Furthermore on dashboards for maintenance developers

What would a dashboard for visualizing and managing the flow of messages between actors and their dependents look like? My skills run in the direction of information architecture and not visual design, unfortunately. I can tell you what should be on the dashboard, the relationships between the contents  controls, the visual and interactive priorities of these, and how all of this changes over time. On a Friday night, this is not something I am prepared to do; which is really an excuse as I am nearing the end of my interest in this thought experiment. Nevertheless, here are a few ideas.

The transitions of a message between the actor and the dependent is

Actor sends the message to Dependent, or fails to send it.
Dependent receives the message, or fails to receive it.
Dependent responds with a response-message to the received-message, or fails to respond.
Actor receives the response-message, or fails to receive it.

We can symbolize these statuses as

A display for showing details of actors, messages, and listeners (dependents) might be

Each message is given a row and the delivery and response status is detailed for each listener. My bare tabular example would have much more detail on it in practice. This is not a overview display and so concerns with overwhelming the user with too much detail is not of relevance. If you only have to show a few listeners and perhaps a brief time window of messages this display will quickly show specific problem with delivery and response. 

Inverting and aggregating the above example leads to the tighter display

We are, again, showing each message, but the columns now indicate how many listeners are in each of the delivery or response states.

Lastly, as everyone loves a set of small multiples graphs here is 40 minutes of activity and status where the green line is the number of listeners, the black lines show positive trends and the red negative ones. 

Man, that is an ugly chart (and is playing loose with small multiples).