How to use the ITopicSubscriber in a dashboard panel

[Jan Thielemann]

Hey Guys,

i have a dashboard panel to keep track of the users (who is logged in, who is offline, send them broadcast messages).

To keep track of login/logout events, i use a event handler of MSession where i use the IMessageService to publish these events:

private void publishEvent(int createdBy, String topic) {

Map<String, Integer> properties = new HashMap<String, Integer>();

properties.put(topic, new Integer(createdBy));

IMessageService service = Service.locator().locate(IMessageService.class).getService();

if (service != null) {

ITopic<Map<String,Integer>> itopic = service.getTopic(topic);

itopic.publish(properties);

}

}

In my dashboard panel, i implemented the ITopicSubscriber

IMessageService service = Service.locator().locate(IMessageService.class).getService();

if (service != null) {

ITopic<Map<String,Integer>> intopic = service.getTopic(ON_USER_LOGGED_IN_TOPIC);

intopic.subscribe(this);

ITopic<Map<String,Integer>> outtopic = service.getTopic(ON_USER_LOGGED_OUT_TOPIC);

outtopic.subscribe(this);

}

@Override

public void onMessage(Map<String,Integer> message) {

if(message.keySet().contains(ON_USER_LOGGED_IN_TOPIC)){

treeModel.userLoggedIn(message.get(ON_USER_LOGGED_IN_TOPIC));

}else if(message.keySet().contains(ON_USER_LOGGED_OUT_TOPIC))

treeModel.userLoggedOut(message.get(ON_USER_LOGGED_OUT_TOPIC));

}

I can receive the events and read the user id from it but as soon as i try to refresh my tree model, i get the following error:

java.lang.NullPointerException

at org.compiere.util.CLogErrorBuffer.publish(CLogErrorBuffer.java:192)

at java.util.logging.Logger.log(Logger.java:610)

at com.hazelcast.logging.StandardLoggerFactory$StandardLogger.log(StandardLoggerFactory.java:50)

at com.hazelcast.logging.LoggingServiceImpl$DefaultLogger.log(LoggingServiceImpl.java:146)

at com.hazelcast.impl.ListenerManager.callListeners(ListenerManager.java:336)

at com.hazelcast.impl.BaseManager$2.run(BaseManager.java:1382)

at com.hazelcast.impl.executor.ParallelExecutorService$ParallelExecutorImpl$ExecutionSegment.run(ParallelExecutorService.java:212)

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)

at java.lang.Thread.run(Thread.java:744)

at com.hazelcast.impl.ExecutorThreadFactory$1.run(ExecutorThreadFactory.java:38)

I'm wondering what i am doing wrong. Maybe i didn't get the concept of the message service or the topicsubscriber right and i would really appreciate a hint into the right direction. It would be great if somebody could explain the whole concept to me so that i could write a tutorial in our wiki.

[Heng Sin Low]

Where is that NPE comes from ( the log is cut off ) ? Perhaps you need to use ServerPushTemplate or AEnv.executeAsyncTask to refresh your model.

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[Jan Thielemann]

Hi Hengsin,

thanks for the answer. The log is not cut of. It is all i get. Maybe you can check it directly. The code can be found here:

https://bitbucket.org/evenos-consulting/org.evenos.broadcaster

How would i use the suggestions you made? My knowledge in zk is still miles away from yours...

[Hiep Lq]

Hi Jan, I interest with new things.

where's code of 

[Jan Thielemann]

This piece of code is in the event handler which i use as a replacement for model validator.

[Heng Sin Low]

Ok, so the root exception is lost due to the NPE at CLogErrorBuffer. Use a try catch block in your onMessage method to get the actual exception and it should be straightforward after we know what it is.

To view this discussion on the web visit https://groups.google.com/d/msgid/idempiere/dc33145c-89e3-494b-8962-253d5dd3807f%40googlegroups.com.

[Jan Thielemann]

org.zkoss.zk.ui.UiException: You cannot access a desktop other than an event listener

at org.zkoss.zk.ui.AbstractComponent.checkDetach(AbstractComponent.java:407)

at org.zkoss.zk.ui.AbstractComponent.checkParentChild(AbstractComponent.java:1073)

at org.zkoss.zk.ui.AbstractComponent.setParent(AbstractComponent.java:966)

at org.zkoss.zul.Treeitem.setParent(Treeitem.java:419)

at org.zkoss.zk.ui.AbstractComponent.detach(AbstractComponent.java:1669)

at org.zkoss.zul.Tree.onTreeDataRemoved(Tree.java:1391)

at org.zkoss.zul.Tree.onTreeDataChange(Tree.java:1340)

at org.zkoss.zul.Tree.access$1200(Tree.java:159)

at org.zkoss.zul.Tree$2.onChange(Tree.java:1465)

at org.zkoss.zul.AbstractTreeModel.fireEvent(AbstractTreeModel.java:108)

at org.zkoss.zul.DefaultTreeNode$TreeNodeChildrenList.remove(DefaultTreeNode.java:278)

at org.zkoss.zul.DefaultTreeNode$TreeNodeChildrenList.remove(DefaultTreeNode.java:226)

at org.zkoss.zul.DefaultTreeNode.remove(DefaultTreeNode.java:185)

at org.evenos.trees.BroadcasterTreeModel.removeNodesRecursivly(BroadcasterTreeModel.java:91)

at org.evenos.trees.BroadcasterTreeModel.refresh(BroadcasterTreeModel.java:77)

at org.evenos.trees.BroadcasterTreeModel.userLoggedIn(BroadcasterTreeModel.java:446)

at org.adempiere.webui.dashboard.DPBroadcaster.onMessage(DPBroadcaster.java:193)

at org.adempiere.webui.dashboard.DPBroadcaster.onMessage(DPBroadcaster.java:1)

at org.idempiere.hazelcast.service.TopicImpl$TopicSubscriberAdapter.onMessage(TopicImpl.java:83)

at com.hazelcast.impl.ListenerManager.callListener(ListenerManager.java:419)

at com.hazelcast.impl.ListenerManager.callListeners(ListenerManager.java:334)

[Heng Sin Low]

You have to use ServerPushTemplate for that. Execute the model refresh code in the IServerPushCallback.updateUI method. For the desktop reference, I believe your dashboard gadget should have a reference to it. Also, you need to verify that the desktop is still alive ( desktop.isAlive() ).

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[Jan Thielemann]

Can you give me some additional explaination? I never heard of IServerPushCallback, neither do i know how to use or implement it.

[Nicolas Micoud]

Hi,

Have a look here, i think it is related:  https://groups.google.com/d/msg/idempiere/zAvniZgekhM/wsb1dF_yTBEJ

Nicolas

[Jan Thielemann]

Thank you guys, now it works. :)