Microservices - also known as the microservice architecture - is an architectural style that structures an application as a collection of services that are:
The microservice architecture enables an organization to deliver large, complex applications rapidly, frequently, reliably and sustainably - a necessity for competing and winning in today’s world.
Let’s look at why its important to deliver software rapidly, frequently, reliably and sustainably.
In order to thrive in today’s volatile, uncertain, complex and ambiguous world, businesses must be nimble, agile and innovate faster. Moreover, since modern businesses are powered by software, IT must deliver that software rapidly, frequently and reliably - as measured by the DORA metrics.
Rapid, frequent, reliable and sustainable delivery requires the success triangle, a combination of three things:
Teams work independently most of the time to produce a stream of small, frequent changes that are tested by an automated deployment pipeline and deployed into production.
Let’s now look at when you typically need to use microservices in order to have a loosely coupled, testable and deployable architecture.
Let’s imagine that you responsible for a business critical business application that has a monolithic architecture and you are struggling to meet the needs of the business. Should you consider migrating to a microservice architecture? The short answer is that it depends.
It’s important to make the most of your monolithic architecture, e.g. adopt DevOps, and reorganize into loosely coupled, small teams.
In many cases, once you have embraced the success triangle, your monolithic architecture is sufficiently loosely coupled, testable and deployable to enable rapid software delivery.
But sometimes an application can outgrow its monolithic architecture and become an obstacle to rapid, frequent and reliable software delivery. This typically happens when the application becomes large and complex and is developed by many teams. For example, its deployment pipeline become a bottleneck. When this occurs, you should consider migrating to microservices.
My presentation Considering Migrating a Monolith to Microservices? A Dark Energy, Dark Matter Perspective describes how to decide whether to migrate to microservices.
If you have decided to migrate to microservices then the next step is to design a target architecture.
Picking technologies - Kubernetes, message broker etc - is important
But what’s critically important is designing a good service architecture: identifying services; defining their responsibilities; their APIs and collaborations. If you get it wrong you risk creating a distributed monolith, which will slow down software delivery.
What’s more, designing the service architecture is challenging because it’s a creative activity - not something you can buy, download or read in a manual.
Assemblage is an architecture definition process that you can can use to define your microservice architecture. It distills your requirements into system operations and subdomains; uses the dark energy and dark matter forces to group the subdomains into services; and designs the distributed system operations.
Assemblage works in conjunction with the Microservice architecture pattern language, which is your guide when designing a technical architecture
After defining a target microservice architecture you then need to refactor your existing monolith.
There are numerous principles for migrating a monolithic application to microservices.
One key principle is to incrementally migrate to microservices using the Stranger Fig pattern - no big bang rewrite. By using this pattern, you rapidly validate your design decisions and deliver new, useful functionality much earlier.
It’s also important to avoid the Microservices adoption antipatterns.
Take a look at the resources for adopting the microservice architecture
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
Application architecture patterns
Refactoring to microservicesnew
Cross cutting concerns
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.
Got a specific microservice architecture-related question? For example:
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Take a look at my Manning LiveProject that teaches you how to develop a service template and microservice chassis.
Chris offers numerous resources for learning the microservice architecture.
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.
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Engage Chris to create a microservices adoption roadmap and help you define your microservice architecture,
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.
Engage Chris to conduct an architectural assessment.