Adds the given channel to the storage.
Channel to add.
Deletes the given notification channel from the storage. Returns true if the channel existed.
The identifier of the notification channel
Returns the requested channel.
undefined if no match was found or if the notification channel expired.
The identifier of the notification channel.
Returns the identifiers of all notification channel entries that have the given identifier as their topic. The identifiers can potentially correspond to expired channels.
The identifier that is the topic.
Updates the given notification channel.
The id and the topic can not be updated.
The channel to update.
Stores all the information necessary to keep track of notification channels. Besides the standard channel info it also stores features specific to a certain channel type.
This storage assumes that a channel can only have a single identifier as its topic.