Calling simple web service (.asmx file) from AJAX and JQuery using JSON - parse error

Question

Hi all,
Making my first steps in trying to use all these technologies together.. I'm having some toubles..
Here is my Server side:

[WebMethod(EnableSession = true)]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public string simplestMethod()
{
  return "Simplest method returned";
}

And here is my client side:

 $(document).ready(function(){
   $("a").click(function(event){     
      $.ajax({
      type: "POST",
      url: "http://localhost:53346/d2/TAPI.asmx/simplestMethod",
      data: "{}",
      contentType: "application/json; charset=utf-8",
      dataType: "json",
      success: function (data) {
       alert(data.d);
      },
      error: function (XMLHttpRequest, textStatus, errorThrown) {
       alert("Error Occured!" +" | " + XMLHttpRequest +" | " + textStatus +" | " + 
       errorThrown );
      }
   });
  });
 });

The result is an alert that says:
Error Occured! | [object XMLHttpRequest] | parseerror | undefined.
What parsing failed and why?
I should mention that calling the WS method directly does work.
Thanks a lot!

Answer 1

Your code looks like good with one suspected place: url. You should replace url to something like "TAPI.asmx/simplestMethod" or "/d2/TAPI.asmx/simplestMethod".

Moreover if you want study to how to call web method with parameters or return more complex data from the web method look at http://stackoverflow.com/questions/2737525/how-do-i-build-a-json-object-to-send-to-an-ajax-webservice/2738086#2738086 and http://stackoverflow.com/questions/3445859/asmx-web-service-json-javascript-jquery/3446517#3446517, http://stackoverflow.com/questions/2670147/can-i-return-json-from-an-asmx-web-service-if-the-contenttype-is-not-json/2671583#2671583. How to decode error messages from the exception inside of web method see http://stackoverflow.com/questions/3635133/get-xhr-object-in-vb-net-while-ajax-calling-fails/3644248#3644248.