Has there been any prior effort to build Google Pub/Sub as an extension similar to Kafka or AMPQ? I would like to understand the underlying complexity of adding an extension. One of the strong reasons for going in this direction is not having to manage the operational side of Kafka or AMQP and using cloud-based queues if not using AxonServer.
I’m not aware of any such effort. Supporting all use cases, like both a subscribing and a streaming event processor, could be quite a lot of work. In addition, it should also be possible to use an extension without spring boot, which likely requires quite some glue code.
Unless you’re really passionate about this, it’s likely not worth it. If needed, in a project and using Spring Boot, you can use the spring-cloud-gcp-starter-pubsub, and create a normal event processor to publish events via an outbound channel adapter and an inbound channel adapter to read the events.
Some additional complexity with the mentioned extensions is also with getting the exact same Axon Event back. This is done using converters. But for a single-use case, this might be a lot simpler. For example, just the payload might be enough.
I hope this was helpful. If you do plan to create a new extension, we could maybe adopt it at some time.