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SOAP 1.2 Attachment Feature review

From: Hugo Haas <hugo@w3.org>
Date: Wed, 2 Oct 2002 17:27:35 +0900
To: www-ws-arch@w3.org
Message-ID: <20021002082735.GL6585@w3.org>

As per my action item, I have reviewed the 24 September 2002 Last Call
Working Draft of the SOAP 1.2 Attachment Feature[1].

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.

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.

Regards,

Hugo

  1. http://www.w3.org/TR/2002/WD-soap12-af-20020924/
  2. http://www.w3.org/TR/2002/WD-soap12-part2-20020626/#soapinhttp
-- 
Hugo Haas - W3C
mailto:hugo@w3.org - http://www.w3.org/People/Hugo/
Received on Wednesday, 2 October 2002 04:27:39 GMT

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