Question

I have a WCF service which has one method returning a stream.

[ServiceContract]
public interface IService1
{
    [OperationContract]
    MyMessage Test();
}

Now, MyMessage is defined like this:

[MessageContract]
public class MyMessage
{
    public MyMessage(string file)
    {
        this.Stream = File.OpenRead(file);
        this.Length = Stream.Length;
    }

    [MessageHeader]
    public long Length;

    [MessageBodyMember]
    public Stream Stream;
}

Peachy.

The service has a streamed response, using basicHttpBinding. This is the binding configuration:

  <basicHttpBinding>
    <binding name="BasicStreaming"
             maxReceivedMessageSize="67108864" maxBufferSize="65536" transferMode="StreamedResponse" />
  </basicHttpBinding>

Now this is where things start to get interesting. When calling this service, the last byte is lost if i read the stream in a particular way. Here is the code illustrating the two different approaches:

        Service1Client client = new Service1Client();

        //this way the last byte is lost
        Stream stream1;
        var length = client.Test(out stream1);
        var buffer1 = new byte[length];
        stream1.Read(buffer1, 0, (int)length);
        File.WriteAllBytes("test1.txt", buffer1);
        stream1.Close();

        //here i receive all bytes
        Stream stream2;
        length = client.Test(out stream2);
        var buffer2 = new byte[length];
        int c = 0, b;
        while ((b = stream2.ReadByte()) != -1)
        {
            buffer2[c++] = (byte)b;
        }
        File.WriteAllBytes("test2.txt", buffer2);
        stream2.Close();

I am sure I’m missing something, but can anyone point out to me exactly why this is happening? The biggest problem is that in another service, whichever way i read the stream, i lose the last byte, but maybe by identifying the problem here I can solve that one too.

Technical details:

• IIS 7.0
• .NET 3.5
• Basic HTTP Binding
• Streamed response mode

Note: I have uploaded the project isolating the problem, so anyone can try it out: mediafire

Answer 1

I don’t have an exact answer as to why this works (my brain isn’t fully engaged at the moment), however this DOES work:

var buffer1 = new byte[length+2];
stream1.Read(buffer1, 0, buffer1.Length);

(and, yes, you end up with a buffer that’s too large. It’s just a starting point for further thinking)

In testing I found +1 isn’t large enough, but +2 is.