This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Just some remarks on your short summary (please check the API for the parameters and return types)
request.getParameter() - For HTML form elements(including cookies)
getting cookies is done by calling request.getCookies()
request.getAttribute() - For requests forwarded via RequestDispatcher
For objects stored in the request (those are probably set by calling request.setAttribute() before calling the RequestDispatcher)
ServletConfig.getInitParameter() - For paramers defined using <init-param> in DD
Be careful here, this are the init parameters for the Servlet defined inside the <servlet> element, you also have init parameters for the whole web-application (ServletContext) defined in the <context-param> element of the DD
ServletContext.getAttribute() - For Objects stored in ServletContext(Shared b/w mutiple request for same servlet)
These objects are shared through the whole web-application, so for all the servlets defined in de DD!