General principles

An application subscribes to messages from other applications by sending them a Perl regular expression. Each regex is attached to a callback. The callback is called when a received message match the regex, with captured groups as arguments.

The matching is done on the sender side : when an application sends a message, the message is matched against all regular expressions it gots, and only the captured groups are sent to other applications.

Example 1

Lets say we have 2 applications connected on the bus :

welcome that subscribed to ^Hello, I'm (.*).
client1 that subscribed to (.*)

If client1 wants to send the message Hello, I'm John., it will match it against the regex from welcome and extract and send the captured groups. In this case, only John will be sent to welcome. welcome will execute its corresponding callback with John as argument.

If in return welcome answers with Welcome John!, answer will match this message against client1 regex. Since client1 regex match any message (this is a bad practice), the complete message will be send.

Example 2

Lets say we have 3 applications connected on the bus :

temp logger that subscribed to ^.*temp:(.*)°C.*
moisture logger that subscribed to ^.*moist:(.*)%.*
sensor that subscribed to ^sensor start ([0-9]+) and ^sensor stop

If sensor sends temp:18°C, temp logger will receive a message that will trigger it first (and only) callback with 18 as argument.

If sensor sends temp:15°C, moist:68%, temp logger triggers its 1st callback with 15 as argument, and moist logger trigger its 1st callback with 68 as argument.

If temp logger or moisture logger send sensor start 5, sensor tiggers its 1st callback with 5 as argument.

If temp logger or moisture logger send sensor stop, sensor tiggers its 2nd callback without any arguments.