HI Nic,
Thanks for the explanation it was great. Yes tomcat was giving me
back 302 found. But one more thing. I had wrote a Server long time ago which
just printed the request a browser sends (to see the headers etc) when I
used that with IE. I received the request from IE (which was printed on
Servers console) & then I wrote back a 302 Found response back to IE so that
now it should send a second response its it. But it didnt send any response
the second time.
Why was it so.
Thanks for the explanation once again.
Bye,
Jiger
>From: Nic Ferrier <[EMAIL PROTECTED]>
>Reply-To: "A mailing list for discussion about Sun Microsystem's Java
> Servlet API Technology." <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: Re: Default Files
>Date: Tue, 6 Feb 2001 05:58:28 +0000
>
> >>> Jiger Patel <[EMAIL PROTECTED]> 06-Feb-01 5:18:47 AM >>>
>
>Before I start to answer this you should be aware that this is the
>wierdest part of the API (it's not really the APIs fault that it's
>wierd - it's the fault of webservers and the way we use operating
>systems).
>
>
> > Now my Client if asking for a URL like
> > java myclient "http://m1:8080/eShoppe"
> >
> >then it gives back 302 Found error.
> >
> >Then if I add a slash to my url Like this
> > java myclient "http://m1:8080/eShoppe/"
> >
> >then it gives me index.jsp as wanted. This is when
> >my Servlet Engine is JWSDK.
>
>Don't use JWSDK: it's magnificently out of date.
>
> >Now I start tomcat & go thru the same procedure but
> >neither with nor without slash returns the index.jsp.
>
>What does Tomcat return? 302?
>
>
> >But If I use my browser to ask for that same URL then
> >it returns the index.jsp I also went thru the HTTP specs
> >but didnt find anything missing.
>
>This problem is related to mappings and to webservers. Note that a
>webserver is different from a servlet engine, a webserver serves
>static file like images and html files (consider a JSP a static page
>for now).
>
>There are, oooh, about a zillion different combinations and different
>ways of matching a path to the correct servlet. The servlet API
>specifies that it must be done by specifying a servlet against a path
>mapping of some kind.
>
>
>First, understand that a path ending in a slash is what we call a
>directory mapping.
>
>A path that doesn't end in a slash and where the last part of the
>path has a "." in it is called a file-mapping.
>
>So these are some directory mappings:
>
> /dir1/
> /dir1/dir2/
>
>and these are some file mappings:
>
> /dir1/file.txt
> /dir1/dir2/file.jsp
>
>So what is this?
>
> /dir1/file.jsp/
>
>A file mapping? Wrong! It's a directory mapping. And this:
>
> /dir1.jsp/dir1.jsp
>
>is a file mapping.
>
>
>But: what if a path that hasn't got an end "/" or a last part "."?
>It's just neither one nor the other. It can't really be classified as
>a directory mapping because there might be a file called dir1 and if
>it was considered a directory it wouldn't get served. But it can't be
>considered as a file mapping either because if it was a directory then
>it wouldn't get served. So the webserver has to guess what you mean
>based on the contents of the directory.
>
>The servlet engine (Tomcat not JWSDK - that's very old and probably
>broken) can map servlets to basically any path:
>
> /dir1/
> /dir1/file.jsp
> /dir1
>
>Within the servlet engine the mapping:
>
> /dir1
>
>is treated just the same as a directory mapping.
>
>But this is not how the webserver sees it. Remember that the
>webserver is the default servlet. What is the default servlet? The
>default servlet is the servlet that recieves all requests that haven't
>been matched to another servlet.
>
>So if you ask the server for /dir1 and you don't have a mapping for
>it within the servlet engine then the default servlet (also known as
>the webserver servlet or the file servlet) gets it.
>
>The webserver servlet behaves like a webserver and webservers have
>rules about paths that aren't either file paths or directory paths.
>
>The rule goes like this:
>
>- if there is a file with this name then return the file
>- if there is a directory with this name then return a redirect to
>the proper directory name
>
>So if on server nics.tfltd.net:9000 you have a directory:
>
> /dir1
> /index.jsp
> /pamela.jpg
> /brad.gif
>
>and you request this:
>
> nic.tfltd.net:9000/dir1
>
>when the default servlet recieves your request it will:
>
>- search for a file dir1
>- not find one
>- search for a directory dir1/
>- find one
>- send you a 302 response with the new location: /dir1/
>
>If you were using a browser the browser would automatically follow
>the 302 response to the new location which is why you can type a
>non-directory path into the browser and get the response you want.
>
>If you want a Java client to behave the same way you have to
>implement the correct response to the 302.
>
>What is the coirrect action to take on recieving 302? You just issue
>another request to the server for the directory specified in the
>"Location:" header of the 302 response.
>
>So your code looks something like:
>
> String path=getArgument();
> int code=sendRequestToServer(path);
> while(code==302)
> {
> path=getHeader("Location");
> code=sendRequestToServer(path);
> }
>
>
>If you choose to use an HttpURLConnection this is all done for you by
>setting followRedirects on the connection before you open it.
>
>I'd really advise you to use the HttpURLConnection rather than
>writing direct to the Socket because it could solve other problems for
>you as well.
>
>
>Nic
>
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