As most of the systems I’m building are .NET based, I typically use NuGet Packages (published on an internal NuGet repository like Azure Artifacts or MyGet) to share my message contracts between different parts of the system.
The main disadvantage of this approach is that it creates platform coupling and is not a good solution if you are in a polyglot environment using different platforms and programming languages.
What if we could write our message contracts in a language neutral way? That is exactly what AsyncAPI has to offer.
From the AsyncAPI website:
AsyncAPI is an open source initiative that seeks to improve the current state of Event-Driven Architectures (EDA). Our long-term goal is to make working with EDAs as easy as it is to work with REST APIs. That goes from documentation to code generation, from discovery to event management. Most of the processes you apply to your REST APIs nowadays would be applicable to your event-driven/asynchronous APIs too.
To make this happen, the first step has been to create a specification that allows developers, architects, and product managers to define the interfaces of an async API. Much like OpenAPI (fka Swagger) does for REST APIs.
The AsyncAPI specification started as an adaptation of the OpenAPI specification so there are a lot of similarities.
Here is an example payload for one of my projects:
In the example above, we have a ‘Mail Service’ application that is linked to a RabbitMQ broker. The application behaves both as a producer and consumer as it subscribers to ‘SendMailCommand’ messages and publishes ‘MailSentEvent’ messages.
If you want to learn what the different parts mean, check out the great documentation provided here.
The AsyncAPI community has created an Async API studio which allows you to load, edit and view your specifications in a user-friendly way:
