Sampe WCF Rest Service , Along with accessing CROSS Domain Service, also access JSON request by Javascript and also in Dynamics CRM

Most of us would have faced the problem of "Access Denied" or "Transport Error" while accessing cross domain calls from CRM.

I have a small example here with a sample WCF service along with JSONP Query below to fetch the data from Cross Domain Service


Create a Sample WCF Application by selecting the "WCF Service Application" template from Projects as shown below.

We are just creating a sample method which takes bookid as parameter and returns the same. Use the following code to create an interface and class method.

///Interface which has the method GetBookByID

namespace WcfRestSample

{
    [ServiceContract]
    [System.Web.Script.Services.ScriptService]
    public interface IBookService
    {
        [OperationContract]
        [WebInvoke(Method="GET",ResponseFormat=WebMessageFormat.Json,BodyStyle=WebMessageBodyStyle.Wrapped,UriTemplate  = "Book/{id}")]

        Book GetBookById(string id);

    }
}


If you observe the attributes "WebMessageFormat.Json" specifies that the response format from the service shall be JSON and we also provided the rest format like "Book/{id}"  to call the service.


We have a class implementing the service which provides the implementation of the method

 Please make the following changes in the config file to make it Rest based JSON Service

 If you observe keenly there are two major things you need to consider , one to enable the service as RestBased Service you need to set Binding as "webHttpBinding" and the other crossDomainScriptAccessEnabled="true" , this makes the service accessible for cross domain request as well.


Now your service is ready. Let us see how client calls the same using $.getJSON and the other way by using original javascript to read a JSON request. No difference if called in Dynamics CRM or through a normal ASP.Net page


There are two ways to consume the service from Javascript using JSONP

Method 1: $.getJSON to read a JSONP request

 If you observe above code it just uses the URL as it is and at the end of the URL you have "callback=parseRequest" which will call back the method by that name and returns the result.

Method 2 original JavaScript to read a JSONP request

Refer to the following link in MSDN for more details