Microservice Architecture

Supported by Kong
pattern   service collaboration   implementing queries  

Pattern: Command Query Responsibility Segregation (CQRS)

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 KGBJMRAM to sign up for $195 (valid until March 8th, 2023)

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. Also, if you have applied the Event sourcing pattern then the data is no longer easily queried.

Problem

How to implement a query that retrieves data from multiple services in a microservice architecture?

Solution

Define a view database, which is a read-only replica that is designed to support that query. The application keeps the replica up to data by subscribing to Domain events published by the service that own the data.

Examples

Resulting context

This pattern has the following benefits:

  • Supports multiple denormalized views that are scalable and performant
  • Improved separation of concerns = simpler command and query models
  • Necessary in an event sourced architecture

This pattern has the following drawbacks:

  • Increased complexity
  • Potential code duplication
  • Replication lag/eventually consistent views

See also

  • Eventuate, which is a platform for developing transactional business applications.

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.
pattern   service collaboration   implementing queries  
Copyright © 2023 Chris Richardson • All rights reserved • Supported by Kong.

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 workshops.

Remote consulting session

Got a specific microservice architecture-related question? For example:

  • Wondering whether your organization should adopt microservices?
  • Want to know how to migrate your monolith to microservices?
  • Facing a tricky microservice architecture design problem?

Consider signing up for a two hour, highly focussed, consulting session.

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 KGBJMRAM to sign up for $195 (valid until March 8th, 2023). There are deeper discounts for buying multiple seats.

Learn how to create a service template and microservice chassis

Take a look at my Manning LiveProject that teaches you how to develop a service template and microservice chassis.

Learn more

Signup for the newsletter


LEARN about microservices

Chris offers numerous resources for learning the microservice architecture.

Training classes

Chris teaches comprehensive workshops, training classes and bootcamps for executives, architects and developers to help your organization use microservices effectively.

Avoid the pitfalls of adopting microservices and learn essential topics, such as service decomposition and design and how to refactor a monolith to microservices.

Delivered in-person and remotely.

Get the book: Microservices Patterns

Read Chris Richardson's book:

Example microservices applications

Want to see an example? Check out Chris Richardson's example applications. See code

BUILD microservices

Ready to start using the microservice architecture?

Consulting services

Engage Chris to create a microservices adoption roadmap and help you define your microservice architecture,

The Eventuate platform

Use the Eventuate.io platform to tackle distributed data management challenges in your microservices architecture.

Eventuate is Chris's latest startup. It makes it easy to use the Saga pattern to manage transactions and the CQRS pattern to implement queries.

ASSESS your architecture

Assess your application's microservice architecture and identify what needs to be improved.

Consulting services

Engage Chris to conduct an architectural assessment.

Join the microservices google group

Topics

Note: tagging is work-in-process

anti-patterns   ·  application api   ·  application architecture   ·  architecting   ·  architecture documentation   ·  assemblage   ·  dark energy and dark matter   ·  deployment   ·  design-time coupling   ·  development   ·  devops   ·  docker   ·  glossary   ·  hexagonal architecture   ·  implementing commands   ·  implementing queries   ·  inter-service communication   ·  loose coupling   ·  microservice architecture   ·  microservice chassis   ·  microservices adoption   ·  microservicesio updates   ·  multi-architecture docker images   ·  observability   ·  pattern   ·  refactoring to microservices   ·  resilience   ·  sagas   ·  security   ·  service api   ·  service collaboration   ·  service design   ·  service discovery   ·  service granularity   ·  service template   ·  software delivery metrics   ·  success triangle   ·  team topologies   ·  transaction management   ·  transactional messaging

All content

The patterns