Today we are going to look at how we can describe asynchronous APIs that we create when we design event-driven architectures.
Join the DZone community and get the full member experience. In this article, I am going to be talking about how we can define your event-driven architectures using the AsyncAPI definition. A while ago, I published an article about how you can document REST APIs using Open API 3 specification. This was for synchronous APIs. Today we are going to look at how we can describe asynchronous APIs that we create when we design event-driven architectures. Let’s look at the various parts of an AsyncAPI specification that are most useful. There are also tags and external docs section, But right now it’s not that important for a new start. You can always refer to the documentation about these sections in more detail here. If you are already familiar with the OpenAPI definition, then these sections are more or less the same. Here is a nice page to understand the similarity between OpenAPI and AsyncAPI. Now that we have looked at the various sections. Let’s look at a minimal definition. Now, In this, I am creating an API definition to connect to Kafka, wherein a producer is publishing a transaction event to a Kafka topic named banking.transaction.000 Usually, when we dealt with OpenAPI 3 specification for synchronous communication, We always knew who was the server and the client. The server implements the OpenAPI definition and the client uses the definition to know how to interact with the server. Now, there is a difference in the case of asynchronous communication. We don’t have a nation of servers and clients. An application can consume an event and also emit an event. So let’s look a little deeper at the channel section from the above definition to understand this better.
