[minutes] BPWG Content Transformation Task Force Teleconference 2007-12-18

DRAFT -
Please find the minutes of today's CT Task Force teleconference at [1]
and as text below.

Jo

[1] http://www.w3.org/2007/12/18-bpwg-minutes.html



Mobile Web Best Practices Working Group Teleconference
18 Dec 2007

Agenda

See also: IRC log
Attendees

Present
    Bryan, Jo, Francois, Kemp, Andrew
Regrets
    SeanP, Magnus
Chair
    Jo
Scribe
    Jo, kemp

Contents

    * Topics
         1. Review of Requirements in Current Draft
         2. Next Meeting
         3. AOB
    * Summary of Action Items

 

 

<trackbot-ng> Date: 18 December 2007

<jo> Current Draft
Review of Requirements in Current Draft

<jo> Scribe: Jo

jo: bryan - did you get the chance to catch up on comments on section 2

bryan: no I didn't get the chance yet ...

<kemp> Scribe: kemp

jo: section 3 of the current draft... we need to combine the
perspectives in sections 2 and 3... we have content looking at each leg
of the journey, while brian's contributions are formatted differently...
bryan, can we reformat yours?

Bryan: i don't object, but i imagined there would be text around these
-- i was trying to outline basic capabilities and then build use cases
around them... but i am fine with incorporating them

<jo> Commentary on Section 2

jo: ok... let's go through these quickly... 2.1.1... not clear what
"service features" are... bryan?

Bryan: service features are what the proxy does to the extent that we
expose user controllable features... not a strong requirement, some
proxies may operate implicitly

jo: ok... i think we should put something in the document about the user
controlling the proxy, and say that the user may control the proxy in a
variety of ways
... but we don't want to specify the nature of the interaction...

Bryan: that's exactly right... i expect the CT providers will come up
with ways to express this at the application layer at least... if there
is a protocol layer, maybe we need to specify it...

jo: ok... moving on to 2.1.2. misleading to say "highest quality" -- we
don't want the maximum size/color depth for images... what does this
mean?

Bryan: an example specific to markup languages... if you are going to
change the markup, you want to go to the highest quality markup -- the
one with the most user experience features (eg, use XHTML over WML where
possible)

jo: i think the language we want here is something like "most consistent
with the author's expectations"
... ok, under 2.1.4... is what we are saying that we should allow to CT
to fake the user agent and accept headers or not?

Bryan: i think we are... we should allow the user to tell the proxy "be
transparent" and the proxy should honour that request... expect when
that conflicts with the users' need for service

jo: ok... under 2.1.5, original representation... the question arose:
how (technically) does one achieve this?

Bryan: well, many services are stateful... so you can't make multiple
requests... most likely thing to do is cache...

jo: the thought arises as to how you would signal from the user agent
that you want the cached copy, and not the transformed copy, and
secondly, how long the CT should maintain the cache for
... would be interesting to know if this has been implemented anywhere

Bryan: well, first, honour the cache-control header... second, an
implementation specific decision based on resources available (disk,
memory)

jo: it seems you can't assume the original representation is available
necessarily

Bryan: well we would do something like cache things for the expected
session lifetime

jo: what would you do about distinguishing a second request for the
transcoded representation, as opposed to the original representation?

Bryan: i didn't have a particular approach in mind -- i was focusing on
the ability to do this at the user level. maybe a link at the bottom of
the page to the original

kemp: that's what we (google) do now

Bryan: just to be clear, i didn't intend for us to say _how_, just to
say that there should be a way

jo: i just think it's going to be hard to introduce new http
mechanisms...

AndrewS: i don't actually see an implementation difficulty. given the
way CT's work, the page will be cached anyway (for the session lifetime)

jo: right, but what if the cache-control headers say "no-cache?"... i am
concerned we would end up specifying something complex for a limited
usecase...
... but i do understand it's implemented already and people do want this

AndrewS: can we just leave out the implementation details?

jo: yes, but i think we should be clear that we don't think this will be
implemented by ad-hoc http headers... so if we are saying the original
document should be maintained, we should be clear about the case where
cache-control: none is set

<Bryan> we need to make a statement so the readers understand we will
not propose new headers, but expect that the expressed need will drive
needed standards work and market innovation

jo: moving on to section 2.3.1.. i think this leaves the door open to CT
proxies doing what they like... the question in my mind is "who knows
better" and why should the origin server accept that the CT knows what
is dangerous and what is not
... my preference is that we don't say that it is OK to override the
preferences of the origin server, but that we say unless the origin
server has good reason, it doesn't specify no-transform

kemp: imagine no-transform + html on a wml phone

jo: ok, but if they put no-transform, presumably they are aware, and
don't want a proxy getting in the way...

kemp: i wonder what we should do if we know markup is going to crash the
phone? display a page saying that ? pass it through? refuse?

Bryan: i think there is an escape clause there - so that we can show a
user a message saying "this won't work on your phone, do you want us to
adapt it?".
... so basically, does a user have the right to override no-transform?

jo: interesting... i suppose what it comes down to is that i believe the
origin server should be in a better position to decide -- maybe they
have a fancy application scheme that the proxy doesn't know about and
the proxy will harm
... i don't think we can recommend violation of what HTTP says -- if
HTTP says no-transform, we can't say otherwise...

Bryan: i think the point i was trying to raise is that there are two
actors who are in control -- the content provide and the user -- the
presumption is that the user should have an equal role.

<dom> [does a user have the right to disable style sheets on a web page
in her browser? Yes, she does - I think that when a proxy works directly
on the user behalf, it works in the same spirit]

Bryan: maybe a preference setting that tells the CT, as a default
preference, if something is going to break, do your best on my behalf...

<jo> [but Dom, the Proxy is not acting with the users consent in many
cases]

<dom> [I was alluding to what I read from Bryan, i.e. when the user is
asked for consent]

kemp: but in the case bryan offered, it is acting with user consent

<jo> [tks Dom, narrowing it down in that way works]

jo: right so if we narrow it down to those cases where there is user
consent that's ok

Bryan: i think we should make a statement about user consent... can it
be implicit? if i'm configured to use a proxy, that proxy is acting as
my user agent and implicitly
... i want it to perform actions on my behalf... by using the proxy i am
asking for it to provide the best experience possible

jo: the problem is that this assumption has been made in the past and as
a result some origin sites are not working because the proxies are
getting in the way...
... so there is an issue of consent here... i think we need a way for
origin servers to strongly say, "look, get out of the way"

Bryan: i think the proxy has a role as a user agent and some preferences
may be implicit, but that we need to do a better job so that these
situations don't arise

jo: ok... moving on, we'll likely come back to this. i don't have any
other points on section 2. does anyone have anything on section 3 that i
should consider while doing the editorial work of merging section 3 into
2?
... ok anything in general from anybody? if not, let's close the call...

Bryan: one thing i didn't put into the requirements is the ability to
escape the behaviour for certain sites based on preconfigured knowledge
so that we don't mess things up for specific sites.
... wildcards for example to indicate a certain domain doesn't stand up
to transformation well...

jo: yes i think we should at least mention policy based approaches, but
it's not up to us to specify their use... but we should mention them --
much the same as the interaction with the user.
Next Meeting

jo: looks to me that the next meeting will be the 8th of january
AOB

<jo> [meeting closed with Festive Greetings all round!]

<jo> [Thanks to Aaron for scribing]

<jo> ACTION: Jo to produce new draft - due 8 Jan 2008 [recorded in
http://www.w3.org/2007/12/18-bpwg-minutes.html#action01]

<trackbot-ng> Created ACTION-615 - produce new draft [on Jo Rabin - due
2008-01-08].
Summary of Action Items
[NEW] ACTION: Jo to produce new draft - due 8 Jan 2008 [recorded in
http://www.w3.org/2007/12/18-bpwg-minutes.html#action01]
 
[End of minutes]

Received on Tuesday, 18 December 2007 16:02:17 UTC