Apollo Federation concepts in GraphQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Apollo Federation in GraphQL?

Apollo Federation is a way to combine multiple GraphQL services into one unified graph, allowing teams to build and maintain parts of the graph independently.

beginner

What is a @key directive in Apollo Federation?

The @key directive marks a field or set of fields as the unique identifier for an entity in a subgraph, so it can be referenced and resolved across services.

intermediate

Explain the role of the @extends directive in Apollo Federation.

The @extends directive is used to indicate that a type or field is extending an entity defined in another subgraph, allowing services to add fields to shared types.

intermediate

What does the @external directive do in Apollo Federation?

The @external directive marks a field as owned by another subgraph, so the current subgraph can reference it but does not provide its value.

beginner

How does Apollo Gateway work in Apollo Federation?

Apollo Gateway acts as a single entry point that composes the subgraphs' schemas into one federated schema and routes incoming queries to the appropriate subgraphs.

What is the purpose of the @key directive in Apollo Federation?

A To define query resolvers

B To extend types from other subgraphs

C To mark fields as owned externally

D To mark fields as unique identifiers for entities

The @key directive identifies the unique fields that represent an entity across subgraphs.

Which component composes multiple subgraphs into a single schema in Apollo Federation?

A Apollo Server

B GraphQL Client

C Apollo Gateway

D Apollo Studio

Apollo Gateway combines subgraphs into one federated schema and routes queries.

What does the @external directive indicate?

A Field is owned by another subgraph

B Field is a unique key

C Field is deprecated

D Field is a query root

The @external directive marks fields that belong to other subgraphs.

How do subgraphs share and extend types in Apollo Federation?

A Using <code>@extends</code> directive

B Using <code>@key</code> directive

C Using <code>@external</code> directive

D Using <code>@deprecated</code> directive

The @extends directive allows subgraphs to add fields to types defined elsewhere.

What is the main benefit of Apollo Federation?

A Caches all queries on the client

B Enables multiple teams to build parts of a graph independently

C Automatically generates database schemas

D Replaces REST APIs completely

Apollo Federation allows independent teams to develop and deploy parts of a unified graph.

Describe how Apollo Federation allows multiple GraphQL services to work together as one.

Think about how different teams can build parts and how they connect.

Explain the roles of the @key, @extends, and @external directives in Apollo Federation.

Focus on how these directives help share and extend types.