How to update progressbar while doing serverside processing?

Question

Hi,
I have the following use case:
- When the user clicks a button a file must be downloaded. Because it can take some time before the server gathered the data, a progressindicator must be shown. After that the file is presented to the user.
Currently, I have clientside javascript that shows the popup, and then queues a server event that starts the serverside processing. A poller is running that should keep track of the progress.
My problem is that the popup only shows at the end of the serverside method. Also, the poller doesnt poll while the serverside method is executed, and resumes at the end of the serverside method execution. So even when the popup would show, it wouldnt properly display the progress.
I have the following code:function showProgressPopup(event) {
                            var popup = AdfPage.PAGE.findComponent("pt:progressPopup");
                            var hints = {};
                            hints[AdfRichPopup.HINT_ALIGN] = AdfRichPopup.ALIGN_OVERLAP;
                            hints[AdfRichPopup.HINT_ALIGN_ID] = "pt:downloadButton";           
                            popup.show(hints);
                            var source = event.getSource();
                            AdfCustomEvent.queue(source, "startDownload", {}, false); //at this moment, popup should show and serverside processing starts
<af:panelGroupLayout id="pgl6">
                <af:poll id="poller"/>
                <af:commandButton text="Download in Excel-formaat" id="downloadButton" partialSubmit="true">
                    <af:clientListener type="action" method="showProgressPopup"/>
                    <af:serverListener type="startDownload" method="#{CombinotaExportBean.startDownload}"/>
                </af:commandButton>
                <af:popup id="progressPopup" clientComponent="true">
                  <af:dialog id="downloadDialog" type="cancel" modal="true" closeIconVisible="false" title="Downloading..." partialTriggers="downloadButton poller">
                    <af:switcher id="downloadSwitcher" defaultFacet="showRunning"
                                 facetName="#{CombinotaExportBean.value == CombinotaExportBean.maximum ? 'showReady' : 'showRunning'}">
                      <f:facet name="showRunning">
                        <af:panelGroupLayout id="pgl7">
                          <af:panelHeader text="One moment please" id="ph3"/>
                          <af:progressIndicator id="progressIndicator" value="#{CombinotaExportBean}" partialTriggers="poller">
                            <af:outputFormatted styleUsage="instruction" value="Data is being collected..." id="of1"/>
                          </af:progressIndicator>
                        </af:panelGroupLayout>
                      </f:facet>
                      <f:facet name="showReady">
                        <af:goLink text="Click to download file" id="gl1" partialTriggers="poller" destination="#{CombinotaExportBean.downloadFile}">
                          <af:clientListener type="click" method="closeProgressPopup"/>
                        </af:goLink>
                      </f:facet>
                    </af:switcher>
                  </af:dialog>
                  <af:clientListener method="downloadDialogCanceled" type="popupCanceled"/>
                  <af:serverListener type="downloadCanceled" method="#{CombinotaExportBean.downloadCanceled}"/>
                </af:popup>
                </af:panelGroupLayout>When I start a new Thread in my serverside CombinotaExportBean.startDownload method, it works because then that method returns while the server is still processing. However then I have problems with quering my RowSetIterators, they start throwing NPE's. Multithreading is evil in webapps I guess.
So how can I do this in one thread? How can I make sure my popup shows first, and my poller keeps polling while the server collects data?
with kind regards,
Gerben

Answer 1

Hi Frank,
Thanks for your suggestion. In my current implementation I'm basically using a animated image, because I'm now using the ProgressIndicator without BoundedRangeModel and then it just shows a running clock.
However, in my case its quite easy to monitor the progress on the server thread. So I thought this is the typical use case for a real ProgressIndicator. Unfortunately I can only find 10g examples of the progress indicator and I dont get the 11g progressindicator to work like that. So what I am curious about is, if a typical ProgressIndicator use case is any different. And if there's any example of it, with or without the usage of the poller.
I already found the answer to part of my question. If I set noResponseExpected to the serverevent, the client event finishes and is effective immediately, before the server event is finished:var source = event.getSource();
var customEvent =  new AdfCustomEvent(source, "startDownload", {}, false);
customEvent.noResponseExpected();
customEvent.queue(true);with kind regards,
Gerben