In the previous chapter, we connected our images service to the comments service via Spring Cloud Stream. This let us transmit new comments over the wire to a service dedicated to storing them in a MongoDB data store.
The following screenshot shows us entering a new comment:
To carry on this use case to its natural conclusion, it's expected that after storing a message, we'd want to share it with everyone, right? To do so, let's pick up with the comment microservice's CommentService.
In the previous chapter, the comments service transformed an incoming stream of Flux<Comment> into a Flux<Void>, a stream of voids. This had the effect of, essentially, dropping the stream at this point. In this chapter, we want to take that incoming stream of comments and forward them.
This is accomplished by altering the Comment.save() operation as follows:
@StreamListener
@Output(Processor.OUTPUT)
public Flux<Comment> save(@Input(Processor...