[OperationContract]
[WebInvoke(Method = "GET",
BodyStyle = WebMessageBodyStyle.WrappedRequest,
UriTemplate = "/MobileLoginUser?username={username}&password={password}")]
string MobileLoginUser(string username,string password);

HttpGet request = new HttpGet("http://something.com/MobileLoginUser?username="+params[0]+"&password="+params[1]);
    request.setHeader("Accept", "application/json");
    request.setHeader("Content-type", "application/json");
    DefaultHttpClient httpClient = new DefaultHttpClient();
    HttpResponse response = httpClient.execute(request);
    HttpEntity httpEntity = response.getEntity();
    userDetail = EntityUtils.toString(httpEntity);