Bill,
An alternative to using a file serving servlet for your image files would be
to put something like the following:
<% out.println("<base href='"
+ request.getScheme()
+ "://"
+ request.getServerName()
+ ":"
+ request.getServerPort()
+ "/my/base/path/'>"
);
%>
in your jsp files so that you can use urls relative to "/my/base/path/" for
image files allowing the web server to serve them. (This is what web servers
are really good at! :) ) This path could also be passed from the servlet
that is dispatching it.
John Zerbe - Mellon Bank
Phone: 412-234-1048 E-Mail: [EMAIL PROTECTED]
> -----Original Message-----
> From: Bill O'Keefe [SMTP:[EMAIL PROTECTED]]
> Sent: Thursday, June 03, 1999 12:09 AM
> To: [EMAIL PROTECTED]
> Subject: Re: A question using the RequestDispatcher
>
> Craig,
>
> >> I have a servlet that reads a list of JSP pages from
> >> a property I defined (in the 'init' method). When a request
> >> is sent to my servlet, it uses the RequestDispatcher to
> >> 'forward' each request it receives to the next page in
> >> the list. It keeps track of the current page in it's
> >> session data.
> >>
> >> Each JSP presents a form to collect information from the user.
> >> When the form is submitted, it will create an XML document,
> >> which it will POST back to my servlet. My servlet will save
> >> the XML in the session data, then 'forward' the request to
> >> the next JSP in the list. Once all have been run, my servlet
> >> will parse and validate the complete XML document that has been
> >> constructed by each JSP page, then make the appropriate updates
> >> to a database. It will then reset the session data so that the
> >> next request will start the process all over again.
> >>
> >> Since servlet/JSP/XML programming is still new to me, I am wondering
> >> if the above approach makes sense, or if there is a better way
> >> to accomplish the above.
> >>
> >
> >In general, this seems like a pretty reasonable approach. If the XML you
> >create as a result of each form is independent of that created on other
> forms,
> >an alternative might be to just collect the input fields in your session,
> and
> >then produce the final XML document after the last one has been entered
> --
> but
> >this is really an issue of which is easier to write and maintain.
>
> Since others will be developing the JSPs, and hence defining their XML
> documents (along with their DTDs), it seems cleaner to me to just
> let each JSP create it's XML, and then when all have finished, my
> servlet will parse and process the composite document. Of course,
> I suppose I could impose a form field naming convention on each JSP
> writer, but I'm trying to keep the rules for writing these JSP scripts
> as simple as possible. Of course, I haven't thought this through
> completely, so I may be missing something.
>
> >> One thing I notice when I 'forward' the request to a JSP page
> >> is that the URL path seems to be set to that of the servlet.
> >> Thus, even though I forward to a URL in another directory,
> >> relative references to graphics, etc in the JSP page don't work,
> >> since they are looked for in /servlet/xxx.gif, which of course,
> >> doesn't exist. Do I have to include absolute URLs to get this to
> >> work? Or is there a way to change the pathname in the request?
> >>
> >
> >When you do a RequestDispatcher.forward(), the "redirection" happens on
> the
> >server side, without the client browser knowing about it.
>
> Understood.
>
> >..If you really want
> >the browser URL to change, you can do a sendRedirect() instead, but then
> >you're paying the performance penalty of an extra round trip across the
> >network. Users of dynamic web applications (as opposed to your typical
> web
> >site) need to understand that the URLs that are displayed are basically
> >irrelevant, because you can't just bookmark into the middle and proceed
> from
> >there. In most cases, I run these kinds of apps in frames (where the
> visible
> >URL does not change anyway), or in a new browser window that doesn't even
> show
> >the URL, to emphasize the fact that navigation controls on the page are
> the
> >only way to move around.
>
> I'm not too concerned with the URL that is displayed. I just want
> the JSP writer to be able to place their JSP anywhere on the same
> web site, and be able to use relative URIs to reference images and
> stuff as they would expect.
>
> >For your image references, the servlet engine will normally let you
> define a
> >"default" servlet for the application that is executed when no servlet
> path
> >can be found in a URL. If this servlet is a file-serving servlet, then
> it is
> >easy to use paths for images (such as "/images/xxx.gif" in a way that is
> local
> >to your application. You just need to worry about configuring the
> associated
> >servlet context to tell it what the document root directory is. This is,
> in
> >fact, how the 2.1 JSDK servlet engine serves static resources, and most
> other
> >2.1 engines will have something similar.
>
> I think this is what I need to do, but I don't quite understand how.
> Can you be a bit more specific? Thanks very much for your help.
> I really appreciate it.
>
> BTW, I'm using JWS 2.0 for now, so if you know details on how
> to configure JWS to do the above in that environment, please let me know.
> Thanks again.
> -- Bill
>
> --
> Bill O'Keefe [EMAIL PROTECTED]
> Open Market, Inc. http://www.openmarket.com/
> One Wayside Road TEL: 781.359.7296
> Burlington, MA 01803 FAX: 781.359.8200
>
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