I have created a **SharePoint Hosted App** and wanted to get response from some external `webservice`.

I am able to get the response in SharePoint Hosted App's `default.aspx` but says **FORBIDDEN** when it is executed from **ClientWebPart** !!

for code reference - https://msdn.microsoft.com/en-us/library/office/fp179895.aspx.
I used exactly the same code and tried with `JSOM` and `REST` both, but no hope.
I am getting the same error with `Northwind.svc` also.