Question

I’m working on creating a WCF web service that communicates via JSON. I got the service to a point that it’s working and I’m trying to set up the help page so the developers that will consume the service can have some documentation to work by.

The issue that I’m running into is that when I did get the help page up and running, all the responses being sent out by my service changed from JSON to XML.

I’ll be the first to admit that I’m very new to this. There might be some fundamental flaw with how I’ve structured my service, or it might be as simple as a flag I missed in the web.config… I’m really at a loss at this point.

What I found, through basically just trial and error and beating my head against the wall, was if I change the name attribute of the following line in the Web.config:

<standardEndpoint name="serviceEndpoint" helpEnabled="true" automaticFormatSelectionEnabled="true">

To be empty string:

<standardEndpoint name="" helpEnabled="true" automaticFormatSelectionEnabled="true">

The help page magically shows up, but my services are now spitting out XML instead of JSON.

I think it’s probably better to over-share than to under-share for something as specific as this, so here’s what I think is the relevant bits of the set-up. I apologize for the mono-tone code, I can edit it to be more readable if I figure out how.

Service Interface:

[OperationContract]
[Description("DESCRIPTIONATION HAPPENS")]
[WebInvoke(Method = "GET",
                RequestFormat = WebMessageFormat.Json,
                ResponseFormat = WebMessageFormat.Json,
                UriTemplate = "GetYears")]
GetYearsReply GetYears();
...

Service Implementation:

[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class MPG : IMPG
{
    public GetYearsReply GetYears()
    {
        GetYearsReply reply = new GetYearsReply();
        reply.YearList = generateYears();
        return reply;
    }
...

Global.asax:

<%@ Application Codebehind="Global.asax.cs" Inherits="MPG_Service.Global" Language="C#" %>

Global.asax.cs:

namespace MPG_Service
{
    public class Global : System.Web.HttpApplication
    {
        void Application_Start(object sender, EventArgs e)
        {
            RegisterRoutes();

        }

        private void RegisterRoutes()
        {
            RouteTable.Routes.Add(new ServiceRoute("garage", new WebServiceHostFactory(), typeof(MPG)));
        }
    }
}

Web.config:

<?xml version="1.0"?>
<configuration>

    <system.web>
        <compilation debug="true" targetFramework="4.0" />
    </system.web>

    <system.webServer>
        <modules runAllManagedModulesForAllRequests="true">
            <add name="UrlRoutingModule" type="System.Web.Routing.UrlRoutingModule, System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
        </modules>
    </system.webServer>

    <system.serviceModel>

        <behaviors>
            <serviceBehaviors>
                <behavior>
                    <serviceMetadata httpGetEnabled="true"/>
                    <serviceDebug includeExceptionDetailInFaults="false"/>
                </behavior>
            </serviceBehaviors>
        </behaviors>

        <serviceHostingEnvironment multipleSiteBindingsEnabled="true" aspNetCompatibilityEnabled="true" />

        <standardEndpoints>
            <webHttpEndpoint>
                <!-- 
                    Configure the WCF REST service base address via the global.asax.cs file and the default endpoint 
                    via the attributes on the <standardEndpoint> element below
                -->
                <standardEndpoint name="serviceEndpoint" helpEnabled="true" automaticFormatSelectionEnabled="true">
                    <!--<security mode="Transport">
                        <transport clientCredentialType="None"/>
                    </security>-->
                </standardEndpoint>
            </webHttpEndpoint>
        </standardEndpoints>  

    </system.serviceModel>

</configuration>

If anyone has any insight into why this behavior is happening, or any other major screw-ups in my code I’d love any input.

Answer 1

Your client is saying that it accepts XML (application/xml), so that’s what WCF is returning. That is consistent with the Automatic Formatting rules (see details at http://msdn.microsoft.com/en-us/library/ee476510.aspx). If you don’t want that behavior, then set autoFormatSelectionEnabled to false in your configuration.