CommandWire

A command in its wire form: { type, id, requestId, ref, body, expectedVersion, scope, headers, causation, operator, replyTo }. type is the command type's model name, which the receiver reads body by; the wait plan does not travel, only a wait context does.

replyTo is set only on a command a saga sends to another context (an addition within format 1): where the target sends the receipt of a rejection, and, when it asks for one, of the commit. operator (an addition within format 1 too) is the command's operator; a reader of an older version ignores it, and one reading an older writer's command has none.

caller (an addition within format 1 too) is who sent the command, as admission resolved them (Command.caller): the target's access policy compares its claims. A derived command has none, and neither does an older writer's command nor one a producer wrote without one: under an access policy, a command that is not derived and has no caller is refused. Its claims travel in the cluster channel's requests and stay in the command topic's records for the topic's retention; they are never recorded in the log.