streamSocket.InputStream.AsStreamForRead() vs new DataReader(streamSocket.InputStream)/LoadAsync()

I'm using a StreamSocket in my WP8.1 (xaml) app and when reading data it sometimes returns 0.

my code looks like this:

var stream = _streamSocket.InputStream.AsStreamForRead(BufferSize);
var buffer = new byte[BufferSize];
while (true)
{
    var readCount = await stream.ReadAsync(buffer, 0, buffer.Length).ConfigureAwait(false);
    if (readCount <= 0)
        throw new InvalidOperationException("No data to read in socket stream"); <---- error happens here
        
    // process data and stop when marker in data is reached
}

my app sends a request to an http like server then expects to receive a response in the code above.

my question is: why does this happen ?

I recently switch from DataReader to standard .Net streams (using AsStreamForRead) and before the switch I wasn't getting this kind of error.



code before looked like this:

using (var dataReader = new DataReader(socket.InputStream))
{
    dataReader.InputStreamOptions = InputStreamOptions.Partial;
    await dataReader.LoadAsync(BufferSize).AsTask().ConfigureAwait(false);
    // read as much as dataReader.UnconsumedBufferLength bytes....    
    dataReader.DetachStream();
}

can it happen that Stream.ReadAsync() doesn't wait for data to come in the socket

while DataReader/LoadAsync() does ?