Always Upgrade

[martinthomson]

We need to resolve whether an Upgrade is always necessary, or whether clients can start the HTTP/2.0 session immediately if they have prior knowledge about server capabilities.

Requiring upgrade might be necessary if the set of intermediaries or servers that are involved are potentially homogenous. For example, a phased upgrade of a load-balanced server farm might result in some servers being HTTP/2.0-capable and others not.

[mnot]

Based on list discussion, it appears that we will allow connections (HTTP and HTTPS) to go without Upgrade, but with the Magic. We'll need to give some implementation guidance, of course.

[martinthomson]

Sounds like a resolution to me.