I found these 3 ways from implementing messaging with Google Pub Sub:
with client libraries https://cloud.google.com/pubsub/docs/publisher
with spring integration message channels and PubSubTemplate API https://dzone.com/articles/spring-boot-and-gcp-cloud-pubsub
without message channels but with PubSubTemplate API https://medium.com/bb-tutorials-and-thoughts/gcp-how-to-subscribe-and-send-pubsub-messages-in-spring-boot-app-b27e2e8863e3
The problem is I don't understand exactly the differences between them / when each is best to use and which would be useful for my case. I have to implement a single Topic and a single Subscription to get the queue functionality. I think I'd rather not use Spring message channels if not needed , they seem to intermediate the communication between Pub Sub topic and the subscription and I don't want that. I want things simple , so I think the option 3 would be best but I am also wondering about option 1.
What is your advice? What are the pros/cons for each? Thanks!