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From "Richard W. Adams" <RWADA...@UP.COM>
Subject Re: Background Threading
Date Tue, 06 May 2014 13:59:10 GMT
Well for starters, the example seems to require Hibernate (which our 
organization doesn't allow us to use). This correct?

Second, I don't have the flexibility implement a service. I have to send 
Javascript back to the client, and the corporate Javascript framework then 
renders the progress bar.

What is the 'context' class you refer to? Where is it instantiated and 
where is it stored? 




From:   Ernesto Reinaldo Barreiro <reiern70@gmail.com>
To:     "users@wicket.apache.org" <users@wicket.apache.org>
Date:   05/06/2014 07:52 AM
Subject:        Re: Background Threading



Hi,


On Tue, May 6, 2014 at 2:11 PM, Richard W. Adams <RWADAMS1@up.com> wrote:

> Interesting approach. Our use case is more complex, as it runs a
> background task in a separate thread. Our task has three basic
> requirements. It must:
>
> 1. Be cancellable.
>
> 2. Report its outcome (success/failure/warning).
>
> 3. Report incremental progress.
>
> Our fundamental problem is not how to display the progress bar, it's how
> to determine the outcome of the background thread. That's an 
unexpectedly
> a tough nut to crack. The vast majority of examples we've seen use the
> Runnable interface (which doesn't help us, as it can't be canceled or
> return a value), rather than Callable interface (which meets our needs,
> but doesn't seem to play well with Wicket)
>

Really? Is it that hard?

1-Create a "context" class to pass information to/from WEB
threads/background thread.
2-Both threads keep a copy of it: so you can report progress, cancel
generation and so on.

I have implemented something like that ages ago

https://code.google.com/p/antilia/wiki/OSGiPowered



>
>
>
>
> From:   Colin Rogers <Colin.Rogers@objectconsulting.com.au>
> To:     "users@wicket.apache.org" <users@wicket.apache.org>
> Date:   05/05/2014 08:14 PM
> Subject:        RE: Progress Bar
>
>
>
> There is a pretty nifty, jquery based progress bar, in wicket-jquery-ui
> library...
>
> 
http://www.7thweb.net/wicket-jquery-ui/progressbar/DefaultProgressBarPage
>
> Cheers,
> Col.
>
> -----Original Message-----
> From: Richard W. Adams [mailto:RWADAMS1@UP.COM]
> Sent: Tuesday, 6 May 2014 3:19 AM
> To: users@wicket.apache.org
> Subject: Progress Bar
>
> We have a requirement to implement a progress bar for long-running 
server
> operations. We can't use the code at
> https://github.com/wicketstuff/core/wiki/Progressbar, because it doesn't
> meet our corporate user interface look-and-feel standards.
>
> So, we started our own implementation. Our test page contains these
> methods below (the TestExecutor below class implements
> Callable<ExecutorResult>).
>
>
> 
//----------------------------------------------------------------------------------------------
> private Component createButton() {
>         return new AjaxButton("start-button") {
>                 private static final long serialVersionUID = -1;
>
>                 @Override protected void onSubmit(final 
AjaxRequestTarget
> ajax, final Form<?> form) {
>
>                         final ExecutorService service = Executors.
> newSingleThreadExecutor();
>                         try {
>                                 final ProgressBarTestPage page =
> ProgressBarTestPage.this;
>                                 final TransactionData data = new
> TransactionData (page.getId(), false);
>                                 final TestExecutor executor = new
> TestExecutor(data, getPermissions());
>
>                                 executor.addListener(page);     // 
Request
> notification when done
>                                 future = service.submit(executor); //
> Begin execution
>                                 progressBarUpdater.start(ajax, 
executor);
> // Start polling for progress
>
>                         } catch (final Exception ex) {
>                                 throw new RuntimeException(ex);
>                         }
>                         service.shutdown();     // Terminate gracefully
> (VM probably
>                 }               //      won't exit if we fail to do 
this)
>         };
> }
>
> 
//----------------------------------------------------------------------------------------------
> /**
>    Observer Pattern method to let us know when the task is done so we 
can
> check how things went.
> */
> @Override public void executionComplete(final EnmCallableExecutor
> executor) {
>
>         try {
>                 if (!future.isCancelled()) { //
> Unless execution was canceled
>                         final ExecutorResult result = future.get(); //
> Get the outcome
>                         System.out.println(result);
>                         /*
>                          * TODO: Show success or error message
>                          */
>                 }
>         } catch (final Exception ex) {
>                 ex.printStackTrace();
>         }
> }
>
> The ProgessBarUpdater class has this method:
>
>
> 
//----------------------------------------------------------------------------------------------
> /**
>  * Displays the progress bar &amp; begins the polling. We don't start 
the
> polling until
>  * explicitly told to do, for efficiency purposes.
>  * @param ajax The Ajax request wrapper.
>  * @param reporter The object to query for progress data.
>  */
> public void start(final AjaxRequestTarget ajax, final ProgressReporter
> reporter) {
>
>         add(new AjaxSelfUpdatingTimerBehavior(Duration.seconds(2)) {
>                 private static final long serialVersionUID = 1L;
>
>                 @Override protected void onPostProcessTarget(final
> AjaxRequestTarget ajax) {
>
>                         final Progress progress = 
reporter.getProgress();
>                         final String script =                   // Build
> script to update
>                                 ProgressScript.build(progress);  //
> progress bar
>                         ajax.appendJavascript(script);
>                         if (progress == null) {                 // If
> operation is finished
>                                 final ProgressBarUpdater updater =
>                                         ProgressBarUpdater.this;
>                                 updater.remove(this); //
> Stop timer to prevent
>                                 ajax.addComponent(updater);  // 
pointless
> polling
>                         }
>                 }
>         });
>         ajax.addComponent(this);
> }
>
> The page also contains a Future object so we can check the result after
> the thread finishes:
>
>         private Future<ExecutorResult> future;
>
> __________________________________________
>
> Having said all that, here's the problem: When I click the page's 
button,
> Wicket throws this error:
>
>         Unable to serialize class: java.util.concurrent.FutureTask
>
> The FutureTask object, I believe, is coming from the service.submit call
> whose return value we store in our Future variable.
>
> Does anyone know how to get around this roadblock?
>
>
>
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-- 
Regards - Ernesto Reinaldo Barreiro



**

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