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Re: HTTP entities ?

From: Martin Presler-Marshall <mpresler@us.ibm.com>
Date: Thu, 21 Jun 2001 08:33:06 -0400
To: www-p3p-dev@w3.org
Message-ID: <OF477F59F3.ABB4AFCF-ON85256A72.0044D013@raleigh.ibm.com>
     Oops, I meant to send this reply to the mailing list too.

     -- Martin

Martin Presler-Marshall - Program Manager, Privacy Technology
E-mail: mpresler@us.ibm.com
Phone: (919) 254-7819 (tie-line 444-7819) Fax: (919) 254-6430 (tie-line
444-6430)
---------------------- Forwarded by Martin Presler-Marshall/Raleigh/IBM on
06/21/2001 08:41 AM ---------------------------

Martin Presler-Marshall
06/21/2001 08:27 AM

To:   "Christophe Brun-Franc" <cbf@profileup.com>
cc:
From: Martin Presler-Marshall/Raleigh/IBM@IBMUS
Subject:  Re: HTTP entities ?  (Document link: Martin Presler-Marshall)

Christophe Brun-Franc asked:
> "Note that policies are applied at the level of HTTP entities. An entity,
> retrieved by fetching a URI, has a P3P policy associated with it. A
"page"
> from the user's perspective may be composed of multiple HTTP entities;
each
> entity may have its own P3P policy associated with it. As a practical
note,
> however, placing many different P3P policies on different entities on a
> single page may make rendering the page and informing the user of the
> relevant policies difficult for user agents. Additionally, services
SHOULD
> attempt to craft their policy reference files such that a single policy
> reference file covers any given "page"; this will speed up the user's
> browsing experience. "

> What do you mean exactly by HTTP entities ?
> ( For instance, when an HTTP request send more than one HTML File as for
> FrameSet HTML Page )
> ( Or http://www.cbf.com/test.htm#start and
http://www.cbf.com/test.htm#end
> is two differents entities
>    and i should take care of that when the HTTP request is
> http://www.cbf.com / )

HTTP 1.1 defines an "entity" as follows:
entity
     The information transferred as the payload of a request or response.
     An entity consists of metainformation in the form of entity-header
     fields and content in the form of an entity-body, as described in
     section 7.

     So, some examples:
- a plain HTML page which uses no graphics and no stylesheets or any other
external content will be a single entity.
- a non-frame HTML page is generally multiple "entities" - one for the
HTML, and one for each image in the page, plus one for each external style
sheet the page loads (plus more if it's using Java, or ...)
- imagine a frameset with left and right sections; the left HTML has three
imbedded images, while the right has a stylesheet and 9 images. The result
is 16 entities: 1 frameset HTML, two "framed" pieces of HTML, one
stylesheet, and 12 images.
- anchors within a single HTML document are not seperate entities. The P3P
spec, for example, uses many internal anchors to help readers navigate the
document. Those internal anchors are not different entities.

> Thanks in advance.
You're welcome. I hope this clarifies.

     -- Martin

Martin Presler-Marshall - Program Manager, Privacy Technology
E-mail: mpresler@us.ibm.com
Phone: (919) 254-7819 (tie-line 444-7819) Fax: (919) 254-6430 (tie-line
444-6430)
Received on Thursday, 21 June 2001 08:33:12 GMT

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