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RE: AFTF requirements list with comments, pre-2003/01/28 telcon (revised)

From: David Orchard <dorchard@bea.com>
Date: Thu, 30 Jan 2003 10:35:40 -0800
To: <xml-dist-app@w3.org>
Message-ID: <017a01c2c89f$d540e370$4b0ba8c0@beasys.com>

BEA comments on said requirements:

* in the intro, define 'attachments' as 'a technology that allows for
the encapsulation of and reference to arbitrary data, including that
which is not legally serialized into XML 1.0 (e.g., binary)'

* define 'parts' as 'units of arbitrary data'

Considerations:
* The specification should aid message construction and parsing with simple
tools.

R15. The specification should be conveniently describable by languages such
as WSDL.

RNew. The specification should include sample changes to WSDL 1.2 and/or
extensions to WSDL.

DR6. The specification must permit parts to be identified by URIs or URI
References.  This is similar to ChrisF's comment.

DR12. Any message parts should be readily locatable/indentifiable.

DR11, preferred wording is (b)

RNew. The specification should support streaming of parts, ie chunked
encoding.  A sample scenario of this should also be provided.

RNew. The specification should support securing of messages and message
parts, such as use of encryption and signatures, in a simple manner.  This
is different than the proposed "support ws-security requirement", in that it
covers application of encryption and signature without necessarily meaning
use of ws-security.

RNew. The specification may provide manifest functionality.

RNew. The specification must provide specification of media types for parts.

Cheers,
Dave


> -----Original Message-----
> From: xml-dist-app-request@w3.org
> [mailto:xml-dist-app-request@w3.org]On
> Behalf Of Mark Jones
> Sent: Wednesday, January 29, 2003 7:23 AM
> To: xml-dist-app@w3.org
> Subject: AFTF requirements list with comments, pre-2003/01/28 telcon
> (revised)
>
>
>
> AFTFers,
>
> Here is another version of our draft list.  I've added in-line the
> comments received so far on the requirements so we can more easily
> consider the feedback we've gotten.
>
> I've also appended a summary of three new draft requirements recently
> proposed by Jeff Schlimmer (Microsoft) and commented on by Sanjiva and
> John Barton.
>
> --mark
>
> ________________________________________________________________
>
>
> Concrete Attachment Feature Requirements
> ----------------------------------------
>
> Considerations
> --------------
>
> * The specification should not invent a packaging scheme.
>
> <barton
> href="//http://lists.w3.org/Archives/Public/xml-dist-app/2003J
> an/0027.html">
> Perhaps I don't quite understand the meaning of "packaging scheme" but
> the way I interpret this is "the ARTF is going to pick between SwA and
> DIME", which isn't truly possible since neither are sound enough.
> Perhaps you mean The specification should resemble existing packaging
> schemes.
> </barton>
>
> <markH
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0029.html">
> I think there's a (perhaps not clearly made) distinction between
> packaging scheme and attachment specification. My take on
> 'not invent a
> packaging scheme' is that the attachment specification will use an
> existing technology like MIME or DIME or ZIP (or tar or jar
> or ...) as
> the underlying packaging technology rather than inventing everything
> from the ground up. The attachment specification would
> describe how to
> use the underlying packaging scheme for packaging SOAP messages and
> attachments.
> </markH>
>
>
> * The specification should aid debugging with simple tools.
>
> <chris
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0025.html">
> This has me baffled. What is it that you have in mind in the way of
> tools, and more specifically, are you suggesting that the
> specification would define said tools or that the specification would
> define a concrete binding that had as a design consideration that an
> implementation would be inherently debuggable? Further, what manner of
> "debugging" are we talking about here?
> </chris>
>
> <barton
> href="//http://lists.w3.org/Archives/Public/xml-dist-app/2003J
> an/0027.html">
> I think this one was added at my suggestion.  I would word it:
>   The specification should rely on plain ASCII headers.
> Plain ASCII (no not internationalized) makes debugging message systems
> considerably easier.  Compare anyone's experience in working
> with HTTP on
> the one hand and RPC/Jini/Corba on the other.  Please note
> that ASCII does
> not mean unformatted ASCII.  Processing many small messages (~packet
> size) would benefit from fixed formats.
> </barton>
>
> <markJ
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0028.html">
> John Barton suggested this one and his reply to your note
> captures his intention.
> </markJ>
>
>
>
> General Requirements
> --------------------
>
> R8. The specification must describe its relationship to the
>      properties defined in Table 1 (att:SOAPMessage and
>      att:SecondaryPartBag) in the SOAP 1.2 Attachment Feature
>      specification.
>
> R9. The specification must describe its points of extensibility.
>
> R15. The specification should not unnecessarily preclude convenient
>       description by languages such as WSDL.
>
> <chris
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0025.html">
> Hmmm... Why wouldn't the specification provide a normative
> WSDL binding
> extension mechanism? Afterall, what authority is better suited to
> define the extension than that which specifies the concrete binding
> itself?
>
> Yes, I realize this is the XMLP WG and not the WSDL WG, but the WSDL
> WG is not chartered with the specification of all WSDL
> extensions, just
> the WSDL core syntax, processing model, extension points and
> framework.
>
> It seems to me that not defining the WSDL binding extension for this
> feature would be like the XMLP defering a schema definition of SOAP
> to the XML Schema WG. Clearly, we would not do that, why
> would we defer
> the definition of the WSDL?
> </chris>
>
> <jean-jacques
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0026.html">
> If nothing else, this may be a timing issue. WSDL is evolving
> rapidly; the SOAP 1.2 support is still in a state of flux; it
> will take a little while before things are stable enough for the
> ARTF so start dealing with this issue.
>
> Also, it may well turn out that we need WSDL extensions for
> dealing with attachments. It might make sense to built them into
> the core.
> </jean-jacques>
>
> <markJ
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0028.html">
> Jean-Jacques's reply touched on some of this.  Noah suggested
> the somewhat convoluted wording to try to convey the sense that WSDL
> is still evolving and that it may need to stretch a bit also.  (We
> won't necessarily need the flexibility, but this gives us a litle
> wiggle room.)
> </markJ>
>
>
>
> DR17. The specification must work with the SOAP 1.2 HTTP binding and
>       with as many other bindings as possible.
>
>
>
> Representation
> --------------
>
> DR1. The specification must define a means to carry multiple
> data parts.
>
> DR2. The specification must define a means for parts to carry
>      arbitrary data, including non-XML data (e.g., binary data and XML
>      fragments).
>
> DR3. The specification must admit a reasonably time-efficient means of
>      identifying parts.
>
> <chris
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0025.html">
> I think that rather than "identifying" this is intended to refer to
> resolving or dereferencing, no? If not, then I guess I don't
> understand
> the requirement's indended interpretation.
> </chris>
>
> <markJ
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0028.html">
> "identifying" in this sense is more tied to finding parts in
> the packaging -- byte lengths, boundary strings, etc.
> </markJ>
>
> DR4. The specification must use a reasonably space-efficient
>      representation.
>
> DR5. The representation must efficiently support the addition and
>      deletion of parts.
>
> <chris
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0025.html">
> Hmmm... While it is clear that an implementation of the
> specification
> would likely carry this requirement, it is less than clear that the
> requirement is applicable to the specification itself. Further, one
> would imagine that by this statement, it would be the
> intended to cover the
> insertion or in-line deletion of parts, or had you only
> appending and
> truncation in mind?
>
> Again, it isn't clear that this requirement, as written is either
> testable of a specification or relevant for a specification
> that is not
> intended to be implementation-specific.
> </chris>
>
> <markJ
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0028.html">
> The point here was to make the spec relatively friendly to
> intermediaries that might need to modify the attachment bundle in
> straightforward ways.  (roughly resonant with the fact that insertions
> and deletions of headers in a SOAP envelope are pretty straightforward
> syntactically, for example).
> </markJ>
>
>
> DR13. The specification must provide support for large parts.
>
> <chris
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0025.html">
> And small ones as well one would imagine. How large? Arbitrarily
> large? Just "pretty big", really, really large" or "incomprehensibly
> large"? :)
>
> What about parts who's size is not known at the time that
> the serialization is begun?
> </chris>
>
> <markJ
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0028.html">
> These points have been discussed briefly.  This one needs more work.
> </markJ>
>
> <barton
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0030.html">
> The reason for this kind of requirement is the dominant impact of I/O
> and memory allocation on performance.  For small messages, all
> attachment scheme will be equal since CPUs are infinitely fast.
> "Large" of course changes over time as hardware resources improve.
> Design for messages between 1MB and 1GB.  5 years from now, when
> this standard is in use, allocators can bite off 1MB but 1GB
> will likely
> still call for disk.  You can shift these numbers around, but
> they will
> factor into the design: might as well discuss them explicitly.
>
> In my opinion, parts whose size is not known should not be "attached"
> to SOAP messages.  Rather one should use messages to set up an
> out of band stream mechanism.
> </barton>
>
>
> Reference to Parts
> ------------------
>
> DR6. The specification must permit parts to be identified by URIs.
>
> <chris
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0025.html">
> Hmmm... I think that the specification should require that parts be
> identified by URI, but that they may be identified using other means
> as well. Of course, they could be identified by relative URI,
> not just
> absolute URI.
> </chris>
>
> <markJ
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0028.html">
> We can consider your wording instead.
> </markJ>
>
>
> DR7. The URI identification scheme must be robust under the addition
>      and deletion of parts -- i.e., it must not require that URIs to
>      other parts be altered, it must be relatively easy to avoid URI
>      conflicts, etc.
>
> DR11. (a) The specification should permit an initial human readable
>           part.
>       (b) The specification should not specify a particular ordering
>           of parts.
>       [still noodling on which version to prefer]
>
> <chris
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0025.html">
> Not sure I follow this...
> </chris>
>
> <markJ
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0028.html">
> There was some sentiment for flexibility in part ordering -- for
> example, having a text part preceeding even the SOAP message.
> </markJ>
>
>
> DR12. The SOAP message part should be readily locatable/identifiable.
>
> <chris
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0025.html">
> Should it not be the case that ALL parts be identified,
> identifiable?
> What would make the SOAP part unique in this regard?
> </chris>
>
> <markJ
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0028.html">
> We wanted to make sure if there were multiple SOAP message
> parts that we could identify which one was the primary part and which
> were attachments.  This may be an issue if order were arbitrary, for
> example.
> </markJ>
>
>
> DR16. The part identifier scheme to be determined by sending
>       application.
>
> <chris
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0025.html">
> "scheme" seems to imply "URI", but my guess is that it does not.
> Again, I would strongly recommend that parts be identified by URI
> (relative or absolute).
> </chris>
>
> <markJ
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0028.html">
> URI is what I have in mind.
> </markJ>
>
> ________________________________________________________________
>
> New proposed requirements:
> --------------------------
>
> DR18. The specification must define a means to format messages for
> down-level receivers that do not understand the specification.
>
> <sanjiva
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0034.html">
> How can any spec say something about those who don't understand the
> spec? I'm confused.
> </sanjiva>
>
> <barton
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0033.html">
> Maybe you can clarify this one Jeff...the way I read it, it sounds
> impossible.
> </barton>
>
>
>
> DR19. The specification must enable efficient allocation of buffers by
> receivers.
>
> <sanjiva
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0034.html">
> I'm again confused; while a statement like "this spec must be
> implementable as efficiently as possible" is reasonable (and
> motherhood-and-apple-pie IMO), speaking specifically about
> buffer allocation seems rather pointed.
> </sanjiva>
>
> <barton
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0033.html">
> This one motivates some of the other requirements but it implies that
> the sender understand the receiver's memory allocation capabilities.
> On one extreme the requirement could amount to "give the content
> length of attachments up front", but at the other extreme it
> could require the interleaving of parts to achieve a serialization
> optimal for receiver processing.
>
> As an example of the latter, the UPNP Printing folks worried about how
> an extremely long XHTML doc with many inline images could be a printed
> with one page buffer.  While that may seem like an example far from
> the one most SOAP folks consider, once you get to pipelined processing
> of composed
>
> SOAP services the differences begin to fade.  These are cases you want
> to be able to handle and they are cases that non-XML systems deal
> with.
>
> Of course the serialization of XHTML is well-defined.  Serialization
> for arbitrary receiver processing isn't.  That makes this requirement
> difficult to spell out absent information on the receiver buffer
> capability.  Consequently one might go for a requirement that asks the
> spec. to allow attachments to be placed in the stream physically near
> their first point of XML reference rather than getting into buffers.
> That would pick up the critical use case without getting mired in an
> open-ended problem.
> </barton>
>
>
> DR20. The specification must allow messages to be secured using the
> mechanisms defined in WS-Security.
>
> <sanjiva
> href="http://lists.w3.org/Archives/Public/xml-dist-app/2003Jan
> /0034.html">
> WS-Security only applies to SOAP envelopes. This requirement would
> hence have the effect of precluding MIME/DIME style packaging ..
> </sanjiva>
>
Received on Thursday, 30 January 2003 15:42:22 GMT

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