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Re: SOAP 1.2 Attachment Feature review

From: Hugo Haas <hugo@w3.org>
Date: Fri, 11 Oct 2002 10:29:06 +1000
To: www-ws-arch@w3.org, David Orchard <dorchard@bea.com>, Mark Jones <jones@research.att.com>
Message-ID: <20021011002906.GK2788@w3.org>

Following today's teleconference, I am kicking off the finalization of
the text we will send to the XML Protocol Working Group.

* Hugo Haas <hugo@w3.org> [2002-10-02 17:27+0900]
> In a few words, the document specifies an abstract model for modeling
> "attachments" (synonym for secondary part, object, thing, etc) along
> with a SOAP envelope, how to reference those "attachments" from the
> envelope, and what is expected from a binding which support this SOAP
> feature.
> FWIW, I prefer the term secondary part and find attachment confusing,
> because I really picture an attachment traveling along with the SOAP
> envelope, like when sending an email with MIME attachments, whereas it
> is not required for the envelope and the secondary parts to travel
> together, e.g. see comment 2.
> Comment 1:
> ==========
> The specification emphasizes in several places that a secondary part
> may be identified by multiple URIs. Here is the justification:
> | Note: the ability to identify a single part with multiple URIs is
> | provided because, in general, the Web architecture allows such
> | multiple names for a single resource. It is anticipated that most
> | bindings will name each part with a single URI, and through the
> | use of base URIs, provide for absolute and/or relative URI
> | references to that URI.
> While this is certainly true, I don't think that this is desirable and
> was afraid that the text was too neutral about that. I don't think
> that we would want to encourage this.
> As a matter of fact, I just realized that this is inconsistent with
> the definition given in section 3 which says that secondary parts are
> identified by _a_ URI.

It seems that other people expressed comments about use of URIs in
this specification.

Dave and Mark, could you please send a written version of yours?

> Comment 2:
> ==========
> As an example of implementation, the document reads:
> |    3. The primary SOAP message part may be exchanged using the HTTP
> |       protocol binding without any further encapsulation and the JPEG
> |       image transmitted using a separate HTTP GET request.           
> Basically, this describes a SOAP message which would be carried using
> the HTTP binding, as defined in SOAP Version 1.2 Part 2[2], and which
> would contain references (hyperlinks) outside the envelope.
> I was wondering how far the current HTTP binding was from supporting
> the attachment feature, since it seems that getting attachments in
> this case is just a matter for the SOAP processor of doing HTTP GET
> requests to get representations of the resources referenced.

There was some confusion about the HTTP binding, HTTP hyperlinks in a
SOAP message and the Attachment Feature.

I am proposing to reword this part as follows:

  The SOAP encoding allows references by IDREFs inside the SOAP
  envelope. A natural and common way to reference something on the Web
  is to use a reference to a resource using an http: URI. The
  Attachment Feature document suggests that such references are to be
  handled by the Attachment Feature (example 3 in section 6[3]).

  It is unclear, with the current SOAP Version 1.2 specification, how
  such URIs would be dereferenced, i.e. as part of the HTTP binding,
  by the SOAP processor, etc. Some clarity about this example is

Does that represent the opinions expressed on the call?



  3. http://www.w3.org/TR/2002/WD-soap12-af-20020924/#implementation
Hugo Haas - W3C
mailto:hugo@w3.org - http://www.w3.org/People/Hugo/
Received on Thursday, 10 October 2002 20:29:22 UTC

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