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Re: WiSH: A General Purpose Message Framing over Byte-Stream Oriented Wire Protocols (HTTP)

From: Van Catha <vans554@gmail.com>
Date: Thu, 24 Nov 2016 13:39:04 -0500
Message-ID: <CAG-EYCjwptZcsHeDKwyRBhLTREEC4zxXxtTZvNLe2m1ei2r55g@mail.gmail.com>
To: Takeshi Yoshino <tyoshino@google.com>
Cc: "ietf-http-wg@w3.org Group" <ietf-http-wg@w3.org>, Wenbo Zhu <wenboz@google.com>, Martin Thomson <martin.thomson@gmail.com>
Thanks for clarification. Unfortunate that so little attention was paid to
this.  Looks like some of us will be on HTTP1.1 for a long time.

On Mon, Nov 21, 2016 at 11:14 PM, Takeshi Yoshino <tyoshino@google.com>
wrote:

> Ah, no. Martin just warned us that we might face the same issue that SSE
> faced.
>
> Mark's suggestion is a separate thing. The co-chairs (Mark and Patrick)
> said that this (WiSH) doesn't seems to be a topic that should be discussed
> in the HTTP WG given the charter of the WG, I think.
>
> On Sun, Nov 20, 2016 at 12:26 PM, Van Catha <vans554@gmail.com> wrote:
>
>> I do not understand what this means.  Is the suggestion to ignore WiSH
>> for now in favor of SSE?
>>
>> On Fri, Nov 18, 2016 at 1:55 AM, Takeshi Yoshino <tyoshino@google.com>
>> wrote:
>>
>>> I'd like to share the feedback on WiSH from IETF 97.
>>>
>>> ----
>>>
>>> Due to limited time, I got just one on-site comment from Martin about
>>> comparison with Server-sent event (EventSource).
>>>
>>> As mentioned in the I-D, yes, this is kinda full-duplex SSE with the WS
>>> framing, and it might suffer from unexpected buffering by intermediaries if
>>> any as Martin said.
>>>
>>> WiSH should work well for deployment with TLS only (possibly with some
>>> non-TLS part beyond server side front-end but are under control of the
>>> service providers). Given the wide trend of encouraging TLS and browser
>>> vendors' implementation status of H2, I think we should prioritize layering
>>> simplicity than taking care of gain of WiSH/H2/TCP + transparent proxy
>>> (with unexpected buffering) case. For H2-less TLS-less environment, we can
>>> just use the WebSocket protocol.
>>>
>>> There can still be some risk of MITM (trusted) proxy and unexpected
>>> buffering with AntiVirus/Firewall for deployment with TLS, but other
>>> WebSocket/H2 mapping proposals also have issues of possible blocking,
>>> buffering, etc. WebSocket/TCP's handshake success rate for non-TLS port 80
>>> was also not so good when it started getting deployed, and got improved
>>> gradually. I think the problems will get resolved once WiSH is accepted
>>> widely, and I believe the total pain and cost would be smaller.
>>>
>>> ----
>>>
>>> Mark suggested that we should find some other right place than HTTP WG.
>>> I'll discuss this with Mark. Maybe we'll consult the DISPATCH WG.
>>>
>>> ----
>>>
>>> Thanks everyone for the feedback.
>>>
>>> Takeshi
>>>
>>> On Thu, Nov 3, 2016 at 3:20 AM, Costin Manolache <costin@gmail.com>
>>> wrote:
>>>
>>>> Good timing -  http://httpwg.org/http-exte
>>>> nsions/encryption-preview.html is addressing my concerns for
>>>> webpush ( and general 'encrypted content' ), we're still discussing
>>>> some details, but for this use
>>>> case metadata won't be needed.
>>>>
>>>> Costin
>>>>
>>>>
>>>> On Tue, Nov 1, 2016 at 10:34 PM Takeshi Yoshino <tyoshino@google.com>
>>>> wrote:
>>>>
>>>>> On Mon, Oct 31, 2016 at 5:57 AM, Wenbo Zhu <wenboz@google.com> wrote:
>>>>>
>>>>>
>>>>>
>>>>> On Sun, Oct 30, 2016 at 10:25 AM, Costin Manolache <costin@gmail.com>
>>>>> wrote:
>>>>>
>>>>> Thanks for the answer and pointers. From earlier responses, it seems
>>>>> possible to use GET
>>>>> or a non-web-stream request to would avoid the extra cost of the
>>>>> pre-flight.
>>>>>
>>>>>
>>>>>
>>>>> Yeah, at least the Content-Type in the HTTP request gets eliminated.
>>>>>
>>>>>
>>>>> One more question/issue: in some cases it would be good to send some
>>>>> metadata (headers) along with binary frames. For example in webpush
>>>>> the content is an encrypted
>>>>> blob, and needs headers for the key/salt. I would assume a lot of
>>>>> other 'binary' messages would
>>>>> benefit if simple metadata could be sent along. Would it be possible
>>>>> to use one of the reserved
>>>>> bits for 'has metadata' and add some encoded headers ? I know in
>>>>> websocket they are intended
>>>>> for 'extensions', but 'headers' seems a very common use case.
>>>>>
>>>>> Q about webpush: is the metadata different for each binary message?
>>>>>
>>>>> We discussed about metadata and how to use one of RSV bits etc. For
>>>>> the current version, let's make sure the WS compatibility is fully
>>>>> addressed (with minimum wire encoding like WiSH)
>>>>>
>>>>>
>>>>> Agreed. Let's discuss the metadata needs separately. I agree it's
>>>>> important.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Having the binary frame use some MIME encoding to pass both text
>>>>> headers and the binary blob
>>>>> is possible - but has complexity and overhead.
>>>>>
>>>>> OTOH, if the binary blob relies on text headers (metata) to be useful,
>>>>> then you probably need define a dedicated MIME encoding.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Costin
>>>>>
>>>>> On Sun, Oct 30, 2016 at 5:27 AM Takeshi Yoshino <tyoshino@google.com>
>>>>> wrote:
>>>>>
>>>>> Thanks, Van, Costin.
>>>>>
>>>>> On Sun, Oct 30, 2016 at 2:43 AM, Costin Manolache <costin@gmail.com>
>>>>> wrote:
>>>>>
>>>>> Good point - websocket is widely deployed, including IoT - and the
>>>>> header is pretty easy to handle anyways.
>>>>> +1.
>>>>>
>>>>> One question: is this intended to be handled by browsers, and exposed
>>>>> using the W3C websocket API ?
>>>>> Will a regular app be able to make WiSH requests and parse the stream
>>>>> by itself, without browser
>>>>> interference ? And if yes, any advice on how it interact with CORS ?
>>>>>
>>>>>
>>>>> The first step would be using Streams based upload/download via the
>>>>> Fetch API + protocol processing in JS.
>>>>>
>>>>> The next step could be either introduction of an optimized native
>>>>> implementation of WiSH parser/framer in the form of the TransformStream
>>>>> which can be used as follows:
>>>>>
>>>>> const responsePromise = fetch(url, init);
>>>>> responsePromise.then(response => {
>>>>>   const wishStream = response.body().pipeThrough(wishTransformStream);
>>>>>   function readAndProcessMessage() {
>>>>>     const readPromise = wishStream.read();
>>>>>     readPromise.then(result => {
>>>>>       if (result.done) {
>>>>>         // End of stream.
>>>>>         return;
>>>>>       }
>>>>>
>>>>>       const message = result.value;
>>>>>       // Process the message
>>>>>       // E.g. access message.opcode for opcode, message.body for the
>>>>> body data
>>>>>       readAndProcessMessage();
>>>>>     });
>>>>>   }
>>>>>   readAndProcessMessage();
>>>>> });
>>>>>
>>>>> and provide a polyfill that presents this as the WebSocket API, and
>>>>> (or skip the step and) go further i.e. native implementation for everything
>>>>> if it turns out optimization is critical.
>>>>>
>>>>> We need to discuss this also in W3C/WHATWG.
>>>>>
>>>>> Regarding CORS, if the request includes non CORS-safelisted headers,
>>>>> fetch() based JS polyfills will be basically subject to the CORS preflight
>>>>> requirement. We could try to exempt some of well defined headers if any for
>>>>> CORS like WebSocket handshake's headers and server-sent event's
>>>>> Last-Event-Id are exempted. Regarding the proposed subprotocol negotiation
>>>>> in the form of combination of the Accept header and the Content-Type
>>>>> header, the Accept header is one of the CORS-safelisted headers, so it's
>>>>> not a problem. The Content-Type header is considered to be
>>>>> non-CORS-safelisted if it's value is none of the CORS-safelisted media
>>>>> types. So, WiSH media type would trigger the preflight unless we exclude it.
>>>>>
>>>>> Origin policy https://wicg.github.io/origin-policy/ might also help.
>>>>>
>>>>>
>>>>>
>>>>> Costin
>>>>>
>>>>> On Fri, Oct 28, 2016 at 12:06 PM Takeshi Yoshino <tyoshino@google.com>
>>>>> wrote:
>>>>>
>>>>> Sorry for being ambivalent.
>>>>>
>>>>> We can of course revisit each design decision we made for RFC 6455
>>>>> framing and search for the optimal again. But as:
>>>>> - one of the main philosophies behind WiSH is compatibility with
>>>>> WebSocket in terms of both spec and implementation
>>>>> - the WebSocket is widely deployed and therefore we have a lot of
>>>>> implementations in various languages/platform
>>>>> - most browsers already have logic for the framing
>>>>> - the framing is not considered to be so big pain
>>>>> inheriting the WebSocket framing almost as-is is just good enough.
>>>>> Basically, I'm leaning toward this plan.
>>>>>
>>>>> Takeshi
>>>>>
>>>>> On Sat, Oct 29, 2016 at 3:12 AM, Takeshi Yoshino <tyoshino@google.com>
>>>>> wrote:
>>>>>
>>>>> On Sat, Oct 29, 2016 at 2:55 AM, Loïc Hoguin <essen@ninenines.eu>
>>>>> wrote:
>>>>>
>>>>> On 10/28/2016 08:41 PM, Costin Manolache wrote:
>>>>>
>>>>> Current overhead is 2 bytes if frame is up to 125 bytes long - which I
>>>>> think it's not very common,
>>>>> 4 bytes for up to 64k, and 10 bytes for anything larger.
>>>>> IMHO adding one byte - i.e. making it fixed 5-byte, with first as is,
>>>>> and next 4 fixed length would
>>>>> be easiest to parse.
>>>>>
>>>>>
>>>>> Is making it easy (or easier) to parse even a concern anymore?
>>>>>
>>>>> Considering the number of agents and servers already supporting
>>>>> Websocket, the numerous libraries for nearly all languages and the great
>>>>> autobahntestsuite project validating it all, reusing the existing code is a
>>>>> very sensible solution.
>>>>>
>>>>>
>>>>> Yeah, I've been having similar feeling regarding cost for
>>>>> parser/encoder implementation though I might be biased.
>>>>>
>>>>>
>>>>> There are obviously too many options to encode and each has benefits -
>>>>> my only concern was
>>>>> that the choice of 1, 2, 8 bytes for length may not match common sizes.
>>>>>
>>>>> ( in webpush frames will be <4k ).
>>>>>
>>>>>
>>>>> --
>>>>> Loïc Hoguin
>>>>> https://ninenines.eu
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>
>>
>
Received on Thursday, 24 November 2016 18:39:38 UTC

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