Re: Request order

Stefan,

Did you read this post?
http://groups.google.com/group/google-web-toolkit/browse_thread/thread/6d982ecf9398ddec

Queueing your requests in the client guarantees server side execution
order, albeit it might be a bit drastic.

Is your locking/check mechanism generic?

Kristof

On Nov 21, 2:44 pm, Stefan Bachert <stefanbach...@yahoo.de> wrote:
> Hi Jeff,
>
> > Here's what
> > I'm still not sure of: are you looking to undo/redo at the attribute level,
> > the entity level, transaction (multiple entities) level?
>
> I do no more looking for undo/redo, I solved it at the latter level.
>
> However, the reason for this thread was that I figured out, that
> nothing guaranties, that servlet requests are executed in the same
> order as they are send from browser.
> Meanwhile I did some locking/check to enforce the order.
> I had hoped that someone knows an easy solution, may be some
> configuration entry. However, topic solved.
>
> Stefan Bacherthttp://gwtworld.de
>
> On 20 Nov., 16:22, Jeff Chimene <jchim...@gmail.com> wrote:
>
>
>
>
>
>
>
> > Hi Stefan:
>
> > Perhaps we need a better functional requirement?
>
> > From what I can tell, there is a requirement for transaction semantics; it's
> > difficult to eliminate this requirement based on the conversation so far (In
> > this thread you introduced the concept of interacting servers). Here's what
> > I'm still not sure of: are you looking to undo/redo at the attribute level,
> > the entity level, transaction (multiple entities) level?
>
> > Perhaps there's some Java server-side technology that you can employ?
>
> > On Sat, Nov 20, 2010 at 7:20 AM, Stefan Bachert <stefanbach...@yahoo.de>wrote:
>
> > > Hi,
>
> > > I had a look at gwt-dispatch.
>
> > > I do not see any logic which is able to avoid to execute requests on
> > > the server side in an other order than the client sends it.
> > > This situation may happens rarely but it is not impossible.
>
> > > An example.
>
> > > Client send three requests A,B,C.
>
> > > Servlet-Thread x getrequestA but stops/waits/slowdown for some
> > > reason very early, may be in the dispatcher itself.
>
> > > An other thread y getrequestB and thread z getrequestC.
> > >RequestC may completes first, before B completes, before C completes.
> > > (Not likely, but not impossible)
> > > (Consider running a container on two cpus, too!)
>
> > > gwt-dispatch lacks other problems. It produces too much communication
> > > and latency. When the server is working with transactions, any action
> > > will require one transaction, which slows down the server performance,
> > > too.
> > > So gwt-dispatch is not a good choice for a high performance systems.
>
> > > Stefan Bachert
> > >http://gwtworld.de
>
> > > On 19 Nov., 14:56, ep <eplisc...@googlemail.com> wrote:
> > > > actually, its concern of a client to chain the requests, as only it
> > > > knows in which order the requests are initiated. actually, your user
> > > > shall not be available to execute instructions in parallel, so your
> > > > button has to be disabled until previous calculation (server response)
> > > > has been returned.
>
> > > > again, you may want to have a look at gwt-dispatch project. they
> > > > implement Command Pattern with easy undo support, and chaining. the
> > > > latter would help if you dont want to disable your button whilst
> > > > processing results, so the requests are just queued in order they are
> > > > requested and processed sequentially, each based on the result from
> > > > the other...
>
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