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Re: Clarifying DFDL vs. Binary XML (was RE: use cases: binary XML for scientifc computing)

From: Kenneth Chiu <kchiu@cs.binghamton.edu>
Date: Fri, 3 Dec 2004 10:46:13 -0500 (EST)
To: mike.beckerle@ascentialsoftware.com
cc: brutzman@nps.edu, RogerCutler@chevrontexaco.com, aslom@cs.indiana.edu, sdw@lig.net, whoschek@lbl.gov, xml-dev@lists.xml.org, public-xml-binary@w3.org, mgovinda@cs.binghamton.edu
Message-ID: <Pine.GSO.4.58.0412031037180.6252@rainier.extreme.indiana.edu>

Also, I think one can make the argument:

    A DFDL instance describes a set of binary data files.
    An XML Schema instance describes an set of XML Infosets.

That is, DFDL is to XML Schema as XML Infosets are to binary
data files.

> I would also like to see use cases which clarify the differences between
> binary-xml and DFDL so that we're not constantly revisiting that and we can
> have a positive URL reference to some clarifying point that both Binary XML
> and DFDL teams can depend on. To me the crux of the issue is that in the
> DFDL/descriptive world, you have this problem of data format debugging,
> i.e., what if the description is wrong? This is what you avoid with the
> binary-XML/prescriptive approach, and it is very worth avoiding. This is why
> I see the need for both and their overlap doesn't bother me.
> To that end, here's some language revised from an earlier posting, which
> makes this point about presecriptive vs. descriptive formats. You can adapt
> it as you see fit.
> Binary-XML is a prescriptive approach, that is, it specifies a universal
> format that is used for data. Binary-XML shares this category with ASN.1 and
> XDR, but leverages the popularity of the XML family of standards. The DFDL
> approach is descriptive. That is, the data has some format. You describe in
> DFDL the format the data is in. Use-cases where this approach is preferable
> include high-performance programs which often want to arrange for data
> structures to be aligned and directly mappable into memory layouts or
> randomly accessible on disk. DFDL allows data to meet these requirements
> while still being universally described for interchange with other programs.
> Other important DFDL use cases include the broad array of legacy data
> formats. DFDL also leverages XML technologies for describing the logical
> structure of the data, but adds the ability to describe a different physical
> realization.
> Pros and Cons: The Binary-XML prescriptive approach is preferable for new
> programs which simply need the improved performance and density of a binary
> encoding. The prescriptive approach is in a strong sense preferable to
> descriptive as use of a prescriptive approach avoids the entire issue of
> "data format debugging" which is insuring that the data and the description
> of it match properly, and correcting any errors in the description. The DFDL
> descriptive approach is preferable for pre-existing data formats, as well as
> certain high-performance needs, but use of DFDL necessarily creates this
> issue of data format debugging, which must be overcome by applications
> developers.
> Mike Beckerle
> Co-chair GGF DFDL WG
> Ascential Software
> > -----Original Message-----
> > From: Don Brutzman [mailto:brutzman@nps.edu]
> > Sent: Thursday, December 02, 2004 9:14 AM
> > To: mike.beckerle@ascentialsoftware.com
> > Cc: RogerCutler@chevrontexaco.com; aslom@cs.indiana.edu;
> > sdw@lig.net; whoschek@lbl.gov; xml-dev@lists.xml.org;
> > public-xml-binary@w3.org; kchiu@cs.binghamton.edu;
> > mgovinda@cs.binghamton.edu
> > Subject: Re: use cases: binary XML for scientifc computing
> >
> > mike.beckerle@ascentialsoftware.com wrote:
> > > I do believe that GGF DFDL is relevant to the discussion here.
> > > https://forge.gridforum.org/projects/dfdl-wg/ is the site, and
> > >
> > https://forge.gridforum.org/docman2/ViewProperties.php?group_id=113&ca
> > > tegory_id=803&document_content_id=2973
> > >
> > <https://forge.gridforum.org/docman2/ViewProperties.php?group_id=113&c
> > > ategory_id=803&document_content_id=2973> (or
> > > http://tinyurl.com/435j7 in case email clobbered the long
> > URL) is the
> > > most recent presentation. Around slide 7 is where you'll
> > find content.
> >
> > I agree this is quite relevant, and hope that we at least
> > have a use case which compatibly describes the subset of
> > shared motivations between DFDL and the XBC effort.
> >
> > all the best, Don
> > --
> > Don Brutzman  Naval Postgraduate School, Code USW/Br
> > work +1.831.656.2149
> >                MOVES Institute, Monterey CA 93943-5000 USA
> > fax  +1.831.656.7599
> > Virtual worlds/underwater robots/X3D/XMSF
> > http://web.nps.navy.mil/~brutzman
> >
Received on Friday, 3 December 2004 15:56:35 UTC

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