So over the weekend I published a post intended to introduce the notion of the "fediverse" to friends and colleagues who are interested in exploring options other than the big, commercial, centralized social media outfits. The W3C spec for ActivityPub took a starring role in my presentation, because it's fundamental to the operation of Mastodon, the social communication server software on which I focused. But this morning (thanks to a Mastodon post from @Wu-Lee, a fellow social.coop user) I learned that not everyone is so boosterish about the protocol.
In fact, Mike Macgirvin voices some significant criticism of ActivityPub in an October 2017 interview for Sean Tilley's We Distribute blog. Macgirvin is the author of Hubzilla, a FOSS "platform for creating interconnected websites." Among other criticisms, he opines:
As far as protocols go, ActivityPub is a poor quality specification. This is unfortunate for a protocol with such high expectations, coming from an organization whose only function is to produce working specifications for the web. The places where we needed guidance to produce interoperable products (such as privacy and encryption and signatures and even allowed message content) were left undefined or poorly defined. Many of the things that were specified with any precision turned out to be things that are critical to interoperation and cross-federation of existing web services and the specification restricts the ability for them to interact in some fundamental ways.
The entire interview is well worth a read, as is all of Tilley's blog. It focuses on the fediverse, the free web, and the people involved in building its components. Among the things you'll find there is a recent, deep-dive article entitled "The Do-Everything System: An in-depth review of Hubzilla 3.0." if you want to learn more about that platform.