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) From: Colin Rogers <colin.rog...@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:rwada...@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 & 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. 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