Hi Armela,
Well, the examples in link sent by Stefano has no DotNET variables. Everything in the Kuffmann code is in AL with no DotNet code or variables (Note that you can use DotNet in D365BC on-premise extension development ).
So, you can use JSon objects (or XML objects) with http objects in AL to send and receive data(bar code) via Web Services API.
Best Regards