.NET Microservices

@schneidenbach Microservices in .NET Spencer Schneidenbach

@schneidenbach My Background

@schneidenbach

@schneidenbach and …and React

@schneidenbach Microservices. Why do I care?

@schneidenbach I DON’T LIKE TAKING CALLS AFTER 5 PM.

@schneidenbach I have lots of tools to help in this
regard • Code reviews • Expectation setting with clients • CypressJS (for automated testing) • And, to some degree, microservices

@schneidenbach Thus, microservices

@schneidenbach Thus, microservices But, like, pragmatically

@schneidenbach We got things to talk about • What are
microservices? • What’s the good/bad/ugly? • What does “the .NET” have? (Azure? AWS?)

@schneidenbach What are microservices?

@schneidenbach Not a tech stack- a mentality

@schneidenbach Microservices have some common elements

@schneidenbach Loosely coupled

@schneidenbach Loosely coupled Two systems are loosely coupled if changes
to the design, implementation, or behavior in one won't cause changes in another. https://www.capitalone.com/tech/software-engineering/how-to-avoid-loose-coupled- microservices

@schneidenbach Data ownership

@schneidenbach Separately deployable

@schneidenbach Monitored

@schneidenbach Highly testable and tested

@schneidenbach

@schneidenbach Case Study #1

@schneidenbach

@schneidenbach Requirements • Decoupled from main app for rapid, iterative
release • If main app went down (it did sometimes) make sure it would get message later • Push text noti fi cations to employees to ensure timely response

@schneidenbach

@schneidenbach Message Queue

@schneidenbach

@schneidenbach Microservice communication

@schneidenbach Microservice communication • HTTP • Message bus

@schneidenbach

@schneidenbach Microservice communication • Message bus to carry events/commands •
Use pointers and then provide HTTP endpoints to get data later

@schneidenbach Requirements • Decoupled from main app for rapid, iterative
release • If main app went down (it did sometimes) make sure it would get message later • Push text noti fi cations to employees to ensure timely response

@schneidenbach My First Microservice Awwwwwwww how cute

@schneidenbach This is a microservices talk, so I’ll answer this
question: are monoliths inherently bad?

@schneidenbach No.

@schneidenbach How many of you work on existing monoliths?

@schneidenbach Monoliths are fi ne… until they’re not

@schneidenbach Oftentimes, microservices is a good pattern to break off
a piece that is particularly tricky for some reason or another (reliability, performance, etc.)

@schneidenbach How Bout That Dot Net?

@schneidenbach ASP.NET Core is a great start

@schneidenbach ASP.NET Core is a great start (Examples forthcoming)

@schneidenbach “Serverless” • Azure Functions • AWS Lambda • …whatever
it is that Google has - ask Jon Skeet

@schneidenbach Comparing • Azure Functions • AWS Lambda

@schneidenbach Examples • Azure Function - https://docs.microsoft.com/en-us/azure/ azure-functions/functions-bindings-service-bus-trigger • AWS
Lambda Quick Hits - https:// nodogmablog.bryanhogan.net/2022/04/net-6-on-aws- lambda-quick-demos/

@schneidenbach How about that ASP.NET Core thing?

@schneidenbach Three major choices • Write your own queue readers
and processors • Use a free library, MassTransit • Use a not-so-free library, NServiceBus

@schneidenbach I recommend MassTransit or NServiceBus • That said, if
you’re new to service-based architectures, be prepared to read their docs a lot and copy/paste sample code.

@schneidenbach NServiceBus pros • Enterprise-focused • Amazing support team •
Lots of other tooling that comes with the NServiceBus system (for monitoring, etc)

@schneidenbach MassTransit pros • Free and open source • Decent
support, but no centralized support (basically, Google, StackOver fl ow, samples, and their Discord channel)

@schneidenbach Let’s look at some code

@schneidenbach Some useful microservice patterns/tools you should be aware of

@schneidenbach BFFs

@schneidenbach https://www.allrecipes.com/recipe/216391/easy-sausage-gravy-and-biscuits/

@schneidenbach Backends for Frontends

@schneidenbach Backends for Frontends Basically: service and data aggregation

@schneidenbach Versioning

@schneidenbach Versioning Let’s assume SendEmail supports one attachment

@schneidenbach public class SendEmail { public string From { get;
set; } public string To { get; set; } //other stuff public Attachment Attachment { get; set; } }

@schneidenbach public Attachment[] Attachments { get; set; } public Attachment
Attachment { get; set; } to

@schneidenbach public class SendEmailV2 { public string From { get;
set; } public string To { get; set; } //other stuff public Attachment[] Attachments { get; set; } }

@schneidenbach Monitoring • Azure Application Insights • Other products like
Datadog

@schneidenbach Using correlation IDs for monitoring Link

@schneidenbach API Gateway • Management tool between client and published
APIs • Often handles authentication, documentation, rate limiting, etc.

@schneidenbach Containers/Kubernetes

@schneidenbach Containers/K8S

@schneidenbach Kubernetes

@schneidenbach Case Study #2

@schneidenbach Client of mine • Startup in a speci fi
c vertical • They process a lot of fi les that get sent to them

@schneidenbach

@schneidenbach Advantages • Used all of the Azure bits •
Storage queues for messages and fi le storage • Event Grid to listen for incoming fi les • Azure SQL for, well, stu ff you’d put in a database • Easy-ish to monitor using Application Insights

@schneidenbach Problems • Reached limits on the database • Reached
execution limits on Azure Functions - oh and it got really ‘spensive

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@schneidenbach Microservice anti- patterns

@schneidenbach

@schneidenbach Dependency disorder

@schneidenbach Distributed monolith

@schneidenbach

@schneidenbach Shared database

@schneidenbach

@schneidenbach Layered Services

@schneidenbach

@schneidenbach Shared codebases

@schneidenbach Some more links • eShop on Containers - https://github.com/dotnet-
architecture/eShopOnContainers

@schneidenbach Thank you!

.NET Microservices

.NET Microservices

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