REST Service only with NW DevStudio

Hello

all blog and demos of consuming an REST Service are using the NW DevStudio. Is it not possible to use the new REST Adapter in PI if I only implement it direct at the Enterprise Service Builder?

I I tried to implement an scenario like PI REST Adapter - Consuming synchronous RESTful service, but I can't use a wsdl or something like this to create an External Definition or it's not possible to import the DataTypes from a JSON Response like https://maps.googleapis.com/maps/api/geocode/json?address=stuttgart. Maybe somebody knows the answer.

regards

Joerg