A simple, open, server-to-server webhook-based pubsub (publish/subscribe) protocol for any web accessible resources. Parties (servers) speaking the PubSubHubbub protocol can get near-instant notifications (via webhook callbacks) when a topic (resource URL) they're interested in is updated. The protocol in a nutshell is as follows: An resource URL (a "topic") declares its Hub server(s) in its HTTP Headers, via Link: <hub url>; rel=”hub” .
NGINX HTTP Push Module
The Advanced Message Queuing Protocol (AMQP) is an open standard application layer protocol for message-oriented middleware. The defining features of AMQP are message orientation, queuing, routing (including point-to-point and publish-and-subscribe), reliability and security. Overview AMQP is a binary, application layer protocol, designed to efficiently support a wide variety of messaging applications and communication patterns. It provides flow controlled, message-oriented communication with message-delivery guarantees such as at-most-once (where each message is delivered once or never), at-least-once (where each message is certain to be delivered, but may do so multiple times) and exactly-once (where the message will always certainly arrive and do so only once), and authentication and/or encryption based on SASL and/or TLS. It assumes an underlying reliable transport layer protocol such as Transmission Control Protocol (TCP). AMQP