// *** Service Calling Proxy Class
function serviceProxy(serviceUrl) {
    var _I = this;
    this.serviceUrl = serviceUrl;

    // *** Call a wrapped object
    this.invoke = function(method, data, callback, callbackparms, error, errorparms, bare) {
        // *** Convert input data into JSON - REQUIRES Json2.js
        var json = JSON2.stringify(data);

        // *** The service endpoint URL
        var url = _I.serviceUrl + method;

        $.ajax({
            url: url,
            data: json,
            type: "POST",
            processData: false,
            contentType: "application/json; charset=utf-8",
            timeout: 10000,
            dataType: "text",  // not "json" we'll parse
            success:
                function(res) {
                    if (!callback) return;

                    // *** Use json library so we can fix up MS AJAX dates
                    var result = JSON2.parse(res);

                    // *** Bare message IS result
                    if (bare)
                    { callback(callbackparms, result); return; }

                    // *** Wrapped message contains top level object node
                    // *** strip it off
                    for (var property in result) {
                        callback(callbackparms, result[property]);
                        break;
                    }
                },
            error:
                function(xhr) {
                    if (!error) return;

                    if (xhr.responseText) {
                        var err = JSON2.parse(xhr.responseText);

                        if (err)
                            error(errorparms, err);
                        else
                            error(errorparms, { Message: "Unknown server error." })
                    }

                    return;
                }
        });
    }
}
// *** Create a static instance
// var Proxy = new serviceProxy("JsonService.svc/");