WCF compressing JSON response

Question

I have a WCF web service based on JSON and POST method which have a function called website returning a JSON with more 2KB content. This service has more than 10K requests per second. So, I have lots of textual data to be passed via network and I/O. I think I can reduce this volume of data by compressing the response automatically. I know that by setting a header in client side for accepting zipped content, the client can notify the server that compressed content is acceptable. But how the server can send compressed content?

I have read this link, and implement it. But it works only for SOAP which is xml-based, not JSON. I mean that this configuration:

<customBinding>
  <binding name="BinaryCompressionBinding"> 
    <binaryMessageEncoding compressionFormat="GZip"/> 
    <httpTransport /> 
  </binding>
</customBinding> 

can not work with JSON because we have to use binaryMessageEncoding, where as JSON needs webMessageEncoding and it does not support compressionFormat.

Also, IIS dynamic compression can not help me too. I have added markup it needs to compress JSON.

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Update: This is my applicationhost.config:

<httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files" minFileSizeForComp="0"> <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" /> <dynamicTypes> <add mimeType="application/json" enabled="true" /> <add mimeType="application/json; charset=utf-8" enabled="true" /> </dynamicTypes> </httpCompression>

Answer 1

As an alternative and more control , you can manually compress your responses with c# code within a Message Inspector.

For WebApi I did something similar using delegating handler. You can wrap my code into a Message Inspector for WCF i think.

Compress WebApi Response using delegating handler

Message Inspectors

Or to use IIS level compression add

<add mimeType="application/json; charset=utf-8" enabled="true" />

On your applicationhost.config. See about json compression enabled mime type here

---

Update: With special thanks to @AnestisKivranoglou, I have successfully implemented a gzip compression for Json responses of WCF. To make the answer of @AnestisKivranoglou more accurate, I want to add some details to his answer.

You have to change the AfterReceiveRequest and BeforeSendReply of Message Inspector like bellow:

object IDispatchMessageInspector.AfterReceiveRequest(ref Message request, System.ServiceModel.IClientChannel channel, System.ServiceModel.InstanceContext instanceContext)
        {
            try
            {
                var prop = request.Properties[HttpRequestMessageProperty.Name] as HttpRequestMessageProperty;
                var accept = prop.Headers[HttpRequestHeader.AcceptEncoding];

                if (!string.IsNullOrEmpty(accept) && accept.Contains("gzip"))
                {
                    var item = new DoCompressExtension();
                    OperationContext.Current.Extensions.Add(item);
                }
            }
            catch { }

            return null;
        }


void IDispatchMessageInspector.BeforeSendReply(ref Message reply, object correlationState)
        {
            if (OperationContext.Current.Extensions.OfType<DoCompressExtension>().Count() > 0)
            {
                HttpResponseMessageProperty httpResponseProperty = new HttpResponseMessageProperty();
                httpResponseProperty.Headers.Add(HttpResponseHeader.ContentEncoding, "gzip");
                reply.Properties[HttpResponseMessageProperty.Name] = httpResponseProperty;                                
            }            
        }

These 2 snippet of codes let you know whether the client can accept gzip or not! So, you implemented a behaviorExtensions that can capture a request before reply and after receive. Now you need to implement a bindingElementExtensions using this link. Note that you have to fix the GZip problem using this link. Finally it remains a small number of changes listed bellow:

1. Add an item to ApplyConfiguration function:

case "webMessageEncoding":binding.innerBindingElement = new WebMessageEncodingBindingElement();break;

2. Change custom binding from innerMessageEncoding="textMessageEncoding" to innerMessageEncoding="webMessageEncoding".

If nothing was missed, you can check and call the service using Post method and Json an receive compressed responses if you add Accept-Encoding:gzip, deflate to your request's header. If you dont add this header you'll receive normal responses which is not compressed.