This talk will examine principles that assist with successfully evolving from a monolith to Microservices. Deciding what to decouple along with when and how to incrementally evolve a system are the main architectural challenges in this process. It is important to commit to "stop adding to the monolith" - all new code is added as microservices; the "Strangler Pattern". The new features are microservices, occasionally replacing part of the monolith. Also, when writing new microservices code, it is important to avoid dependencies to the monolith.

Target Audience: English, Developers, Architects, QAs, Testers
Prerequisites: Basic Understanding of architecture and microservices and familiarity with domain modeling
Level: Advanced

Extended Abstract:
Being Agile, with its attention to extensive testing, frequent integration, and focusing on important product features, has proven invaluable to many software teams. When building complex systems, focus on features provides a lot of value and starting with a monolith architecture can be advantageous. However, over time, although you might be committed to keeping the code clean, and having lots of tests — the architecture can become harder to evolve. Ultimately technical debt and design problems will creep in until it becomes muddy, making it hard to deliver new features quickly and reliably. Also, evolving the system quickly can become harder. If things are changing quickly with lots of teams, evolving using the microservices architectural style can have many possible benefits.

Many Microservices architectures start from the evolution of a Monolith system by gradually applying the microservices architectural style. There are considerations and principles that assist with successfully evolving from a monolith to Microservices. Deciding what to decouple along with when and how to incrementally evolve a system are the main architectural challenges in this process. There are good principles that help with this evolutionary process. For example, it is important to commit to "stop adding to the monolith" - all new code is added as microservices. This is the core of the "Strangler Pattern". The new features are microservices, occasionally replacing part of the monolith. Also, there might be important pieces of the monolith that are getting hard to maintain and you want to pull these out. When this happens, you find design seams within the monolith, refactoring these out to components, that can ultimately be replaced with microservices. Early on, it is ok to create macro services first and then evolve (refactor) them to microservices. Also, when writing new microservices code, it is important to avoid dependencies to the monolith. Finally, you can use DDD modeling to identify aggregates and bounded contexts to pull them out from the monolith. This talk will examine various patterns when evolving from the monolith to microservices specifically with variations of the Strangler Pattern.