wiki.trwnh.com/content/tech/activitypub/activity.md

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Activity

an Activity is just an object that has an actor

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what does it mean to be an Activity

for C2S: do not wrap it in a Create when it gets POSTed to outbox

implementations

mastodon

supported activity types https://github.com/mastodon/mastodon/tree/main/app/lib/activitypub/activity

• Accept (accept a follow request)
• Add (adds hashtag or status to featured collection)
• Announce (reblog a status)
• Block (block an account)
• Create (create a message or status)
• Delete (delete account or status)
• Flag (report accounts and/or statuses)
• Follow (request to follow a local account)
• Like (favourite a status)
• Move (migrate an account's followers)
• Reject (reject follow request or remove follower)
• Remove (removes hashtag or status from featured collection)
• Undo (undoes some activities if possible)
• Update (update account info or edit a status)

extended logic

• Accept
  • Accept Follow -- authorize a follow request
    • (when relay is findable by object as follow_activity_id)
    • (when object is uri of existing follow request)
    • (when object is embedded Follow)
      • Accept Follow <Account>
• Add
  • (must have target)
  • (target must be a toot:featured collection)
  • (object must be inlined?)
  • Add Hashtag to target<featured> -- feature a hashtag
    • (takes object.name and removes prefix #)
    • (creates FeaturedTag entity for the actor's account)
  • Add object<Status> to target<featured> -- pin a status
    • (object must be transformable to status)
    • (status must be authored by actor)
    • (status must not already be pinned)
• Announce
  • (must be related to local activity)
    • (i.e. actor<Account> followed by local accounts)
    • (or requested through relay)
    • (or object refers to a status whose account is local)
  • (object resolves to a status)
  • Announce object<Status> -- creates a reblog of a status
    • (stop if:)
      • (no status)
      • (status not boostable)
      • (requested through relay)
    • (find existing reblog or create)
• Block
  • (object resolves to an account)
    • (the resolved account exists and is local)
  • Block object<Account> -- block an account
    • (unfollow the object<Account>)
    • (force object<Account> to unfollow you)
    • (reject any follow requests from object<Account>)
    • (create a block asynchronously)
• Create
  • (dereference the object)
  • Create EncryptedMessage -- creates an encrypted message
    • (tries to find a device id)
    • (extracts messageType, cipherText, digest, messageFranking)
  • Create object<Status> -- creates a status
    • (rejected if)
      • (unsupported object type)
        • (object is a string)
        • (not in supported types)
          • Note
          • Question
        • (not in converted types)
          • Image
          • Audio
          • Video
          • Article
          • Page
          • Event
      • (or invalid origin)
      • (or tombstone exists for object uri)
      • (or not related to local activity)
• Delete
  • (if actor matches object)
    • Delete object<Account> -- delete your own account
  • Delete object<Status> -- delete a status
    • (create tombstone unless origin is invalid)
    • (forward deletion if forwardable)
    • (remove status from database and timelines)
• Flag
  • (object array is resolved as accounts and statuses)
    • (then filtered for local)
  • Flag object<Account,Status> -- report an account and/or statuses
    • (foreach account get reported statuses)
    • (create a report against the account w/ optional status ids and content)
• Follow
  • (object must be a local account that exists)
  • Follow object<Account> -- request to follow a local account
    • (create or update follow request)
    • (auto-reject if:)
      • (object<Account> is blocking actor<Account>)
      • (object<Account> is domain-blocking actor's domain)
      • (object<Account> has moved/redirected)
      • (object<Account> is the instance actor)
    • (send an Accept Follow if a follow already exists)
    • (otherwise create a follow request)
      • (if you are silenced or they are locked, send frq notification)
      • (otherwise send Accept Follow and follow notification)
• Like
  • (resolve status from object)
  • Like object<Status> -- favourite a status
    • (stop if:)
      • (no status resolved)
      • (status is not from a local account)
      • (delete arrived first)
      • (you already favourited this status)
    • (create a favourite by actor<Account> for object<Status>)
• Move
  • (actor must match object and resolve to account)
  • (resolve target as account)
  • Move object<Account> to target<Account> -- migrate your followers
    • (stop if:)
      • (no target<Account>)
      • (target<Account> is suspended)
      • (target.alsoKnownAs doesn't include object)
    • (set a redirect)
    • (async move followers from object<Account> to target<Account>)
• Reject
  • Reject Follow -- reject a follow request or remove follower
    • (when relay is findable by object as follow_activity_id)
    • (when object is uri of existing follow request)
    • (when object is uri of existing follow)
      • (call UnfollowService for actor<Account>)
    • (when object is embedded Follow)
      • Reject Follow Follow.object<Account>
• Remove
  • (must have target)
  • (target must be a toot:featured collection)
  • (object must be inlined?)
  • Remove Hashtag from target<featured> -- unfeature a hashtag
    • (takes object.name and removes prefix #)
    • (deletes FeaturedTag entity for the actor's account)
  • Remove object<Status> from target<featured> -- unpin a status
    • (object must be transformable to status)
    • (status must be authored by actor)
    • (destroy pin if existing pin found)
• Undo
  • (object should be inlined or else it may not be handled)
  • Undo Announce -- unreblog a status
    • (stop if no Announce.id)
    • (resolve Announce.id as status reblog)
    • (call RemoveStatusService on status)
  • Undo Accept -- unfollow an account [yes this is the assumption]
    • (find follow by object.object.id and revoke it)
  • Undo Follow
    • (resolve object.object as account)
      • (stop if not exists or not local)
    • Undo Follow <Account> -- unfollow an account
      • (Undo.actor unfollows Follow.object<Account> if following)
  • Undo Like
    • (resolve object.object as status)
    • (stop if no status or if status is not local)
    • Undo Like <Status> -- unfavourite a status
      • (if actor has favourited the status:)
        • (find a favourite on that status by that account)
        • (destroy it)
  • Undo Block
    • (resolve object.object as account)
    • (stop if not exists or not local)
    • Undo Block <Account> --unblock an account
      • (call UnblockService if actor is blocking Block.object<Account>)
  • Undo object<IRI>
    • (try_undo_announce)
      • (find reblogged status by object uri and actor)
      • (if found, remove reblog and stop, else continue)
    • (try_undo_accept)
      • (do nothing, continue) [because Accept uri is not stored]
    • (try_undo_follow)
      • (find actor<Account> follow request/relation by object uri)
      • (if found, destroy it and stop, else continue)
    • (try_undo_like)
      • (do nothing, continue) ["too costly", no index by Like uri]
    • (try_undo_block)
      • (find actor<Account> block by object uri)
      • (if found, call UnblockService and stop, else continue)
• Update
  • (dereference object)
  • (if object.type in Application Group Organization Person Service)
    • Update object<Account> -- update an account's info
      • (stop if actor.id does not match object.id)
      • (call ProcessAccountService)
  • (else if object.type in Note Question)
    • Update object<Status> -- edit a status
      • (stop if invalid origin)
      • (resolve object as status)
      • (stop if no status)
      • (call ProcessStatusUpdateService)