Re: Asynchronous transformation in a (Java) Web app

But is creating threads directly from servlets considered a
normal/safe practice?
Some sources on asynchronous servlets I've been reading through
suggest that it is bad (or J2EE non-compliant) design, and provide
more complex solutions, involving JMS for example, like here:
http://www.javaranch.com/journal/2004/03/AsynchronousProcessingFromServlets.h
tml
So I'm confused regarding the implementation of the job queue itself.

On Sat, Sep 11, 2010 at 5:08 PM, Andrew Welch <andrew.j.welch@xxxxxxxxx>
wrote:
> On 11 September 2010 15:02, Martynas Jusevicius
> <martynas.jusevicius@xxxxxxxxx> wrote:
>> Hey list,
>>
>> while asynchronous processing is a broad subject, I hope my question
>> is not off-topic as it applies directly to XSLT.
>>
>> The scenario is pretty simple, and I guess not uncommon: user uploads
>> a (potentially heavy) file, then XSLT transformation(s) process it,
>> and the result is presented back to the user. The program runs as a
>> Java Servlet web application.
>>
>> The problem is, that the transformations can take quite some time, up
>> to one minute for example. Therefore I started looking into ways of
>> running them asynchronously, not blocking the servlet and presenting
>> the result later.
>> I guess I need some kind of thread-based subsystem to run and
>> transform in the background, but my knowledge ends pretty much there.
>>
>> Any advice on approaches/techniques or specific tools/libraries would
>> be appreciated.
>
> In JAXP, the TransformerFactory and the compiled stylesheet (the
> "Templates" object) are both thread safe, but the Transformer is not.
> So for each request create a new thread passing in the source, the
> TransformerFactory, the Templates object and the response writer, then
> create the Transformer in the thread and run the transform (although
> its been a while since did any coding at the servlet level...
> hopefully that's a point in the right direction).
>
>
>
> --
> Andrew Welch
> http://andrewjwelch.com