Composition

This packages implements federation composition for GraphQL and static router configuration generation.

Composition

Use Federate to produce a federated subgraph from a set of subgraphs:

package main

import (
	"fmt"
	"log"

	"github.com/wundergraph/cosmo/composition-go"
)

func main() {
	federated, err := composition.Federate(&composition.Subgraph{
		Name: "A",
		Schema: `type Query {
			query: Nested @shareable
		  }

		  type Nested @shareable {
			nest: Nested2
		  }

		  type Nested2 @shareable {
			nest: Nested3
		  }

		  type Nested3 @shareable {
			nest: Nested4
		  }

		  type Nested4 {
			name: String
		  }`,
	}, &composition.Subgraph{
		Name: "B",
		Schema: `type Query {
			query: Nested @shareable
		  }

		  type Nested @shareable {
			nest: Nested2
		  }

		  type Nested2 @shareable {
			nest: Nested3
		  }

		  type Nested3 @shareable {
			nest: Nested4
		  }

		  type Nested4 {
			age: Int
		  }`,
	})
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(federated.SDL)
}

Router configuration generation

Use BuildRouterConfiguration to produce generate a static data source configuration for the router:

package main

import (
	"fmt"
	"log"

	"github.com/wundergraph/cosmo/composition-go"
)

func main() {
	config, err := composition.BuildRouterConfiguration(&composition.Subgraph{
		Name: "A",
		Schema: `type Query {
			query: Nested @shareable
		  }

		  type Nested @shareable {
			nest: Nested2
		  }

		  type Nested2 @shareable {
			nest: Nested3
		  }

		  type Nested3 @shareable {
			nest: Nested4
		  }

		  type Nested4 {
			name: String
		  }`,
	}, &composition.Subgraph{
		Name: "B",
		Schema: `type Query {
			query: Nested @shareable
		  }

		  type Nested @shareable {
			nest: Nested2
		  }

		  type Nested2 @shareable {
			nest: Nested3
		  }

		  type Nested3 @shareable {
			nest: Nested4
		  }

		  type Nested4 {
			age: Int
		  }`,
	})
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(config)
}

Contributing

The composition-go library uses code from composition and shared, which is bundled into index.global.js. To keep this code up to date, run go generate within this package.

Performance considerations

By default, this package uses the goja runtime to run the composition algorithm. This has no dependencies and supports all platforms, but depending on your inputs it can be too slow.

For better performance, a V8 backend is also available using the wg_composition_v8 build tag, which is ~50x times faster. This uses the V8 JS engine to run the algorithm, but it increases the binary size and doesn't work on Windows, so it's not enabled by default. To enable it, use go build -tags wg_composition_v8 when compiling.