I vaguely remember seeing a tool for visualizing data flows between systems, e.g. you'd describe a queue with multiple consumers and would describe what e.g. fan-out does and then you can trigger that action, seeing how data travels along the queue vertices to its consumers. Anyone know what I'm talking about or sth in that direction?

the rabbitmq simulator sounds like it http://tryrabbitmq.com/ https://vimeo.com/51363470