felixfoertsch/decentralized-ecosystem
1
0
Fork 0
mirror of https://gitlab.com/bluesky-community1/decentralized-ecosystem.git synced 2026-04-17 23:08:34 +02:00
Code Issues Packages Projects Releases Wiki Activity

Proofread and edit applications

Browse Source
This commit is contained in:
Jay Graber
2020-07-07 12:41:28 -07:00
parent 2c2cd9ea28
commit ffa92f43ae
10 changed files with 85 additions and 79 deletions
Download Patch File Download Diff File Expand all files Collapse all files

47
protocols/activitypub.md
View File

@@ -1,20 +1,20 @@
# ActivityPub
ActivityPub is a federated protocol that defines a set of interoperable social network interactions through specific APIs. Any server that implements this protocol can communicate with the rest of the network. It reached W3C recommendation status in 2018. It is one of several related specs produced by the Social Web Working Group.
ActivityPub is a federated protocol that defines a set of interoperable social network interactions through specific APIs. Any server that implements this protocol can communicate with the rest of the network. It reached W3C recommendation status in 2018. It is one of several related specs produced by the [Social Web Working Group](https://www.w3.org/wiki/Socialwg).
ActivityPub consists of two layers: A server to server federation protocol, and a client to server protocol. In order to federate with the ActivityPub ecosystem, a service only has to implement the server-to-server protocol.
Mastodon is a popular federated alternative to Twitter built on ActivityPub. Other ActivityPub applications include Pleroma, PixelFed, Friendica, and PeerTube.
ActivityPub consists of two layers: A server-to-server federation protocol, and a client-to-server protocol. In order to federate with the ActivityPub ecosystem, a service only has to implement the server-to-server protocol.
### Identity
User identities in ActivityPub are conceptualized as actor objects. To be spec compliant, each actor _must_ have an "inbox" and an "outbox". They also _should_ have "following" and "followers". They _may_ have "liked" collections, and many other predefined possibilities. These are endpoints, URLs which are accessible on the server.
Users in ActivityPub are conceptualized as actor objects. Actor to actor communication bears a resemblance to email. To be spec compliant, each actor _must_ have an "inbox" and an "outbox" endpoint, as URLs which are accessible on the server. They also _should_ have "following" and "followers". They _may_ have "liked" collections, and many other predefined possibilities.
Each actor has a publicly accessible JSON-LD document.
[Authentication](https://www.w3.org/wiki/SocialCG/ActivityPub/Authentication_Authorization): Server to server federation is authenticated using HTTP Signatures. Each actor has a public and private keypair, and a publicly accessible JSON-LD document retrievable over HTTP which contains its public key. Each message the server sends on behalf of an Actor is signed by this key. When a remote server receives a POST to its inbox, it verifies the signature on the HTTP request. To verify object integrity, linked data signatures are used to sign the object with the publicKey of the actor who authored it.
A [paper](https://github.com/WebOfTrustInfo/rwot5-boston/blob/master/final-documents/activitypub-decentralized-distributed.md) from the 2017 Rebooting the Web of Trust conference describes how distributed, cryptographic identities could be added to ActivityPub.
### Networking
ActivityPub is federated through a server-to-server protocol that passes messages between systems.
ActivityPub is a federated server-to-server protocol that passes messages between systems.
ActivityPub servers do not proactively network with each other, so they are unaware of each other's presence until a user finds and follows someone on another server. Servers maintain a list of remote accounts its users follow and subscribe to their posts.
@@ -22,38 +22,32 @@ ActivityPub messages are not limited to HTTP only. This allows it to potentially
### Data
ActivityPub messages are objects wrapped in an "activity", indicating what it is. There is an [Activity Vocabulary](https://www.w3.org/TR/activitystreams-vocabulary/) that defines Activity, Object, and Actor types that are common to social web applications.
ActivityPub messages are objects wrapped in an "activity", indicating what it is. There is an [Activity Vocabulary](https://www.w3.org/TR/activitystreams-vocabulary/) that defines Activity, Object, and Actor types common to social web applications.
ActivityPub is not opinionated about how messages are persisted on the server as long as each server follows the protocol message requirements.
Server implementions may [cache](https://flak.tedunangst.com/post/what-happens-when-you-honk) frequent requests, such as follower actor objects, public keys of other servers, and images and attachments on posts.
ActivityPub is not opinionated about how messages are persisted on the server as long as each server follows the protocol message requirements. Server implementions may [cache](https://flak.tedunangst.com/post/what-happens-when-you-honk) frequent requests, such as follower actor objects, public keys of other servers, and images and attachments on posts.
### Moderation & Reputation
Moderation is primarily handled by server implementations. ActivityPub defines a "block" activity to help users control their experience.
Moderation is primarily handled by server implementations. Server admins can block individuals or entire instances. Banning instances can lead to the isolation of an ActivityPub server instance if it is banned by many others, limiting its users to communication with each other.
The use of server-level bans to block content can lead to the isolation of an ActivityPub server instance if it is banned by many other servers, limiting its users to communication within its instance.
ActivityPub defines a "block" activity to help users control their experience.
ActivityPub adoption has reached a threshold where spam and harassment have become ongoing problems that protocol developers currently seek to address. [Keeping Unwanted Messages off the Fediverse](https://github.com/WebOfTrustInfo/rwot9-prague/blob/master/topics-and-advance-readings/ap-unwanted-messages.md#org2158b95) is a list of suggested solutions.
### Social & Discovery
Messages are addressed to a user at their home server, or published to a public inbox. Normal DNS and IP address routing are used to find the server addressed.
If posts are limited in visibility (followers only, direct message), they will be delivered to a user's inbox, such as `https://example.com/users/alice`.
If posts are limited in visibility (followers only, direct message), they will be delivered to a user's inbox, such as `https://example.com/users/alice`. The "outbox" is a URL where an actor's recent activities can be retrieved from.
Servers also may accept delivery of messages addressed as 'public' to a shared inbox available to all on the server, but are not required to. Social network implementations with public feeds may publish posts to the public inbox, such as `https://example.com/inbox`.
"Like"s and "Follow"s may be used by servers to determine which public messages to accept/retrieve.
The "outbox" is a URL where an actor's recent activities can be retrieved from.
There is no global search capability, as each server monitors a different set of messages. Searching for the same keyword on different instances yields different results. The federated timeline shows public posts that the user's server knows about. Essentially, users have access to posts of people followed by people on their instance.
There is no global search capability, as each server monitors a different set of messages.
### Privacy & Access Control
Server to server federation is authenticated using HTTP signatures in conjunction with the signing key from the actor's publicKey field. To verify object integrity, linked data signatures are used to sign the object with the publicKey of the actor who authored it.
When a remote server receives a POST to its inbox, it verifies the signature on the HTTP request by checking it against the sending server's publicKey.
Mastodon is currently [adding e2e encryption to ActivityPub](https://github.com/tootsuite/mastodon/pull/13820). Previously, messages were unencrypted on the server.
### Interoperability
@@ -76,7 +70,7 @@ The ActivityPub ecosystem scales up by adding more server capacity to the networ
[W3C Implementation Report](https://activitypub.rocks/implementation-report/)
- [Mastodon](https://mastodon.social/about) (the largest federated network built on ActivityPub) has 2699 nodes and 2.6M users as of 5/2020 (Mastodon home page asserts 4.4M, a bit more than what the-federation.info stats provide; maybe some servers are not counted)
- [Mastodon](https://mastodon.social/about) (the largest federated network built on ActivityPub) has 2699 nodes and 2.6M users as of 5/2020
- [Pleroma](https://pleroma.social/) is another federated social network. According to stats at [the-federation.info](the-federation.info), Pleroma has 620 nodes with 35K users as of 5/2020.
- [PixelFed](https://pixelfed.org/) is an ActivityPub based image-sharing platform.
- [Friendica](https://friendi.ca/) is a decentralized social network with support for ActivityPub, as well as the OStatus and diaspora protocols.
@@ -92,8 +86,7 @@ The IndieWeb protocols and community are also related to ActivityPub through a s
### Links
[W3C ActivityPub Spec](https://www.w3.org/TR/activitypub/)
[Social Web Working Group](https://www.w3.org/wiki/Socialwg)
[SocialHub, ActivityPub discussion forum](https://socialhub.activitypub.rocks/)
[Notes from an ActivityPub implementator](https://flak.tedunangst.com/post/ActivityPub-as-it-has-been-understood)
[Reading ActivityPub](https://tinysubversions.com/notes/reading-activitypub/)
- [W3C ActivityPub Spec](https://www.w3.org/TR/activitypub/)
- [SocialHub, ActivityPub discussion forum](https://socialhub.activitypub.rocks/)
- [Notes from an ActivityPub implementator](https://flak.tedunangst.com/post/ActivityPub-as-it-has-been-understood)
- [Reading ActivityPub](https://tinysubversions.com/notes/reading-activitypub/)