Event Based interaction style in REST

Question

I am currently struggling with a design issue involving REST. The application I am designing has a requirement to send out events and also support pub/sub style of interaction.

Answer 1

I'd recommend the Distributed Observer Pattern by Duncan Cragg as a good read (bit difficult to grok but worth the effort).

As others have indicated its likely you'll need to use polling but as you rightly say subscribers could register their own interest (POST to create subscription). If you view the subscription as its own resource, a contract between the publisher and subscriber, then I wouldn't view it as a breaking REST constraints (see State and Statelessness at page 217 of RESTful Web Services for the difference between application and resource state)