Explore microservices in-depth and understand when to use them.

Scalability & System Design for Developers

In this module, we’ll explore microservices in depth and understand when to use them. Beyond that, learn about micro and macro architecture, strategies for migrating old systems, the role of Docker in this architecture, and technologies for implementing microservices.

An Introduction to Microservice Principles and Concepts

# Combining approaches to migration
- The ideas concerning typical migration strategies from the lesson on [typical migration strategies](https://www.educative.io/courses/introduction-microservice-principles-concepts/typical-migration-strategies) fit very well to the
concept of **self-contained systems (SCS)**. The migration can therefore simply separate a part of the legacy system
into an SCS.

* Rules for authentication or communication between microservices as well as between microservices and the legacy system can be the starting point of a **macro architecture** (see
[chapter 3](https://www.educative.io/courses/introduction-microservice-principles-concepts/introduction-qAj0kkomoNk)). A domain macro architecture is
very useful, which can also include the legacy system in addition to
microservices.

* **Frontend integration** can make sense for the integration between the legacy system and microservices.

* **Asynchronous microservices** fit very well with migration because they allow for a loose coupling. Especially for a migration, it can be sensible to continue to use an existing messaging technology for asynchronous communication to
minimize the effort.

* **Synchronous microservices** should
be used cautiously because this creates a tight coupling and resilience becomes difficult.
  
* **Kubernetes, PaaS, or Docker** are also interesting in a migration scenario. However, they represent a *new environment* that needs to be operated. It may, therefore, make sense to use a classical deployment and operation environment at least at the beginning to reduce the initial migration effort. In the long term, however, such environments have many
advantages. In addition, of course, the old system can be operated
in such an environment.


The ideas for migration can easily combine with many other approaches. Let's study a few.

Variations

Combining approaches to migration