Question

I have a WCF Service which returns a string. I am trying to call it using a cross domain JsonP request. This is working in IE but no other browser. I get a parser error back in Firefox and Chrome.

From reading through various articles i seem to think that maybe the service needs to be returning the result back as a different format. Any ideas would be helpful, here is my code.

WCF Service Code

[OperationContract]
[WebGet(ResponseFormat = WebMessageFormat.Json, RequestFormat = WebMessageFormat.Json)]
public string SponsorLayout2(string projectScope, int projectYear, int imageHeight)
{
   // Mock data
   projectScope = "uk";
   projectYear = 2012;
   imageHeight = 42;

   // Get projectId
   var project = Projects.GetProjectByProjectScopeAndYear(projectScope, projectYear);

   // Get project sponsor layouts
   var projectSponsorLayout = ProjectSponsorLayouts.GetProjectSponsorLayout(project.Id, imageHeight);

   // Return the sponsors
   if (projectSponsorLayout != null)
      return projectSponsorLayout.Body;

      return null;

}

Jquery Ajax Call

$.ajax({
cache: false,
type: "GET",
async: false,
data: {},
url: "http://127.0.0.1:8082/HtmlService.svc/SponsorLayout2",
contentType: "application/json; charset=utf-8",
dataType: "jsonp",
crossDomain: true,          
success: function (data) {  
    alert("success");       
},
error: function (xhr) {
          alert("error");
    alert(xhr.statusText);
},
complete: function(jqXHR, textStatus) {     
          alert(textStatus); 
      } 
});

Answer 1

I found out why I was getting the problem stated above and thought I would share this with you.
For some reason there was a conflict between this attribute

[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]

which sits on top of my class

public class MyClass

and this rule in my web.config file

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

I have ended up commenting the rule out in my web.config and everything come to life. Because my service is an AJAX ready service, the attribute is added above the class out of the box. Anyway this worked for me and hope it helps anyone else in the same situation.