wcf - the content type 'application/json; charset=utf-8' was not the expected type 'text/xml; charset=utf-8'

Question

When using firebug, I got this wired error "NetworkError: 415 Cannot process the ...xt/xml; charset=utf-8'. - http://localhost:59899/wsccc1/wscccService.svc/RunTts" in my asp.net mvc 4 project.

The code:

<script lang="javascript" type="text/javascript">
    function ttsFunction() {
        serviceUrl = "http://localhost:59899/wsccc1/wscccService.svc/RunTts";
        var data = new Object();
        data.text = $('#speak').val();
        var jsonString = JSON.stringify(data);
        $.ajax({
            type: 'POST',
            url: serviceUrl,
            data: jsonString,
            contentType: 'application/json; charset=utf-8',
            dataType: 'json',
            success: function() { alert('ok')},
            error: function (xhr,status,error) {
                console.log("Status: " + status);
                console.log("Error: " + error);
                console.log("xhr: " + xhr.readyState);
            },
            statusCode: {
                404: function() {
                    console.log('page not found');
                }
            }
        });
    }
</script>

The service code:

 [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
[ServiceBehavior(IncludeExceptionDetailInFaults = true)]
public class wservice:Iwservice
{
    public string RunTts(string value)
    {
        return value.ToUpper();
    }
}

The interface is:

namespace service
{
     [ServiceContract]
     public interface Iwservice
     {
        [OperationContract]
        [WebInvoke(Method = "POST", RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Wrapped, UriTemplate = "RunTts")]
        string RunTts(string text);
     }
}

And web config, I used file-less in WCF.:

<?xml version="1.0"?>
<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.5"/>
    <httpRuntime targetFramework="4.5"/>
  </system.web>
  <system.serviceModel>
    <serviceHostingEnvironment >
       <serviceActivations>
         <add factory="System.ServiceModel.Activation.ServiceHostFactory" 
     relativeAddress="./wsccc1/wscccService.svc" 
     service="service.wservice"/>
      </serviceActivations>
    </serviceHostingEnvironment>
   <behaviors>
     <serviceBehaviors>
        <behavior>
          <serviceMetadata httpGetEnabled="true"/>
        </behavior>
     </serviceBehaviors>
   </behaviors>
  </system.serviceModel>
</configuration> 

Answer 1

You need to use the WebServiceHostFactory, instead of the regular ServiceHostFactory in your code. That will configure the endpoint with the appropriate binding (webHttpBinding) and behavior (webHttp) to honor the [WebInvoke] attribute.

<serviceHostingEnvironment >
   <serviceActivations>
     <add factory="System.ServiceModel.Activation.WebServiceHostFactory"
          relativeAddress="./wsccc1/wscccService.svc" 
          service="service.wservice"/>
  </serviceActivations>
</serviceHostingEnvironment>