Last November I was in Antwerp attending NAVTechDays. During the pre-conference workshops I hosted a workshop on Json & NAV.
All the exercise code, both for CAL and AL you can download here -> NAVTechDays2017-JsonMeetsNAV
We where using the Development Preview image. Try your own by following http://aka.ms/navdeveloperpreview.
It was a really good workshop, learned some good stuff – there are always 100 ways to solve a request. Thank you for your effort!