I presented this at Boston Code Camp 2018.
You can view the slides here: https://docs.google.com/presentation/d/1G3ASMkwMfU_BDvfnCnJU1VgbBmZtoTKruLUpfCQqun8/edit?usp=sharing
patwritescode/graphql-for-legacy-meetup
Building a GraphQL Server in front of legacy services
TypeScript