Command 

command/<module>/<code>/<receiver>[/<component>]

Examples:

comamand/tlc/2/45fe             # M0002 set signal plan status (for main component) on node 45fe
comamand/traffic/17/45fe/sg.1   # hyopthetical M0017 set detector treshold for sigmal group 1 on node 45fe

All devices subscribe to a command topic that includes their id, which the supervisor can publish to.

Device subscribe to command/<id>/<component>/<module>/<cmd>

id: the id of the device itself module: the sxl module (category of command) cmd: the command

The payload contains the parameters in JSON format.

For example, a traffic light with id 45fe might subscribe to all command for all components using either single level wildcards with: command/45fe/+/+/+

Or using a multi-level wildcard: command/45fe/#

Now the supervisor can send commands to this particular traffic light and component by publishing to command/45ef/<component>/...

Suppose the traffic light has these components:

  • main: the main controller, handles, eg. signal program changes
  • sg1: signal group 1
  • sg2: signal group 2
  • dl1: detector logic 1
  • dl2: detector logic 2

And let’s suppose the traffic light supports these modules:

  • tlc: traffic light controller commands
  • detector: traffic detectors used for local traffic control

Change signal plan

command/45fe/main/tlc/plan

We send the command to the main component. We use plan command in the tlc module.

The payload would include the arguments, like what plan to switch to.

Set detector sensibility

command/45fe/dl1/detector/sensibility

We send the command to the dl1 component. We use sensibility command in the detector module.

The payload would include the arguments, like the sensibility value.

Sending to many devices

A traffic light with id 45fe could subscribe to a topic with the id ‘all’: command/all/#

Or a bit more selectively: command/all/main/tlc/+ command/all/+/detector/+

The supervisor can publish to this topic to e.g. change the signal plan on all traffic lights at the same: command/all/main/tlc/plan

Or change the detector sensibility on all detector logics in a particular traffic lights: command/45fe/all/detector/plan

Or change the detector sensibility on all detector logics in all traffic lights: command/all/all/detector/sensibility

Result

How would command results be handled? We would use the request-result pattern, which is based on Result Topics. When you send a command, you pass a topic that would want to result to be published to. A supervisor sending a command could pass the result topic: result/<supervisor_id>/component/module/command.

When a supervisor with id 22ba changing plan with command/45fe/main/tlc/plan, the respons would be send to result/22ba/main/tlc/plan.

All supervisor can receive result if the just subscribe to result/+/main/tlc/plan.