On Oct 31, 2013, at 7:58 PM, Matthew Jordan <mjordan at digium.com> wrote: > Hey everyone - > > At AstriDevCon, we mentioned that two features ARI would need were the ability to raise MWI and the ability to publish state (device state, but theoretically, any event package for some subscribable resource). Initially, we discussed needing two resources in ARI - one that represents the state of mailboxes, and one that represents the state of a "device". > > The more we've thought about it, the more it feels like - from ARI's perspective - these are the same concepts. From the perspective of an ARI client, you want the ability to define a resource that someone can subscribe to. You want to be notified when something subscribes to it; when they unsubscribe to it; and when a resource's state changes. In turn, you want to publish state about that resource to the subscribers. The fact that the resource is a mailbox, or a device, or who knows what else - is immaterial. The application itself should determine this. > > (Plus, we forgot that in addition to device state and MWI, there's also presence state in Asterisk. So we were already up to 3 things anyway) > > We need a more generic concept - a 'blinky light' resource, if you will. > > The trick, unfortunately, is that in the guts of Asterisk, these are not the same concepts. MWI and device state (or presence state, for that matter) are all handled very differently. As much as it'd be fun to say "let's unify all the implementations!" - that's unrealistic and potentially harmful. So whatever we choose, there has to be a way to map the generic concept back to the actual implementation inside Asterisk. If the implementation is really different, then I question whether the API's really ought to be similar. Having a consistent API is excellent, but using the same API for different but similar things can become problematic where they become dissimilar. > The following is a proposal on how I think this might work: > > Add a new resource to ARI to represent a generic resource that can be subscribed to/published about, 'topics'. A topic is something that something can subscribe to, that has state, and that the ARI client can publish state about. (Note that I chose the name 'topic' as it's what the XMPP folks used for their publish/subscribe XEP (XEP-0060), and 'resource' isn't a good name as it's a generic term in REST. Hopefully it doesn't get too confusing with Stasis message bus topics.) > > Objects: > > Topic: > type: string - Valid types initially would be 'mailbox', 'device', 'presence' > uri: string - The URI subscribers use to subscribe to the topic > subscribers: List[Subscriber] - A list of active subscriptions > id: string - A unique ID for the topic > > Subscriber > id: string - A unique ID for the subscriber > topic_id: string - The topic ID this subscription refers to > endpoint: Endpoint - If available, the endpoint that subscribed to this Topic > > TopicSubscriptionCreated : Event - Event raised when a new subscription is created for a topic > subscriber : Subscriber > topic: Topic > > TopicSubscriptionDestroyed : Event - Event raised when a subscription is destroyed for a topic > subscriber : Subscriber > topic : Topic > > TopicEvent : Event - Event raised in relation to a topic > topic : Topic > body : JSON > > TopicCreated : Event - Event raised when a new topic is created > topic : Topic > > TopicDestroyed : Event - Event raised when a topic is destroyed > topic : Topic
