Webservice callback handler

Question

Hello everybody,
I am trying to figure out how to implement a callback listener or handler. The thing is that I can talk to a webservice but I am supposed to get something back. The reply might get back to me in unknown ammount of time and sometimes without me initiating the conversation. So I should be able to listen to the webservice at any given time.
My understanding of this is that my callback listener should be more like a webservice where I can accept calls any time. I am not sure if I am understanding this correctly, can anybody help me with the first step :)

Answer 1

Upon further research, the problem is the Namespace. It seems
that you cannot use a namespace prefix in the labelField attribute
of a mx:ComboBox. I was able to get the label set correctly in the
combo by using a labelFunction instead of setting the labelField:
private function getMarketBasketName(data:Object):String {
return data.mb::Name;
My Webservice event handler callback now looks like this:
private function
handleMarketBasketsResult(event:ResultEvent):void {
mbCombo.dataProvider = event.result.mb::MarketBasket;
Note that "mb" is now defined (scoped) as a module Namespace
variable since I'm using it in multiple functions. Also, I do not
set any labelField property of the combo since I've defined a
labelFunction of "getMarketBasketName".
I've also noted a similar phenomenon with binding a DataGrid
to an XML type that contains a Namespace. To get values to appear
in the columns, I've had to write labelFunctions for every column.
Yuk!!! There may be a way to do this with a single function if you
follow a convention or do something with string replacement but....
Unless someone posts an alternative technique, the lesson I
have learned is always convert an XML data type to an object (using
manual or automated serialization) and bind the data controls to
that object (or array of objects) instead of directly to the XML.
It will save the headaches of writing all these little functions to
deal with namespaces.