Apollo Federation allows you to orchestrate different GraphQL services into a single GraphQL gateway. In this playlist, we'll introduce you to the core concepts of Apollo Federation to get you started by improving an example app for Snowtooth Mountain. 

The lift ops team has created a Lift service that provides lift status reporting for skiers and the ability to change the lift status for ski patrollers. The mountain ops team has created their own service to report on Trail status. These are completely separate GraphQL APIs, and we'll turn them into federated APIs that work under one gateway.

Apollo Federation allows you to orchestrate different GraphQL services into a single GraphQL gateway. In this video, we'll take a closer look at how different services run at different endpoints and how the gateway brings these federated services together. 

WTF is Apollo Federation?

In order to implement Apollo Federation, you must make your GraphQL APIs federated services. A federated service can communicate with the Apollo Gateway and extend other federated services. In this lesson, we will convert two regular GraphQL APIs into Apollo federated services.

Set Up Apollo Federated Services

Federated services can be orchestrated behind a Gateway API. The Gateway is a single API that clients can use to access data from any of the federated services. In this lesson, we will create an Apollo Gateway that orchestrates the lift and trail services which will allow us to query both lifts and trails from a single endpoint.

Create an Apollo Gateway

Entities are types that can be extended and resolved by external federated services. This allows for a separation of concerns among our federated services. This means that one service can extend the types that are owned by a completely separate service.

Extend an External Entity with Apollo Federation

Federated services can also resolve external entities using references. When a service resolves an external entity, it only needs to return a reference to that entity. These references are resolved by the service that defined the entity with a special resolver called `__resolveReference`.

Getting Started with Apollo Federation

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