The durable-message chapter introduced the durable message and named the four interlocking concepts that together form the operational foundation of coordinated work. The role-playing chapter established the discipline through which participants take on roles and react within them. This chapter establishes one of the four: the message handler, the role that selects a communication mode from a sorted list of available modes and dispatches the message via that mode.
What a Message Handler Does
The message handler is a role within the role-playing discipline. A role player who has taken on the handler role performs the two acts the role-playing chapter established: taking on the role, then reacting. The handler's defining act is routing. The role-playing chapter's three foundational reacting capabilities — responding to requests, reacting to current conditions, reporting status — apply to the handler's work as routing, tracking, and broadcasting status updates.
Taking on the Role
The role description tells the handler to route, and names the modes available for routing.
A mode is a means of communication — a way the message can travel from sender to recipient. Phone, email, text, in-person conversation, mailed letter, radio call, courier delivery. The sorted list of available modes is the list of these the handler can choose from for the message at hand.
The role description may contain the sorted list directly. Or the role description may name where the handler obtains the list. Either pattern is valid; the choice is the orchestrator's. The handler's work is the same in both cases: act on the sorted list it was given.
Reacting as the Message Handler
Once the role is held, the handler's work is request-response in nature. The role-playing chapter named three foundational reacting capabilities. Each applies to the handler's work.
Responding to requests applies as routing. The receptionist who picks up the phone and decides whether to transfer the call, take a message, or interrupt the person being called is routing. The mailroom clerk who routes an incoming envelope to the right department is routing. The 911 dispatcher who takes the call and assigns the right unit to respond is routing.
Reacting to current conditions applies as tracking. The handler observes whether the dispatched message has produced its expected outcome within the situation's window, and acts on what observation reveals. Handing off a package to the mailroom is a dispatch; the tracking number that comes back is what lets the handler know whether the package arrived, when it arrived, and what to do if it did not.
Reporting status applies as broadcasting status updates. The handler produces outgoing information about the state of the dispatched messages and the handler's work. The receptionist who logs the day's calls and gives the report to the manager is broadcasting status updates. The mailroom clerk who reports the day's mail volumes to the supervisor is broadcasting status updates. The 911 dispatcher who logs each call into the shift report is broadcasting status updates.
The Foundation
The message handler is one of the four interlocking concepts that together form the operational foundation of coordinated work. The other three — the durable message, the role player, and the messenger — depend on the handler the way the handler depends on them. Without the handler, durable messages have no means of reaching role players, and the work of the messenger has no dispatch decision to act on. Without durable messages, the handler has nothing to dispatch. Without role players, the handler's dispatch has no destination. Without the messenger, the handler's dispatch decision cannot be carried to the recipient.