Add ServiceHost extension by code

Question

I have this XML snipped of a App.config which I found here:

<?xml version="1.0"?>
<configuration>
  <system.serviceModel>
    <extensions>
      <bindingElementExtensions>
        <add name="gzipMessageEncoding" type="Microsoft.Samples.GZipEncoder.GZipMessageEncodingElement, GZipEncoder, Version=4.0.0.0, Culture=neutral, PublicKeyToken=null" />
      </bindingElementExtensions>
    </extensions>
...

For some reasons I don't want to hardcode the asembly and I don't want to use a XML file for that.

Curriently I use this code:

Uri baseAddress = new Uri("http://localhost:80/Test");
WebHttpBinding binding = new WebHttpBinding(
                                    WebHttpSecurityMode.TransportCredentialOnly);
binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Basic;
ServiceHost host = new ServiceHost(typeof(ExampleWebService), baseAddress);
host.Extensions.Add(new GZipMessageEncodingElement());

But the last line does not work how can I fix that? I think it must be possible to do that by code.

---

Curriently I found almost an solution I have just a problem when I try to use the JsonSerialisator however I use this binding now:

CustomBinding cb = new CustomBinding(binding);
MessageEncodingBindingElement inner = (MessageEncodingBindingElement)cb.Elements.ToArray()[0];
cb.Elements.RemoveAt(0);
cb.Elements.Insert(0, new GZipMessageEncodingBindingElement(inner));

The GZipMessageEncoder is a little modified to make the compression optinal:

public override ArraySegment<byte> WriteMessage(Message message, int maxMessageSize, BufferManager bufferManager, int messageOffset) {
    var req = WebOperationContext.Current.IncomingRequest;
    var encoding=req.Headers[HttpRequestHeader.AcceptEncoding]; // crash while debug
    //Use the inner encoder to encode a Message into a buffered byte array
    ArraySegment<byte> buffer = innerEncoder.WriteMessage(message, maxMessageSize, bufferManager, 0);
    if(encoding != null && encoding.ToLower().Contains("gzip")) {
        WebOperationContext.Current.OutgoingResponse.Headers[HttpResponseHeader.ContentEncoding] = "gzip";
        WebOperationContext.Current.OutgoingRequest.Headers[HttpResponseHeader.ContentEncoding] = "gzip";
        //Compress the resulting byte array
        return CompressBuffer(buffer, bufferManager, messageOffset);
    } else {
        return buffer;
    }
}

But my code let visual studio crash while debugging in the marked line. Any ideas?

Answer 1

It doesn't work this way. WebHttpBinding will never use your binding element. BindingElementExtensions in configuration file just defines new elements which can be used to define CutomBinding in the config file. If you need to do that in the code you just create a new instance of CustomBinding and fill it with binding elements you want to use (classes derived from BindingElement) - you will useGZipMessageEncodingBindingElement. The linked sample describes that code as well:

ICollection<BindingElement> bindingElements = new List<BindingElement>();
HttpTransportBindingElement httpBindingElement = new HttpTransportBindingElement();
GZipMessageEncodingBindingElement compBindingElement = new GZipMessageEncodingBindingElement ();
bindingElements.Add(compBindingElement);
bindingElements.Add(httpBindingElement);
CustomBinding binding = new CustomBinding(bindingElements);