delegateTo

[getDataFnc,length] = delegateTo(provider,delegate,URI) sets up a delegate ContentProvider to provide all or part of the subsequent data in a RequestMessage. This method initializes properties in the delegate using properties of this object and supplied parameters, as if a new message was about to be transmitted using that delegate, and invokes the complete, expectedContentLength, and start methods in the delegate. It returns a handle to a function, getDataFnc, that you invoke to obtain data from the delegate:

[data, stop] = getDataFcn(length)

where the arguments are as described for getData. You can use any value of length, but normally you make this call in your getData method, passing the same value that was passed to your method.

To delegate to a provider that provides the entire contents of a message, call delegateTo in your start method. If you use the delegate to obtain part of the message content, then call delegateTo at the appropriate time in your putData method.

To obtain data from the delegate, always use the returned getDataFnc. Do not call the delegate's getData directly because the delegate might provide its data through some other means.

[getDataFnc,length] = delegateTo(___,force) indicates if the expectedContentLength method should return the length of the data.