[dfdl-wg] Draft document just under the wire for "official" commentary at GGF15

[Robert E. McGrath]

Greetings,

Thanks for the updated draft!  Now there is lot's of flesh on the bones.

I have a very basic question (or maybe 2).  Perhaps this has been 
discussed but simiply omitted from the document.

On page 19, Section 12.2. of the 8-26 draft:

"The primary purpose of complex types in a DFDL implmentation is to
determine where their sub-elements begin and end in the data stream."


1. What is the definition of "a DFDL implementation"?

   (I suspect this is something like 'a program that uses DFDL schema
    to interpret a data object')

2. What is the definition of "the data stream"?

   The document seems to have many unstated assumptions about data streams,
   they seem to be continuous arrays of bytes, etc., they are byte addressable,
   etc.

   In other places, there are references to "a data file" p. 26, p. 27, and
   so on, and seems to assume that "stream" and "file" are the same thing.

   This becomes an issue when the stored representation 'on disk' isn't the same
   as the IO stream, e.g., data from a relational database.

   It would be good to try to clearly define these terms, perhaps
   with a model of IO WRT what DFDL is describing.

Thanks for your attention.

    --REMcG

---
Robert E. McGrath
National Center for Supercomputing Applications
University of Illinois, Urbana-Champaign
Champaign, Illinois 61820
(217)-333-6549

mcgrath at ncsa.uiuc.edu