Re: Feedback on content transformation guidelines ( LC-2066 LC-2067 LC-2068 LC-2069 LC-2070 LC-2071 LC-2073 LC-2072 LC-2074 LC-2075 LC-2076 LC-2077 LC-2078 LC-2079 LC-2080 LC-2081 LC-2082 LC-2083 LC-2084)

I've seen mobile content services where repeat-GETs cause problems. For
instance:

1. Download services that limit the number of downloads (GETs) to protect
content assets;

2. Download services which trigger the build of an asset server-side (e.g.
JAR file for MIDlet) based on the User-Agent of the first hit;

3. Statistical analysis of server logs where double-hits can affect page
views, etc.

All these are IMHO common techniques that I've seen more than one provider
of mobile content use.

2009/11/24 Luca Passani <passani@eunet.no>

>
> Hi Mark, I am not part of BPWG, but I followed the work of the WG very
> closely and I think I can provide some of the answers  to your questions
> (Disclosure: I am the author of the Manifesto for Responsible Reformatting,
>
> http://wurfl.sourceforge.net/manifesto/
>
> The Manifesto addressed the same issues CTG that is addressing with
> overwhelming support from the community, operators and a few key transcoder
> vendors too)
>
> comments (and answers) in-line
>
>
> Mark Nottingham wrote:
>
>>
>> * 4.1.5.1 "The theoretical idempotency of GET requests is not always
>> respected by servers. In order, as far as possible, to avoid misoperation of
>> such content, proxies should avoid issuing duplicate requests and
>> specifically should not issue duplicate requests for comparison purposes."
>> Existing proxies can and do already retry GETs; I'm not sure who you're
>> trying to protect here.
>>
> They are protecting Novarra Inc. ( http://www.novarra.com/ ). "GET
> idempotency" is an excuse to kill a reasonable approach to test whether a
> website has a mobile experience ready for visitors or not. Proxies could
> make a request with unaltered HTTP headers, ascertain that there is no
> mobile experience ready for that device and move on to spoof the UA string
> for that site from that moment on (if there is a mobile experience in place,
> then their intervention is not needed and in fact totally undesirable).
>
> The problem with this approach (for Novarra) is that this would not allow
> their proxy to fool the website and extort full-web content also in the
> presence of a mobile experience.
>
> Please also observe that "probing" is what some commercial proxies do (and
> performance is not an issues, because nothing prevents that a proxy caches
> the result of recent "probs" for a few hours).
>
>
>  My concern is that Recommending this document will cause more harm than
>> good to the Web overall (even if it does represent a consensus of sort among
>> a more limited community).
>>
>
> I of course agree. Just wanted to observe how the "limited community" is in
> fact "very limited", since it only accounts for the needs of some transcoder
> vendors and Vodafone. The overwhelming majority of the mobile ecosystem
> hates transcoders and support for the aforementioned Manifesto proves this.
>
> Thank you
>
> Luca
>
>
>
>


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