This document specifies a method to provide clients authoritative access
to HTTP origins at a different network location and/or using a different
protocol stack. The requested publication type is Proposed Standard.
Review and Consensus
The document started as an individual draft which provided a potential
solution to several related problems in the HTTP space, helping clients
become aware of multiple network or protocol endpoints for an origin
that could serve the same content in different ways. It drew inspiration
from an existing proprietary solution, Alternate-Protocol, used by
Chromium during SPDY development.
During the HTTP/2 standardization process, the Alt-Svc document was
discussed and worked on in parallel; HTTP/2-specific pieces were
originally added to the HTTP/2 specification at the time of adoption,
but were moved into this document after HTTP/2's extension story was
Technical discussions involved a broad section of the working group,
with the most focus from a few client and proxy implementers. There has
been some back and forth about the right balance between utility and
security, but the document now reflects general consensus. This is
reflected by a thoroughly-discussed Security Considerations section,
which covers ways in which Alt-Svc could be used to track clients or
persist attacks, and gives guidance to implementations on ways to
minimize the potential impacts.
Mike Bishop is the document shepherd; Barry Leiba is the responsible