From David Alexander
September 4, 2003


Hello All,


In response to the phone meeting today, as Joseph suggested, I'm putting
down some ideas to start an email discussion.  I think David's paper is
one of the most comprehensive attempts at a definition of dataset that
speaks to an application developer who wants to design a piece of
software that uses datasets.  I hope I'm not being to bold to suggest
some semantic changes (and maybe one new idea) to the defining
properties of a dataset to spark more off-line discussion.  I wanted to
(1) see if I understand what David Adams' definition of a dataset is,
and (2) hopefully clarify it for others.

***********************************************
DEFINING PROPERTIES OF A DATASET:
If an object has all the following 4 properties 
(the last two are optional), then the object is 
defined as a dataset.

0. Unique Identifier
1. Data Description
2. Dataset Reference
3. Essential Provenance
4. Additional Production Details (Optional)
5. Additional Metadata (Optional)
*********************************************

Where the changes are:

0. Same as David's except uniqueness emphasized.

1. "Content" alone was too confusing with the data itself.  In fact,
David refers to "content description" in the Mapping paragraph, so I
like "Data Description" here to distinguish it as indeed being
meta-data.

2. Here I merged of David's "2. Location" and "3. Mapping" into "Dataset
Reference".  What I mean by "Dataset Reference" is either a data
location map (which is the combining of David's two ideas) or a catalog
reference (which is the new idea).  There are two lines of reasoning
here.  The first is that if the mapping is non-trivial, then the
location list by itself isn't very useful for getting particular records
or sub-sets of data from the dataset, so why not combine them into a
"location map", which will always include the locations in addition to
the more complicated mapping.  The second line of reasoning is that for
datasets that are indeed virtual and do not physically exist before
requests there *is* no location and one can only get the dataset from a
catalog (or some other generating engine I suppose).  Reference is then
a generic term to mean either "location map" or "catalog", but the main
point is that with the reference you can actually get the data.

3. Just added the word "essential" to distinguish it more from what
David was calling "History".

4. Emphasized here that the history is really about production details.
Any other types of information can go in the catch-all metadata.

5. Here "Additional" reminds us that all the properties are really
meta-data, but there are other types of meta-data to include.


Is this any better?  Does it make sense?

dave


_________________________________________________
David Alexander                desk: 303-448-7751
Tech-X Corporation             fax:  303-448-7756
Boulder, CO            email: alexanda@txcorp.com
(303)448-7751             http: www.techxhome.com


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