Pattern: API Composition

Want to learn more about this pattern?

Take a look at my self-paced, online bootcamp that teaches you how to use the Saga, API Composition, and CQRS patterns to design operations that span multiple services.

The regular price is $395/person but use coupon YXEERWTJ to sign up for $195 (valid until May 26th, 2022)

Context

You have applied the Microservices architecture pattern and the Database per service pattern. As a result, it is no longer straightforward to implement queries that join data from multiple services.

Problem

How to implement queries in a microservice architecture?

Solution

Implement a query by defining an API Composer, which invoking the services that own the data and performs an in-memory join of the results.

Example

An API Gateway often does API composition.

Resulting context

This pattern has the following benefits:

  • It a simple way to query data in a microservice architecture

This pattern has the following drawbacks:

  • Some queries would result in inefficient, in-memory joins of large datasets.

See also

Learn more

  • My book Microservices patterns describes this pattern in a lot more detail
  • Take a look at my self-paced, online bootcamp that teaches you how to use the Saga, API Composition, and CQRS patterns to design operations that span multiple services.

About Microservices.io

Microservices.io is brought to you by Chris Richardson. Experienced software architect, author of POJOs in Action, the creator of the original CloudFoundry.com, and the author of Microservices patterns.

Chris helps clients around the world adopt the microservice architecture through consulting engagements, and training classes and workshops.

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New virtual bootcamp: Distributed data patterns in a microservice architecture

My virtual bootcamp, distributed data patterns in a microservice architecture, is now open for enrollment!

It covers the key distributed data management patterns including Saga, API Composition, and CQRS.

It consists of video lectures, code labs, and a weekly ask-me-anything video conference repeated in multiple timezones.

The regular price is $395/person but use coupon YXEERWTJ to sign up for $195 (valid until May 26th, 2022). There are deeper discounts for buying multiple seats.

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