W3C home > Mailing lists > Public > www-mobile@w3.org > November 2001

Re: CC/PP profile repository overworked?

From: Johan Hjelm <johan.hjelm@era-t.ericsson.se>
Date: Thu, 22 Nov 2001 08:41:39 +0900
Message-ID: <3BFC3BB3.D3CB3938@era-t.ericsson.se>
To: "Butler, Mark" <Mark_Butler@hplb.hpl.hp.com>
CC: "'Suryanarayana, Lalitha'" <lalitha@tri.sbc.com>, www-mobile@w3.org
Keio University proved that the profile caching made the data transfer
considerably more efficient in their SASA implementation, in the paper presented
at MDM'01.


"Butler, Mark" wrote:

> Lalitha
> Firstly I regard these as implementation issues rather than issues that
> require changes to the specification as they are primarily concerned with
> efficiency.
> My concern is although it is legal for requests to omit profile references,
> if they do then the origin server cannot cache profiles, reducing the
> efficiency of the origin server. Note when I say caching I mean the
> reference profile, not the profile diff. If servers cache the reference
> profile, they can still cope with turning the sound off or changing location
> as you describe. Caching by the origin server is not mandated by the
> standard but currently I think it is one way of improving efficiency - see
> my implementation for more details. If someone can explain why it is a bad
> idea or a better approach then let me know - comments or criticisms on my
> implementation are very welcome.
> If caching is done at the gateway this also reduces load on the profile
> repository. However as Nick points out this dramatically increases the size
> of HTTP request headers, which could adversely effect network performance,
> and the gateway supplier has to support this as it's not mandated by the
> standard.
> Also, just to confirm, I've tested DELI and it can cope with requests that
> omit profile references - see the test plan distributed with the source code
> for more details.
> best regards
> Mark Butler
> Research Scientist
> HP Labs Bristol
> -----Original Message-----
> From: Suryanarayana, Lalitha [mailto:lalitha@tri.sbc.com]
> Sent: 21 November 2001 16:00
> To: 'Butler, Mark'
> Cc: www-mobile@w3.org
> Subject: RE: CC/PP profile repository overworked?
> Mark:
> I do not think I understand your concern. The original intent was to be able
> to support the ability to send the profile on every request although the
> expectation was that implementors would use the caching mechanisms etc. The
> rationale was the potential likelihood of changes to the profile CPI in
> between 2 requests (eg location or someone turning sound on or off, etc).
> The headers look fine to me.
> When in doubt I would look at http://www.w3.org/TR/NOTE-CCPPexchange as a
> basis, even for the x-wap-profile and x-wap-profile-diff headers.
> Regarding your other note on RDF on the UAProf mailing list, I noted that
> Johan has forwarded it to the W3C group, which is the right place for the
> issue to be discussed.
> Lalitha
> -----Original Message-----
> From: Butler, Mark [mailto:Mark_Butler@hplb.hpl.hp.com]
> Sent: Tuesday, November 20, 2001 9:08 AM
> To: 'eizdepski@cysive.com'; nick.denny@mci.co.uk
> Cc: www-mobile@w3.org
> Subject: RE: CC/PP profile repository overworked?
> Erich's absolutely right - reading the UAProf specs, section page 38
> "The x-wap-profile header is a general header field which must contain the
> following:
> - a URI referencing the CPI or
> - a reference to a profile difference, transported using the
> x-wap-profile-diff or
> - a combination of multiple instances of these two types of data."
> This means headers of the following form are legal:
> GET /ccpp/html/ HTTP/1.1
> Host: localhost
> x-wap-profile:"1-Rb0sq/nuUFQU75vAjKyiHw=="
> x-wap-profile-diff:1;<?xml version="1.0"?>
>  <rdf:RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:prf="http://www.wapforum.org/profiles/UAPROF/ccppschema-20010430#">
>   <rdf:Description rdf:ID="MyDeviceProfile">
>      <prf:component>
>        <rdf:Description rdf:ID="HardwarePlatform">
>           <rdf:type
>   rdf:resource="http://www.wapforum.org/profiles/UAPROF/ccppschema-
>     20010426#HardwarePlatform"/>
>                 <prf:BitsPerPixel>16</prf:BitsPerPixel>
> </rdf:Description>
>      </prf:component>
>   </rdf:Description>
>  </rdf:RDF>
> I hadn't realised this - I expect DELI will not parse such requests as it
> expects a profile reference. I'll note it as an issue to be fixed in the
> next release.
> However I think this is an inefficient way of working as it means the
> gateway must forward the entire reference profile to the origin server with
> every request. It's more efficient for the origin server to cache the
> reference profile, but this can only be done with a profile reference.
> Therefore I would discourage the OpenWave folks (or anyone else) from using
> this approach. Anybody else thought about this?
> For more information on DELI see http://www-uk.hpl.hp.com/people/marbut/
> Mark H. Butler
> Research Scientist
> HP Labs Bristol
> -----Original Message-----
> From: Erich Izdepski [mailto:eizdepski@cysive.com]
> Sent: 20 November 2001 14:20
> To: nick.denny@mci.co.uk
> Cc: www-mobile@w3.org
> Subject: RE: CC/PP profile repository overworked?
> The WAP gateway can (and I think openwave's will be soon) provide the CC/PP
> profile to the origin server as a HTTP header. The gateway should be
> managing its own cache of profiles that it has collected from other servers,
> in the ideal case. For now, there are no other servers providing CC/PP data
> about device hardware or software, meaning the gateway has to have its own
> database of information. This is OK, it is simple for a gateway to create
> CC/PP data from a local database of phone/handheld information and appended
> it to the device headers. I know the Openwave gateway already appends header
> information about its fax capabilities, so adding a CC/PP profile is not a
> stretch.
> Erich Izdepski
> -----Original Message-----
> From: nick.denny@mci.co.uk [mailto:nick.denny@mci.co.uk]
> Sent: Tuesday, November 20, 2001 5:07 AM
> To: www-mobile@w3.org
> Subject: RE: CC/PP profile repository overworked?
> Hello again,
> Firstly thank you to Erich and Mark for your quick and helpful replies.
> Whilst reading the CC/PP requirements and architecture document
> (specifically section 2.2) I noticed that in the WAP implementation, the
> WAP gateway appears to resolve the profile URL and retreive the profile.
> Is this correct? And if so, what is the Origin Server sent? Is it the
> URL to the profile repository, in which case why does the WAP gateway
> have to resolve it? Or is it a URL to the cached information in the
> gateway?
> Many thanks,
> Nick Denny
> nick.denny@mci.co.uk

  Johan Hjelm, Senior Specialist
     Ericsson Research Japan

  "Do you want to sell sugar water or
change the world" is the wrong question.
  The right question is: "How do you
change the world by selling sugar water?"

  Read more about my recent book

Received on Wednesday, 21 November 2001 18:41:59 UTC

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