Book Image

Hands-On Microservices with C#

By : Matt Cole
Book Image

Hands-On Microservices with C#

By: Matt Cole

Overview of this book

C# is a powerful language when it comes to building applications and software architecture using rich libraries and tools such as .NET. This book will harness the strength of C# in developing microservices architectures and applications. This book shows developers how to develop an enterprise-grade, event-driven, asynchronous, message-based microservice framework using C#, .NET, and various open source tools. We will discuss how to send and receive messages, how to design many types of microservice that are truly usable in a corporate environment. We will also dissect each case and explain the code, best practices, pros and cons, and more. Through our journey, we will use many open source tools, and create file monitors, a machine learning microservice, a quantitative financial microservice that can handle bonds and credit default swaps, a deployment microservice to show you how to better manage your deployments, and memory, health status, and other microservices. By the end of this book, you will have a complete microservice ecosystem you can place into production or customize in no time.
Table of Contents (16 chapters)
11
Trello Microservice – Board Status Updating
12
Microservice Manager – The Nexus

Message subscriptions

Now that we have shown you what a deployment message looks like, let's discuss what happens when you subscribe to a message.

An EasyNetQ subscriber subscribes to a message type (the .NET type of the message class). Once the subscription to a type has been set up by calling the Subscribe method, a persistent queue will be created on the RabbitMQ broker and any messages of that type will be placed on the queue. RabbitMQ will send any messages from the queue to the subscriber whenever it is connected.

To subscribe to a message, we need to give EasyNetQ an action to perform whenever a message arrives. We do this by passing the Subscribe method a delegate such as this:

bus.Subscribe<MyMessage>("my_subscription_id", msg => Console.WriteLine(msg.Text));

Now, every time an instance of MyMessage is published, EasyNetQ will call our delegate and print the message's Text property to the console.