Call external site webmethod using jsonp?

Question

I'm trying to call external site webmethod, and post some data. I tried a lot of different ways and still cannot get the method to be called.

Here is my js code:

$.ajax({
            url: "http://sitename.com/methods.aspx/mywebmethod",
            data: "{'id':'" + 4 + "'}",
            dataType: "jsonp",
            type: "GET",
            contentType: "application/json; charset=utf-8",
            success: function (data) {
                alert(data);
            },
            error: function (XMLHttpRequest, textStatus, errorThrown) {
                alert(errorThrown);
            }
        });

Here is my webmethod code:

[WebMethod()]
        public static bool mywebmethod(int id)
        {
if(id != 0){
            return true;}
else{return false;}
        }

and I always get the same response

Error: jQuery{code} was not called

What I'm missing?

Answer 1

JSONP is not magic.

You can only use JSONP to read data from a URL that returns JSONP script.
ASP.Net WebMethods do not support JSONP.

Answer 2

I guess you're missing the proper attributes, as following (in an .asmx definition):

    [WebMethod(EnableSession = true)] // optional, but usually forgotten
    [ScriptMethod(UseHttpGet = true, ResponseFormat = ResponseFormat.Json)]
    public bool MyMethod(int id)
    {
        return true;
    }

plus, you need to have Content-rewrite module for handling the leading callback parameter as well:

http://www.codeproject.com/Articles/43038/Accessing-Remote-ASP-NET-Web-Services-Using-JSONP