We explored the Microservice Adapter pattern that allows us to connect two elements of a system by adapting one to the other. We explored how to push information from an event broker into an existing system that does not support such capabilities. We also explored how to leverage an adapter to break tight coupling, migrate features into a newer system, and decommission a legacy application seamlessly. We finally connected two event brokers through an adapter microservice, allowing a low-powered IoT device to communicate with a microservices system without draining their battery and without the complexity it would incur to use a more complex communication protocol.This pattern is very powerful and can be implemented in many ways, but it all depends on the exact use cases. You can write an adapter using a serverless offering like an Azure function, no-code/low-code offerings like Power Automate, or C#. Of course, these are just a few examples. The key to designing the correct system is to nail down the problem statement because once you know what you are trying to fix, the solution becomes clearer.Now, let’s see how the Microservice Adapter pattern can help us follow the SOLID principles at cloud-scale:
- S: The microservice adapter helps manage long- or short-term responsibilities. For example, adding an adapter that translates between two protocols or creating a temporary adapter to decommission a legacy system.
- O: You can leverage microservice adapters to dynamically add or remove features without impacting or with limited impact on the rest of the system. For example, in the IoT scenario, we could add support for a new protocol like AMQP without changing the rest of the system.
- L: N/A
- I: Adding smaller adapters can make changes easier and less risky than updating large legacy applications. As we saw in the legacy system decommissioning scenario, we could also leverage temporary adapters to split large applications into smaller pieces.
- D: A microservice adapter inverts the dependency flow between the system it adapts. For example, in the legacy system decommissioning scenario, the adapter reversed the flow from the two dependencies to the legacy system by leveraging an event broker.
