Considering messages in isolation

[mnot@…]

We need to explicitly require each and every HTTP message on the wire to be considered in isolation.

E.g., it's reported that some load balancers can be configured to route the message based upon only the first message's Host header per connection.

Likewise, some broken authentication schemes rely on keeping state between messages in a connection.

[mnot@…]

Probably appropriate in the section on persistent connections (or at least link from there).

[mnot@…]

Add to new message orientation section (see #283) or just to 2.2 Client/Server? messaging:

Recipients MUST consider every message in a connection in isolation; because HTTP is a stateless protocol, it cannot be assumed that two requests on the same connection are from the same client or share any other common attributes.

[julian.reschke@…]

From [1317]:

explain that messages need to be considered in isolation (see #288)

[julian.reschke@…]

From [1324]:

mention NTLM as something that violates the stalessness requirement (see #288)