctly extends the HttpServlet class
• that correctly overrides the appropriate ancestor method

Describe why your servlet must be stateless

• Explain that the servlet model is multithreaded (1 thread/request)
• Develop threadsafe servlets by writing stateless servlets (without declared instance variables)

Not Covered : Servlet Lifecycle init(), init(config), ... Request Differentiate GET and POST HTTP methods

• Explain how parameters are stored in the request : in the URL or in the body of the HTTP request
• Identify what default HTTP method will be used when clicking on a link, submitting a form
• Know that HTML Forms can use both GET and POST
• Know that the HttpServlet.doGet() & doPost() are called accordingly.

Manipulate request Parameters

• Write code that retrieves parameters from the HttpServletRequest
• Identify when getParameter() will return null instead of a valid String
• Write code that handles multi-valued parameters and retrieves all the values that they contain.
• Know the correct syntax to pass parameters through a request added to the URL

Not covered: Questions regarding attributes should be placed in the "Attributes" category. Response Produce the HTTP response body

• Obtain a PrintWriter from the HttpServletResponse object
• Set the content type of the HttpServletResponse and know that it must be set before the content.

Attributes Retrieve and Store attributes in each scope : HttpServletRequest, HttpSession, ServletContext

• Explain that null will be returned by the getAttribute() if no attribute can be found
• Write code that iterates through all the attributes of a given scope
• Remove attributes from a given scope

Not covered: Related listeners Session

Understand JSESSIONID mechanism

• Describe the mechanisms that let the web container bind an incoming request to an existing session
  • cookies
  • URL rewriting
  • hidden field
• Write code that concatenate the JSESSIONID to a URL using the HttpServletResponse.encodeURL() method.

Get the session and manipulate it

• Write code that retrieves an HttpSession object either by using the getSession() method or by creating a new one if needed using the getSession(boolean) method

Not covered: Related listeners are not part of this exam, questions regarding attributes should be placed in the "Attributes" objectives.

Servlet Context Understand the servlet context scope within a web application

• Identify the ServletContext instance is unique within a web application
• Write servlet code that gets a reference to the ServletContext object

Not Covered: Questions regarding attributes should be placed in the "Attributes" objectives. Structure and Deployment

Write a simple Deployment Descriptor

• Configure the web.xml correctly for a basic servlet
  • Write a correct <servlet> element ...
  • ... and the corresponding <servlet-mapping> element
  • Write correct <load-on-startup> element.

Describe a correct directory structure for a WAR file

• Explain the web.xml must be placed in the WEB-INF directory
• .class files in the classes directory
• .jar files in the lib directory
• Static html files can be placed anywhere except inside the WEB-INF directory
• Identify which directories are accessible or not to incoming HTTP request URLs

Not covered: no questions on context listener nor init parameters