BIND 10 #2930: Sending notifications over msgq

[BIND 10 Development]

#2930: Sending notifications over msgq
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            Reporter:  vorner        |                        Owner:
                Type:  task          |  jinmei
            Priority:  medium        |                       Status:
           Component:  Inter-module  |  reviewing
  communication                      |                    Milestone:
            Keywords:                |  Sprint-20130528
           Sensitive:  0             |                   Resolution:
         Sub-Project:  Core          |                 CVSS Scoring:
Estimated Difficulty:  3             |              Defect Severity:  N/A
         Total Hours:  0             |  Feature Depending on Ticket:
                                     |  shared memory data source
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
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Changes (by vorner):

 * owner:  vorner => jinmei


Comment:

 Hello

 Replying to [comment:10 jinmei]:
 >   also: maybe s/subscribed/subscribing/?

 AFAIK no. In my understanding, „subscribe“ is activity that signifies the
 desire to receive something. A client that is „subscribing“ is in the
 (very
 short) process of asking to get the notifications.

 >   Is this supposed to be sent by cfgmgr to the relevant module(s)?  If
 >   so, I suspect cfgmgr shouldn't simply forget it after sending it: it
 >   needs to get a response to see whether the update succeeds (and
 >   whether it succeeds for all that are interested in that config).
 >   For the purpose of this ticket, I'd suggest using more obvious
 >   example for which we know we use notifications: group membership
 >   management.  So the above text would read:

 I changed the example, because of such questions. However, I believe
 there's place for notifications in changes of configuration.

 Currently, if one module wants to know configuration that belongs to
 another one, it „pretends“ to be the other module too, by subscribing to
 the main group of such module. Then it receives the call of
 `config_changed` command, can change the local data accordingly. And it
 does not answer, and it ignores all other modules. That is clearly beyond
 the borderline of hack.

 So, while there must be a mechanism to check the config for validity (and
 I'm not completely sure sending it to the relevant module is the correct
 way, because then there are problems with multiple instances of the module
 and when the module does not currently run), there's place for the
 notification afterward as well.

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Ticket URL: <http://bind10.isc.org/ticket/2930#comment:13>
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