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From "Frank W. Zammetti" <>
Subject Re: HttpServletRequest processing
Date Fri, 02 Sep 2005 17:21:41 GMT
Well, I would defer to Michael to answer this, as I don't know the 
answer myself, I'd have to go research and figure it out.  One thing 
that comes to mind though is doing it with a filter (with a 
RequestWrapper involved I would think) so you would have access to the 
request "as it forms", so to speak.  You would spawn a new thread from 
the filter, giving is a reference to the wrapper, and continue 
processing from there.

That being said, I do not recall his solution being filter-based, so 
there must be another (probably simpler) answer.


Mashama McFarlane wrote:
> Thanks a lot. Actually this is exactly what I was envisioning but my 
> problems is that I don' know what type of thread to write to handle the 
> upload. I mean I am pretty sure I can't write a servlet thread because I am 
> assuming that the servlet container only passes the servlet the request 
> after it has received it in its entirety. Please correct me if I am wrong, 
> but if this is correct then any solution must be at the container level. So 
> the question is what kind of thread? At what level? And is it even possible? 
> Thanks for your help.
> Sincerely,
> Mashama
> On 9/1/05, Frank W. Zammetti <> wrote:
>>There really is no straight-forward way of doing this. In theory it
>>goes against the basic nature of HTTP.
>>That being said, Michael McGrady implemented such a solution, and
>>hopefully he will see this and be able to talk about it. I'll do my
>>best to remember the basic theory...
>>You start by targeting your form submission to a new window. This is
>>where your progress bar will display. In your servlet that recieves the
>>request that contains the file upload, you spawn a new thread to handle
>>the upload and return immediately with a page with some Javascript to
>>periodically poll the servlet to get the progress of the upload (every 5
>>seconds for example). The servlet of course has to retain a reference
>>to the thread handling the upload, and it has to have some sort of
>>unique identifier to be able to request the status update. This
>>identifier is passed to the servlet from the progress window. Once the
>>upload completes, a page is returned to inform the user (might be in the
>>popup still, might be a page that redirects the parent window of the
>>popup to a completion page).
>>Michael will hopefully correct me or expand on this as appropriate, but
>>that's what I recall being the basic theory behind his approach. I
>>think his code was on the Struts Wiki at one point, you may want to go
>>have a look and see.
>>Frank W. Zammetti
>>Founder and Chief Software Architect
>>Omnytex Technologies
>>Mashama McFarlane wrote:
>>>I need some help. I am working with file uploads. The ideal file uploads
>>>will be large enough to justify a file upload progress indicator. I am
>>>trying to figure out the easiest way of doing this, but it is much more
>>>complicated than I originally thought. It would be nice if somebody out
>>>there can prove me wrong on that point. I know that if I can monitor the
>>>request as it comes into the servlet container, then I can extract out 
>>>content-length and then everything else is a matter of counting bytes, 
>>>where and how do I do this. This cannot happen in the servlet as, I am
>>>assuming, the whole request has been received in its entirity prior the
>>>servlet servicing the request. So where on the totem pole need I be. 
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Frank W. Zammetti
Founder and Chief Software Architect
Omnytex Technologies

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