I'm interested in hearing from #ActivityPub developers who've successfully mapped #OpenGraph properties from <meta> tags in Web pages onto the Page type and its properties in AS2.
@evan Don’t forget about oEmbed data as well (embedded players for all kinds of things - peertube, funkwhale, etc). It’s currently pulled as part of the link preview generator logic. Many times coming through from the Twitter:player meta tag if no oEmbed exists.
@evan 👀 interested in the replies, as we are thinking about how to federate link previews to avoid having each instance fetch it (and DDOS the link’s server)
Overall, mapping to ActivityStreams was pretty easy. Sherlock is the key component in #Emissary that helps it participate in many different social webs.
@evan yes, and it creates a sort of "thundering herd" unintentional ddos for web sites on underpowered providers. there have been ideas on how to solve the trust issue, like randomly verifying some small subset and tracking reputation, or like deferring to a semi-centralized pre-trusted "link preview provider" that is shared between several instances, or even simply ignoring the issue and depending on people to report misleading links. (i prefer the provider approach)
@trwnh another option is accepting the sender-provided metadata to start, and then verifying on a schedule that recognizes that thundering herd problem -- say, a randomized delay between 1 and 300 seconds, with an exponential backoff. And I definitely think having a trusted shared caching server can help immensely.
@evan@trwnh I'm in favour of third-party providers that give a standardised API for going from link URL to Page or similar representation & provides hashes of the returned object allowing easy verification with the provider
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