I'm setting up a web app where a user can post an activity. Each activity needs participants. One of the features I think would be helpful if the owner of the post was notified when another user joins it.

Would there be a negative impact if a the owner was notified if users leave the activity? I ask this because in most social networks today I'm finding it uncommon to exclude the latter but would also think its unhelpful if the owner isn't aware the number of participants in their activity, especially as the activity's start-date approaches.

4 Answers 4


This feature is implemented in Facebook Messenger App. Users often gets added to a discussion without accepting or joining. When a discussion is going on among a few and each time notifying others who unwillingly was added, one can see that they leave quickly.

It doesn't "notify" with a sound or lock screen message, but when a user enters the discussion it says which users have left and when.

Based on this experience I think it's a good idea to inform the others in the activity stream what's going on (who left and when), but not notify in the common ways of notifying.

Inform: Yes, Notify: No


I remember that few years back when msn messenger was around there used to be a similar feature indicating when someone closed a chat window. Personally to me and friends this caused quite a bit of tensions. it somehow gave the idea that the person on the other end didn't want to keep the chat window open.

In your case as well I would recommend you not show these updates of someone leaving to other users. Why take the risk? While some social networks do have this, we should ask ourself does this add any positive value to the experience?

  • This is exactly what I thought as well! The only challenge I see is if an owner was notified that someone has joined the activity and days later finds out the participant has left, what then? I guess you can compare it here on SO when a user answers a post, the author is notified, returns to the post the answer was deleted. Nov 23, 2015 at 2:02

I think that the answer to your question depends on the context of your application. In other words, in order to assess if there it is valuable for users (of type: owner) to be notified about users leaving an activity, we neeed to know:

  • Does the owner take action based on reduced number of users on his/her activity?
  • Does an owner manage the participants closely e.g. export or report against them?
  • etc.

Given your statement about the importance of the start date of the activity, you could find a workaround: 1. Do not notify for people leaving an activity 2. Notify the owner with a summary of the participants count on specific dates related to the start date (e.g. 3 weeks before, 1 week before, 2 days before, 1 day after the end date)

I hope the workaround helps.


Or, you could do the contrary : instead of telling who left, telling who's in.

It could inform the owner without being intrusive.

Like "You have 6 team members online". Or showing online members avatars.

You can also add a feedback like in Facebook messenger or Google hangout : members avatars appears when online users saw an activity.

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