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Re: New Attachments Issues

From: John J. Barton <John_Barton@hpl.hp.com>
Date: Tue, 10 Jun 2003 10:04:43 -0700
Message-Id: <5.1.1.6.2.20030610094348.02856748@hplex1.hpl.hp.com>
To: Jacek Kopecky <jacek@systinet.com>, Marc Hadley <marc.hadley@sun.com>
Cc: XMLP Dist App <xml-dist-app@w3.org>

Senders and receiver necessarily agree on the data formats.
They will be designed with expectations about the data they
exchange, including the tradeoffs in space and time embodied
in the binary/XML issues.  Intermediates should not alter that
tradeoff willy-nilly.  So there is a fourth option:
         (iv) intermediates cannot alter the attachments.
If the intermediate add some value to the exchange, the
endpoints might allow reformatting in exchange.  But this
would have to be under control: options involving unspecified (i)
or by-luck (ii) rearrangement of the tradeoff won't be useful.



At 04:56 PM 6/10/2003 +0200, Jacek Kopecky wrote:

>Marc, I think your formulation is precisely what I'd say. 8-)
>
>I don't think we ever wanted to consider security mechanisms visible to
>the application that would be aware of any optimizations not visible to
>the application, like the optimization of binary data in SOAP messages.
>I thought the expectation was that dig-sig or encryption would work on
>canonical base64 representation of the data. There can still be some
>optimizations in the implementations, e.g. only do the base64 encoding
>on the fly for signature computation, never store the actual full base64
>version of the data. Base64 encoding is cheap and if the signature code
>can consume a stream, the cost of base64 encoding will be lost in the
>cost of computing the signature, I believe (and somebody else has
>mentioned this before me, too).
>
>Best regards,
>
>                    Jacek Kopecky
>
>                    Senior Architect
>                    Systinet Corporation
>                    http://www.systinet.com/
>
>
>
>
>
>
>On Tue, 2003-06-10 at 16:35, Marc Hadley wrote:
> > So, to paraphrase, you would say that:
> >
> > (1) We DO NOT expect intermediaries to preserve what is serialized as
> > attachments and what is serialized inside the SOAP envelope.
> >
> > (2) The binding determines which nodes to serialize as attachments in
> > an implementation specific manner.
> >
> > That's certainly a coherent answer to the two issues.
> >
> > Your proposed answers probably have some implications for the set of
> > security technologies we can apply to messages containing attachments,
> > e.g. I expect it would prevent use of S/MIME or PGP-MIME. It also means
> > that digital signatures must always be calculated on the text data
> > representation of attachments and verified using the same - i.e. even
> > if you use attachments to optimize the transfer, if you are using XML
> > security that includes the attachment data then you always need to
> > compute the base64 transform at both sender and receiver.
> >
> > Marc.
> >
> > On Tuesday, Jun 10, 2003, at 07:46 US/Eastern, Jacek Kopecky wrote:
> >
> > > As we're only talking about optimization of transfer of binary data
> > > (we're not yet talking about the other aspects of PASWA, like
> > > swa:Representation), it is not critical from our point of view that the
> > > optimization be preserved across intermediaries (1) or that it be done
> > > at all (2). However, I do think we should say something, so I prefer
> > > option (ii) below - that we say your two questions are answered in
> > > implementations in an implementation-specific way.
> > >
> > > It is important that whatever we produce from PASWA emphasizes the fact
> > > that we're providing a possible optimization of binary data transfer
> > > and
> > > how it may be particularly useful with the other stuff like
> > > swa:Representation.
> > >
> > > Best regards,
> > >
> > >                    Jacek Kopecky
> > >
> > >                    Senior Architect
> > >                    Systinet Corporation
> > >                    http://www.systinet.com/
> > >
> > >
> > >
> > >
> > >
> > > On Fri, 2003-06-06 at 18:25, Marc Hadley wrote:
> > >> All,
> > >>
> > >> Following the resolution of issue 429[1], I'd like to raise the
> > >> following new issues:
> > >>
> > >> 1: "What are the semantics of attachments w.r.t. SOAP intermediaries.
> > >> E.g. do we expect intermediaries to preserve what is serialized as
> > >> attachments and what is serialized inside the SOAP envelope."
> > >>
> > >> 2: "How does the binding determine which nodes to serialize as
> > >> attachments ?"
> > >>
> > >> Amongst the many possible answers, the following spring immediately to
> > >> mind:
> > >>
> > >> (i) We don't specify that.
> > >> (ii) An implementation specific mechanism (similar to (i) but we
> > >> explicitly say so).
> > >> (iii) Its triggered by something in the infoset - if so, what.
> > >>
> > >> Thanks,
> > >> Marc.
> > >>
> > >> [1] http://www.w3.org/2000/xp/Group/xmlp-issues#x429
> > >>
> > >> --
> > >> Marc Hadley <marc.hadley@sun.com>
> > >> Web Technologies and Standards, Sun Microsystems.
> > >
> > >
> > --
> > Marc Hadley <marc.hadley@sun.com>
> > Web Technologies and Standards, Sun Microsystems.

______________________________________________________
John J. Barton          email:  John_Barton@hpl.hp.com
http://www.hpl.hp.com/personal/John_Barton/index.htm
MS 1U-17  Hewlett-Packard Labs
1501 Page Mill Road              phone: (650)-236-2888
Palo Alto CA  94304-1126         FAX:   (650)-857-5100
Received on Tuesday, 10 June 2003 13:05:17 GMT

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