Architecture Patterns with Python: Enabling Test-Driven Development, Domain-Driven Design, and Event-Driven Microservices

As Python continues to grow in popularity, projects are becoming larger and more complex. Many Python developers are taking an interest in high-level software design patterns such as hexagonal/clean architecture, event-driven architecture, and the strategic patterns prescribed by domain-driven design (DDD). But translating those patterns into Python isn't always straightforward.

With this hands-on guide, Harry Percival and Bob Gregory from MADE.com introduce proven architectural design patterns to help Python developers manage application complexity-and get the most value out of their test suites.

Each pattern is illustrated with concrete examples in beautiful, idiomatic Python, avoiding some of the verbosity of Java and C# syntax. Patterns include:

• Dependency inversion and its links to ports and adapters (hexagonal/clean architecture)
• Domain-driven design's distinction between Entities, Value Objects, and Aggregates
• Repository and Unit of Work patterns for persistent storage
• Events, commands, and the message bus
• Command-query responsibility segregation (CQRS)
• Event-driven architecture and reactive microservices

After an idyllic childhood spent playing with BASIC on French 8-bit computers like the Thomson T-07 whose keys go "boop" when you press them, Harry Percival spent a few years being deeply unhappy as a management consultant. Soon he rediscovered his true geek nature, and was lucky enough to fall in with a bunch of XP fanatics, working on the pioneering but sadly defunct Resolver One spreadsheet. He worked at PythonAnywhere LLP, spreading the gospel of TDD world-wide at talks, workshops and conferences. He is now with MADE.COM.

Bob Gregory is a UK-based software architect with MADE.COM. He has been building event driven systems with domain-driven design for more than a decade.