gtkatakura / schema-stitching-handbook

Guided examples exploring GraphQL Tools v6+ Schema Stitching

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Schema Stitching Handbook

Guided examples of Schema Stitching doing awesome things. Focuses on the new (GraphQL Tools v6+) stitching using type merging, not legacy Apollo Stitching.

Table of Contents

Foundation

  • Combining local and remote schemas

    • Adding a locally-executable schema.
    • Adding a remote schema, fetched via introspection.
    • Adding a remote schema, fetched from a custom SDL service.
    • Avoiding schema conflicts using transforms.
    • Authorization headers.
    • Basic error handling.
  • Mutations & subscriptions

    • Adding a remote mutation service.
    • Adding a remote subscription service.
    • Adding a subscriber proxy.
  • Single-record type merging

    • Type merging using single-record queries.
    • Query/execution batching.
  • Array-batched type merging

    • Type merging using array queries.
    • Handling array errors.
    • Nullability & error remapping.
  • Nullable merges

    • Selecting nullability for merged fields.
    • Returning nullable and not-nullable results.
  • Cross-service interfaces

    • Distributing a GraphQL interface across services.
  • Merged types with multiple keys

    • Configuring multiple key access for a merged type.
  • Computed fields

    • Configuring computed fields.
    • Sending complex inputs to subservices.
    • Normalizing subservice deprecations in the gateway.
  • Stitching directives SDL

    • @key directive for type-level selection sets.
    • @merge directive for type merging services.
    • @computed directive for computed fields.
    • @canonical directive for preferred element definitions.

Architecture

  • Hot schema reloading

    • Hot reload of the combined gateway schema (no server restart).
    • Polling for remote subschema changes.
    • Mutations for adding/removing remote subservices.
    • Handling subservice request timeouts.
  • Versioning schema releases

    • Using GitHub API to manage a simple schema registry.
    • Hot reloading from a remote Git registry.
    • Running development and production environments.
  • Continuous Integration (CI) testing

    • Adding test coverage to a stitched schema.
    • Mocking subservices as local test fixtures.
  • Public and private APIs

    • Filtering unwanted fields from the final stitched schema.
    • Serving public (filtered) and private (unfiltered) API versions.

Other Integrations

  • Federation services

    • Integrating Apollo Federation services into a stitched schema.
    • Fetching and parsing Federation SDLs.
  • Subservice languages

    • JavaScript schemas created with:

      • graphql-js
      • nexus
      • type-graphql
    • Ruby schemas created with:

      • Class-based definitions
      • Parsed definitions string

Appendices

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Guided examples exploring GraphQL Tools v6+ Schema Stitching

License:MIT License


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