The Salmon Protocol is a message exchange protocol running over HTTP designed to decentralize commentary and annotations made against newsfeed articles such as blog posts.
It allows a single discussion thread to be established between the article's origin and any feed reader or "aggregator" which is subscribing to the content.
The origin supplies a Salmon end point – a URL in the metadata of an RSS/Atom (standard) feed.
The comment will be base64 encoded, digitally signed, placed in an envelope and POSTed back to the origin via the endpoint.
A member of one server can publish an article which is disseminated to other users over the network via Salmon who in turn can comment back in a similar fashion.