For modules that require multiple output destinations. Often times in
elaborate scripts, you find that you need to report things to multiple
destinations: TTY, logfile, etc. It would be handy to simply post the
information once and have some controls at your disposal as to where it
MessageStream is a role that implements the necessary Supplier/Supply/tap
incantations to provide a single, flexible message sending .post() in your
class that can be acted on by multiple subscribers.
Implement a receiver method, instantiate a MessageStream to a destination,
then subscribe as many different receivers as necessary.
You send a message (and any options you desire) with .post(). The resulting
stream will convert your string and optional named arguments into a
MessageStream::Message object. post() will marshal that into JSON on
the emit-side, the tap block will unmarshal it, and your receiver(s) can
unpack it in your class. In other words, you .post() and it all arrives
intact and easy to unpack for all of your receivers.
Your receiver method(s) can do whatever they want with the
MessageStream::Message object. They can simply say/put/print/note, maybe
add some color -- AND append the posted message to a file with a prepended
timestamp, AND send to SYSLOG, AND append to a CSV, AND talk to a websocket,
AND perform a POST/PUT to a SharePoint Online list -- all from a single
.post(). Each receiver is yours to craft and do whatever you choose with
the arbitrary stuff that you pumped into the pipeline.
Once a message stream is instantiated, subscribe to it (run-time). If you
want a particular destination to take a rest, unsubscribe from it. Repeat
See the example file.
Compose default receivers
Mark Devine firstname.lastname@example.org