Activity Subscriptions

[csarven]

Actors in the system may want information sent to them about particular shapes or when certain events or activities take place.

Example use cases:

• Guinan wants to be notified when Jean-Luc adds a new photo to his collection.
• Janeway wants to follow Q's travel activities.
• Worf wants to keep up to date with Harry and Tuvok's game of kal-toh.
• Seven wants to keep an eye on Data's daily work log.
• B'Elanna wants to be alerted of potentially dangerous system activities on the ship.
• Kira and Tasha would like to be notified about the changes to Ro's party plans.

General requirements to consider:

• Advertise subscription requirements that can be discovered.
• Mechanism for actors to make a request to be notified about particular activities.
• Identify and verify the requesting actor.
• Verify the validity of the subscription request.
• Notify the receipt of the request or its result.
• Ability to sign notifications and verify it hasn't been tampered with in transit.
• Ability to state and adjust frequency of the subscriptions.
• Ability to unsubscribe from particular activities.

[elf-pavlik]

I think we need to be more specific in some requirements. There are major differences depending on where and how subscriber runs. In #30 we have some specific scenarios where the subscriber:

1. runs on a cloud server where it can receive requests
2. runs on a local device where it can't receive requests but can maintain an open connection
3. runs on a local device where it can be put to sleep, it needs to use a specific mechanism made available by the platform that receives notification and wakes up the subscriber

Guinan wants to be notified when Jean-Luc adds a new photo to his collection.

Just on this example, one could propose, Jean-Luc can give Guinan a call to let them know about it.
I think we should be more specific if Guinan wants a specific application they use on their mobile device to pop up notifications. If they want to receive email on some email address, or maybe they want to receive SMS.

Kira and Tasha would like to be notified about the changes to Ro's party plans.

They could rely on Ola letting them know during lunch break by the water cooler. ✅ 😉

Seriously, how does this one differ from

Worf wants to keep up to date with Harry and Tuvok's game of kal-toh.

Besides different kinds of data, they want to observe?