Abstract

This specification describes the Activity vocabulary.

Author's Note

This section is non-normative.

This draft is heavily influenced by the JSON Activity Streams 1.0 specification originally co-authored by Martin Atkins, Will Norris, Chris Messina, Monica Wilkinson, Rob Dolin and James Snell. The author is very thankful for their significant contributions and gladly stands on their shoulders. Some portions of the original text of Activity Streams 1.0 are used in this document.

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at https://www.w3.org/TR/.

This document was published by the Social Web Working Group as a Candidate Recommendation. This document is intended to become a W3C Recommendation. If you wish to make comments regarding this document, please send them to public-socialweb@w3.org (subscribe, archives). W3C publishes a Candidate Recommendation to indicate that the document is believed to be stable and to encourage implementation by the developer community. This Candidate Recommendation is expected to advance to Proposed Recommendation no earlier than 12 January 2017. All comments are welcome.

Please see the Working Group's implementation report.

Publication as a Candidate Recommendation does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

This document is governed by the 1 September 2015 W3C Process Document.

1. Introduction

The Activity Streams 2.0 Core Syntax defines the JSON syntax for Activity Streams. This document defines the vocabulary properties.

The Activity Streams 2.0 Vocabulary defines a set of abstract types and properties that describe past, present and future Activities. The vocabulary is defined in two parts:

  1. A Core set of properties describing the generalized structure of an Activity; and
  2. An Extended set of properties that cover specific types of Activities and Artifacts common to many social Web application systems.

While not all Activity Streams 2.0 implementations are expected to implement support for the Extended properties, all implementations MUST at least be capable of serializing and deserializing the Extended properties in accordance with the Activity Streams 2.0 Core Syntax.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", " SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].

1.1 Conventions

Unless otherwise specified, all properties defined as xsd:dateTime values MUST conform to the rules defined in Activity Streams 2.0 Core, Section 2.3.

The examples included in this document use the normative JSON serialization defined by this specification.

1.2 At Risk features

The Working Group has marked some features as At Risk and may seek to advance the specification with the removal of these terms if insufficient implementation experience can be gathered.

2. Core Types

The Activity Vocabulary Core Types provide the basis for the rest of the vocabulary.

Base URI: https://www.w3.org/ns/activitystreams#.

The Activity Streams 2.0 Core Types include:

Class Description Example
Object URI: https://www.w3.org/ns/activitystreams#Object
Example 1
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Object",
  "id": "http://www.test.example/object/1",
  "name": "A Simple, non-specific object"
}
Notes: Describes an object of any kind. The Object type serves as the base type for most of the other kinds of objects defined in the Activity Vocabulary, including other Core types such as Activity, IntransitiveActivity, Collection and OrderedCollection.
Disjoint With: Link
Properties:

attachment | attributedTo | audience | content | context | name | endTime | generator | icon | image | inReplyTo | location | preview | published | replies | startTime | summary | tag | updated | url | to | bto | cc | bcc | mediaType | duration

Link URI: https://www.w3.org/ns/activitystreams#Link
Example 2
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Link",
  "href": "http://example.org/abc",
  "hreflang": "en",
  "mediaType": "text/html",
  "name": "An example link"
}
Notes: A Link is an indirect, qualified reference to a resource identified by a URL. The fundamental model for links is established by [ RFC5988]. Many of the properties defined by the Activity Vocabulary allow values that are either instances of Object or Link. When a Link is used, it establishes a qualified relation connecting the subject (the containing object) to the resource identified by the href. Properties of the Link are properties of the reference as opposed to properties of the resource.
Disjoint With: Object
Properties:

href | rel | mediaType | name | hreflang | height | width | preview

Activity URI: https://www.w3.org/ns/activitystreams#Activity
Example 3
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Activity",
  "summary": "Sally did something to a note",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Note",
    "name": "A Note"
  }
}
Notes: An Activity is a subtype of Object that describes some form of action that may happen, is currently happening, or has already happened. The Activity type itself serves as an abstract base type for all types of activities. It is important to note that the Activity type itself does not carry any specific semantics about the kind of action being taken.
Extends: Object
Properties:

actor | object | target | result | origin | instrument

Inherits all properties from Object.

IntransitiveActivity URI: https://www.w3.org/ns/activitystreams#IntransitiveActivity
Example 4
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Travel",
  "summary": "Sally went to work",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "target": {
    "type": "Place",
    "name": "Work"
  }
}
Notes: Instances of IntransitiveActivity are a subtype of Activity representing intransitive actions. The object property is therefore inappropriate for these activities.
Extends: Activity
Properties:

Inherits all properties from Activity except object.

Collection URI: https://www.w3.org/ns/activitystreams#Collection
Example 5
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally's notes",
  "type": "Collection",
  "totalItems": 2,
  "items": [
    {
      "type": "Note",
      "name": "A Simple Note"
    },
    {
      "type": "Note",
      "name": "Another Simple Note"
    }
  ]
}
Notes:

A Collection is a subtype of Object that represents ordered or unordered sets of Object or Link instances.

Refer to the Activity Streams 2.0 Core specification for a complete description of the Collection type.

Extends: Object
Properties:

totalItems | current | first | last | items

Inherits all properties from Object.

OrderedCollection URI: https://www.w3.org/ns/activitystreams#OrderedCollection
Example 6
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally's notes",
  "type": "OrderedCollection",
  "totalItems": 2,
  "orderedItems": [
    {
      "type": "Note",
      "name": "A Simple Note"
    },
    {
      "type": "Note",
      "name": "Another Simple Note"
    }
  ]
}
Notes:

A subtype of Collection in which members of the logical collection are assumed to always be strictly ordered.

Extends: Collection
Properties:

Inherits all properties from Collection.

CollectionPage URI: https://www.w3.org/ns/activitystreams#CollectionPage
Example 7
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Page 1 of Sally's notes",
  "type": "CollectionPage",
  "id": "http://example.org/foo?page=1",
  "partOf": "http://example.org/foo",
  "items": [
    {
      "type": "Note",
      "name": "A Simple Note"
    },
    {
      "type": "Note",
      "name": "Another Simple Note"
    }
  ]
}
Notes:

Used to represent distinct subsets of items from a Collection. Refer to the Activity Streams 2.0 Core for a complete description of the CollectionPage object.

Extends: Collection
Properties:

partOf | next | prev

Inherits all properties from Collection.

OrderedCollectionPage URI: https://www.w3.org/ns/activitystreams#OrderedCollectionPage
Example 8
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Page 1 of Sally's notes",
  "type": "OrderedCollectionPage",
  "id": "http://example.org/foo?page=1",
  "partOf": "http://example.org/foo",
  "orderedItems": [
    {
      "type": "Note",
      "name": "A Simple Note"
    },
    {
      "type": "Note",
      "name": "Another Simple Note"
    }
  ]
}
Notes:

Used to represent ordered subsets of items from an OrderedCollection. Refer to the Activity Streams 2.0 Core for a complete description of the OrderedCollectionPage object.

Extends: OrderedCollection | CollectionPage
Properties:

startIndex

Inherits all properties from OrderedCollection and CollectionPage.

3. Extended Types

Base URI: https://www.w3.org/ns/activitystreams#.

The Activity Streams 2.0 Extended Types include Activity and Object subtypes that are common to many social Web applications. They are divided into three sets:

Support for specific extended vocabulary types is expected to vary, with implementations only selecting the extended types and properties that make sense within the specific context and requirements of those applications. However, to avoid possible interoperability issues, implementations MUST avoid using extension types or properties that unduly overlap with or duplicate the extended vocabulary defined here.

3.1 Activity Types

All Activity Types inherit the properties of the base Activity type. Some specific Activity Types are subtypes or specializations of more generalized Activity Types (for instance, the Invite Activity Type is a more specific form of the Offer Activity Type).

The Activity Types include:

Class Description Example
Accept URI: https://www.w3.org/ns/activitystreams#Accept
Example 9
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally accepted an invitation to a party",
  "type": "Accept",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Invite",
    "actor": "http://john.example.org",
    "object": {
      "type": "Event",
      "name": "Going-Away Party for Jim"
    }
  }
}
Example 10
{
    "@context": "https://www.w3.org/ns/activitystreams",
    "summary": "Sally accepted Joe into the club",
    "type": "Accept",
    "actor": {
      "type": "Person",
      "name": "Sally"
    },
    "object": {
      "type": "Person",
      "name": "Joe"
    },
    "target": {
      "type": "Group",
      "name": "The Club"
    }
  }
Notes: Indicates that the actor accepts the object. The target property can be used in certain circumstances to indicate the context into which the object has been accepted.
Extends: Activity
Properties: Inherits all properties from Activity.
TentativeAccept URI: https://www.w3.org/ns/activitystreams#TentativeAccept
Example 11
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally tentatively accepted an invitation to a party",
  "type": "TentativeAccept",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Invite",
    "actor": "http://john.example.org",
    "object": {
      "type": "Event",
      "name": "Going-Away Party for Jim"
    }
  }
}
Notes: A specialization of Accept indicating that the acceptance is tentative.
Extends: Accept
Properties: Inherits all properties from Accept.
Add URI: https://www.w3.org/ns/activitystreams#Add
Example 12
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally added an object",
  "type": "Add",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": "http://example.org/abc"
}
Example 13
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally added a picture of her cat to her cat picture collection",
  "type": "Add",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Image",
    "name": "A picture of my cat",
    "url": "http://example.org/img/cat.png"
  },
  "origin": {
    "type": "Collection",
    "name": "Camera Roll"
  },
  "target": {
    "type": "Collection",
    "name": "My Cat Pictures"
  }
}
Notes: Indicates that the actor has added the object to the target. If the target property is not explicitly specified, the target would need to be determined implicitly by context. The origin can be used to identify the context from which the object originated.
Extends: Activity
Properties: Inherits all properties from Activity.
Arrive URI: https://www.w3.org/ns/activitystreams#Arrive
Example 14
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally arrived at work",
  "type": "Arrive",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "location": {
    "type": "Place",
    "name": "Work"
  },
  "origin": {
    "type": "Place",
    "name": "Home"
  }
}
Notes: An IntransitiveActivity that indicates that the actor has arrived at the location. The origin can be used to identify the context from which the actor originated. The target typically has no defined meaning.
Extends: IntransitiveActivity
Properties: Inherits all properties fom IntransitiveActivity.
Create URI: https://www.w3.org/ns/activitystreams#Create
Example 15
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally created a note",
  "type": "Create",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Note",
    "name": "A Simple Note",
    "content": "This is a simple note"
  }
}
Notes:

Indicates that the actor has created the object.

Extends: Activity
Properties: Inherits all properties from Activity.
Delete URI: https://www.w3.org/ns/activitystreams#Delete
Example 16
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally deleted a note",
  "type": "Delete",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": "http://example.org/notes/1",
  "origin": {
    "type": "Collection",
    "name": "Sally's Notes"
  }
}
Notes: Indicates that the actor has deleted the object. If specified, the origin indicates the context from which the object was deleted.
Extends: Activity
Properties: Inherits all properties from Activity.
Follow URI: https://www.w3.org/ns/activitystreams#Follow
Example 17
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally followed John",
  "type": "Follow",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Person",
    "name": "John"
  }
}
Notes: Indicates that the actor is "following" the object. Following is defined in the sense typically used within Social systems in which the actor is interested in any activity performed by or on the object. The target and origin typically have no defined meaning.
Extends: Activity
Properties: Inherits all properties from Activity.
Ignore URI: https://www.w3.org/ns/activitystreams#Ignore
Example 18
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally ignored a note",
  "type": "Ignore",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": "http://example.org/notes/1"
}
Notes: Indicates that the actor is ignoring the object. The target and origin typically have no defined meaning.
Extends: Activity
Properties: Inherits all properties from Activity.
Join URI: https://www.w3.org/ns/activitystreams#Join
Example 19
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally joined a group",
  "type": "Join",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Group",
    "name": "A Simple Group"
  }
}
Notes: Indicates that the actor has joined the object. The target and origin typically have no defined meaning.
Extends: Activity
Properties: Inherits all properties from Activity.
Leave URI: https://www.w3.org/ns/activitystreams#Leave
Example 20
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally left work",
  "type": "Leave",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Place",
    "name": "Work"
  }
}
Example 21
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally left a group",
  "type": "Leave",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Group",
    "name": "A Simple Group"
  }
}
Notes: Indicates that the actor has left the object. The target and origin typically have no meaning.
Extends: Activity
Properties: Inherits all properties from Activity.
Like URI: https://www.w3.org/ns/activitystreams#Like
Example 22
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally liked a note",
  "type": "Like",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": "http://example.org/notes/1"
}
Notes:

Indicates that the actor likes, recommends or endorses the object. The target and origin typically have no defined meaning.

Extends: Activity
Properties: Inherits all properties from Activity.
Offer URI: https://www.w3.org/ns/activitystreams#Offer
Example 23
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally offered 50% off to Lewis",
  "type": "Offer",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "http://www.types.example/ProductOffer",
    "name": "50% Off!"
  },
  "target": {
    "type": "Person",
    "name": "Lewis"
  }
}
Notes: Indicates that the actor is offering the object. If specified, the target indicates the entity to which the object is being offered.
Extends: Activity
Properties: Inherits all properties from Activity.
Invite URI: https://www.w3.org/ns/activitystreams#Invite
Example 24
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally invited John and Lisa to a party",
  "type": "Invite",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Event",
    "name": "A Party"
  },
  "target": [
    {
      "type": "Person",
      "name": "John"
    },
    {
      "type": "Person",
      "name": "Lisa"
    }
  ]
}
Notes: A specialization of Offer in which the actor is extending an invitation for the object to the target.
Extends: Offer
Properties: Inherits all properties from Offer.
Reject URI: https://www.w3.org/ns/activitystreams#Reject
Example 25
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally rejected an invitation to a party",
  "type": "Reject",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Invite",
    "actor": "http://john.example.org",
    "object": {
      "type": "Event",
      "name": "Going-Away Party for Jim"
    }
  }
}
Notes: Indicates that the actor is rejecting the object. The target and origin typically have no defined meaning.
Extends: Activity
Properties: Inherits all properties from Activity.
TentativeReject URI: https://www.w3.org/ns/activitystreams#TentativeReject
Example 26
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally tentatively rejected an invitation to a party",
  "type": "TentativeReject",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Invite",
    "actor": "http://john.example.org",
    "object": {
      "type": "Event",
      "name": "Going-Away Party for Jim"
    }
  }
}
Notes: A specialization of Reject in which the rejection is considered tentative.
Extends: Reject
Properties: Inherits all properties from Reject.
Remove URI: https://www.w3.org/ns/activitystreams#Remove
Example 27
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally removed a note from her notes folder",
  "type": "Remove",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": "http://example.org/notes/1",
  "target": {
    "type": "Collection",
    "name": "Notes Folder"
  }
}
Example 28
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "The moderator removed Sally from a group",
  "type": "Remove",
  "actor": {
    "type": "http://example.org/Role",
    "name": "The Moderator"
  },
  "object": {
    "type": "Person",
    "name": "Sally"
  },
  "origin": {
    "type": "Group",
    "name": "A Simple Group"
  }
}
Notes: Indicates that the actor is removing the object. If specified, the origin indicates the context from which the object is being removed.
Extends: Activity
Properties: Inherits all properties from Activity.
Undo URI: https://www.w3.org/ns/activitystreams#Undo
Example 29
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally retracted her offer to John",
  "type": "Undo",
  "actor": "http://sally.example.org",
  "object": {
    "type": "Offer",
    "actor": "http://sally.example.org",
    "object": "http://example.org/posts/1",
    "target": "http://john.example.org"
  }
}
Notes:

Indicates that the actor is undoing the object. In most cases, the object will be an Activity describing some previously performed action (for instance, a person may have previously "liked" an article but, for whatever reason, might choose to undo that like at some later point in time).

The target and origin typically have no defined meaning.

Extends: Activity
Properties: Inherits all properties from Activity.
Update URI: https://www.w3.org/ns/activitystreams#Update
Example 30
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally updated her note",
  "type": "Update",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": "http://example.org/notes/1"
}
Notes:

Indicates that the actor has updated the object. Note, however, that this vocabulary does not define a mechanism for describing the actual set of modifications made to object.

The target and origin typically have no defined meaning.

Extends: Activity
Properties: Inherits all properties from Activity.
View URI: https://www.w3.org/ns/activitystreams#View
Example 31
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally read an article",
  "type": "View",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": {
    "type": "Article",
    "name": "What You Should Know About Activity Streams"
  }
}
Notes: Indicates that the actor has viewed the object.
Extends: Activity
Properties: Inherits all properties from Activity.
Listen URI: https://www.w3.org/ns/activitystreams#Listen
Example 32
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally listened to a piece of music",
  "type": "Listen",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": "http://example.org/music.mp3"
}
Notes: Indicates that the actor has listened to the object.
Extends: Activity
Properties: Inherits all properties from Activity.
Read URI: https://www.w3.org/ns/activitystreams#Read
Example 33
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally read a blog post",
  "type": "Read",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": "http://example.org/posts/1"
}
Notes: Indicates that the actor has read the object.
Extends: Activity
Properties: Inherits all properties from Activity.
Move URI: https://www.w3.org/ns/activitystreams#Move
Example 34
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally moved a post from List A to List B",
  "type": "Move",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": "http://example.org/posts/1",
  "target": {
    "type": "Collection",
    "name": "List B"
  },
  "origin": {
    "type": "Collection",
    "name": "List A"
  }
}
Notes: Indicates that the actor has moved object from origin to target. If the origin or target are not specified, either can be determined by context.
Extends: Activity
Properties: Inherits all properties from Activity.
Travel URI: https://www.w3.org/ns/activitystreams#Travel
Example 35
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally went home from work",
  "type": "Travel",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "target": {
    "type": "Place",
    "name": "Home"
  },
  "origin": {
    "type": "Place",
    "name": "Work"
  }
}
Notes: Indicates that the actor is traveling to target from origin. Travel is an IntransitiveObject whose actor specifies the direct object. If the target or origin are not specified, either can be determined by context.
Extends: IntransitiveActivity
Properties: Inherits all properties from IntransitiveActivity.
Announce URI: https://www.w3.org/ns/activitystreams#Announce
Example 36
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally announced that she had arrived at work",
  "type": "Announce",
  "actor": {
    "type": "Person",
    "id": "http://sally.example.org",
    "name": "Sally"
  },
  "object": {
    "type": "Arrive",
    "actor": "http://sally.example.org",
    "location": {
      "type": "Place",
      "name": "Work"
    }
  }
}
Notes:

Indicates that the actor is calling the target's attention the object.

The origin typically has no defined meaning.

Extends: Activity
Properties: Inherits all properties from Activity.
Block URI: https://www.w3.org/ns/activitystreams#Block
Example 37
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally blocked Joe",
  "type": "Block",
  "actor": "http://sally.example.org",
  "object": "http://joe.example.org"
}
Notes: Indicates that the actor is blocking the object. Blocking is a stronger form of Ignore. The typical use is to support social systems that allow one user to block activities or content of other users. The target and origin typically have no defined meaning.
Extends: Ignore
Properties: Inherits all properties from Ignore.
Flag URI: https://www.w3.org/ns/activitystreams#Flag
Example 38
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally flagged an inappropriate note",
  "type": "Flag",
  "actor": "http://sally.example.org",
  "object": {
    "type": "Note",
    "content": "An inappropriate note"
  }
}
Notes: Indicates that the actor is "flagging" the object. Flagging is defined in the sense common to many social platforms as reporting content as being inappropriate for any number of reasons.
Extends: Activity
Properties: Inherits all properties from Activity.
Dislike URI: https://www.w3.org/ns/activitystreams#Dislike
Example 39
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally disliked a post",
  "type": "Dislike",
  "actor": "http://sally.example.org",
  "object": "http://example.org/posts/1"
}
Notes: Indicates that the actor dislikes the object.
Extends: Activity
Properties: Inherits all properties from Activity.
Question URI: https://www.w3.org/ns/activitystreams#Question
Example 40
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Question",
  "name": "What is the answer?",
  "oneOf": [
    {
      "type": "Note",
      "name": "Option A"
    },
    {
      "type": "Note",
      "name": "Option B"
    }
  ]
}
Example 41
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Question",
  "name": "What is the answer?",
  "closed": "2016-05-10T00:00:00Z"
}
Notes:

Represents a question being asked. Question objects are an extension of IntransitiveActivity. That is, the Question object is an Activity, but the direct object is the question itself and therefore it would not contain an object property.

Either of the anyOf and oneOf properties MAY be used to express possible answers, but a Question object MUST NOT have both properties.

Extends: IntransitiveActivity.
Properties:

oneOf | anyOf | closed

Inherits all properties from IntransitiveActivity.

3.2 Actor Types

Actor types are Object types that are capable of performing activities.

The core Actor Types include:

Class Description Properties
Application URI: https://www.w3.org/ns/activitystreams#Application
Example 42
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Application",
  "name": "Exampletron 3000"
}
Notes: Describes a software application.
Extends: Object
Properties: Inherits all properties from Object.
Group URI: https://www.w3.org/ns/activitystreams#Group
Example 43
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Group",
  "name": "Big Beards of Austin"
}
Notes: Represents a formal or informal collective of Actors.
Extends: Object
Properties: Inherits all properties from Object.
Organization URI: https://www.w3.org/ns/activitystreams#Organization
Example 44
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Organization",
  "name": "Example Co."
}
Notes: Represents an organization.
Extends: Object
Properties: Inherits all properties from Object.
Person URI: https://www.w3.org/ns/activitystreams#Person
Example 45
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Person",
  "name": "Sally Smith"
}
Notes: Represents an individual person.
Extends: Object
Properties: Inherits all properties from Object.
Service URI: https://www.w3.org/ns/activitystreams#Service
Example 46
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Service",
  "name": "Acme Web Service"
}
Notes: Represents a service of any kind.
Extends: Object
Properties: Inherits all properties from Object.

3.3 Object and Link Types

All Object Types inherit the properties of the base Object type. Link Types inherit the properties of the base Link type. Some specific Object Types are subtypes or specializations of more generalized Object Types (for instance, the Like Type is a more specific form of the Activity type).

The Object Types include:

The Link Types include:

Class Description Properties
Relationship URI: https://www.w3.org/ns/activitystreams#Relationship
Example 47
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally is a contact of John",
  "type": "Relationship",
  "subject": {
    "type": "Person",
    "name": "Sally"
  },
  "relationship": "IsContact",
  "object": {
    "type": "Person",
    "name": "John"
  }
}
Notes:

Describes a relationship between two individuals. The subject and object properties are used to identify the connected individuals.

See 5.2 Representing Relationships Between Entities for additional information.

Note: At Risk

The Relationship type is At Risk. The Working Group believes this type to be useful and well-founded. However, if insufficient evidence of implementation can be obtained during the Candidate Recommendation period then the Working Group may seek to advance the specification with this type omitted.

Extends: Object
Properties:

subject | object | relationship

Inherits all properties from Object.

Article URI: https://www.w3.org/ns/activitystreams#Article
Example 48
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Article",
  "name": "What a Crazy Day I Had",
  "content": "<div>... you will never believe ...</div>",
  "attributedTo": "http://sally.example.org"
}
Notes: Represents any kind of multi-paragraph written work.
Extends: Object
Properties: Inherits all properties from Object.
Document URI: https://www.w3.org/ns/activitystreams#Document
Example 49
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Document",
  "name": "4Q Sales Forecast",
  "url": "http://example.org/4q-sales-forecast.pdf"
}
Notes: Represents a document of any kind.
Extends: Object
Properties: Inherits all properties from Object.
Audio URI: https://www.w3.org/ns/activitystreams#Audio
Example 50
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Audio",
  "name": "Interview With A Famous Technologist",
  "url": {
    "type": "Link",
    "href": "http://example.org/podcast.mp3",
    "mediaType": "audio/mp3"
  }
}
Notes: Represents an audio document of any kind.
Extends: Document
Properties: Inherits all properties from Document.
Image URI: https://www.w3.org/ns/activitystreams#Image
Example 51
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Image",
  "name": "Cat Jumping on Wagon",
  "url": [
    {
      "type": "Link",
      "href": "http://example.org/image.jpeg",
      "mediaType": "image/jpeg"
    },
    {
      "type": "Link",
      "href": "http://example.org/image.png",
      "mediaType": "image/png"
    }
  ]
}
Notes: An image document of any kind
Extends: Document
Properties: Inherits all properties from Document.
Video URI: https://www.w3.org/ns/activitystreams#Video
Example 52
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Video",
  "name": "Puppy Plays With Ball",
  "url": "http://example.org/video.mkv",
  "duration": "PT2H"
}
Notes: Represents a video document of any kind.
Extends: Document
Properties: Inherits all properties from Document.
Note URI: https://www.w3.org/ns/activitystreams#Note
Example 53
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Note",
  "name": "A Word of Warning",
  "content": "Looks like it is going to rain today. Bring an umbrella!"
}
Notes: Represents a short written work typically less than a single paragraph in length.
Extends: Object
Properties: Inherits all properties from Object.
Page URI: https://www.w3.org/ns/activitystreams#Page
Example 54
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Page",
  "name": "Omaha Weather Report",
  "url": "http://example.org/weather-in-omaha.html"
}
Notes: Represents a Web Page.
Extends: Document
Properties: Inherits all properties from Document.
Event URI: https://www.w3.org/ns/activitystreams#Event
Example 55
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Event",
  "name": "Going-Away Party for Jim",
  "startTime": "2014-12-31T23:00:00-08:00",
  "endTime": "2015-01-01T06:00:00-08:00"
}
Notes: Represents any kind of event.
Extends: Object
Properties: Inherits all properties from Object.
Place URI: https://www.w3.org/ns/activitystreams#Place
Example 56
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Place",
  "name": "Work"
}
Example 57
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Place",
  "name": "Fresno Area",
  "latitude": 36.75,
  "longitude": 119.7667,
  "radius": 15,
  "units": "miles"
}
Notes: Represents a logical or physical location. See 5.3 Representing Places for additional information.
Extends: Object
Properties:

accuracy | altitude | latitude | longitude | radius | units

Inherits all properties from Object.
Mention URI: https://www.w3.org/ns/activitystreams#Mention
Example 58
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Mention of Joe by Carrie in her note",
  "type": "Mention",
  "href": "http://example.org/joe",
  "name": "Joe"
}
Notes: A specialized Link that represents an @mention.
Extends: Link
Properties: Inherits all properties from Link.
Profile URI: https://www.w3.org/ns/activitystreams#Profile
Example 59
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Profile",
  "summary": "Sally's Profile",
  "describes": {
    "type": "Person",
    "name": "Sally Smith"
  }
}
Notes: A Profile is a content object that describes another Object, typically used to describe Actor Type objects. The describes property is used to reference the object being described by the profile.
Extends: Object
Properties:

describes

Inherits all properties from Object.

Tombstone URI: https://www.w3.org/ns/activitystreams#Tombstone
Example 60
{
  "type": "OrderedCollection",
  "totalItems": 3,
  "name": "Vacation photos 2016",
  "orderedItems": [
    {
      "type": "Image",
      "id": "http://image.example/1"
    },
    {
      "type": "Tombstone",
      "formerType": "Image",
      "id": "http://image.example/2",
      "deleted": "2016-03-17T00:00:00Z"
    },
    {
      "type": "Image",
      "id": "http://image.example/3"
    }
  ]
}
Notes: A Tombstone represents a content object that has been deleted. It can be used in Collections to signify that there used to be an object at this position, but it has been deleted.
Extends: Object
Properties:

formerType | deleted

Inherits all properties from Object.

4. Properties

Base URI: https://www.w3.org/ns/activitystreams#.

The common properties include: actor | attachment | attributedTo | audience | bcc | bto | cc | context | current | first | generator | icon | id | image | inReplyTo | instrument | last | location | items | oneOf | anyOf | closed | origin | next | object | prev | preview | result | replies | tag | target | to | type | url | accuracy | altitude | content | name | duration | height | href | hreflang | partOf | latitude | longitude | mediaType | endTime | published | startTime | radius | rel | startIndex | summary | totalItems | units | updated | width | subject | relationship | describes formerType deleted

The "Domain" indicates the type of Object the property term applies to. The "Range" indicates the type of value the property term can have. Certain properties are marked as a "Subproperty Of" another term, meaning that the term is a specialization of the referenced term. For instance, actor is a subproperty of attributedTo. Properties marked as being "Functional" can have only one value. Items not marked as "Functional" can have multiple values.

Term Description Example
id URI: @id
Example 61
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "name": "Foo",
  "id": "http://example.org/foo"
}
Notes: Provides the globally unique identifier for an Object or Link.
Domain: Object | Link
Range: anyURI
Functional: True
type URI: @type
Example 62
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A foo",
  "type": "http://example.org/Foo"
}
Notes: Identifies the Object or Link type. Multiple values may be specified.
Domain: Object | Link
Range: anyURI
actor URI: https://www.w3.org/ns/activitystreams#actor
Example 63
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally offered the Foo object",
  "type": "Offer",
  "actor": "http://sally.example.org",
  "object": "http://example.org/foo"
}
Example 64
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally offered the Foo object",
  "type": "Offer",
  "actor": {
    "type": "Person",
    "id": "http://sally.example.org",
    "summary": "Sally"
  },
  "object": "http://example.org/foo"
}
Example 65
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally and Joe offered the Foo object",
  "type": "Offer",
  "actor": [
    "http://joe.example.org",
    {
      "type": "Person",
      "id": "http://sally.example.org",
      "name": "Sally"
    }
  ],
  "object": "http://example.org/foo"
}
Notes: Describes one or more entities that either performed or are expected to perform the activity. Any single activity can have multiple actors. The actor MAY be specified using an indirect Link.
Domain: Activity
Range: Object | Link
Subproperty Of: attributedTo
attachment URI: https://www.w3.org/ns/activitystreams#attachment
Example 66
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Note",
  "name": "Have you seen my cat?",
  "attachment": [
    {
      "type": "Image",
      "content": "This is what he looks like.",
      "url": "http://example.org/cat.jpeg"
    }
  ]
}
Notes: Identifies a resource attached or related to an object that potentially requires special handling. The intent is to provide a model that is at least semantically similar to attachments in email.
Domain: Object
Range: Object | Link
attributedTo URI: https://www.w3.org/ns/activitystreams#attributedTo
Example 67
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Image",
  "name": "My cat taking a nap",
  "url": "http://example.org/cat.jpeg",
  "attributedTo": [
    {
      "type": "Person",
      "name": "Sally"
    }
  ]
}
Example 68
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Image",
  "name": "My cat taking a nap",
  "url": "http://example.org/cat.jpeg",
  "attributedTo": [
    "http://joe.example.org",
    {
      "type": "Person",
      "name": "Sally"
    }
  ]
}
Notes: Identifies one or more entities to which this object is attributed. The attributed entities might not be Actors. For instance, an object might be attributed to the completion of another activity.
Domain: Link | Object
Range: Link | Object
audience URI: https://www.w3.org/ns/activitystreams#audience
Example 69
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "name": "Holiday announcement",
  "type": "Note",
  "content": "Thursday will be a company-wide holiday. Enjoy your day off!",
  "audience": {
    "type": "http://example.org/Organization",
    "name": "ExampleCo LLC"
  }
}
Notes: Identifies one or more entities that represent the total population of entities for which the object can considered to be relevant.
Domain: Object
Range: Object | Link
bcc URI: https://www.w3.org/ns/activitystreams#bcc
Example 70
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally offered a post to John",
  "type": "Offer",
  "actor": "http://sally.example.org",
  "object": "http://example.org/posts/1",
  "target": "http://john.example.org",
  "bcc": [ "http://joe.example.org" ]
}
Notes: Identifies one or more Objects that are part of the private secondary audience of this Object.
Domain: Object
Range: Object | Link
bto URI: https://www.w3.org/ns/activitystreams#bto
Example 71
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally offered a post to John",
  "type": "Offer",
  "actor": "http://sally.example.org",
  "object": "http://example.org/posts/1",
  "target": "http://john.example.org",
  "bto": [ "http://joe.example.org" ]
}
Notes: Identifies an Object that is part of the private primary audience of this Object.
Domain: Object
Range: Object | Link
cc URI: https://www.w3.org/ns/activitystreams#cc
Example 72
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally offered a post to John",
  "type": "Offer",
  "actor": "http://sally.example.org",
  "object": "http://example.org/posts/1",
  "target": "http://john.example.org",
  "cc": [ "http://joe.example.org" ]
}
Notes: Identifies an Object that is part of the public secondary audience of this Object.
Domain: Object
Range: Object | Link
context URI: https://www.w3.org/ns/activitystreams#context
Example 73
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Activities in context 1",
  "type": "Collection",
  "items": [
    {
      "type": "Offer",
      "actor": "http://sally.example.org",
      "object": "http://example.org/posts/1",
      "target": "http://john.example.org",
      "context": "http://example.org/contexts/1"
    },
    {
      "type": "Like",
      "actor": "http://joe.example.org",
      "object": "http://example.org/posts/2",
      "context": "http://example.org/contexts/1"
    }
  ]
}
Notes:

Identifies the context within which the object exists or an activity was performed.

The notion of "context" used is intentionally vague. The intended function is to serve as a means of grouping objects and activities that share a common originating context or purpose. An example could be all activities relating to a common project or event.

Domain: Object
Range: Object | Link
current URI: https://www.w3.org/ns/activitystreams#current
Example 74
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally's blog posts",
  "type": "Collection",
  "totalItems": 3,
  "current": "http://example.org/collection",
  "items": [
    "http://example.org/posts/1",
    "http://example.org/posts/2",
    "http://example.org/posts/3"
  ]
}
Example 75
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally's blog posts",
  "type": "Collection",
  "totalItems": 3,
  "current": {
    "type": "Link",
    "summary": "Most Recent Items",
    "href": "http://example.org/collection"
  },
  "items": [
    "http://example.org/posts/1",
    "http://example.org/posts/2",
    "http://example.org/posts/3"
  ]
}
Notes: In a paged Collection, indicates the page that contains the most recently updated member items.
Domain: CollectionPage
Range: CollectionPage | Link
Functional: True
first URI: https://www.w3.org/ns/activitystreams#first
Example 76
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally's blog posts",
  "type": "Collection",
  "totalItems": 3,
  "first": "http://example.org/collection?page=0"
}
Example 77
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally's blog posts",
  "type": "Collection",
  "totalItems": 3,
  "first": {
    "type": "Link",
    "summary": "First Page",
    "href": "http://example.org/collection?page=0"
  }
}
Notes: In a paged Collection, indicates the furthest preceeding page of items in the collection.
Domain: CollectionPage
Range: CollectionPage | Link
Functional: True
generator URI: https://www.w3.org/ns/activitystreams#generator
Example 78
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A simple note",
  "type": "Note",
  "content": "This is all there is.",
  "generator": {
    "type": "Application",
    "name": "Exampletron 3000"
  }
}
Notes: Identifies the entity (e.g. an application) that generated the object.
Domain: Object
Range: Object | Link
icon URI: https://www.w3.org/ns/activitystreams#icon
Example 79
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A simple note",
  "type": "Note",
  "content": "This is all there is.",
  "icon": {
    "type": "Image",
    "name": "Note icon",
    "url": "http://example.org/note.png",
    "width": 16,
    "height": 16
  }
}
Example 80
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A simple note",
  "type": "Note",
  "content": "A simple note",
  "icon": [
    {
      "type": "Image",
      "summary": "Note (16x16)",
      "url": "http://example.org/note1.png",
      "width": 16,
      "height": 16
    },
    {
      "type": "Image",
      "summary": "Note (32x32)",
      "url": "http://example.org/note2.png",
      "width": 32,
      "height": 32
    }
  ]
}
Notes: Indicates an entity that describes an icon for this object. The image should have an aspect ratio of one (horizontal) to one (vertical) and should be suitable for presentation at a small size.
Domain: Object
Range: Image | Link
image URI: https://www.w3.org/ns/activitystreams#image
Example 81
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "name": "A simple note",
  "type": "Note",
  "content": "This is all there is.",
  "image": {
    "type": "Image",
    "name": "A Cat",
    "url": "http://example.org/cat.png"
  }
}
Example 82
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "name": "A simple note",
  "type": "Note",
  "content": "This is all there is.",
  "image": [
    {
      "type": "Image",
      "name": "Cat 1",
      "url": "http://example.org/cat1.png"
    },
    {
      "type": "Image",
      "name": "Cat 2",
      "url": "http://example.org/cat2.png"
    }
  ]
}
Notes: Indicates an entity that describes an image for this object. Unlike the icon property, there are no aspect ratio or display size limitations assumed.
Domain: Object
Range: Image | Link
inReplyTo URI: https://www.w3.org/ns/activitystreams#inReplyTo
Example 83
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A simple note",
  "type": "Note",
  "content": "This is all there is.",
  "inReplyTo": {
    "summary": "Previous note",
    "type": "Note",
    "content": "What else is there?"
  }
}
Example 84
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A simple note",
  "type": "Note",
  "content": "This is all there is.",
  "inReplyTo": "http://example.org/posts/1"
}
Notes: Indicates one or more entities for which this object is considered a response.
Domain: Object
Range: Object | Link
instrument URI: https://www.w3.org/ns/activitystreams#instrument
Example 85
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally listened to a piece of music on the Acme Music Service",
  "type": "Listen",
  "actor": {
    "type": "Person",
    "name": "Sally"
  },
  "object": "http://example.org/foo.mp3",
  "instrument": {
    "type": "Service",
    "name": "Acme Music Service"
  }
}
Notes: Identifies one or more objects used (or to be used) in the completion of an Activity.
Domain: Activity
Range: Object | Link
last URI: https://www.w3.org/ns/activitystreams#last
Example 86
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A collection",
  "type": "Collection",
  "totalItems": 3,
  "last": "http://example.org/collection?page=1"
}
Example 87
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A collection",
  "type": "Collection",
  "totalItems": 5,
  "last": {
    "type": "Link",
    "summary": "Last Page",
    "href": "http://example.org/collection?page=1"
  }
}
Notes: In a paged Collection, indicates the furthest proceeding page of the collection.
Domain: CollectionPage
Range: CollectionPage | Link
Functional: True
location URI: https://www.w3.org/ns/activitystreams#location
Example 88
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Person",
  "name": "Sally",
  "location": {
    "name": "Over the Arabian Sea, east of Socotra Island Nature Sanctuary",
    "type": "Place",
    "longitude": 12.34,
    "latitude": 56.78,
    "altitude": 90,
    "units": "m"
  }
}
Notes: Indicates one or more physical or logical locations associated with the object.
Domain: Object
Range: Object | Link
items URI: https://www.w3.org/ns/activitystreams#items
Example 89
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally's notes",
  "type": "Collection",
  "totalItems": 2,
  "items": [
    {
      "type": "Note",
      "name": "Reminder for Going-Away Party"
    },
    {
      "type": "Note",
      "name": "Meeting 2016-11-17"
    }
  ]
}
Example 90
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally's notes",
  "type": "OrderedCollection",
  "totalItems": 2,
  "orderedItems": [
    {
      "type": "Note",
      "name": "Meeting 2016-11-17"
    },
    {
      "type": "Note",
      "name": "Reminder for Going-Away Party"
    }
  ]
}
Notes: Identifies the items contained in a collection. The items might be ordered or unordered.
Domain: Collection
Range: Object | Link | Ordered List of [Object | Link ]
oneOf URI: https://www.w3.org/ns/activitystreams#oneOf
Example 91
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Question",
  "name": "What is the answer?",
  "oneOf": [
    {
      "type": "Note",
      "name": "Option A"
    },
    {
      "type": "Note",
      "name": "Option B"
    }
  ]
}
Notes: Identifies an exclusive option for a Question. Use of oneOf implies that the Question can have only a single answer. To indicate that a Question can have multiple answers, use anyOf.
Domain: Question
Range: Object | Link
anyOf URI: https://www.w3.org/ns/activitystreams#anyOf
Example 92
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Question",
  "name": "What is the answer?",
  "anyOf": [
    {
      "type": "Note",
      "name": "Option A"
    },
    {
      "type": "Note",
      "name": "Option B"
    }
  ]
}
Notes: Identifies an inclusive option for a Question. Use of anyOf implies that the Question can have multiple answers. To indicate that a Question can have only one answer, use oneOf.
Domain: Question
Range: Object | Link
closed URI: https://www.w3.org/ns/activitystreams#closed
Example 93
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Question",
  "name": "What is the answer?",
  "closed": "2016-05-10T00:00:00Z"
}
Notes: Indicates that a question has been closed, and answers are no longer accepted.
Domain: Question
Range: Object | Link
origin URI: https://www.w3.org/ns/activitystreams#origin
Example 94
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally moved a post from List A to List B",
  "type": "Move",
  "actor": "http://sally.example.org",
  "object": "http://example.org/posts/1",
  "target": {
    "type": "Collection",
    "name": "List B"
  },
  "origin": {
    "type": "Collection",
    "name": "List A"
  }
}
Notes: Describes an indirect object of the activity from which the activity is directed. The precise meaning of the origin is the object of the English preposition "from". For instance, in the activity "John moved an item to List B from List A", the origin of the activity is "List A".
Domain: Activity
Range: Object | Link
next URI: https://www.w3.org/ns/activitystreams#next
Example 95
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Page 2 of Sally's blog posts",
  "type": "CollectionPage",
  "next": "http://example.org/collection?page=2",
  "items": [
    "http://example.org/posts/1",
    "http://example.org/posts/2",
    "http://example.org/posts/3"
  ]
}
Example 96
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Page 2 of Sally's blog posts",
  "type": "CollectionPage",
  "next": {
    "type": "Link",
    "name": "Next Page",
    "href": "http://example.org/collection?page=2"
  },
  "items": [
    "http://example.org/posts/1",
    "http://example.org/posts/2",
    "http://example.org/posts/3"
  ]
}
Notes: In a paged Collection, indicates the next page of items.
Domain: CollectionPage
Range: CollectionPage | Link
Functional: True
object URI: https://www.w3.org/ns/activitystreams#object
Example 97
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally liked a post",
  "type": "Like",
  "actor": "http://sally.example.org",
  "object": "http://example.org/posts/1"
}
Example 98
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Like",
  "actor": "http://sally.example.org",
  "object": {
    "type": "Note",
    "content": "A simple note"
  }
}
Example 99
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally liked a note",
  "type": "Like",
  "actor": "http://sally.example.org",
  "object": [
    "http://example.org/posts/1",
    {
      "type": "Note",
      "summary": "A simple note",
      "content": "That is a tree."
    }
  ]
}
Notes:

When used within an Activity, describes the direct object of the activity. For instance, in the activity "John added a movie to his wishlist", the object of the activity is the movie added.

When used within a Relationship describes the entity to which the subject is related.

Domain: Activity | Relationship
Range: Object | Link
prev URI: https://www.w3.org/ns/activitystreams#prev
Example 100
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Page 1 of Sally's blog posts",
  "type": "CollectionPage",
  "prev": "http://example.org/collection?page=1",
  "items": [
    "http://example.org/posts/1",
    "http://example.org/posts/2",
    "http://example.org/posts/3"
  ]
}
Example 101
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Page 1 of Sally's blog posts",
  "type": "CollectionPage",
  "prev": {
    "type": "Link",
    "name": "Previous Page",
    "href": "http://example.org/collection?page=1"
  },
  "items": [
    "http://example.org/posts/1",
    "http://example.org/posts/2",
    "http://example.org/posts/3"
  ]
}
Notes: In a paged Collection, identifies the previous page of items.
Domain: CollectionPage
Range: CollectionPage | Link
Functional: True
preview URI: https://www.w3.org/ns/activitystreams#preview
Example 102
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Video",
  "name": "Cool New Movie",
  "duration": "PT2H30M",
  "preview": {
    "type": "Video",
    "name": "Trailer",
    "duration": "PT1M",
    "url": {
      "href": "http://example.org/trailer.mkv",
      "mediaType": "video/mkv"
    }
  }
}
Notes: Identifies an entity that provides a preview of this object.
Domain: Link | Object
Range: Link | Object
result URI: https://www.w3.org/ns/activitystreams#result
Example 103
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally checked that her flight was on time",
  "type": ["Activity", "http://www.verbs.example/Check"],
  "actor": "http://sally.example.org",
  "object": "http://example.org/flights/1",
  "result": {
    "type": "http://www.types.example/flightstatus",
    "name": "On Time"
  }
}
Notes: Describes the result of the activity. For instance, if a particular action results in the creation of a new resource, the result property can be used to describe that new resource.
Domain: Activity
Range: Object | Link
replies URI: https://www.w3.org/ns/activitystreams#replies
Example 104
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A simple note",
  "type": "Note",
  "id": "http://www.test.example/notes/1",
  "content": "I am fine.",
  "replies": {
    "type": "Collection",
    "totalItems": 1,
    "items": [
      {
        "summary": "A response to the note",
        "type": "Note",
        "content": "I am glad to hear it.",
        "inReplyTo": "http://www.test.example/notes/1"
      }
    ]
  }
}
Notes: Identifies a Collection containing objects considered to be responses to this object.
Domain: Object
Range: Collection
Functional: True
tag URI: https://www.w3.org/ns/activitystreams#tag
Example 105
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Image",
  "summary": "Picture of Sally",
  "url": "http://example.org/sally.jpg",
  "tag": [
    {
      "type": "Person",
      "id": "http://sally.example.org",
      "name": "Sally"
    }
  ]
}
Notes: One or more "tags" that have been associated with an objects. A tag can be any kind of Object. The key difference between attachment and tag is that the former implies association by inclusion, while the latter implies associated by reference.
Domain: Object
Range: Object | Link
target URI: https://www.w3.org/ns/activitystreams#target
Example 106
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally offered the post to John",
  "type": "Offer",
  "actor": "http://sally.example.org",
  "object": "http://example.org/posts/1",
  "target": "http://john.example.org"
}
Example 107
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally offered the post to John",
  "type": "Offer",
  "actor": "http://sally.example.org",
  "object": "http://example.org/posts/1",
  "target": {
    "type": "Person",
    "name": "John"
  }
}
Notes: Describes the indirect object, or target, of the activity. The precise meaning of the target is largely dependent on the type of action being described but will often be the object of the English preposition "to". For instance, in the activity "John added a movie to his wishlist", the target of the activity is John's wishlist. An activity can have more than one target.
Domain: Activity
Range: Object | Link
to URI: https://www.w3.org/ns/activitystreams#to
Example 108
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally offered the post to John",
  "type": "Offer",
  "actor": "http://sally.example.org",
  "object": "http://example.org/posts/1",
  "target": "http://john.example.org",
  "to": [ "http://joe.example.org" ]
}
Notes: Identifies an entity considered to be part of the public primary audience of an Object
Domain: Object
Range: Object | Link
url URI: https://www.w3.org/ns/activitystreams#url
Example 109
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Document",
  "name": "4Q Sales Forecast",
  "url": "http://example.org/4q-sales-forecast.pdf"
}
Example 110
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Document",
  "name": "4Q Sales Forecast",
  "url": {
    "type": "Link",
    "href": "http://example.org/4q-sales-forecast.pdf"
  }
}
Example 111
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Document",
  "name": "4Q Sales Forecast",
  "url": [
    {
      "type": "Link",
      "href": "http://example.org/4q-sales-forecast.pdf",
      "mediaType": "application/pdf"
    },
    {
      "type": "Link",
      "href": "http://example.org/4q-sales-forecast.html",
      "mediaType": "text/html"
    }
  ]
}
Notes: Identifies one or more links to representations of the object
Domain: Object
Range: xsd:anyURI | Link
accuracy URI: https://www.w3.org/ns/activitystreams#accuracy
Example 112
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "name": "Liu Gu Lu Cun, Pingdu, Qingdao, Shandong, China",
  "type": "Place",
  "latitude": 36.75,
  "longitude": 119.7667,
  "accuracy": 94.5
}
Notes: Indicates the accuracy of position coordinates on a Place objects. Expressed in properties of percentage. e.g. "94.0" means "94.0% accurate".
Domain: Place
Range: xsd:float [>= 0.0f, <= 100.0f]
Functional: True
altitude URI: https://www.w3.org/ns/activitystreams#altitude
Example 113
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Place",
  "name": "Fresno Area",
  "altitude": 15.0,
  "latitude": 36.75,
  "longitude": 119.7667,
  "units": "miles"
}
Notes: Indicates the altitude of a place. The measurement units is indicated using the units property. If units is not specified, the default is assumed to be "m" indicating meters.
Domain: Object
Range: xsd:float
Functional: True
content URI: https://www.w3.org/ns/activitystreams#content
Example 114
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A simple note",
  "type": "Note",
  "content": "A <em>simple</em> note"
}
Example 115
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A simple note",
  "type": "Note",
  "contentMap": {
    "en": "A <em>simple</em> note",
    "es": "Una nota <em>sencilla</em>",
    "zh-Hans": "一段<em>简单的</em>笔记"
  }
}
Example 116
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A simple note",
  "type": "Note",
  "mediaType": "text/markdown",
  "content": "## A simple note\nA simple markdown `note`"
}
Notes:

The content or textual representation of the Object encoded as a JSON string. By default, the value of content is HTML. The mediaType property can be used in the object to indicate a different content type.

The content MAY be expressed using multiple language-tagged values.

Domain: Object
Range: xsd:string | rdf:langString
name URI: https://www.w3.org/ns/activitystreams#name
Example 117
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Note",
  "name": "A simple note"
}
Example 118
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Note",
  "nameMap": {
    "en": "A simple note",
    "es": "Una nota sencilla",
    "zh-Hans": "一段简单的笔记"
  }
}
Notes: A simple, human-readable, plain-text name for the object. HTML markup MUST NOT be included. The name MAY be expressed using multiple language-tagged values.
Domain: Object | Link
Range: xsd:string | rdf:langString
duration URI: https://www.w3.org/ns/activitystreams#duration
Example 119
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Video",
  "name": "Birds Flying",
  "url": "http://example.org/video.mkv",
  "duration": "PT2H"
}
Notes: When the object describes a time-bound resource, such as an audio or video, a meeting, etc, the duration property indicates the object's approximate duration. The value MUST be expressed as an xsd:duration as defined by [ xmlschema11-2], section 3.3.6 (e.g. a period of 5 seconds is represented as "PT5S").
Domain: Object
Range: xsd:duration
Functional: True
height URI: https://www.w3.org/ns/activitystreams#height
Example 120
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Link",
  "href": "http://example.org/image.png",
  "height": 100,
  "width": 100
}
Notes: On a Link, specifies a hint as to the rendering height in device-independent pixels of the linked resource.
Domain: Link
Range: xsd:nonNegativeInteger
Functional: True
href URI: https://www.w3.org/ns/activitystreams#href
Example 121
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Link",
  "href": "http://example.org/abc",
  "mediaType": "text/html",
  "name": "Previous"
}
Notes: The target resource pointed to by a Link.
Domain: Link
Range: xsd:anyURI
Functional: True
hreflang URI: https://www.w3.org/ns/activitystreams#hreflang
Example 122
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Link",
  "href": "http://example.org/abc",
  "hreflang": "en",
  "mediaType": "text/html",
  "name": "Previous"
}
Notes: Hints as to the language used by the target resource. Value MUST be a [BCP47] Language-Tag.
Domain: Link
Range: [BCP47] Language Tag
Functional: True
partOf URI: https://www.w3.org/ns/activitystreams#partOf
Example 123
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Page 1 of Sally's notes",
  "type": "CollectionPage",
  "id": "http://example.org/collection?page=1",
  "partOf": "http://example.org/collection",
  "items": [
    {
      "type": "Note",
      "name": "Pizza Toppings to Try"
    },
    {
      "type": "Note",
      "name": "Thought about California"
    }
  ]
}
Notes: Identifies the Collection to which a CollectionPage objects items belong.
Domain: CollectionPage
Range: Link | Collection
Functional: True
latitude URI: https://www.w3.org/ns/activitystreams#latitude
Example 124
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Place",
  "name": "Fresno Area",
  "latitude": 36.75,
  "longitude": 119.7667,
  "radius": 15,
  "units": "miles"
}
Notes: The latitude of a place
Domain: Place
Range: xsd:float
Functional: True
longitude URI: https://www.w3.org/ns/activitystreams#longitude
Example 125
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Place",
  "name": "Fresno Area",
  "latitude": 36.75,
  "longitude": 119.7667,
  "radius": 15,
  "units": "miles"
}
Notes: The longitude of a place
Domain: Place
Range: xsd:float
Functional: True
mediaType URI: https://www.w3.org/ns/activitystreams#mediaType
Example 126
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Link",
  "href": "http://example.org/abc",
  "hreflang": "en",
  "mediaType": "text/html",
  "name": "Next"
}
Notes:

When used on a Link, identifies the MIME media type of the referenced resource.

When used on an Object, identifies the MIME media type of the value of the content property. If not specified, the content property is assumed to contain text/html content.

Domain: Link | Object
Range: MIME Media Type
Functional: True
endTime URI: https://www.w3.org/ns/activitystreams#endTime
Example 127
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Event",
  "name": "Going-Away Party for Jim",
  "startTime": "2014-12-31T23:00:00-08:00",
  "endTime": "2015-01-01T06:00:00-08:00"
}
Notes: The date and time describing the actual or expected ending time of the object. When used with an Activity object, for instance, the endTime property specifies the moment the activity concluded or is expected to conclude.
Domain: Object
Range: xsd:dateTime
Functional: True
published URI: https://www.w3.org/ns/activitystreams#published
Example 128
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "A simple note",
  "type": "Note",
  "content": "Fish swim.",
  "published": "2014-12-12T12:12:12Z"
}
Notes: The date and time at which the object was published
Domain: Object
Range: xsd:dateTime
Functional: True
startTime URI: https://www.w3.org/ns/activitystreams#startTime
Example 129
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Event",
  "name": "Going-Away Party for Jim",
  "startTime": "2014-12-31T23:00:00-08:00",
  "endTime": "2015-01-01T06:00:00-08:00"
}
Notes: The date and time describing the actual or expected starting time of the object. When used with an Activity object, for instance, the startTime property specifies the moment the activity began or is scheduled to begin.
Domain: Object
Range: xsd:dateTime
Functional: True
radius URI: https://www.w3.org/ns/activitystreams#radius
Example 130
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Place",
  "name": "Fresno Area",
  "latitude": 36.75,
  "longitude": 119.7667,
  "radius": 15,
  "units": "miles"
}
Notes: The radius from the given latitude and longitude for a Place. The units is expressed by the units property. If units is not specified, the default is assumed to be "m" indicating "meters".
Domain: Place
Range: xsd:float [>= 0.0f]
Functional: True
rel URI: https://www.w3.org/ns/activitystreams#rel
Example 131
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Link",
  "href": "http://example.org/abc",
  "hreflang": "en",
  "mediaType": "text/html",
  "name": "Preview",
  "rel": ["canonical", "preview"]
}
Notes:

A link relation associated with a Link. The value MUST conform to both the [HTML5] and [RFC5988] "link relation" definitions.

In the [HTML5], any string not containing the "space" U+0020, "tab" (U+0009), "LF" (U+000A), "FF" (U+000C), "CR" (U+000D) or "," (U+002C) characters can be used as a valid link relation.

Domain: Link
Range: [RFC5988] or [HTML5] Link Relation
startIndex URI: https://www.w3.org/ns/activitystreams#startIndex
Example 132
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Page 1 of Sally's notes",
  "type": "OrderedCollectionPage",
  "startIndex": 0,
  "orderedItems": [
    {
      "type": "Note",
      "name": "Density of Water"
    },
    {
      "type": "Note",
      "name": "Air Mattress Idea"
    }
  ]
}
Notes: A non-negative integer value identifying the relative position within the logical view of a strictly ordered collection.
Domain: OrderedCollectionPage
Range: xsd:nonNegativeInteger
Functional: True
summary URI: https://www.w3.org/ns/activitystreams#summary
Example 133
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "name": "Cane Sugar Processing",
  "type": "Note",
  "summary": "A simple <em>note</em>"
}
Example 134
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "name": "Cane Sugar Processing",
  "type": "Note",
  "summaryMap": {
    "en": "A simple <em>note</em>",
    "es": "Una <em>nota</em> sencilla",
    "zh-Hans": "一段<em>简单的</em>笔记"
  }
}
Notes: A natural language summarization of the object encoded as HTML. Multiple language tagged summaries MAY be provided.
Domain: Object
Range: xsd:string | rdf:langString
totalItems URI: https://www.w3.org/ns/activitystreams#totalItems
Example 135
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally's notes",
  "type": "Collection",
  "totalItems": 2,
  "items": [
    {
      "type": "Note",
      "name": "Which Staircase Should I Use"
    },
    {
      "type": "Note",
      "name": "Something to Remember"
    }
  ]
}
Notes: A non-negative integer specifying the total number of objects contained by the logical view of the collection. This number might not reflect the actual number of items serialized within the Collection object instance.
Domain: Collection
Range: xsd:nonNegativeInteger
Functional: True
units URI: https://www.w3.org/ns/activitystreams#units
Example 136
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Place",
  "name": "Fresno Area",
  "latitude": 36.75,
  "longitude": 119.7667,
  "radius": 15,
  "units": "miles"
}
Notes: Specifies the measurement units for the radius and altitude properties on a Place object. If not specified, the default is assumed to be "m" for "meters".
Domain: Place
Range: "cm" | " feet" | " inches" | " km" | " m" | " miles" | xsd:anyURI
Functional: True
updated URI: https://www.w3.org/ns/activitystreams#updated
Example 137
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "name": "Cranberry Sauce Idea",
  "type": "Note",
  "content": "Mush it up so it does not have the same shape as the can.",
  "updated": "2014-12-12T12:12:12Z"
}
Notes: The date and time at which the object was updated
Domain: Object
Range: xsd:dateTime
Functional: True
width URI: https://www.w3.org/ns/activitystreams#width
Example 138
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Link",
  "href": "http://example.org/image.png",
  "height": 100,
  "width": 100
}
Notes: On a Link, specifies a hint as to the rendering width in device-independent pixels of the linked resource.
Domain: Link
Range: xsd:nonNegativeInteger
Functional: True
subject URI: https://www.w3.org/ns/activitystreams#subject
Example 139
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally is a contact of John's",
  "type": "Relationship",
  "subject": {
    "type": "Person",
    "name": "Sally"
  },
  "relationship": "IsContact",
  "object": {
    "type": "Person",
    "name": "John"
  }
}
Notes: On a Relationship object, the subject property identifies one of the connected individuals. For instance, for a Relationship object describing "John is related to Sally", subject would refer to John.
Domain: Relationship
Range: Link | Object
Functional: True
relationship URI: https://www.w3.org/ns/activitystreams#relationship
Example 140
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally is a contact of John's",
  "type": "Relationship",
  "subject": {
    "type": "Person",
    "name": "Sally"
  },
  "relationship": "IsContact",
  "object": {
    "type": "Person",
    "name": "John"
  }
}
Notes: On a Relationship object, the relationship property identifies the kind of relationship that exists between subject and object.
Domain: Relationship
Range: Object
describes URI: https://www.w3.org/ns/activitystreams#describes
Example 141
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "Sally's profile",
  "type": "Profile",
  "describes": {
    "type": "Person",
    "name": "Sally"
  },
  "url": "http://sally.example.org"
}
Notes: On a Profile object, the describes property identifies the object described by the Profile.
Domain: Profile
Range: Object
Functional: True
formerType URI: https://www.w3.org/ns/activitystreams#formerType
Example 142
{
"@context": "https://www.w3.org/ns/activitystreams",
"summary": "This image has been deleted",
"type": "Tombstone",
"formerType": "Image",
"url": "http://example.org/image/2"
}
Notes: On a Tombstone object, the formerType property identifies the type of the object that was deleted.
Domain: Tombstone
Range: Object
Functional: False
deleted URI: https://www.w3.org/ns/activitystreams#deleted
Example 143
{
"@context": "https://www.w3.org/ns/activitystreams",
"summary": "This image has been deleted",
"type": "Tombstone",
"deleted": "2016-05-03T00:00:00Z"
}
Notes: On a Tombstone object, the deleted property is a timestamp for when the object was deleted.
Domain: Tombstone
Range: Object
Functional: True

5. Implementation Notes

5.1 Audience Targeting

Conceptually, every Object has both a Primary and Secondary audience. The Primary audience consists of those entities directly involved or owning the object. The Secondary audience consists of the collection of entities sharing an interest in the object but who might not be directly involved (e.g."followers").

For instance, suppose a social network of three individuals: Bob, Joe and Jane. Bob and Joe are each friends with Jane but are not friends with one another. Bob has chosen to "follow" activities for which Jane is directly involved. Jane shares a file with Joe.

In this example, Jane and Joe are each directly involved in the file sharing activity and together make up the Primary Audience for that event. Bob, having an interest in activities involving Jane, is the Secondary Audience. Knowing this, a system that produces or consumes the activity can intelligently notify each person of the event.

While there are means (based on the action type, actor, object and target of the activity) to infer the primary audience for many types of activities, heuristics do not work in every case and do not provide a means of identifying the secondary audience. The to, cc, bto and bcc properties MAY be used within an Object to explicitly identify the Primary and Secondary audiences.

The prototypical use case for an Object containing these properties is the publication and redistribution of objects through an intermediary. That is, an event source generates the object and publishes it to the intermediary which determines a subset of items to display to specific individual users or groups. Such a determination can be made, in part, by identifying the Primary and Secondary Audiences for each object.

When the event source generates the object and specifies values for the to and cc fields, the intermediary SHOULD redistribute that object with the values of those fields intact, allowing any processor to see who the object has been targeted to. This is precisely the same model used by the to and cc fields in email systems.

There are situations, however, in which disclosing the identity of specific members of the audience may be inappropriate. For instance, a user may not wish to let other users know that they are interested in various topics, individuals or types of events. To support this option, an implementation generating an object MAY use the bto and bcc properties to list entities to whom the object should be privately targeted. When an intermediary receives an object containing these properties, it MUST remove those values prior to redistributing the object. The intent is that systems MUST consider entities listed within the bto and bcc properties as part of the Primary and Secondary audience but MUST NOT disclose that fact to any other party.

Audience targeting information included within an Object only describes the intent of the object creator. With clear exception given to the appropriate handling of bto and bcc, this specification leaves it up to implementations to determine how the audience targeting information is used.

5.1.1 Audience and Context

This section is non-normative.

Activities are rarely isolated events. Often, multiple individual activities will be performed around a similar context or audience. For instance, a collaborators working on a shared project might perform multiple related activities in the process of achieving some goal. Such activities can be logically grouped together using the context property, and scoped to a particular audience using the audience property.

For instance, the following shows two related activities that share a common context and audience:

Example 144
{
 "@context": "https://www.w3.org/ns/activitystreams",
 "summary": "Activities in Project XYZ",
 "type": "Collection",
 "items": [
   {
     "summary": "Sally created a note",
     "type": "Create",
     "id": "http://activities.example.com/1",
     "actor": "http://sally.example.org",
     "object": {
      "summary": "A note",
       "type": "Note",
       "id": "http://notes.example.com/1",
       "content": "A note"
     },
     "context": {
       "type": "http://example.org/Project",
       "name": "Project XYZ"
     },
     "audience": {
       "type": "Group",
       "name": "Project XYZ Working Group"
     },
     "to": "http://john.example.org"
   },
   {
     "summary": "John liked Sally's note",
     "type": "Like",
     "id": "http://activities.example.com/1",
     "actor": "http://john.example.org",
     "object": "http://notes.example.com/1",
     "context": {
       "type": "http://example.org/Project",
       "name": "Project XYZ"
     },
     "audience": {
       "type": "Group",
       "name": "Project XYZ Working Group"
     },
     "to": "http://sally.example.org"
   }
 ]
}

5.2 Representing Relationships Between Entities

The Relationship object is used to represent relationships between individuals. It can be used, for instance, to describe that one person is a friend of another, or that one person is a member of a particular organization. The intent of modeling Relationship in this way is to allow descriptions of activities that operate on the relationships in general, and to allow representation of Collections of relationships.

For instance, many social systems have a notion of a "friends list". These are the collection of individuals that are directly connected within a person's social graph. Suppose we have a user, Sally, with direct relationships to users Joe and Jane. Sally follows Joe's updates while Sally and Jane have a mutual relationship.

Using the Relationship object, we can model these relationships as:

Example 145
{
"@context": "https://www.w3.org/ns/activitystreams",
"summary": "Sally's friends list",
"type": "Collection",
"items": [
{
 "summary": "Sally is following Joe",
 "type": "Relationship",
 "subject": {
   "type": "Person",
   "name": "Sally"
 },
 "relationship": "IsFollowing",
 "object": {
   "type": "Person",
   "name": "Joe"
 }
},
{
 "summary": "Sally is a contact of Jane",
 "type": "Relationship",
 "subject": {
   "type": "Person",
   "name": "Sally"
 },
 "relationship": "IsContact",
 "object": {
   "type": "Person",
   "name": "Jane"
 }
}
]
}

The relationship property specifies the kind of relationship that exists between the two individuals identified by the subject and object properties. Used together, these three properties form what is commonly known as a " reified statement" where subject identifies the subject, relationship identifies the predicate, and object identifies the object.

While use of reified statements can be problematic and confusing in certain situations, their use within the Activity Streams vocabulary to describe relationships provides a straightforward mechanism of describing changes to an individual's social graph. For instance, to indicate that Sally has created a new relationship to user Matt, an implementer can use the Relationship object together with the Create activity:

Example 146
{
"@context": "https://www.w3.org/ns/activitystreams",
"summary": "Sally became a friend of Matt",
"type": "Create",
"actor": "http://sally.example.org",
"object": {
"type": "Relationship",
"subject": "http://sally.example.org",
"relationship": "IsContact",
"object": "http://matt.example.org",
"startTime": "2015-04-21T12:34:56"
}
}

Additionally, modeling the relationship in this way allows implementers to articulate additional properties of the relationship itself. For instance, the date and time at which the relationship began or ended.

The Activity Streams vocabulary defines four normative values for use with the relationship property.

Implementations may reuse existing vocabularies that have been developed for the purpose of describing relationships, or create their own guided by requirements of their particular implementation. Existing vocabularies include the " Friend of a Friend" and " Relationship" vocabularies.

5.2.1 Modeling "friend requests"

This section is non-normative.

One common use case for many social platforms is the establishment of symmetrical "friend" relationships, in which one user initially extends a request to another user to establish a new connection. Once the connection is made, both users automatically begin receiving notifications about activities performed by the other, and the established relationship becomes visible in either user's "friends list".

The initial "friend request" can be modeled by composing the Offer and Relationship object types as in the following example:

Example 147
{
"@context": "https://www.w3.org/ns/activitystreams",
"id": "http://example.org/connection-requests/123",
"summary": "Sally requested to be a friend of John",
"type": "Offer",
"actor": "acct:sally@example.org",
"object": {
"summary": "Sally and John's friendship",
"id": "http://example.org/connections/123",
"type": "Relationship",
"subject": "acct:sally@example.org",
"relationship": "IsContact",
"object": "acct:john@example.org"
},
"target": "acct:john@example.org"
}

Assuming the "friend request" is accepted, the remaining steps in this common application scenario can be represented as a set of distinct activities:

Example 148
{
"@context": "https://www.w3.org/ns/activitystreams",
"summary": "Sally and John's relationship history",
"type": "Collection",
"items": [
{
 "summary": "John accepted Sally's friend request",
 "id": "http://example.org/activities/122",
 "type": "Accept",
 "actor": "acct:john@example.org",
 "object": "http://example.org/connection-requests/123",
 "inReplyTo": "http://example.org/connection-requests/123",
 "context": "http://example.org/connections/123",
 "result": [
   "http://example.org/activities/123",
   "http://example.org/activities/124",
   "http://example.org/activities/125",
   "http://example.org/activities/126"
 ]
},
{
 "summary": "John followed Sally",
 "id": "http://example.org/activities/123",
 "type": "Follow",
 "actor": "acct:john@example.org",
 "object": "acct:sally@example.org",
 "context": "http://example.org/connections/123"
},
{
 "summary": "Sally followed John",
 "id": "http://example.org/activities/124",
 "type": "Follow",
 "actor": "acct:sally@example.org",
 "object": "acct:john@example.org",
 "context": "http://example.org/connections/123"
},
{
 "summary": "John added Sally to his friends list",
 "id": "http://example.org/activities/125",
 "type": "Add",
 "actor": "acct:john@example.org",
 "object": "http://example.org/connections/123",
 "target": {
   "type": "Collection",
   "summary": "John's Connections"
 },
 "context": "http://example.org/connections/123"
},
{
 "summary": "Sally added John to her friends list",
 "id": "http://example.org/activities/126",
 "type": "Add",
 "actor": "acct:sally@example.org",
 "object": "http://example.org/connections/123",
 "target": {
   "type": "Collection",
   "summary": "Sally's Connections"
 },
 "context": "http://example.org/connections/123"
}
]
}

As illustrated in this example, accepting the "friend request" results in four additional activities including: John following Sally, Sally following John, John adding the relationship with Sally to his collection of Connections, and Sally adding the relationship with John to her collection of Connections.

In this example,

  1. The optional result property is used within the Accept activity to identify the additional activities that occurred as a result of the accept.
  2. The optional context property is used to relate the various activities back to a common reference point, which in this example is the relationship being established. The context allows an implementation to efficiently group related activities together for display or analytic purposes.

5.3 Representing Places

This section is non-normative.

The Place object is used to represent both physical and logical locations. While numerous existing vocabularies exist for describing locations in a variety of ways, inconsistencies and incompatibilities between those vocabularies make it difficult to achieve appropriate interoperability between implementations. The Place object is included within the Activity vocabulary to provide a minimal, interoperable starting point for describing locations consistently across Activity Streams 2.0 implementations.

The Place object is intentionally flexible. It can, for instance, be used to identify a location simply by name:

Example 149
{
"@context": "https://www.w3.org/ns/activitystreams",
"type": "Place",
"name": "San Francisco, CA"
}

Or, by longitude and latitude:

Example 150
{
"@context": "https://www.w3.org/ns/activitystreams",
"type": "Place",
"name": "San Francisco, CA",
"longitude": "122.4167",
"latitude": "37.7833"
}

The Place object can also describe an area around a given point using the radius property, the altitude of the location, and a degree of accuracy.

While publishers are not required to use these specific properties and MAY make use of other mechanisms for describing locations, consuming implementations that support the Place object MUST support the use of these properties.

5.4 Representing Questions

This section is non-normative.

The Question object can be used to express various types of inquiries.

For instance, simple open-ended questions similar to those posted to crowd-sourced question and answer websites:

Example 151
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "name": "A question about robots",
  "id": "http://help.example.org/question/1",
  "type": "Question",
  "content": "I'd like to build a robot to feed my cat. Should I use Arduino or Raspberry Pi?"
}

Multiple-choice questions or "polls" are also supported using either the oneOf or anyOf properties:

Example 152
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "id": "http://polls.example.org/question/1",
  "name": "A question about robots",
  "type": "Question",
   "content": "I'd like to build a robot to feed my cat. Which platform is best?",
   "oneOf": [
     {"name": "arduino"},
     {"name": "raspberry pi"}
   ]
 }

Responses to questions are expressed as Objects containing an inReplyto property referencing the Question.

Example 153
{
 "@context": "https://www.w3.org/ns/activitystreams",
 "attributedTo": "http://sally.example.org",
 "inReplyTo": "http://polls.example.org/question/1",
 "name": "arduino"
}

Because Question objects are also instances of Activity, the result property can be used to express the results or outcome of the Question (as appropriate):

Example 154
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "name": "A question about robots",
  "id": "http://polls.example.org/question/1",
  "type": "Question",
   "content": "I'd like to build a robot to feed my cat. Which platform is best?",
   "oneOf": [
     {"name": "arduino"},
     {"name": "raspberry pi"}
   ],
   "replies": {
     "type": "Collection",
     "totalItems": 3,
     "items": [
       {
         "attributedTo": "http://sally.example.org",
         "inReplyTo": "http://polls.example.org/question/1",
         "name": "arduino"
       },
       {
         "attributedTo": "http://joe.example.org",
         "inReplyTo": "http://polls.example.org/question/1",
         "name": "arduino"
       },
       {
         "attributedTo": "http://john.example.org",
         "inReplyTo": "http://polls.example.org/question/1",
         "name": "raspberry pi"
       }
     ]
   },
   "result": {
     "type": "Note",
     "content": "Users are favoriting &quot;arduino&quot; by a 33% margin."
   }
 }

5.5 Inverse Activities and "Undo"

This section is non-normative.

Several of the core Activity types are defined as natural inversions of one another. These include:

It is important to note that these types of activities are semantically distinct from one another and have no direct relationship on the other. That is, for example, if an actor "likes" a note at one point in time then later "dislikes" it, the "dislike" activity does not "undo" or negate out the prior "like".

The appropriate interpretation for the following is that Sally first liked, then later disliked John's note:

Example 155
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "summary": "History of John's note",
  "type": "Collection",
  "items": [
    {
      "summary": "Sally liked John's note",
      "type": "Like",
      "actor": "http://sally.example.org",
      "id": "http://activities.example.com/1",
      "published": "2015-11-12T12:34:56Z",
      "object": {
        "summary": "John's note",
        "type": "Note",
        "id": "http://notes.example.com/1",
        "attributedTo": "http://john.example.org",
        "content": "My note"
      }
    },
    {
      "summary": "Sally disliked John's note",
      "type": "Dislike",
      "actor": "http://sally.example.org",
      "id": "http://activities.example.com/2",
      "published": "2015-12-11T21:43:56Z",
      "object": {
        "summary": "John's note",
        "type": "Note",
        "id": "http://notes.example.com/1",
        "attributedTo": "http://john.example.org",
        "content": "My note"
      }
    }
  ]
 }

The Undo activity type is defined to provide the specific ability to undo or cancel out a prior activity. The appropriate interpretation for the following, then, is that Sally liked John's note at one point but has explicitly redacted that like later on.

Example 156
{
 "@context": "https://www.w3.org/ns/activitystreams",
 "summary": "History of John's note",
 "type": "Collection",
 "items": [
   {
     "summary": "Sally liked John's note",
     "type": "Like",
     "id": "http://activities.example.com/1",
     "actor": "http://sally.example.org",
     "published": "2015-11-12T12:34:56Z",
     "object": {
       "summary": "John's note",
       "type": "Note",
       "id": "http://notes.example.com/1",
       "attributedTo": "http://john.example.org",
       "content": "My note"
     }
   },
   {
     "summary": "Sally no longer likes John's note",
     "type": "Undo",
     "id": "http://activities.example.com/2",
     "actor": "http://sally.example.org",
     "published": "2015-12-11T21:43:56Z",
     "object": "http://activities.example.com/1"
   }
 ]
}

The end result of the former example is that Sally has indicated that she changed her opinion about John's note and now dislikes it, while in the latter example she currently neither likes or dislikes it.

5.6 Mentions, Tags and Other Common Social Microsyntaxes

This section is non-normative.

Many social software systems use special text-based microsyntaxes that allow users to define special addressing for notifications, linking, or categorization within objects. For example, including text such as "@username" within an object's content will often route the object to a special "mentions" or "inbox" stream for a particular user. Likewise, including text such as " #topic" within the object's content will often mark the object as being related to the topic "topic". Such mechanisms are commonly referred to as "mentions" and "hashtags", respectively.

While such microsyntaxes MAY be used within the values of the content, name, and summary properties on an Activity Streams Object, implementations SHOULD NOT be required to parse the values of those properties in order to determine the appropriate routing of notifications, categorization or linking between objects. Instead, publishers SHOULD make appropriate use of the vocabulary terms provided specifically for these purposes.

For example, suppose that an author wishes to send a note of thanks to another user named "@sally" with a hashtag of "#givingthanks". A typical way this message would appear within the content of a note is shown below:

Fig. 1 A simple note with a mention an a hashtag:
 "Thank you @sally for all your hard work! #givingthanks" 

A typical social software implementation would typically render such a content such that "@sally" is replaced with a hyperlink to "@sally"'s social profile page and "#givingthanks" is replaced with a hyperlink to a listing of other notes that have been "tagged" with the same topic. Most implementations would also send a special notification to sally letting her know that a note mentioning her has been created.

The following illustrates an equivalent Activity Streams Note object:

Example 157
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "name": "A thank-you note",
  "type": "Note",
  "content": "Thank you <a href='http://sally.example.org'>@sally</a>
      for all your hard work!
      <a href='http://example.org/tags/givingthanks'>#givingthanks</a>",
  "to": {
    "name": "Sally",
    "type": "Person",
    "id": "http://sally.example.org"
  },
  "tag": {
    "id": "http://example.org/tags/givingthanks",
    "name": "#givingthanks"
  }
}

The to property indicates that the user "@sally" is to be considered part of the primary audience of the note and should therefore receive notification. The tag property associates the Note with a reference to " http://example.org/tags/givingthanks". Note that the content still includes the "@sally" and " #givingthanks" microsyntaxes but that consuming implementations are not required to parse those in order to make the appropriate associations.

In the case a publisher wishes to indicate a mention without an associated notification, the publisher can use the Mention object type as a value of the tag property.

Example 158
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "name": "A thank-you note",
  "type": "Note",
  "content": "Thank you @sally for all your hard work! #givingthanks",
  "tag": [
    {
      "type": "Mention",
      "href": "http://example.org/people/sally",
      "name": "@sally"
    },
    {
      "id": "http://example.org/tags/givingthanks",
      "name": "#givingthanks"
    }
  ]
}

5.7 Origin and Target

The origin and target properties of an Activity respectively identify the entities from which and to which the action is directed. For instance, in the English statement, "Sally moved the file from Folder A to Folder B", the origin is "Folder A" and the target is "Folder B". This activity is illustrated in the example below:

Example 159
{
    "@context": "https://www.w3.org/ns/activitystreams",
    "summary": "Sally moved the sales figures from Folder A to Folder B",
    "type": "Move",
    "actor": "http://sally.example.org",
    "object": {
      "type": "Document",
      "name": "sales figures"
    },
    "origin": {
      "type": "Collection",
      "name": "Folder A"
    },
    "target": {
      "type": "Collection",
      "name": "Folder B"
    }
  }

The origin property is applicable to any type of activity for which the English preposition "from" can be considered applicable in the sense of identifying the origin, source or provenance of the activity's object.

The target property is applicable to any type of activity for which the English preposition "to" can be considered applicable in the sense of identifying the indirect object or destination of the activity's object.

5.8 Activity Type Motivating Use Cases

This section is non-normative.

The Activity types defined in this vocabulary have been primarily selected to address the commonly implemented social use cases described below.

5.8.1 Content Management

The Content Management use case primarily deals with activities that involve the creation, modification or deletion of content. This includes, for instance, activities such as "John created a new note", "Sally updated an article", and "Joe deleted the photo".

Relevant Activities:

5.8.2 Collection Management

The Collection Management use case primarily deals with activities involving the management of content within collections. Examples of collections include things like folders, albums, friend lists, etc. This includes, for instance, activities such as "Sally added a file to Folder A", "John moved the file from Folder A to Folder B", etc.

Relevant Activities:

5.8.3 Reactions

The Reactions use case primarily deals with reactions to content. This can include activities such as liking or disliking content, ignoring updates, flagging content as being inappropriate, accepting or rejecting objects, etc.

Relevant Activities:

5.8.4 Event RSVP

The Event RSVP use case primarily deals with invitations to events and RSVP type responses.

Relevant Activities:

5.8.5 Group Management

The Group Management use case primarily deals with management of groups. It can include, for instance, activities such as "John added Sally to Group A", "Sally joined Group A", "Joe left Group A", etc.

Relevant Activities:

5.8.6 Content Experience

The Content Experience use case primarily deals with describing activities involving listening to, reading, or viewing content. For instance, "Sally read the article", "Joe listened to the song".

Relevant Activities:

5.8.7 Geo-Social Events

The Geo-Social Events use case primarily deals with activities involving geo-tagging type activities. For instance, it can include activities such as "Joe arrived at work", "Sally left work", and "John is travel from home to work".

Relevant Activities:

5.8.8 Notification

The Notification use case primarily deals with calling attention to particular objects or notifications.

Relevant Activities:

5.8.9 Questions

the Questions use case primarily deals with representing inquiries of any type. See for more information.

Relevant Activities:

5.8.10 Relationship Management

The Relationship Management use case primarily deals with representing activities involving the management of interpersonal and social relationships (e.g. friend requests, management of social network, etc). See 5.2 Representing Relationships Between Entities for more information.

Relevant Activities:

5.8.11 Negating Activity

The Negating Activity use case primarily deals with the ability to redact previously completed activities. See 5.5 Inverse Activities and "Undo" for more information.

Relevant Activities:

5.8.12 Offers

The Offers use case deals with activities involving offering one object to another. It can include, for instance, activities such as "Company A is offering a discount on purchase of Product Z to Sally", "Sally is offering to add a File to Folder A", etc.

Relevant Activities:

A. Non-normative Ontology Definition

This section is non-normative.

A non-normative turtle definition of the Activity Streams 2.0 vocabulary is provided here as a convenience for implementers wishing to use RDF mechanisms for processing Activity Streams 2.0. Note, however, that this document provides the normative definition of the Activity Streams 2.0 vocabulary.

B. Changelog

This section is non-normative.

The following notable changes have been made to this document since the previous candidate recommendation of 2016-09-06.