I agree we have some vocabulary issues to reconsider here, but... I think "mini-stream" is looking at it from the wrong angle. A stream is a complete list of modules from source-to-sink that is deployable as a unit. So anything less than that is a module. A composed module is a black-box from the stream's perspective, i.e. it is just a single module, and it exposes a single input and/or single output channel. It just so happens to be composed of sub-modules that it connects together itself so that they form a single module.