I’m poking about at the Realtime Web Summit, just got out of the PubHubSubbub session.
PuSH is a relatively lightweight protocol for pushing feed updates in more or less real-time using standard web protocols (eg, HTTP!). As currently spec’d, PuSH covers the server-to-server replication space pretty well — publishers send their updates to hubs, which send them on to the callback URLs given by subscribers.
For StatusNet, we’re really interested in two possible extensions to this, which would be outside the scope of the current PuSH spec:
Microblogging metadata extensions. PuSH deals with RSS and Atom feeds, but doesn’t really care what’s inside them. Microblogging and other social-type services will have various metadata — profile name & avatar, friend relations, ratings, comment id links, etc — which could be embedded into activity stream feeds, allowing different services to handle remote subscriptions interoperably.
Of course, we could just push everybody to support OMB… but the PuSH model may be more flexible, allowing subscriptions to blogs etc to be aggregated into your notice stream.
“Last mile” push to clients. There’s still no standardization for real-time communications from an aggregator or social service to end-user web, desktop, or mobile clients. PuSH as spec’d can’t handle this since it needs a URL to post updates to subscribers, which a NAT’d or mobile client obviously isn’t going to have.
A more or less standard way to attach XMPP or long-polling to pull updates from an aggregating hub to client end-points would be very nice; just like common use of the Twitter API has allowed interop between client apps and services (many Twitter clients will happily speak to identi.ca if you just change the API url to https://identi.ca/api!). That third-party ecosystem is mostly restricted to polling, though, and could really benefit from interoperable methods for pushing updates to an open client.