GraphQL is a language. If we teach GraphQL to a software application, that application will be able to declaratively communicate any data requirements to a backend data service that also speaks GraphQL.

Just like a child can learn a new language fast, while a grown-up will have a harder time picking it up, starting a new application from scratch using GraphQL will be a lot easier than introducing GraphQL to a mature application.

To teach a data service to speak GraphQL, we need to implement a runtime layer and expose it to the clients who want to communicate with the service. Think of this layer on the server side as simply a translator of the GraphQL language, or a GraphQL-speaking agent who represents the data service.

This layer, which can be written in any language, defines a generic graph-based schema to publish the capabilities of the data service it represents. Client applications who speak GraphQL can query the schema within its capabilities. This approach decouples clients from servers and allows both of them to evolve and scale independently.ecoders graphql