W3C invites implementations of ActivityPub

The W3C Social Web Working Group is calling for implementations of ActivityPub, which is now a Candidate Recommendation. The ActivityPub protocol is a decentralized social networking protocol based upon the ActivityStreams 2.0 data format. It provides a client to server API for creating, updating and deleting content, as well as a federated server to server API for delivering notifications and subscribing to content. The protocol design iterates significantly on the earlier pump.io protocol, and implementors of pump.io clients and servers are particularly encouraged to update.