Nick Sellen

What's the difference between an event and a notification?

05 Jan 2010

A common thing to expect from a web app is some kind of event feed:

peter liked your photo joe is also going to see blur next week your mum returned home

Another common thing is to receive emails when things happen:

your photo has been approved you are now friends with angie john sent you a message

But what's the difference?

Initially, I put them as separate items, and they were due for separate database tables:

  • event feed items
  • notifications

My examples for notifications though ("nick clicked on a link, your post was commented on") sounded remarkably like items in an event feed though.

Aha! - maybe they're the same thing!

Or, perhaps an event is a mass broadcast thing to any interested person, and a notification is for ONE person about something JUST for them.

Perhaps a notification requires an acknowledgement and an event doesn't.

How does facebook do it?

Notifications seem to be able things that relate to you:

Lucy commented on your Post William accepted your friend request Toby likes your photo

Event feed items seem to be able things that have happened to other people, or actual content:

Felicity joined the group Petition against Arts Funding being siphoned for the Olympics Stephen is now friends with Adam AVATAR on IMAX. fuck yeah...and I got tickets this time

The actual content of Lucy's comment also appears, as well as the photo that Toby liked

Facebook also has Requests - these are things that need you to do something, and email notifications - usually just duplicates of requests or other notifications.

What does facebook say about it?

Email serves to notify users of time-sensitive or user-requested application activity in their off-Facebook email inbox

Requests ask or prompt a user to take an action that will change something. And unless the user responds, nothing will change. For example, requests are used to request permission to change user status, content, event attendance status or friend connections. If content will change without action by the recipient, a notification about the change would be more appropriate. Though many requests today are actually invitations wrapped within a question, invitations are a sub-category of requests.

User-to-user notifications inform a user of a change in content that has already taken place, almost always public content changed by another user and typically as a directed action towards the recipient.

Application-to-user notifications are sent on an application's behalf to a user of the application and do not require an active session. These do not need to be triggered by or pertain to social actions.

Unlike notifications, which communicate about changes in a user's own content, Feed stories expose new content or actions that the user's friends have taken.

Well that was quite useful. They've not surprisingly had a think about it. It's still a bit confusing though and isn't general enough to translate to all web apps.

Can you do any better Nick?

I've come up with 5 types of occurrence:

  1. something happened that you might want to know about
  2. something happened that involves you
  3. there is some new content you might want to see
  4. there is some new content that involves you
  5. you have to do something

...and 5 notification types:

  1. email message
  2. item in a content feed
  3. item in a notification feed
  4. sticky message that requires acknowledgement or some action
  5. real time notification

Can you think of anything that doesn't fit this?