Designing cloud-native microservices using patterns By Jeremy Perkins From Unsplash

Who am I? Felix Coutinho @ CI&T Canada https://twitter.com/felixcoutinho https://www.linkedin.com/in/felixcoutinho/

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Design Patterns

Design patterns “A design pattern is a general repeatable solution to a commonly occurring problem in software design. A design pattern isn't a finished design that can be transformed directly into code. It is a description or template for how to solve a problem that can be used in many different situations.” - Alexander Shvets on Dive into Design Patterns

Design patterns The problem “An intersection between two roads is causing issues. People are getting injured and traffic is getting slow.”

A traffic light By Jean Carlo Emer From Unsplash The Solution #1

A roundabout By Lucas Miguel From Unsplash The Solution #2

Design patterns “A design pattern isn't a finished design that can be transformed directly into code” - Alexander Shvets on Dive into Design Patterns You need to identify the problem, understand the scenario and choose the best solution

You need to design By Scott Graham from Unplash

Cloud Native

Cloud Native Definition “Cloud-native applications are a collection of small, independent, and loosely coupled services.” https://www.redhat.com/en/topics/cloud-native-apps * Small * Independent * Loosely Coupled

“Cloud Native Is about Culture, Not Containers” Holly Cummins Innovation Leader, IBM

Microservices Design Patterns

Decomposition

Problem How to decompose an application into services?

Decompose by subdomain * Small * Loosely Coupled Solution Define services corresponding to Domain-Driven Design (DDD) subdomains.

Source Łukasz. 2018. "The nature of Domain Driven Design - what the heck is it?" Braintelligence, Accessed on May 2021

Data management

Problem What’s the database architecture in a microservices application?

Database per service * Loosely Coupled Solution Keep each microservice’s persistent data private to that service and accessible only via its API.

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A service’s transactions only involve its database.

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

(CQRS) Command Query Responsibility Segregation * Independent 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.

Source https://microservices.io/patterns/data/cqrs.html Accessed on May 2021

Code Duplication Eventual Consistency

Problem How to query data from different services without couple the services?

Materialized Views * Independent * Loosely Coupled Solution Generate, in advance, a view that materializes the data in a format suited to the required results set

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Eventual Consistency

Problem How to reliably/atomically update the database and publish messages/events?

Event sourcing / Fan-out * Independent * Loosely Coupled Solution Whenever the state of a business entity changes, a new event is appended to the list of events. When a service saves an event in the event store, it is delivered to all interested subscribers.

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Eventual Consistency

Observability

Problem How to understand the behavior of several application instances and troubleshoot the problems?

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Distributed tracing * Independent Solution Assigns each external request a unique id and includes this id in all log messages associated.

Source https://lightstep.com/distributed-tracing/ Accessed on May 2021

It costs a lot of money

Security

Problem How to communicate the identity of the requestor to the services that handle the request?

Access Token * Independent * Loosely Coupled Solution User a access token (possible JWT) that securely identifies the requestor in each request to the services.

That’s all folks

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Who am I? Felix Coutinho @ CI&T Canada https://twitter.com/felixcoutinho https://www.linkedin.com/in/felixcoutinho/

References Books Dive into Design Patterns - Alexander Shvets Microservices patterns - Chris Richardson Domain-Driven Design - Eric Evans Designing Distributed Systems - Brendan Burns Monolith to Microservices - Sam Newman Building Microservices - Sam Newman Beyond the Twelve-Factor App - Kevin Hoffman Patterns, Principles, and Practices of Domain-Driven Design - Scott Millett, Nick Tune Cloud Design Patterns - Alex Homer, John Sharp, Larry Brader, Masashi Narumoto, Trent Swanson Building Event-Driven Microservices - Adam Bellemare Links https://github.com/cncf/toc/blob/main/DEFINITION.md https://docs.microsoft.com/en-us/dotnet/architecture/cloud-native/definition https://www.redhat.com/en/topics/cloud-native-apps https://microservices.io/index.html

Bonus!

Problem How do you migrate a legacy monolithic application to a microservice architecture?

Strangler application Solution Incrementally developing a new (strangler) application around the legacy application.

Source https://microservices.io/patterns/refactoring/strangler-application.html Accessed May 2021