|
76 | 76 | -- |
77 | 77 | -- * Whether messages will be taken from the mailbox first, or the event bus. |
78 | 78 | -- |
| 79 | +-- Since the event bus uses STM broadcast channels to communicate with agents, |
| 80 | +-- no message written to the bus successfully can be lost. |
| 81 | +-- |
| 82 | +-- Agents can also receive messages via their mailboxes - these are subject to |
| 83 | +-- the same guarantees as all inter-process message sending. |
| 84 | +-- |
| 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 |
| 91 | +-- one receiver. |
| 92 | +-- |
| 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. |
| 95 | +-- |
| 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. |
| 100 | +-- |
| 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. |
| 105 | +-- |
| 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. |
| 112 | +-- |
79 | 113 | -- [Management Data API] |
80 | 114 | -- |
81 | 115 | -- Both management agents and clients of the API have access to a variety of |
|
144 | 178 | -- > monitorNames = getSelfPid >>= nsend "name-monitor" |
145 | 179 | -- > monitorNames2 = getSelfPid >>= mxNotify |
146 | 180 | -- |
147 | | --- For some real-world examples, see the distributed-process-platform package. |
148 | | --- |
149 | 181 | -- [Performance, Stablity and Scalability] |
150 | 182 | -- |
151 | 183 | -- /Management Agents/ offer numerous advantages over regular processes: |
|
0 commit comments