Dotnetnuke WebService with jquery Post - ajax

Question

I am developing a dotnetnuke module and have lots of issues connecting to a webservice through javascript to retrieve data.
I have the folloiwng javascript:
function Test() {
$.ajax({
type: "POST",
url: 'http://localhost/DNN11/service1.asmx/TestMethod',
data: "{'data':'" + "abc" + "'}",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function(msg) {
alert("success");
},
error: function(e) {
alert("error");
}
});
}
Then the following WebMethod in my webservice
[WebMethod]
public string TestMethod(String data)
{
return "Hello World";
}
However when the post is not being called successfully, I am not able to get through my webservice. It keeps giving me a 500 Internal Server error page.
What could be wrong please? Is there any other way I need to go about this?
Thanks
[Edit]
This is the entire code
<script type="text/javascript">
function Test() {
$.ajax({
type: "POST",
url: '<%=ResolveUrl("~/DesktopModules/ModuleTest/WebService1.asmx/TestMethod")%>',
data: '{ data: "test" }',
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function(msg) {
alert("Success: " + msg);
},
error: function(msg) {
alert("Failed: " + msg.status + ": " + msg.statusText);
}
});
}
</script>
<div>
<input type="button" value="Load" onclick="Test(); return false;" />
</div>
[System.Web.Script.Services.ScriptService]
public class WebService1 : System.Web.Services.WebService
{
[WebMethod]
[ScriptMethod()]
public string TestMethod(string data)
{
return "Hello World";
}
}
I have tried putting the Webservice in the DotNetNuke folder in a new folder and both in the local project.. I also put the ScriptMethod() Tag in the WebService which allows scripts to call it.. but still nothing

Answer 1

Looks like your problem is the cross domain calls. In case if your page hosted on the same server with the web service, your code should be fine. If you need to interact with the service from another domains you have to use jsonp requests. Look at this good step-by-step guide with the code example here.
UPDATE
In case if everything on the same app try to use relevant URL. Instead of url: '<%=ResolveUrl("~/DesktopModules/ModuleTest/WebService1.asmx/TestMethod")%>' try to url: '/DesktopModules/ModuleTest/WebService1.asmx/TestMethod'.

Answer 2

In order to post to a DNN webservice from the page you're going to have to pass in the Context of the module. I have some sample code that works against DNN6 at
http://slidepresentation.codeplex.com/SourceControl/changeset/view/69709#1181962
Mainly the
servicesFramework: $.ServicesFramework(<%=ModuleContext.ModuleId %>)
line
I haven't tested that against DNN7 though with the latest service framework WebAPI changes.