Strange Error on item update

[mnenchev]

Hi,

i began to get this strange error:

ER onItemUpdate exception
this.LS_QfY.LS_WPo is undefined

Where this seems to be property from my schema, but i do not have such in it(i can see what are the schema properties from the ls console).
I am getting the exception from here :
var msg = itemUpdate.getNewValue(schema[i]);
It seems that schema[i] is undefined, but why?
I noticed that this only happens when i change my schema and call restart :

private native void restart(JavaScriptObject nvt, NonVisualGWTClient thiz, JavaScriptObject page, JavaScriptObject map, String [] schema) /*-{
																															nvt.setDataAdapter(map['adapter_name']);
																															nvt.setSnapshotRequired(false);
																															
																															this.@com.trinitas.ls.client.NonVisualGWTClient::nvt.onItemUpdate = function(item, itemUpdate, itemName) {
																																	for (i=0;i<=schema.length;i++) {
																																				var msg = itemUpdate.getNewValue(schema[i]);
																																				if (msg !=null) {
																																					thiz.@com.trinitas.ls.client.NonVisualGWTClient::onMessage(Ljava/lang/String;Ljava/lang/String;)(msg, schema[i]);
																																				}
																																	}
																															}
																															
																															page.addTable(nvt,"tnvt");
																															}-*/;

But right before i call restart i printed the schema and it is exactly as it should be. So where does this LS_QfY.LS_WPo come from?

And one other thing: before now i used the following:

var msg=itemUpdate.getNewValue(schema[i]);																																			if(msg!=null){																																					    onMessage(Ljava/lang/String;Ljava/lang/String;)(msg, schema[i]);
}

Now i removed this if (msg != null) and i began to receive null messages, but i never send null message. Why is that?Why ls sends null Strings?

[DarioCrivelli]

The error seems not related with your schema variable, but with library internal structures; therefore it looks like a bug.
On the other hand, unexpected values on [I]schema could explain null values returned by getNewValue.

Can you replicate the issue?
In that case, may you please check schema[i] before invoking getNewValue and compare it with the outcome from getNewValue?
Does replicating the issue involve any previous removal of the involved table object?

[DarioCrivelli]

I see that I didn't refresh the forum thread page before answering and I didn't see your latest changes.
Are you using a library for embedding the browser in a native application?
In this case, we cannot ensure that our javascript library works properly.
May you please provide us with more information on your scenario?

[mnenchev]

Hi,

well since last week every thing worked perfectly. I didn't do any thing connected with the ls code.
I inject the js from ls in my GWT application and use native calls to it:
I needed dynamically to subscribe/unsubscribe from items and dynamically to change the schema:
Here is simple code:

	private native void restart(JavaScriptObject nvt, NonVisualGWTClient thiz, JavaScriptObject page, JavaScriptObject map, String [] schema) /*-{
																															nvt.setDataAdapter(map['adapter_name']);
																															nvt.setSnapshotRequired(false);
																															
																															this.@ls.client.NonVisualGWTClient::nvt.onItemUpdate = function(item, itemUpdate, itemName) {
																																	for (i=0;i<=schema.length;i++) {
																																	            
																																				var msg = itemUpdate.getNewValue(schema[i]);
																																				if (msg !=null) {
																																					thiz.@ls.client.NonVisualGWTClient::onMessage(Ljava/lang/String;Ljava/lang/String;)(msg, schema[i]);
																																				}																																				
																																	}
																															}
																															
																															page.addTable(nvt,"tnvt");
																															}-*/;

// abstract method 
protected abstract void onMessage(String message, String schemaId);

As you can see i have abstract onMessage method that is implemented in the derived class and implements the logic for the received message.
When i want to change my schema or group i create new NVT and call restart.

I am not sure i understand what you mean by "embeding the browser in a native application"
I have web app that is compiled to js and i inject
<script src="ls/lscommons.js"></script>
<script src="ls/lspushpage.js"></script>
It may bo compared to HTML + JS app.

[DarioCrivelli]

Ok, sorry, I was misled by the wrong formatting of your code snippets (by the way, do you see them as expected?).

I see that you iterate on schema from 0 to schema.length;
the last call is redundant and may account for some null you see coming from getNewValue.
Could it even account for the exception? Unfortunately, I couldn't manage to replicate that.

So, for now, it seems that there is a bug in the library.
We need all available information on the error context.

• Does it happen immediately after you call restart?
• If you issue removeTable("tnvt") before calling restart, does it still happen?
• Could you test itemUpdate.LS_QfY.LS_WPo before calling itemUpdate.getNewValue and see if you can find it undefined before the exception is thrown?

[mnenchev]

Hi,

Sorry for my delay.
No, the formating is bad, maybe it is my mistake...
Thanks, i really missed this "=". I don't get this LS_QfY.LS_WPo is undefined now.
But i am still receiving null messages from lightstreamer. And one other thing. I need to send command like messages to the client. For example: The server sends notification that the client must request (do) something. I use text format for the the command like messages (every command has unique id). But if i send one command two times only the first one is executed because i use MERGE type(i also stream market prices). So i changed it to RAW, in order to send all messages. But the result is the same. I can see from the ls console that every command message is received but not every one is sent to the client.