In ActivityPub, posts, comments, and users themselves are identified by URLs consisting of DNS names and small sequential IDs, with the same entity having a different ID at each instance it is federated to. For example, the comment I’m replying to is ID 6283426 on its home instance, and 5909380 on my instance, and 5405408 on the home instance of the community this thread is in.
In ATP (bluesky’s protocol) everything is identified by cryptographic hashes and digital signatures, while the DNS-based URL of a user’s current “personal data server” at the time they created a post is not part of the post’s identity.
The difference in data models is a major impediment to bridging the two protocols. If two different bridges convert the same post (or other entity) from either one of these protocols to the other, they will always be creating duplicates.
I’m not an expert on either protocol but it seems to me that the only way to bridge them in a way that works well would be for both protocols to be substantially modified for the specific purpose of interoperating with each other, and so far I haven’t seen any indication that either side is interested in doing that.
In ActivityPub, posts, comments, and users themselves are identified by URLs consisting of DNS names and small sequential IDs, with the same entity having a different ID at each instance it is federated to. For example, the comment I’m replying to is ID 6283426 on its home instance, and 5909380 on my instance, and 5405408 on the home instance of the community this thread is in.
In ATP (bluesky’s protocol) everything is identified by cryptographic hashes and digital signatures, while the DNS-based URL of a user’s current “personal data server” at the time they created a post is not part of the post’s identity.
The difference in data models is a major impediment to bridging the two protocols. If two different bridges convert the same post (or other entity) from either one of these protocols to the other, they will always be creating duplicates.
I’m not an expert on either protocol but it seems to me that the only way to bridge them in a way that works well would be for both protocols to be substantially modified for the specific purpose of interoperating with each other, and so far I haven’t seen any indication that either side is interested in doing that.