Limitation of Federation

Introduction

Netflix became popular for its streaming services by reaching out to a large number of users. They scaled their services to accommodate this growth. Dealing with the increasing complexity of data and its relationships was a challenge in the past. According to the Netflix TechBlog 2020, the Netflix API team found the Apollo Federation specification as the ideal way to scale their GraphQL architecture. In this model, the individual GraphQL schemas (tables) tend to become subgraphs (flowchart-like things) which are composed into a unified supergraph (bigger chart). In this way, they also retained their integrated “Consumer Edge” API which is actually how businesses get to know their consumer behavior. As a result, they could provide faster delivery without compromising the customers usability experience. They do not have any official documentation about their API use but the developers get to access the data about movie reviews, ratings etc from their (Netflix) data catalog....

History

They launched their public API on October 1st 2008, they had a blog, code samples from developers etc. They also developed applications on their API like InstaWatcher, WhichFlicks etc. Earlier Netflix app used a different graph-API technology called Falcor. In 2012, GraphQL did not exist so Falcor was used both have similar concepts but by 2020, GraphQL was way more popular so the latter is used. They use federation in their API. It can be explained as a way of breaking the API into pieces that can be further developed independently, as it tends to handle a single domain. By July of 2019, Netflix started building a GraphQL gateway based on Apollo’s reference implementation. They used Kotlin (used for Java) to get access to their Java ecosystem for efficient fetching etc. This federation has resulted in explosive growth over the years....

GraphQL and Federation

GraphQL is an open-source query language and server-side runtime which is built around the concept of “get exactly what you asked for” without any under or over fetching of data. For example, consider GraphQL as the grocery list for our API. We just need to specify what data we need and the server (grocer) delivers just that. It is considered as a successor to REST APIs. GraphQL makes it easier to gather data from multiple sources and uses a type system to describe data (rather than multiple endpoints)....

How Netflix Scales its API with GraphQL?

It starts by breaking your API apart it into chunks that can be developed independently, as a single domain usually. They are usually implemented by domain experts. Then a graph-aware gateway, which is a central junction in this architecture, ties them together into a single API. But it doesn’t contain any business logic. It tends to follow a declarative configuration that tells it which data comes from which service. This is the federation used for scaling. There are usually three components in a federated architecture, namely, graph services, schema registry and graph gateway. The graph services consists of GraphQL servers only. They display only a portion of their overall schema and publish it via schema registry. This registry mainly holds schemas for all of the services. And the gateway usually takes single query from client and breaks it into sub queries that later executed against the servers. They tend to process the request in two ways, query planning and execution. Query plan looks through the client request and collects the related fields for each service. Query plan execution traverses through the entire query plan starting from root node in either parallel or in sequence and merges the overall response....

Limitation of Federation

Only Apollo Gateway is a ready-to-use, self-hosted federation gateway implementation; the rest are still under development and not fully functional. It has limited support for custom directives (instructions within GraphQL to increase functionality). a. No built-in mechanism for federated directives. b. Per-service directives, if any, get removed by the gateway. c. Workarounds (or temporary solutions) exist but-unsupported. Service Startup: “Hello World” scenario assumes services are already running when the gateway starts which is not considered ideal for disaster management. It has type naming conflicts like the term “Service” which is commonly used by tooling can not be used for anything else. It does not support subscriptions currently....

Conclusion

In conclusion, Netflix’s adoption of GraphQL and the Apollo Federation specification for its API architecture has been instrumental in scaling its services to reach a large user base. By breaking down the API into smaller, independent services and using a central gateway to compose them into a unified graph, Netflix has achieved faster delivery without compromising user experience. It has some limitations, GraphQL and Federation have enabled Netflix to handle the growing complexity of data and its relationships, ensuring the continued success of its streaming services....