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4.3 KiB
authors, status, dateReceived
| authors | status | dateReceived |
|---|---|---|
| a <a@trwnh.com> | DRAFT | 2022-12-09 |
FEP-fb2a: Actor metadata
Summary
It is useful for actors to publish additional structured information about themselves without necessarily defining an extension property or additional vocabulary. This FEP describes a way for actors to publish generic key-value pairs representing their metadata.
History
Mastodon v2.4.0 (March 2018) implemented "bio fields" [1], a feature that allows adding structured data to profiles. This feature was federated via the attachment field, filtering for array items that had a type of PropertyValue derived from schema.org's vocabulary. Each item used name from the ActivityStreams Vocabulary, and value from the schema.org context. The schema.org namespace was defined as schema and (erroneously) mapped to http://schema.org# (instead of http://schema.org/ or https://schema.org) within the JSON-LD context property.
Misskey (December 2018) implemented "user fields" [2], following the same federation logic as Mastodon (filtering for a type of PropertyValue, then taking name and value).
Pleroma (August 2019) implemented "custom profile fields" [3], following the same federation logic as Mastodon (filtering for a type of PropertyValue, then taking name and value).
1. Using ActivityStreams Note instead of schema.org PropertyValue
Rather than depending on an additional (and unnecessary) vocabulary, it makes sense to define a more "native" way of expressing the same idea of a key-value pair representing structured metadata about the actor. To this end, this FEP proposes using the existing Note type from the ActivityStreams 2.0 Vocabulary (instead of schema.org's PropertyValue), as well as the existing content property (instead of schema.org's value). Note that the name property exists within both the ActivityStreams 2.0 Vocabulary and the schema.org vocabulary, with largely the same semantic meaning; however, the use of schema.org vocabulary is out of scope of this FEP.
Thus, we can define a standard for actor metadata, largely drawing from prior art.
2. Defining actor metadata
General-purpose actor metadata fields SHOULD be included in the attachment array on the actor. If a more specific property exists and is a better fit for the specific metadata being expressed, then implementations MAY use that instead of or in addition to the more generic actor metadata.
- Each metadata field MUST have a type of
Note. - Each metadata field MUST have a property of
namerepresenting the name (key) of the field. - Each metadata field MUST have a property of
contentrepresenting the content (value) of the field.
3. Backwards compatibility with legacy implementations
(This section is non-normative.)
Existing implementations currently using http://schema.org#PropertyValue and http://schema.org#value may wish to maintain backwards compatibility during a transitional period. The following algorithm may be used to support the legacy implementations while also favoring the implementation within this FEP:
- Filter the
attachmentarray for items of typeNote. Takenameandcontentfrom each remaining item. - If none are found, filter the
attachmentarray for items of typehttp://schema.org#PropertyValue. Takenameandhttp://schema.org#valuefrom each remaining item.
After some transitional period, implementations may wish to simplify their logic by filtering only for items of type Note and drop support for http://schema.org#PropertyValue, http://schema.org#value, and the schema.org context entirely (assuming those implementations do not use any other vocabulary from the schema.org context).
References
- [ActivityPub] Christine Lemmer Webber, Jessica Tallon, ActivityPub, 2018
- [1] Gargron, Add bio fields (#6645)
- [2] mei23, Show user fields (#3590)
- [3] minibikini, Add custom profile fields (!1488)
Copyright
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
To the extent possible under law, the authors of this Fediverse Enhancement Proposal have waived all copyright and related or neighboring rights to this work.