Thanks for the ideas but I've discovered the problem is specific to running
my servlet in JBuilder 3. If I deploy it to my web server with JRun I don't
have the problem. I'll try to find out more info from Inprise.
- David
----- Original Message -----
From: Nikolaos Giannopoulos <[EMAIL PROTECTED]>
To: 'A mailing list for discussion about Sun Microsystem's Java Servlet API
Technology.' <[EMAIL PROTECTED]>
Cc: 'David Galimberti' <[EMAIL PROTECTED]>
Sent: Tuesday, February 01, 2000 6:23 AM
Subject: RE: New Session in Img Src Servlet
> David,
>
> I mention the following since your session implementation on your web
> server probably defaults to cookies.
>
> We had a similar problem in that we wanted to set a cookie from a servlet
> that returned a img i.e. was part of a source tag as in your example. We
> could not get the cookie to be written back to the users browser i.e.
> subsequent invocations could not find the cookie. Mind you we might have
> not configured things properly on the servlet engine - which is possible.
>
> The only explanation I have is that this has to do with the fact that the
> html page already has its response header returned (which would have
> returned any cookies to set on the users browser) and now you are trying
to
> write a cookie back into a response header of a url that this page
accesses
> BUT the response header has already been received therefore the browser
> ignores it. I would think though that this would be a bug in browser
> implementations - if what I am saying is true - which I can't tell for c
> ertain. The only thing I can tell you is that it didn't work with NN 4.5
> or IE 4.72.
>
> BUT we did find a way to do this and it works quite well (FOR US) - albeit
> its a work around and maybe not the best solution in your case. Since we
> had a very small html page and we wanted to refresh the image contained in
> it we set the url of the page via javascript with GET parameters and had
> the servlet return a text/html page that contained the desired image path
> written in the html INSTEAD of a servlet selectively returning a binary
> image stream.
>
> There are some PROs - I believe - for this approach:
>
> (1) Chances are quite high that the image being returned is larger than
the
> html page content and therefore this approach allows the web server AND
NOT
> the servlet engine to stream back the image data. Who better to return
> content than a web server which is specifically designed to do so.
>
> (2) The servlet engine would be in a position to handle requests more
> efficiently than before since the time spent on any given request is
> reduced. This could make a BIG difference on a high traffic site as was
> our case.
>
> (3) You can take advantage of any caching that the web server uses to
> buffer recently accessed files as I believe most good web servers probably
> do. Servlet engines are not designed to cache files although that doesn't
> stop you from maintaining some sort of memory cache yourself - although I
> find this approach depends highly on the quantity and size of data
> maintained and can be more unweildly than its worth.
>
> The CONs - that I can see:
>
> (1) Page structure is more static and more difficult to maintain if the
> structure changes - since it is part of the servlet and not part a simple
> html page that can be updated by something as simple as a text editor. In
> our case this was not an issue because the content returned was simply a
> frame with an image - the bulk of the content was still maintained in html
> pages that are easily maintained.
>
> If you have any feedback or find out otherwise please let me know....
>
> Good Luck,
>
> --Nikolaos
>
>
> On Tuesday, February 01, 2000 12:19 PM, David Galimberti
> [SMTP:[EMAIL PROTECTED]] wrote:
> > I am having problems with session managment for a servlet that is the
src
> of an HTML img tag, for example:
> >
> > <img src="/servlet/imageServlet">
> >
> > Prior to using the servlet I created a session for the user but the
> servlet does not find one for the request (i.e. request.getSession(false)
> returns null). If I access the servlet via a redirect I can get to the
> session just fine.
> >
> > Does anyone know if there is something "special" about a request of a
> servlet that is the src of an img?
> >
> > Thanks!
> >
> > - David
> > << File: ATT00060.html >>
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