[OperationContract]
    [WebInvoke(UriTemplate = "PlaceQuestion",
        RequestFormat = WebMessageFormat.Json,
        ResponseFormat = WebMessageFormat.Json,
        Method = "POST",
        BodyStyle = WebMessageBodyStyle.Bare)]
    string PlaceQuestion(Questions question);

<httpProtocol>
     <customHeaders>
        <add name="Access-Control-Allow-Origin" value="*"/>
     </customHeaders>
</httpProtocol>

var json = JSON.stringify({
        Type : 0,
        Question: "testing"
    });

    var url = 'http://localhost:49753/RestServiceImpl.svc/PlaceQuestion';

    var params = 'json=' + json;
    var headers = new Headers();
    headers.append('Content-Type', 'application/json');

    return this._http.post(url, params, {
        headers: headers
    })
    .map(res => res.json());