[asterisk-app-dev] MWI implementation

[Mark Michelson]

A while back, a discussion of a "blinky lights" proposal appeared on 
this list [1]. A wiki page [2] was created as a result of the discussion.

We're now at the point where we plan to implement externally-initiated 
MWI in ARI and AMI. While the actual ARI approach has been agreed upon, 
the under the hood aspects have not been discussed yet, so I want to 
talk about it some.

The current plan is to have Asterisk be a target for MWI updates. 
Asterisk can be told that the number of messages for a given mailbox has 
updated, and Asterisk will in turn notify interested parties (such as 
SIP phones) of the change. Asterisk will also persist the data (using 
sorcery) so that the data will be accessible if Asterisk is restarted. 
The current MWI state can also be retrieved externally.

Asterisk will not, however, have any other insight into voicemail or 
other mailbox-related matters that are handled through ARI. So for 
instance, if an ARI voicemail system were created, Asterisk would 
happily make recordings, play them back, and store them. However, the 
actual knowledge that the data is voicemail related or to what mailbox 
messages belong would be the responsibility of the application writer. 
The justification for this is that voicemail's machinations should be 
completely at the discretion of the application writer, and Asterisk 
should only become  expressly involved in areas that are absolutely 
necessary, such as MWI.

If there are objections to any of this, then please speak up.
Mark Michelson

[1] 
http://lists.digium.com/pipermail/asterisk-app-dev/2013-October/000198.html
[2] 
https://wiki.asterisk.org/wiki/display/AST/Blinky+Lights+API#BlinkyLightsAPI-Proposaltwo%3AFirstclassresources