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Rules to Better Microservices - 2 Rules

A microservice architecture is an application architecture where an application consists of many loosely-coupled services. The communications between services are kept lightweight, and the API interfaces between them need to be carefully managed. They are designed to allow different teams to work on different parts of the application completely independently.

  1. Microservices - Do you break down your apps?

    There are two common types of application architecture:

    • Monoliths (aka N-Tier applications)
    • Microservices

    Monoliths have their place. They are easy to get going and often make a lot of sense when you are starting out. However, sometimes your app may grow in size and become difficult to maintain. Then you might want to consider Microservices...

    Microservices let you break down your app into little pieces to make them more manageable, replaceable and maintainable. You can also scale out different parts of your app at a granular level.

    .NET 6 and Azure have heaps of great tools for developing simple APIs and worker services in a Microservices pattern.

    Watch the below video from 35:40 - 46:50

    The tools of the trade

    • .NET Worker Services make it easier to implement dependency injection, configuration and other syntactic sugar using the same patterns you are familiar with in other types of .NET applications
    • Azure Container Apps give you a way to host different little subsections of the application
    • Azure Functions gives you a great way to build applications in small, modular, scalable and easy to manage chunks. It provides triggers other than http to handle other common microservice patterns
    • Minimal APIs give you a way to write APIs in just a few short lines of code

    What's the point?

    • Cost - Provides separation of scalability, keep the hot parts of your app hot and the cold parts of your app cold to achieve maximum pricing efficiency
    • Maintainability - Keep code more manageable by making it bite sized chunks
    • Simplify code - Write minimal APIs
    • Deployment - Standardize deployment with containers
    • Testing - Easier to find problems since they are isolated to a specific part of the app
    • Cognitive Complexity - Devs can focus on one aspect of the app at a time
    • Data - You can use the best way of storing data for each service
    • Language - You can use the best language for each service

    What's the downside?

    • Upfront Cost - More upfront work is required
    • Cognitive Complexity - While individual apps are simpler, the architecture of the app can become more complex
    • Health Check - It's harder to know if all parts are alive
    • Domain boundaries - You need to define the separation of concerns between different services. Avoid adding dependencies between services because you can create a domino of failures...a house of cards.
    • Performance normally suffers as calls are made between services
    • Without adequate testing it's harder to maintain
    • Using multiple languages and datastores can be both more expensive to host and require more developers

    What new techniques are required

    • Contract Testing - To mitigate the risk of changes in one service breaking another, comprehensive tests that check the behaviour of services is required
  2. Microservice architectures consist of a number of components

    These often include:

    • An API Gateway (think APIM, Ocelot, YARP, Azure Front Door)
    • Support different types of frontends: Web, Desktop, Mobile
    • Flexible deployment model in subsequent microservices
    • Each microservice is in charge of its own data store
    • Event driven
    • VNet integration
    • Messaging system (used to decouple services, think Azure SendGrid or ServiceBus)
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