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Profiles and negotiation

An RTVBP profile is the complete interoperable combination of:

  1. a transport binding,
  2. an envelope, and
  3. a payload catalog.

The separation matters: the catalog defines call-control meaning, the envelope maps semantic requests, responses, and events onto control messages, and the transport carries control and media.

Compatibility rule

An existing profile name never changes meaning. A different combination receives a new negotiated name, so adding a transport cannot silently change deployed behavior.

The exact current tokens, accepting-endpoint preference, composition, reserved signaling, and media constraints are generated from the executable profile registry. The sections below explain how to apply those generated facts.

rtvbp.v1​

The currently deployed profile selects the WebSocket binding, the generated classic.v1 envelope, and the generated babelforce.v1 catalog.

WebSocket peers negotiate profiles with Sec-WebSocket-Protocol:

  • Clients normally offer rtvbp.v1.
  • Servers select a mutually supported offered profile.
  • An explicit offer with no supported profile is rejected.
  • For compatibility with deployed peers, absence of the header means the effective profile is rtvbp.v1; the server does not echo a subprotocol the client did not offer.

The demonstration catalog uses rtvbp.demo.v1: WebSocket ws.v1, the same classic.v1 envelope, and the generated demo.v1 catalog. Non-default profiles use rtvbp.<catalog-name>.<catalog-major> while the transport and envelope remain the profile's documented fixed components. New combinations receive new names rather than changing an existing profile.

rtvbp.webrtc.v1​

The optional webrtcws.v1 binding keeps classic control on WebSocket text messages and carries audio as PCMU over WebRTC. It uses the same classic.v1 envelope and frozen babelforce.v1 catalog as rtvbp.v1.

It is additive. A server can support both names, but the client explicitly offers the binding it is prepared to use. rtvbp.v1 remains the plain WebSocket-audio default, including when the subprotocol header is absent.

Reserved transport signaling​

Operation methods beginning with transport. are reserved for envelope-independent transport signaling. The WebRTC binding uses transport.webrtc.offer before catalog dispatch begins. The reservation applies across every catalog and envelope, and catalog validation rejects such operation names. It does not reserve event names.