3. Applicability of the Extensible Priority Scheme

The priority scheme defined by this document is primarily focused on the prioritization of HTTP response messages (see Section 3.4 of [HTTP]). It defines new priority parameters (Section 4) and a means of conveying those parameters (Sections 5 and 7), which is intended to communicate the priority of responses to a server that is responsible for prioritizing them. Section 10 provides considerations for servers about acting on those signals in combination with other inputs and factors.

The CONNECT method (see Section 9.3.6 of [HTTP]) can be used to establish tunnels. Signaling applies similarly to tunnels; additional considerations for server prioritization are given in Section 11.

Section 9 describes how clients can optionally apply elements of this scheme locally to the request messages that they generate.

Some forms of HTTP extensions might change HTTP/2 or HTTP/3 stream behavior or define new data carriage mechanisms. Such extensions can themselves define how this priority scheme is to be applied.

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