syncron-oss / federation-jvm

JVM support for Apollo federation

Apollo Federation on the JVM

Packages published to our bintray repository and available in jcenter; release notes in RELEASE_NOTES.md.

An example of graphql-spring-boot microservice is available in spring-example.

Getting started

Dependency management

Make sure JCenter is among your repositories:

repositories {
    jcenter()
}

Add a dependency to graphql-java-support:

dependencies {
    implementation 'com.apollographql.federation:federation-graphql-java-support:0.2.0'
}

graphql-java schema transformation

graphql-java-support produces a graphql.schema.GraphQLSchema by transforming your existing schema in accordance to the federation specification. It follows the Builder pattern.

Start with com.apollographql.federation.graphqljava.Federation.transform(…), which can receive either:

• A GraphQLSchema;
• A TypeDefinitionRegistry, optionally with a RuntimeWiring;
• A String, Reader, or File declaring the schema using the Schema Definition Language, optionally with a RuntimeWiring;

and returns a SchemaTransformer.

If your schema does not contain any types annotated with the @key directive, nothing else is required. You can build a transformed GraphQLSchema with SchemaTransformer#build(), and confirm it exposes query { _schema { sdl } }.

Otherwise, all types annotated with @key will be part of the _Entity union type, and reachable through query { _entities(representations: [Any!]!) { … } }. Before calling SchemaTransformer#build(), you will also need to provide:

• A TypeResolver for _Entity using SchemaTransformer#resolveEntityType(TypeResolver);
• A DataFetcher or DataFetcherFactory for _entities using SchemaTransformer#fetchEntities(DataFetcher|DataFetcherFactory).

A minimal but complete example is available in InventorySchemaProvider.