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PubSubHubbub

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PubSubHubbub (PuSH) is a notification-based protocol for publishing and subscribing to feeds/streams in real time. Currently there are no known indieweb sites that subscribe to anything using PuSH.

Contents

IndieWeb Examples

There are several indieweb sites producing PuSH notifications, but none that visibly consume any (there are some with indie reader feature support in development with skeleton consumers).

Tantek

Tantek Çelik uses Falcon to send PuSH notifications of each post in his tantek.com Atom feed file since 2010-02-01.

Aaron Parecki

Aaron Parecki uses p3k to send PuSH notifications for each item in his aaronparecki.com notes and articles Atom feed files since ????-??-?? (at least 2014-??-??).

Bret Comnes

Bret Comnes sends PuSH notifications for his bret.io Github Pages/Jekyll Atom feed file since 2014-03-16.

Kyle Mahan

Kyle Mahan uses Red Wind to send PuSH notifications for new/edited posts and new mentions in his kylewm.com Atom feed file since 2014-03-23(possibly earlier).

Barnaby Walters

Barnaby Walters uses Taproot to send PuSH notifications for each new post on his WaterPigs.co.uk homepage HTML feed using PuSH 0.4 and Superfeedr since 2014-03-25.

Hubs

Arbitrary Content

Since version 0.4 it is possible to push arbitrary content like json or html (microformats)

To push your posts/comments you have to:

  • add a rel-self header pointing to the site itself
  • add a rel-hub header pointing to superfeedr (the only hub that supports spec 0.4 yet)
  • send a post to the hub with this body: hub.mode=publish&hub.url=URL_OF_YOUR_SITE

Superfeedr also offers the ability to subscribe to fragments on a page, using the # symbol. For example, if you subscribe to http://tantek.com/#.hentry, you will receive POST to your webhook/callback endpoint with the content of the first element of class "hentry" on http://tantek.com/

How To

Subscribe to a PuSH-enabled feed

Summary:

  • detect the hub for the feed, optionally falling back to a polling hub (like Superfeedr) if none is found
  • send a subscription request to the hub for that URL, with a callback URL for the hub to ping with new content
  • respond correctly to the verification of intent
  • receive new content from the feed, POSTed straight to the callback URL

Hub discovery algorithm as described by julien51 [1]:

  1. Find resource you want to subscribe
  2. Check for a "Link" header which points to a hub.
    • If there is one => Subscribe to the hub designated
    • If there is none, continue
  3. Check for a linking element (a or link) with rel~=hub
    • If there is one, subscribe using the designated hub
    • Otherwise, continue
  4. Check for a <atom:link> element which points to a hub.
    • if there is one => Subscribe to the designated hub
    • If there is none => Subscribe using the Superfeedr default hub : push.superfeedr.com

Also, along with the hub link (both in the HTTP headers or the ATOM/RSS), you should check for a self link and use this one as the hub.topic you want to subscribe.

The Superfeedr documentation has a more detailed guide: http://documentation.superfeedr.com/subscribers.html

Testing your PuSH-enabled feed

There are several ways you can test whether or not your PuSH feed and pings are working properly:

RSS Reader

Most popular RSS Readers do implement PubSubHubbub, you can just subscribe to your feed on one of them, and see if the update as been propagated after you added content.

Status.net

  1. subscribe to your home page from a Status.net account
  2. publish stuff on your home page
  3. see updates appear in real time on your Status.net account


Bots

There are several XMPP/IRC bots which allow you to subscribe to feeds and be notified of updates via any XMPP or IRC client. You’ll need an XMPP account, or an IRC client.

Notifix

Notifix is a bot (see above for source code). It's constantly connected to irc.freenode.net. Send him a private message like +help to see available commands. Subscribe with +subscribe <feed>, publish your content and see if you get the ping straight via IRC.

  • I have had better experiences with notifixlite than PuSH Bot --Waterpigs.co.uk 03:16, 5 June 2013 (PDT)

Discussion

Issues

  • There are only 3 hosted hubs according to this list of which the one run by Google looks like a side-project (and I suspect it does not offer any service level guarantees) and I haven't heard much about Ayup. Which essentially means there is only one hosted hub to speak. Hubs are complex by design and therefore not something indieweb people can/should run themselves. This is not a healthy situation for something to be considered as indieweb infrastructure -Www.sandeep.io 06:09, 3 July 2013 (PDT)
    • That's the same problem you have with IndieAuth --Notizblog.org 06:32, 3 July 2013 (PDT)
      • I agree, but that says nothing about what you think about the problem described above. -Www.sandeep.io 13:01, 14 July 2013 (PDT)
    • The 'side project' assessment about the Google hub is both wrong and ill-intended. PubSubHubbub is actually key to Google's crawling capabilities and we can safely expect Google to keep maintaining it.
      • Why would you assume ill-intent? Google's hub does not seem like an official product/service (I haven't found any references claiming otherwise). It's just a URL and associated code. The video says nothing about the hub and only talks about Google acting like a subscriber and also emphasize very limited use: "There is a very limited amount in which we will use pubsubhubbub to help improve our crawl". Nothing about the hub is official so I have no choice but to assume it's a side-project unless you cite references clearly stating otherwise. -Www.sandeep.io 13:01, 14 July 2013 (PDT)
    • There are a bunch of OSS implementations of PubSubHubbub hubs that *you* you use, or you could also write your own. Not sure why this would not be a *healthy situation*... :0
      • If I don't want to take on the complexity of running a hub (which IMO, is what is attractive about PuSH) and pending clarification of the official status of Google's hub, there is only one hosted hub "out there" which makes it a SPOF. -Www.sandeep.io 13:01, 14 July 2013 (PDT)

See Also