MMSP: MultiMedia Subscription Protocol

A JSON-based protocol for subscribing to and consuming multimedia content feeds. MMSP is a pull-only semantic superset of RSS 2.0 and Atom, built around calm consumption as a first-class design constraint.

Status: Community Specification, draft-mmsp-00

MMSP is an independent, open community specification. The draft-NN versioning borrows IETF Internet-Draft naming as a familiar convention only: MMSP has not been submitted to the IETF, is not an IETF work product and is not affiliated with or endorsed by the IETF, the IESG or ISOC. “Pre-IETF” describes an intention to potentially pursue that track in future, not current standing.

Why this exists

RSS answered the early web’s question: how do I follow a site’s articles without visiting it? The current web poses a broader one. A publisher’s output now spans video, audio, articles, images, releases and events across disconnected platforms and every push-based alternative monetises attention. RSS 2.0 and Atom model one content form well; everything else arrives through namespace extensions, platform APIs or not at all.

MMSP is the answer as a protocol rather than a platform: JSON-based, pull-only and defined as a semantic superset of RSS 2.0 and Atom. Twelve first-class item types carry the multimedia model, formal JSON Schemas make a publisher’s output mechanically verifiable, discovery works from a bare domain via /.well-known/mmsp.json and calm consumption is enforced at the wire level (no push, a 300 second poll floor) instead of being left as a cultural norm.

The project is run like a standards effort: a versioned specification with RFC-style normative language, worked examples, a conformance suite targeting every normative statement and a working reference client, Meridian, that proves the normalization rules against real feeds. The spec keeps the client honest; the client keeps the spec real.

The suite is not decorative. It runs on every proposed change to the specification and it gates publication of this site, so the draft text you are reading has never been published while the tests proving it internally consistent were failing.

Full reasoning at crankthecode.com.

Why MMSP and not RSS, Atom or JSON Feed?

JSON Feed already proved the appetite for JSON-native syndication but stops at the document: it is a file format. MMSP specifies the protocol around the format and is built on four commitments those formats do not make:

Calm consumption as a design constraint. At the wire level MMSP is pull-only with no server-push mechanism and mandates a 300-second minimum poll interval; both are normative, not advisory. How a client surfaces new items, including whether it notifies, is a presentation concern addressed by the optional Calm Consumption Profile (Section 4.1).
Polling discipline. Conditional GET (ETag / Last-Modified), 429 back-off, cursor pagination and partial-feed tolerance are part of the spec, so every conformant client behaves predictably under load and failure.
Filter expressions. A defined ABNF filter grammar (Appendix A) lets subscribers narrow a feed at the protocol level, not as a client-specific feature bolted on top.
A real item taxonomy. 12 first-class item types instead of one generic “entry”, with unknown types degrading gracefully rather than breaking clients.

Any RSS 2.0 or Atom feed normalizes cleanly into the MMSP item schema, so adoption costs nothing on the consumption side.

Key Properties

Format: JSON, MIME type application/mmsp+json
Transport: HTTPS only, pull-only, no server push
Poll floor: 300 seconds minimum
12 item types: video, audio, article, image, short, document, gallery, event, release, newsletter, course, livestream
Backwards compatible: any RSS 2.0 or Atom feed normalizes to MMSP item schema
Forward compatible: versioned MAJOR.MINOR; unknown item types and fields degrade gracefully instead of breaking clients
Robust polling: conditional GET (ETag / Last-Modified), 429 back-off, cursor pagination and partial-feed tolerance for malformed items
Discovery: /.well-known/mmsp.json or HTML <link rel="alternate">
User-Agent: MMSP/<version>, optionally a client token (e.g. MMSP/1.0 Meridian/2.3); never subscriber- or install-identifying

Resources

License

Apache License 2.0