Let say I have a business object with 20 properties. I create a store with JsonReader and 5 fields mapped to 5 of those 20 properties. Then I hook up a GridPanel with 5 columns to that store. I bind a generic list of those business objects to the store. When the page renders, I see all 20 properties for each object are sent to the client. Is there a way to only send the data specified in the store?

Also, is there a way to have the grid load the data on demand instead of rendering it onto the page? For example, when the page loads, the grid or store calls a webservice to load the data. I am guessing I have to use a different proxy for the store?