Passing data from the adapter to the client as an object

eweinberg

Hi All,

I’m slowly making progress using lightstreamer but I have only been able to pass data from the adapter to the client in the form of a string.
For ex:

...
//somewhere in the DataAdapter
Map jmsData = (Map)objectMessage.getObject(); //get a Map from a JMS queue. 

//SomeObject is some complex Object 
SomeObject data = jmsData.get(“data”);

Map sendToClient = new HashMap();
sendToClient.put(“name”, data.getName());
sentToClient.put(“age”, Integer.toStrign(data.getAge());

itemEventListener.smartUpdate(itemHandle, sendToClient, false);
…

Is there a way to pass a representation of SomeObject to the client maybe using JSON, or am I limited to just Strings?

Dario Crivelli

Lightstreamer requires that data is split into distinct fields, so that the Server can easily distinguish changing fields, to be transmitted, from unchanged fields, not to be transmitted.
If your objects have a complex structure and you can't represent them as a collection of fields, then you can sacrifice transmission efficiency and serialize your objects in whichever way into a single String field. However, deserialization must be performed by custom code on the client side (JSON helps this very much).
This can be done by using a NonVisualTable and implementing the "onItemUpdate" event handler so as to get the data, deserialize it and manage any display actions (and indeed I suppose that, with complex objects, our support for VisualTables made up of push cells would also not be useful).

eweinberg

Thanks for the info. I didn't realize that there was a check to see if the fields needed to be updated. I just wanted to verify that the server makes the check. If a change isn't found, the info doesn't get sent by lightstreamer. If that's the case, it might not be worth sending a string representation of the object. i can just break my the objects down into Strings in the Data Adapter.

leduchieu02

@eweinberg, Wrote: Thanks for the info. I didn't realize that there was a check to see if the fields needed to be updated. I just wanted to verify that the server makes the check. If a change isn't found, the info doesn't