Example app of using GrapQL. Here you can find two of most common approaches implementation of GrapQL:
- Standalone app based on GrapQL, where server has GrapQL provider and other client can communicate using schema
- Legacy app with REST interfaces proxied by GrapQL apollo server and other client app can communcate using schema

Backend (Java):
-Spring Boot with GrapQL provider
-H2 Database
Backend (Proxy apollo server using node.js)
-Apollo server

You can build your own using whatever you want and communicate using GrapQL

To communicat you can use Postman or GrapQL playground by clicking link below
https://www.graphqlbin.com/v2/new

To run backend made in SpringBoot just simply import build.gradle in IDE you are using and run "gradlew build" command to build project, then configure SpringBootApplicatio and run it

To run Apollo server proxy, run "npm install" and then "npm start" to run Apollo server :)