firstlegoleague/mq-protocols

Message queue bus protocols

mq-protocols's Issues

Restructure message topics

Currently, most (all?) topics used by the FLL apps are using a colon as separator between a 'subsystem' of an app and a 'command/event', e.g. clock:arm.
Also, nodes are currently used for specifying an 'app' (e.g. overlay).

However, MHub's topic system (and especially the pattern matching for subscribing and e.g. permission management) is based on path-like topics, e.g. /some/topic, i.e. separated with slashes.
MHub nodes should also mostly be seen as 'virtual hosts', i.e. most components in a system would normally connect to the default node.

The proposal is to change the naming scheme of nodes and topics as used by all current FLL apps to be more consistent with MHub's underlying concepts.

This basically means changing the node name of each app to default, and changing the topic 'schema' to something like /app/subsystem/event, e.g. /overlay/clock/arm, /scoring/ranking/published/qualifying.

Advantages:

• better pattern matching possibilities (for subscribe, but also for specifying more detailed publish and subscribe permissions)
• easier to understand that topics can be a 'hierarchy' of events (like the ranking message, above)
• the default node is already always available in the default MHub configuration, so for a simple setup it works out-of-the-box
• easier to support 'multi-room' events (by using nodes for the 'rooms', e.g. pit area and practice area, which will have e.g. twitter streams and general announcements in common, but not scoring)
• better compatibility with future features in MHub

Disadvantages:

• need to change the nodes/topics in existing apps (displaySystem, fllscoring, twitterAdmin, more?)
• may have to inform external parties of this change (I think this is only jpschewe's app right now)
• need to update mq-protocols documentation
• using old with new apps will break if we don't have backwards compatible messages

I suppose the work is manageable, and we could even have a simple MHub Relay transform to also forward specific new style messages to their old naming or vice-versa, if necessary.

Starting pause clock works different in clock file and display file

When pause the clock using the command prob (mhub-client -t clock:pause)
and later send a message to start the clock (mhub-client -t clock:start)

The clock file will reset its time
The overlay will continue counting down

(This does not happen if you use the overlay control window)