[getDataFnc,length] = delegateTo(provider,delegate,URI)sets up adelegateContentProviderto provide all or part of the subsequent data in aRequestMessage. 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 thecomplete,expectedContentLength, andstartmethods in thedelegate. 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 forgetData. You can use any value oflength, but normally you make this call in yourgetDatamethod, passing the same value that was passed to your method.

To delegate to a provider that provides the entire contents of a message, calldelegateToin yourstartmethod. If you use the delegate to obtain part of the message content, then calldelegateToat the appropriate time in yourputDatamethod.

To obtain data from the delegate, always use the returnedgetDataFnc. Do not call the delegate'sgetDatadirectly because the delegate might provide its data through some other means.

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