Book Image

Event-Driven Architecture in Golang

By : Michael Stack
5 (1)
Book Image

Event-Driven Architecture in Golang

5 (1)
By: Michael Stack

Overview of this book

Event-driven architecture in Golang is an approach used to develop applications that shares state changes asynchronously, internally, and externally using messages. EDA applications are better suited at handling situations that need to scale up quickly and the chances of individual component failures are less likely to bring your system crashing down. This is why EDA is a great thing to learn and this book is designed to get you started with the help of step-by-step explanations of essential concepts, practical examples, and more. You’ll begin building event-driven microservices, including patterns to handle data consistency and resiliency. Not only will you learn the patterns behind event-driven microservices but also how to communicate using asynchronous messaging with event streams. You’ll then build an application made of several microservices that communicates using both choreographed and orchestrated messaging. By the end of this book, you’ll be able to build and deploy your own event-driven microservices using asynchronous communication.
Table of Contents (18 chapters)
Part 1: Event-Driven Fundamentals
Part 2: Components of Event-Driven Architecture
Part 3: Production Ready

Converting the order creation process to use a Saga

In this section, we will be implementing the create order process described earlier in this chapter as an orchestrated saga method. To do so, we will use the SEC from the previous section. We will be doing the following to accomplish this task:

  • Updating the modules identified as participants to add new streams, handlers, and commands
  • Creating a new module called cosec, short for Create-Order-Saga-Execution-Coordinator, that will be responsible for orchestrating the process of creating new orders

Let’s begin by learning how to add commands.

Adding commands to the saga participants

The existing CreateOrder command for the application in the Order Processing module looks like this:

order, err := h.orders.Load(ctx, cmd.ID)
// 1. authorizeCustomer
err = h.customers.Authorize(ctx, cmd.CustomerID)
if err != nil { return err }
// 2. validatePayment
err = h.payments.Confirm(ctx, cmd.PaymentID)
if err != nil...