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Re: transcoders bad

From: Francois Daoust <fd@w3.org>
Date: Wed, 06 Aug 2008 16:46:51 +0200
Message-ID: <4899B95B.9030806@w3.org>
To: Terren Suydam <terren@singleclicksystems.com>
CC: public-bpwg-comments@w3.org

Terren Suydam wrote:
> Thanks Francois, I appreciate it. If you'll indulge me, I'd like to 
> present the most articulate and complete presentation of the points I 
> would like to make if I had anywhere near the grasp on the issues as E 
> Casais, whose post on the WMLProgramming list last night perfectly 
> represents my views.
> If you're going to record any comments at all, I urge you to record this 
> one below.

We do record all comments, and will reply to each of them.

Besides, note that all the messages sent to the 
public-bpwg-comments@w3.org are publicly archived:

Eduardo already sent comments that address most of the points below in 
two previous emails to the public-bpwg-comments@w3.org mailing-list:

I am not adding the following as additional "tracked" comments since:
- most of them are already part of the above mentioned emails
- this is more a discussion than specific comments. Note that the 
Working Group will take all the discussions that followed the initial 
comments, and this one in particular, into account when it comes to 
deciding about changes and officially replying to the comments.
- Eduardo will send a third list of comments himself if he wants to 
complete the first two lists he already sent, I suppose.


> Best,
> Terren
> E Casais wrote:
> Maybe I can have my turn at trying to clear things up?
>  >What I personally don't understand, and I think the people behind this
>  >document, is why this leads to conclusions like "don't change
>  >User-Agent". That does not have to do with telling a transcoder to
>  >leave you alone.
> Well, follow the reasoning:
> 1. What is relevant is not "content", understood as some kind of
> generic markup that is delivered over a neutral communication link
> to a terminal; what is in place is a content delivery chain where
> clients communicate their capabilities to the server, which uses
> this information to deliver the most appropriate service. These
> capabilities are communicated via HTTP header fields, and this has
> been the case since the inception of the WWW. Thus, all elements
> are relevant: content, communication link and end-point capabilities.
> 2. The mobile Web comprises a large number of established sites
> that have been delivering content specially optimized for mobile
> devices -- WAP 1 capable, WAP 2 capable, i-Mode capable, and also
> WWW capable ones -- sometimes for many years. In that environment,
> information from HTTP fields such as user-agent is essential
> (device detection), as well as accept (supported MIME types),
> accept-charset (supported encodings), and x-wap-profile (device
> capabilities), plus other ones (e.g. cookies) depending on the
> application.
> 3. The fact: transcoders deployed in the field substitute the
> user-agent field, eliminate the x-wap-profile, change accept
> and accept-charset to unrecognizable ones, and modify POST
> requests into GET ones. The consequence: the delivery chain
> no longer works. Mobile Web sites can no longer recognize the
> clients and deliver mobile-optimized content to them (or any
> content at all in some situations).
> 4. The CTG intent is to describe a (lightweight) mechanism for
> Web sites to communicate to transformation proxies possibly present
> between server and client that the content provisioning chain is
> not to be disturbed, so that mobile optimized content can be
> delivered unhindered. The proposal consists essentially in relying
> upon the directive no-transform.
> 5. Once the no-transform directive has been sent, the provisioning
> chain is supposed to be left untouched. According to the CTG (and
> the discussions in the list), this is not the case: even after
> receiving such a directive, the proxies can modify HTTP fields
> at will. Concretely: proxies never get out of the way in the
> content delivery chain, and never behave as transparent proxies.
> The CTG indicates that original HTTP header fields can be found
> in alternative X-fields.
> 6. The fact: current proxies are known to disturb the content
> delivery chain in other important ways not dealt with by the CTG
> (e.g. POST vs GET requests). Besides, current proxies perform
> egregious content transformations, such as inserting extraneous
> advertisements and content, despite origin servers loudly
> signalling that they are delivering mobile-optimized content
> that is not to be disturbed (via special URL, no-transform
> directives, MIME types, DOCTYPE declarations, copyright meta
> tags, all together). The effect of transformation across
> character encodings is a question mark (remember that proxies
> do actually change the accept-charset field). Finally, there
> can be cascaded proxies cumulating their effect on the content
> delivery chain.
> This is a description of the situation. Now come the points of
> disagreement.
> Position of mobile Web developers:
> a) There is no justification for the situation in (5); since
> proxies are not supposed to play a role in the delivery
> chain of original mobile-Web services, why should they be
> officially allowed to disrupt it even when explicitly told
> not to -- and have this stamped as a "best practice"?
> b) Transformation proxies are supposed to adapt full WWW
> content for non-full-WWW terminals. Why should deployed
> mobile Web applications that have nothing to do with the
> full-WWW be impacted and be retrofitted to proxies by
> changing the way they deal with the content delivery chain,
> especially HTTP header fields?
> c) The CTG is silent on the aspects listed in (6). How
> could such a fragmentary guideline help when it leaves many
> avenues open to disable the content delivery in the mobile
> Web?
> d) For the past year, there has been a wide deployment of
> transcoders purportedly to enhance the browsing experience
> of mobile users by enabling access to the full WWW. The
> actual consequence has been a dramatic degradation of the
> experience in the existing mobile optimized Web. Why should
> we condone officially some of the dubious practices of
> these transcoding firms, thus granting them a precedent
> for further deviant behaviour (streaming? Java? Flash?
> Synchronization?)
>  From the, ahem, lively debate going on in the W3C and
> WMLProgramming lists, mobile developers interpret the
> attitude of the W3C and the resulting Draft CTG as follows:
> a) "We do not have any justification for this inconsistency,
> but every proxy is doing it, so it is not a problem.  Why don't
> you develop for the full WWW and rely upon proxies so that you
> do not have to deal with those pesky HTTP fields?"
> b) "It doesn't matter. Access to the full WWW is paramount. The
> mobile Web must adapt to the proxies, ideally proxies should
> not have to bother about the mobile Web. Why don't you just
> develop for the full WWW and let proxies do their work?".
> c) "We have not thought about it, and dealing with this makes
> the life of proxies too complicated. Why don't you just
> develop for the full WWW to avoid these issues?".
> d) "The W3C is the leading organization defining the future
> of the WWW, so we have to follow, and especially follow the
> quirks a few proxy players have just started to do, not what
> the mobile application industry at large has been doing for a
> decade or what we would reasonably plan to do in a standards
> body. If you just developed for the full WWW you would
> understand the benefits of this approach".
> That is formulated a bit sharply, but until the W3C puts
> out a convincing and logical answer to a, b, c, and d,
> this will remain the predominant feeling -- and I do not
> see how the positions could then come closer.
>  >Or why it leads to conclusions like "don't transcode
>  >https".
> This is another discussion, the conclusion of thoughts
> about security, usability and what it means to have
> end-to-end secure connections. But the basic logic applies:
> if proxies are told to leave the content delivery chain
> untouched, via a no-transform for instance, why should
> they still insist in manipulating it?
>  >1) Transcoders provide a lot of value too.
>  >I personally love them since I don't have a fancy phone.
> They do, but only under two conditions:
> 1. When accessing the full-WWW from non-full-WWW devices;
> 2. And when not disrupting mobile-Web content provisioning.
> I have not tried recent transcoders, so I cannot comment on
> the extent of the value they provide with respect to (1).
> However, I have experienced what they do in (2), and
> unfortunately, in their present instantiations, they do
> not add any value to the existing mobile Web; rather, they
> destroy it. It is just a fact, the sad reality of the
> transcoding world for over a year now.
>  >I would not want to be shut out of 99.9% of the web while
>  >waiting for those great mobile developers to port the whole
>  >web to XHTML, lovely as that would be. Without a doubt
> This is another discussion, but this kind of view of the
> mobile Web lost most of its relevance several years ago.
> Mobile Web and Full WWW address different needs; the
> applications are different, they are not really replicas
> (scaled up or down) from each other. Think about this: how
> many wallpapers or ringing tones or GPS mapping downloading
> sites for PC are there? How many 2-D "barcodes" scanning and
> browsing applications on PC? How many electronic tram tickets
> do you order and pay with your PC? Even "sibling" mobile/fixed
> applications from the same company are different: for instance,
> mobile versions of social sites have capabilities optimized
> to take advantage of direct feeds of mobile-originated
> photos and videos, whereas media uploading takes place
> with different modalities on the PC version.
>  >I agree there are "good" and "bad" behaviors for transcoders,
>  >and we should talk about that.
> The broadsides you receive from some quarters has much to do
> with the fact that they want you (i.e. W3C) to act, not to
> talk, that they consider the draft CTG as not taking a firm
> stand with respect to these practices, that they view the
> guidelines as weak, and that they feel the whole affair
> revolves around rubber-stamping the bad practices of some
> players instead of attempting to push things in the right direction.
>  >That is not the extreme conclusion that transcoders are bad.
> I agree in theory. In practice, the current crop of
> transcoders is bad, not for the full-WWW, but for the
> mobile Web (see conditions 1 and 2 above).
>  >2) Transcoders exist, dude. Sorry. They're not going away.
> I do not mind about this personally. What I am concerned
> about is giving a W3C stamp of approval to obnoxious practices
> that destroy the value of the existing mobile Web infrastructure,
> or proposing a document so vague that it implicitly allows
> such misbehaviour.
> E. Casais
> Francois Daoust wrote:
>> Hi Terren,
>> Just a quick message to let you know that I recorded your comment in 
>> our Tracking System.
>> The Mobile Web Best Practices Working Group will address it as soon as 
>> possible and get back to you with some official proposed resolution.
>> In the meantime, please note that the discussion it triggers does not 
>> reflect the position of the Mobile Web Best Practices Working Group or 
>> of the W3C.
>> Thanks,
>> Francois Daoust,
>> W3C Staff Contact,
>> Mobile Web Best Practices Working Group.
>> Terren Suydam wrote:
>>> Hello,
>>> As the technical lead for SingleClick Systems mobile development, I'm 
>>> writing to protest the W3C's failure to provide a clear rule against 
>>> the modification of the User-Agent header.
>>> As mobile developers, my team spends a lot of time creating the 
>>> mobile experience *we* want our users to see. If our users are 
>>> subjected to the confusing experience of transcoding, we lose money.
>>> I urge the W3C to adopt the standards set forth by Luca Passani's 
>>> Manifesto, of which I'm sure you're aware.
>>> Sincerely,
>>> Terren Suydam
Received on Wednesday, 6 August 2008 14:46:21 UTC

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