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Re: Re: Quick review for draft-svirid-websocket2-over-http2 (Was: Re: Draft HTTPbis Agenda For Seoul IETF 97)

From: Kari Hurtta <hurtta-ietf@elmme-mailer.org>
Date: Thu, 20 Oct 2016 12:33:55 +0300 (EEST)
To: HTTP working group mailing list <ietf-http-wg@w3.org>
CC: Kazuho Oku <kazuhooku@gmail.com>, Tom Bergan <tombergan@chromium.org>, Ilari Liusvaara <ilariliusvaara@welho.com>, Van Catha <vans554@gmail.com>
Message-Id: <20161020093357.AB25113BFC@welho-filter2.welho.com>
> This could be the case for any HTTP/2 gateway that translates incoming
> requests to HTTP/1, that does not reject unknown schemes. And whether
> such gateway needs to reject schemes that do not match to the
> request-response model of HTTP seems to be vague in reading RFC 7540.
> Section 8.1.2.3 states that:
> 
>       ":scheme" is not restricted to "http" and "https" schemed URIs.  A
>       proxy or gateway can translate requests for non-HTTP schemes,
>       enabling the use of HTTP to interact with non-HTTP services.
> 
> My interpretation of this paragraph would be that it is permitted for
> an HTTP/2 intermediary to transmit requests with schemes other than
> "http" or "https", expecting that an upstream server would process the
> request according to the scheme, considering the fact that (per my
> understanding) such action is permitted in HTTP/1.1.

Yes. HTTP/2 explicitly uses HTTP/1.1 semantic. 

8.  HTTP Message Exchanges
https://tools.ietf.org/html/rfc7540#section-8

|   Thus, the specification and requirements of HTTP/1.1 Semantics and
|   Content [RFC7231], Conditional Requests [RFC7232], Range Requests
|   [RFC7233], Caching [RFC7234], and Authentication [RFC7235] are
|   applicable to HTTP/2.  Selected portions of HTTP/1.1 Message Syntax
|   and Routing [RFC7230], such as the HTTP and HTTPS URI schemes, are
|   also applicable in HTTP/2, but the expression of those semantics for
|   this protocol are defined in the sections below.

3.1.  Client Handshake Request
https://tools.ietf.org/html/draft-svirid-websocket2-over-http2-00#section-3.1

| 3.1.  Client Handshake Request
| 
|    The client MUST use the :method GET.
| 
|    The client MUST send a sec-ws2-version header that MUST specify the
|    websocket2 version being used.
| 
|    The client MAY send a sec-ws2-compression header that advertises the
|    compression methods the client supports.  Valid key value pairs
|   include:

↡

| The client MUST NOT set the END_STREAM flag when sending the headers.


Note however that this apply:

4.3.1.  GET
https://tools.ietf.org/html/rfc7231#section-4.3.1

|   A payload within a GET request message has no defined semantics;
|   sending a payload body on a GET request might cause some existing
|   implementations to reject the request.
|
|   The response to a GET request is cacheable; a cache MAY use it to
|   satisfy subsequent GET and HEAD requests unless otherwise indicated
|   by the Cache-Control header field (Section 5.2 of [RFC7234]).


Changing of scheme does not change semantic of methods.

2.  Resources
https://tools.ietf.org/html/rfc7231#section-2

|   One design goal of HTTP is to separate resource identification from
|   request semantics, which is made possible by vesting the request
|   semantics in the request method (Section 4) and a few
|   request-modifying header fields (Section 5).  If there is a conflict
|   between the method semantics and any semantic implied by the URI
|   itself, as described in Section 4.2.1, the method semantics take
|   precedence.

( scheme is part of URI )

2.7.  Uniform Resource Identifiers
https://tools.ietf.org/html/rfc7230#section-2.7

|   Uniform Resource Identifiers (URIs) [RFC3986] are used throughout
|   HTTP as the means for identifying resources (Section 2 of [RFC7231]).
|   URI references are used to target requests, indicate redirects, and
|   define relationships.


/ Kari Hurtta
Received on Thursday, 20 October 2016 09:34:31 UTC

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