"What kind of java business applications, how do they differ from regular java classes, etc.
Well, these are ordinary classes. They are launched by the application server. An "application server" is often just a JVM, but sometimes it expands or modifies or extends a provider. But that should not bother you. An application server (such as the JVM) uses a class loader (possibly configured by the provider) to load a servlet (any class that implements the HttpServlet interface). Any other classes (not just J2EE classes, but all classes) will be loaded by the class loader. From there, this is your Java code. Hope this gives you the answer you want. Reading J2EE documents (even aimed at developers) usually entails meaningless words.
I would recommend you check out Sun's J2EE tutorial. It is free and iterates through the basics you need to know before moving on to a framework (like Struts). And, of course, you need to know if you just want to use J2EE directly.
You can familiarize yourself with some of them:
Some useful facts:
- JSP compiled into servlet. They were designed so that your servlets would not need to be developed using the Output Writer to process each content for writing to the page (JSP will be compiled for this). i.e.: out.println ("<html> etcetc ...")
- The request object (HttpServletRequest) represents the request.
- the response object (HttpServletRespone) will build the response. (both http headers and content).
- Session and Context objects are also important. The first is for transferring objects with a session area (managed by the application server) and is mapped to a client-side jsessionid cookie (so that it knows which client (i.e., request) has which objects on the server side). A context object is used for initial settings.
- You will want to go through web containers to fit all of these.
Zombies
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