Subscription keys

This API supports storing a link between a key and a user. You can then later use the API to get a list of users subscribing to a key. A key can be anything you want formatted as a URI.

Access the API by getting an instance of the ISubscriptionService interface lets you subscribe or unsubscribe a user and find users that subscribe to a particular key.

This API is just a supporting service, and subscriptions are independent of user notifications; no calls are made from one to the other. That means you must use the subscriptions API to populate the recipient field when creating a notification message because an event happened in the system. If the sender is also a subscriber, you may have to filter the list before sending the message to avoid the person triggering the event also getting notified.

A subscription key is in URI format and identifies something that can be notified. The format is unconstrained but should match the item it identifies.

The subscription key indicates that the user is interested in that item and the items below it, which are items with a key that starts with the subscribed key.

Use the SubscribeAsync methods to add one or more users to a subscription.

Use the UnsubscribeAsync method to remove one or more users from a subscription.

You can hook into the UserSubscribed and UserUnsubscribed events. They are only triggered for changes. If a user is added to a subscription twice, it only triggers for the first.

By calling ClearUserAsync, subscriptions for that user are removed so use it only when you delete a user from the system. The ClearSubscriptionAsync method removes users from that particular subscription. The UserCleared and SubscriptionCleared events are called for these respectively.

ListSubscriptionsAsync returns a list of subscriptions for a user.

ListSubscribersAsync returns a list of users that subscribe to a specified subscription. The FindSubscribersAsync method returns users that match a subscription key, fully and partly (begins-with).