@@ -76,6 +76,40 @@
77-- * Whether messages will be taken from the mailbox first, or the event bus.
77-- * Whether messages will be taken from the mailbox first, or the event bus.
79+-- Since the event bus uses STM broadcast channels to communicate with agents,
80+-- no message written to the bus successfully can be lost.
82+-- Agents can also receive messages via their mailboxes - these are subject to
83+-- the same guarantees as all inter-process message sending.
85+-- Messages dispatched on an STM broadcast channel (i.e., management event bus)
86+-- are guaranteed to be delivered with the same FIFO ordering guarantees that
87+-- exist between two communicating processes, such that communication from the
88+-- node controller's threads (i.e., MxEvent's) will never be re-ordered, but
89+-- messages dispatched to the event bus by other processes (including, but not
90+-- limited to agents) are only guaranteed to be ordered between one sender and
93+-- No guarantee exists for the ordering in which messages sent to an agent's
94+-- mailbox will be delivered, vs messages dispatched via the event bus.
96+-- Because of the above, there are no ordering guarantees for messages sent
97+-- between agents, or for processes to agents, except for those that apply to
98+-- messages sent between regular processes, since agents are
99+-- implemented as such.
101+-- The event bus is serial and single threaded. Anything that is published by
102+-- the node controller will be seen in FIFO order. There are no ordering
103+-- guarantees pertaining to entries published to the event bus by other
104+-- processes or agents.
106+-- It should not be possible to see, for example, an @MxReceived@ before the
107+-- corresponding @MxSent@ event, since the places where we issue the @MxSent@
108+-- write directly to the event bus (using STM) in the calling (green) thread,
109+-- before dispatching instructions to the node controller to perform the
110+-- necessary routing to deliver the message to a process (or registered name,
111+-- or typed channel) locally or remotely.
79-- [Management Data API]
113-- [Management Data API]
81-- Both management agents and clients of the API have access to a variety of
115-- Both management agents and clients of the API have access to a variety of
@@ -144,8 +178,6 @@
144-- > monitorNames = getSelfPid >>= nsend "name-monitor"
178-- > monitorNames = getSelfPid >>= nsend "name-monitor"
145-- > monitorNames2 = getSelfPid >>= mxNotify
179-- > monitorNames2 = getSelfPid >>= mxNotify
147−-- For some real-world examples, see the distributed-process-platform package.
149-- [Performance, Stablity and Scalability]
181-- [Performance, Stablity and Scalability]
151-- /Management Agents/ offer numerous advantages over regular processes:
183-- /Management Agents/ offer numerous advantages over regular processes: