According to the Reactive Manifesto, a reactive system should have some essential characteristics which include: responsiveness, resiliency, elasticity, and being message-driven. Out of all the aspects, the most significant differentiating factor of Reactive Microservices from others is its characteristic of being message-driven. Using messages as the glue that holds your Microservices application together, you can design systems that isolated. High degree of isolation also helps enhance the scalability of a system which is an essential aspect of a Microservices application.

In the realms of Microsoft Azure, you can build Reactive Microservices Application using Azure Event Grid, Azure Functions, and Logic Apps. Azure Event Grid provides flexible event routing in the cloud, Azure Functions offer excellent Serverless execution environment for Microservices, and Logic Apps help you orchestrate the business logic of your Microservices and also provide connectivity to third-party applications and databases. In fact today Azure Functions and Logic Apps are getting adopted heavily by organizations that are trying to reshape their monolithic systems to drive more value out of them.

I won’t be covering Logic Apps in this article, and I won’t take your time talking about the basics of either Azure Functions or Azure Event Grid because both of them are covered extensively on the web. Here are the links to getting started guides that you can use to make yourself familiar with these services:

Use Case

We will build a straightforward Reactive Microservices application that handles orders placed by a customer on an e-commerce application. To make this scenario as unrealistic as possible (just to make it simple to implement), we will assume that the store has all the items available in any quantity requested. Following is a visual representation of the components that are part of the solution.

Reactive Microservices

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