p:commandbutton update not updating immediately for ScheduledExecutorService - jsf

Question

I'm working on a JSF + Primefaces Web App in which I need to make a RESTful GET request every 20 seconds to a server, and display the data returned. This currently works, with the exception of the "every 10 seconds" part. I can click my command button to retrieve and show the data. I tried to implement the repitition with ScheduledExecutorService. Now when I click the commandButton, the backing function runs every 10 seconds (I can see this through System.out.println output), but the table will not update to show data until the button is clicked a second time. Here is my code below:
HTML (This is embedded inside a form)
<p:commandButton id="andon_layout--board0--loadboard0"
value="Load board"
actionListener="#{decryptionBean.loadBoardListen0}"
update="dataPanelGrid" />
<div id="andon_layout--board0--display_div"
class="ui-datatable ui-widget ">
<h:panelGrid id="dataPanelGrid"
columns="#{decryptionBean.displayBoardArray[0].datatableNumberOfCols}"
headerClass="ui-datatable ui-widget-header ">
<f:facet name="header">
<h:outputText
value="#{decryptionBean.displayBoardArray[0].locationName}" />
</f:facet>
<c:forEach var="row"
items="#{decryptionBean.displayBoardArray[0].displayData}">
<c:forEach var="value" items="#{row}">
<div class="ui-dt-c">#{value}</div>
</c:forEach>
</c:forEach>
</h:panelGrid>
</div>
JAVA
#ManagedBean
#ViewScoped
public class DecryptionBean implements Serializable {
...
private Updater left = new Updater(0);
public void loadBoardListen0(ActionEvent event){
left.stopBoardLoading();
left.beginBoardLoading();
}
public final class Updater {
#PreDestroy
public void destroy() {
fScheduler.shutdownNow();
}
private ScheduledExecutorService fScheduler;
//
private long fDelayBetweenRuns = 10;
int boardNumber;
/**
* If invocations might overlap, you can specify more than a single
* thread.
*/
private int NUM_THREADS = 1;
public int isRunning = 0;
private boolean DONT_INTERRUPT_IF_RUNNING = false;
private ScheduledFuture<?> loadBoardFuture;
private class BoardLoaderTask implements Runnable {
private int boardNumber;
public BoardLoaderTask(int boardNumber) {
this.boardNumber = boardNumber;
}
public void run() {
DecryptionBean.this.loadBoard(boardNumber);
}
}
public Updater(int boardNumber){
this.boardNumber = boardNumber;
fScheduler = Executors.newScheduledThreadPool(NUM_THREADS);
}
void beginBoardLoading(){
if(isRunning == 1){
this.stopBoardLoading();
}
isRunning = 1;
Runnable boardLoaderTask = new BoardLoaderTask(this.boardNumber);
loadBoardFuture = fScheduler.scheduleWithFixedDelay(boardLoaderTask,
0, fDelayBetweenRuns, TimeUnit.SECONDS);
}
void stopBoardLoading(){
if(isRunning == 1){
isRunning = 0;
Runnable stopBoard = new StopLoadingTask(loadBoardFuture);
fScheduler.schedule(stopBoard, 0, TimeUnit.SECONDS);
}
isRunning = 0;
}
private class StopLoadingTask implements Runnable {
StopLoadingTask(ScheduledFuture<?> aSchedFuture) {
fSchedFuture = aSchedFuture;
}
private ScheduledFuture<?> fSchedFuture;
#Override
public void run() {
// TODO Auto-generated method stub
fSchedFuture.cancel(DONT_INTERRUPT_IF_RUNNING);
}
}
}
loadBoard(int boardNum) is kind of a large function, so I haven't posted it here, however I will if you guys deem it necessary.
It seems to me that the problem comes from the p:commandbutton update attribute: it seems like the dataPanelGrid is being updated at the start of loadBoardListen0, as opposed to the end. To be clear: The backing function runs on the first click, but only updates the GUI on the second, third, fourth etc. click Any guidance on this one? Thanks in advance!
EDIT 1:
I'm now trying to do this using PrimePush and a socket, but I'm running into trouble there too. I added this to my code:
HTML
<p:socket onMessage="handleMessage" channel="/IPVS" autoConnect="false"/>
...
function handleMessage(data) {
console.log("data received: " + data);
var elm = "andon_layout--board" + data + "--display_div";
elm.style.display="none";
var redrawFix = elm.offsetHeight;
elm.style.display="block";
}
JAVA (at the end of loadBoard(int))
System.out.println("Loading data... no exceptions thrown");
System.out.println("context created");
PushContextFactory.getDefault().getPushContext().push("/IPVS", Integer.toString(displayBoardNum));
System.out.println("Just pushed to /IPVS");
Whenever I attempt to run the code, it simply halts at the PushContextFactory line. The output I get is as follows:
Loading data... no exceptions thrown
context created
And simply no more. This also prevents the loop from running. Note that I am still using a ScheduledExecutorService, and just trying to push some data every time the task completes. Any ideas?

Answer 1

You should try using the Primefaces poll tag. This will fire an ajax event every x seconds. You could use this to call your "getData" method on your backing bean. This will move the logic of the polling into your JSF page, rather than the backing bean.
For example:
<p:poll interval="10" listener="#{decryptionBean.getData}" update="dataPanelGrid" />
This requires you to have a simple "getData" method in your backing bean, without the scheduling code.