Workflow: Monitoring Presence by Using the Oracle Radio WebSocket API

Open an authenticated WebSocket connection for an enabled Radio user. Presence results and updates are limited to Radio users in the authenticated user's Identity Domain.

1. Follow Subscribing to Oracle Radio WebSocket Presence Updates to send SUBSCRIBE_PRESENCE.

   {
     "type": "SUBSCRIBE_PRESENCE"
   }

2. Wait for PRESENCE_SUBSCRIBED. Record the returned domain when it is present, and begin retaining each PRESENCE_UPDATE event in the order that the connection receives it.

3. Follow Getting Oracle Radio WebSocket Presence to send GET_PRESENCE. Supply userId to request one user's presence, or omit it to list online users visible in the Identity Domain.

   {
     "type": "GET_PRESENCE"
   }

4. While the snapshot request is pending, continue retaining PRESENCE_UPDATE events. Use PRESENCE as the baseline for one supplied user identifier. Use PRESENCE_LIST as the online-user baseline when userId is omitted.

5. After installing the baseline, apply the retained PRESENCE_UPDATE events in receive order. Then apply each new event to its matching userId. An event can report online, offline, or away. Its optional channel is a representative current channel, not a complete membership list.

6. For each channel in affectedChannels that your client displays and is authorized to access, refresh the user list with LIST_CHANNEL_USERS. An empty array requires no channel-list refresh. A user can leave one channel while remaining online through another session.

• If the service returns ERROR, correct the request or connection state and repeat the applicable operation.
• An interval without PRESENCE_UPDATE can mean that no visible presence changed. Follow Checking an Oracle Radio WebSocket Connection before treating the absence of updates as a failed connection.
• After reconnecting, first repeat Subscribing to Oracle Radio WebSocket Presence Updates and wait for a new PRESENCE_SUBSCRIBED confirmation. Retain updates, repeat Getting Oracle Radio WebSocket Presence for a current baseline, and then apply the retained updates before continuing with new events.