WebSub
WebSub (formerly PubSubHubbub) is an
In October 2017, PubSubHubbub was renamed to WebSub for simplicity and clarity.[2] As of January 2018[update], the WebSub protocol has been adopted by the
Protocol
Under WebSub, there is an ecosystem of publishers, subscribers, and hubs.[4]
A subscriber first retrieves content from an HTTP resource (
Publishers expose their content with the inclusion of hub references in the HTTP headers. They post notifications to those referenced hubs whenever they publish something. Thus, when a publication event occurs, the publisher calls its hubs and the hubs call their subscribers.
WebSub includes a simple verification of intent mechanism in order to prevent abusive subscriptions, and a validation mechanism allows for subscriptions to private or protected web resources. When the subscriber sends the subscription request to the hub, the subscriber address and a code needs to be included. The hub immediately sends a verification message to the subscriber with the URL of the topic and the above code. The subscription request will only be accepted if the subscriber sends a positive response to the verification request of the hub.
In order to provide a secure chain, subscribers should share a secret with the hub, which will be used by the hub to compute an HMAC key that will be sent to the subscriber. The latter can then easily verify the origin by comparing the supplied signature with a similarly computed signature on their end.
Usage
WebSub is used to push content by many websites, including all
Subscribing services (“feed readers”) include Flipboard, Feedly, NewsBlur, among other popular options.[8]
Community Hosted hub providers include pubsubhubbub.appspot.com (operated by Google),[9] pubsubhubbub.superfeedr.com (operated by Superfeedr),[10] and websubhub.com.[11]
Superfeedr provides a detailed PubSubHubbub guide for implementation.[12]
See also
- Publish–subscribe pattern
- RSS Cloud
- RSS to email
References
- ^ PubSubHubbub
- ^ "WebSub @ W3C".
- ^ "WebSub W3C Recommendation 23 January 2018".
- ^ "WebSub".
- ^ "Rub-a-Dub-Dub in the PubSubHubbub". The WordPress.com Blog. 3 March 2010. Retrieved 6 February 2018.
- ^ "Companies". pubsubhub - Google Code. Retrieved 2 September 2014.
- ^ "Superfeedr Blog - Medium supports PubSubHubbub". Retrieved 3 May 2015.
- ^ "State of PubSubHubbub". Superfeedr blog. Retrieved 2 September 2014.
- ^ Welcome to the Google PubSubHubbub Hub!
- ^ Superfeedr Open PubSubHubbub Hub
- ^ WebSubHub
- ^ Superfeedr Blog - How to implement PubSubHubbub