adding GZIP to WCF REST service in C#

Question

I'm having trouble enabling GZIP compression on my C#.NET WCF web service and was hoping someone might know what I'm missing in my App.conf configuration file, or what extra is needed when making the call to start the web service in the code.

I've followed the link Applying GZIP Compression to WCF Services that points to the download of Microsoft example of adding GZIP but the example does not correlate with how I'm setting up my web service.

So my App.conf looks like

<?xml version="1.0"?>
<configuration>
  <system.serviceModel>
    <services>
      <service name="MyService.Service1">
        <endpoint address="http://localhost:8080/webservice" binding="webHttpBinding" contract="MyServiceContract.IService"/>
      </service>
    </services>
    <behaviors>
      <endpointBehaviors>
        <behavior>
          <webHttp />
        </behavior>
      </endpointBehaviors>
    </behaviors>
    <extensions>
      <bindingElementExtensions>
        <add name="gzipMessageEncoding" type="MyServiceHost.GZipMessageEncodingElement, MyServiceHost, Version=4.0.0.0, Culture=neutral, PublicKeyToken=null" />
      </bindingElementExtensions>
    </extensions>
    <protocolMapping>
      <add scheme="http" binding="customBinding" />
    </protocolMapping>
    <bindings>
      <customBinding>
        <binding>
          <gzipMessageEncoding innerMessageEncoding="textMessageEncoding"/>
          <httpTransport hostNameComparisonMode="StrongWildcard" manualAddressing="False" maxReceivedMessageSize="65536" authenticationScheme="Anonymous" bypassProxyOnLocal="False" realm="" useDefaultWebProxy="True"/>
        </binding>
      </customBinding>
    </bindings>
  </system.serviceModel>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
  </startup>
</configuration>

I simply copied the config and GZIP classes from the MS example into my project and added my relevent web service configs. The code I'm using to start the windows service is:

WebServiceHost webserviceHost = new WebServiceHost(typeof(MyService.Service1));
webserviceHost.Open();

The webservice runs fine but Fiddler does not detect any response coming back with GZIP compressesion when making a call from a web browser. I also tried programmatically to setup and run the webservice with GZIP but failed miserably. Being green I'm not sure what else I need to configure, any advice is greatful

I've delved deeper into this and found out that since I'm running the webservice as a WebServiceHost object that it must be overriding the custom GZIP binding in the app.conf file with the WebHTTPBinding object that WebServiceHost defaults to, which means anything coming out of the web service will not be encoded. To get around this I figured that I would programmatically write the custom GZIP binding into the code

var serviceType = typeof(Service1);
var serviceUri = new Uri("http://localhost:8080/webservice");
var webserviceHost = new WebServiceHost(serviceType, serviceUri);
CustomBinding binding = new CustomBinding(new GZipMessageEncodingBindingElement(), new HttpTransportBindingElement());
var serviceEndPoint = webserviceHost.AddServiceEndpoint(typeof(IService), binding, "endpoint");
webserviceHost.Description.Endpoints[0].Behaviors.Add(new WebHttpBehavior { HelpEnabled = true });
webserviceHost.Open();

The problem is that it won't allow a custom binding with the WebHttpBehavior. But if I remove the behavior then my REST webservice turns ugly and expects Stream objects as inputs in my contracts. I'm not sure how to configure behaviours so any help is greatful.

Answer 1

In response to your comment about GZIP not natively supported by WCF, it has been added in .Net 4.5. See here.

Answer 2

If you are using RestService and IIS (>=7.0), you will not have to do this by yourself !

IIS 7 supports dynamic compression which allows automatic compression of content created in your own applications (ASP.NET, MVC, WCF or otherwise!). The scheme is based on content-type sniffing and so it works with any kind of Web application framework.

Please find a complete tutorial here.

Answer 3

For some reason I could not get the above implementation working for self-hosted WCF REST with Json + compression, only for XML.

After looking around for a while frustrated, finally found the solution from a very recent blog below. Hope this helps anyone who is still looking for the same thing.

https://blogs.msdn.microsoft.com/carlosfigueira/2016/02/23/using-automatic-format-selection-with-a-compression-encoder-in-self-hosted-scenarios/

Answer 4

So Here's the programmatic solution I've come up with after spending days on this. Note that I do not know how to configure the solution in the app.config file but only through code. Firstly follow this Link to obtain and fix the GZIP classes in Microsoft's coding samples. Then use the below example code as a basis for configuring your own web service.

//Some class class to start up the REST web service
public class someClass(){
    public static void runRESTWebservice(){
        webserviceHost = new WebServiceHost(typeof(Service1), new Uri("http://localhost:8080));
        webserviceHost.AddServiceEndpoint(typeof(IService), getBinding(), "webservice").Behaviors.Add(new WebHttpBehavior());
        webserviceHost.Description.Behaviors.Add(new ServiceMetadataBehavior { HttpGetEnabled = true });
    }

    //produces a custom web service binding mapped to the obtained gzip classes
    private static Binding getBinding(){
        CustomBinding customBinding = new CustomBinding(new WebHttpBinding());
        for (int i = 0; i < customBinding.Elements.Count; i++)
        {
            if (customBinding.Elements[i] is WebMessageEncodingBindingElement)
            {
                WebMessageEncodingBindingElement webBE = (WebMessageEncodingBindingElement)customBinding.Elements[i];
                webBE.ContentTypeMapper = new MyMapper();
                customBinding.Elements[i] = new GZipMessageEncodingBindingElement(webBE);
            }
            else if (customBinding.Elements[i] is TransportBindingElement)
            {
                ((TransportBindingElement)customBinding.Elements[i]).MaxReceivedMessageSize = int.MaxValue;
            }
        }
        return customBinding;
    }
}

//mapper class to match json responses
public class MyMapper : WebContentTypeMapper{
    public override WebContentFormat GetMessageFormatForContentType(string contentType){
        return WebContentFormat.Json;
    }
}

//Define a service contract interface plus methods that returns JSON responses
[ServiceContract]
public interface IService{
    [WebGet(UriTemplate = "somedata", ResponseFormat = WebMessageFormat.Json)]
    string getSomeData();
}

//In your class that implements the contract explicitly set the encoding of the response in the methods you implement
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]
public class Service1 : IService
{
    public string getSomeData()
    {
        WebOperationContext.Current.OutgoingResponse.Headers[HttpResponseHeader.ContentEncoding] = "gzip";
        return "some data";
    }
}

I worked most this out by following this link.

Note: It somewhat baffles me how Microsoft haven't built GZIP natively into WCF being such an essential part of any REST webservice returning large sets of data.