Using GraphQL and REST Together

Use GraphQL and REST for for different purposes at different layers of the stack

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If you're looking for more material on this topic, watch Dan Boerner's keynote at API Summit 2023: GraphQL and REST: true BFFs.

It's common to hear GraphQL and REST pitted against each other as competing technologies. While these technologies overlap, most organizations adopting GraphQL use both for different purposes and at different layers of the stack.

This page outlines:

Approaches organizations typically take
Where GraphQL best fits into the architectural toolbox
How it can help drive a resilient API strategy

Traditional N-tier architecture

In a traditional N-tier architecture, at least three layers comprise the stack: Presentation, Application, and Data. Each of these has a distinct purpose:

The Presentation layer is where customers interact with products, experiences, and API marketplaces.
The Application layer is where services and business logic live and through which Presentation apps access data.
The Data layer stores data about your company, customers, products, etc.

However, friction between the Presentation and Application layers can prevent organizations from getting products and data into customers' hands.

From the Application layer perspective:

"Our job is to expose everything we know, all the data we have access to, and all the capabilities we must deliver in the most efficient, most performant, least opinionated way we can. How clients consume, aggregate, orchestrate, and enrich what we provide via API endpoints isn't our job. Remember, separation of concerns!"

From the Presentation side, the thinking is different:

"We're frustrated that the APIs we access either require too much aggregation or orchestration or don't provide what we need, are too slow, that there's too many of them, and they are always changing without notice!"

Change is constant in both the Presentation and the Application layers. There are always new clients, new data access and product requirements, new data, new services, new business logic, and other changes.

API strategy goals

Setting high-level goals should be part of deciding your organization's API strategy. Common goals include:

Offering rapid self-service
Creating an insulating contract
Magnifying existing investments
Governing the middle layer

Offering rapid self-service

A key goal of any API strategy should be to enable API consumers. That means having as little friction as possible for consumers onboarding onto your API. The more a consumer can self-serve, the better.

Creating an insulating contract

Your API strategy should shield API consumers from the complexities of backend services. Conversely, the strategy should insulate the impact of upstream client changes on downstream services.

The contract, the interface over which your API consumers communicate with your API, should act as an abstraction.

Magnifying existing investments

Any API investment should positively impact its current and future use cases.

Governing the middle layer

An API should have a defined stewardship and governance model, including appropriate stakeholders.

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Approaches to growing complexity

Organizations frequently use a client-managed or Backend for Frontend (BFF) approach to handle complexity between Presentation and Application layers. These approaches can have limitations in achieving the goals of a resilient API strategy.

Client-managed

In a client-managed approach, each app talks directly to each backend service, creating a multitude of connections and dependencies.

Analysis

Many API strategies start as client-managed, but this strategy can quickly get out of control. Every client is on their own, leading to inconsistencies and maintainability issues.

Problems

No separation of concerns
"Thick" clients and inconsistent UX
Logic is thrown away on every client rewrite
Not rapid or self-service
Not an insulating contract
Doesn't magnify existing investments
No governance

Backend for Frontend APIs (BFFs)

In a Backend for Frontend (BFF) approach, each app has a dedicated API that they own called a BFF. This BFF is specific to the app, is maintained by the app team, and is responsible for the data orchestration needs of that app.

Analysis

BFFs can offer a viable solution for addressing certain issues associated with the client-managed approach. The BFF approach lets consumers aggregate data from many backend APIs. However, as your organization adds more and more clients, this approach can also grow out of control. This can especially become an issue for organizations using micro-frontends. Maintainability and governance can become increasingly challenging.

Problems

Number of BFFs can expand to the point that it becomes impossible to manage them
Doesn't magnify existing investments
While an API Gateway can provide some governance of BFFs, it still doesn't provide much governance of data retrieval

ⓘ NOTE

You may still need a BFF in addition to GraphQL for "Utility" endpoints specific to your application. In this case, you could use a passthrough pattern to direct data fetching and mutations through your BFF to your GraphQL layer.

Using GraphQL

When using GraphQL, all apps talk to a common GraphQL middle layer that then orchestrates the calls to downstream data services.

This middle layer translates the needs of the Presentation layer to the Application layer. By its nature, GraphQL is self-serve. A GraphQL schema acts as an insulating contract, and all investments are magnified since all consumers benefit from all investments. It is highly governable since a single endpoint exposes all data with declarative policies.

Rapid self-service

✅ GraphQL enables rapid self-service for Presentation layer clients by replacing one-off handwritten BFF APIs with declarative queries.

Queries are on-demand definitions of only what the Presentation layer needs, regardless of the data source. Each frontend use case (and each micro-frontend if you use them) defines a declarative query to fetch precisely the data it needs in a single request.

GraphQL enables demand-driven API creation without creating new endpoints. Every client sends requests to the same endpoint to be executed by a query planner and distributed efficiently to the underlying Application and Data layers.

Creating an insulating contract

✅ GraphQL provides an insulating contract between Presentation and Application layers that is flexible enough to manage constant change while stable enough to prevent breaking changes.

The most stable portion of any enterprise data model is the fundamental objects that drive the business—for example, Customers, Orders, or Products. These objects endure, even as the underlying data storage and service models that define them are rebuilt.

Modernization means that every part of a stack has a fixed lifetime, and that lifetime shortens every year. The answer is to model these entities in a declarative layer that is not embedded in code and can survive and evolve.

Magnifying investments

✅ GraphQL goes beyond preserving the value of our existing APIs to magnifying investments through federation and its ability to connect and compose independent APIs.

GraphQL provides an abstraction layer that allows organizations to add new data entities and fields over time without directly impacting the consuming clients. API clients can navigate across APIs without awareness that they're retrieving data from different teams, different APIs potentially written in different languages, with different API protocols, etc.

All investments in the graph pay dividends because they provide value to both current and potential future clients.

Governance

✅ GraphQL provides a declarative control plane as the crucial middle layer of your architecture.

GraphQL enables organizations to centralize all core domain entities into a unified layer, catering to custom queries from clients without the need for individualized endpoints. This is great for governance since it gives organizations a single, static location to define their entire API surface area instead of managing hundreds of endpoints.

Conclusion

GraphQL is not in competition with REST. Rather, it is best suited as a new layer in the stack with a different purpose—to bridge the gap between the Presentation and Application layers.

GraphQL enables organizations to drive a resilient API strategy that provides governance and ownership while reducing friction and allowing API consumers to increase their velocity through self-service.

To use GraphQL and REST together:

✅ Use REST for backend data services
✅ Use GraphQL as a middle layer which aggregates data from your backend data services
✅ Use GraphQL to abstract away the implementation details of your backend services

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