server-client concept

Hi

  Ina Gardner gave me this adress where I could ask   my questions. Well,
  let's say that although I've read 1 1/2 Java books and a    bit of JavaScript I'm still fustrated since I've not get    some important concepts. I don't know if you know were I    could find a general text that can answer to my questions   rather than the usual chapters in
  books that explain the Security Manager restrictions or   so...

  In 'Developing Professional Java Applets', page 124 they   gives this:

    myFile=new File("File.txt");
    ......
    ...
    File myDirectory=new File("...\\...");
    ...
    ...

  There's no URL specified in any operation related to such   classes in
  this chapter. In a chapter about socket, one could find   things like:
  outbound.writeBytes("GET /HTTP/1.0\r\n\r\n");

  Before I start to code extensivelly and buid a website, I   want to be
  sure if I have correctly some basical concepts:

 a)If I'm dealing with a provider (let's say my one ,VIR    communications)
   than there's no way to use classical databases in an       application. If my computer is shut down, a remote PC can
   access this site as long
   as a VIR server is available, but it is no longer my PC
   business once the applets are upload to this space       reserved on VIR server, right? So a database on my Hard    Drive is useless for my application
   normally except if I have enough space on a URL adress to    upload it in advance with FTP, right?  There's a couple     of examples with images in my book, but I'm not sure if     the princip can be really the same for databases like
   Oracle or so. I suppose that they have always an image
   of what you upload on their disk, no?

 b) I've not yet my website but it'll come soon.I think the     usual pattern is this one: the provider has a HTML wich
   is calling an applet that run  permanently ( the server).
   When someone access my URL and HTML scrip MY applet is    transfered to client's machine before to be interpreted.
   But since it is executed on client's machine, no data    
   can be write on my URL, they can just be read, right?    
   I've an example of a server applet in my book, but I    
   don't know how this one could run on a permanent base on    the server side (if I want to perform database operations    or so). How could I do if I want my own server applet to    run constently and respond rather than my provider's   applet???

  Thanks in advance