Activity Feeds

Last edit: Oct 26, 2022

An activity is a semantic description of an action.

Get familiar with the W3C Recommendation for Activity Streams 2.0. Most examples and part of the implementation you'll find in this guide are based on this specification, that provides a JSON-based syntax that is sufficient to express metadata about activities in a rich, human-friendly but machine-processable and extensible manner. This can include constructing natural-language descriptions or visual representations about the activity, associating actionable information with various types of objects, communicating or recording activity logs, or delegation of potential actions to other applications.


Activities (activity list) is an activity stream and it is an immutable list of immutable objects (activities/events that happened it the past).

  • By design you can only add an entry (update and delete operands are denied)
  • Generally, you are not allowed to change the list or any item from the list
  • Each activity has a unique UUID
  • Activities are to be shared between actors of the system
  • A single activity record is a representation of an event that happened in a system

After each specified action, you have to create an activity and then publish the activity UUID to specific feeds.


Sample scenario

A user joins a private group by sending a membership request to the group moderator. Later the moderator reviews and accepts the user's request. The user becomes a group member.

Actions and activities

In this scenario you can distinguish 3 actions:

  1. User requests group membership
  2. Group moderator accepts user's request
  3. User joins the group

For each action, you can create an activity as follows:

actor type object target
1. user create relationship group
2. moderator approve relationship group
3. user join group

Sample code

	"actor": {
		"type": "Person",
		"id": "User.1",
		"name": "Sally Smith"
	"type": "Join",
	"object": {
		"type": "Group",
		"id": "Customization.1",
		"name": "SuperGroup"

Activity feeds

You can define multiple different activity feeds.

  • Private feed: your FB main page for example is your private feed - your friends' activities are posted there
  • Public feed: there is also a public feed - your activities displayed for your friends

You can specify the following activity feed types:

feed type visibility purpose
user-notifications private notifications only displayed to the user
user-activities public user's public activities
group-activities public all group related public activities

In the example scenario, the activity distribution could be like this:

activity feeds
user-create-relationship-to-group moderator's user-notifications
moderator-approve-relationship-to-group user's user-notifications
user-join-group user's group activities
group's group-activities


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