<CROSSPOSTED to EGL>
Dave Odom wrote:
Joe,
When you speak of Metadata is your definition of Metadata a Metadata
dictionary as is often found for a data warehouse or is Metadata for EGL
just another way of saying a REF file for all definitions for all
variables for all programs in an application/system?
Dave, the metadata in EGL is true metadata in the sense that you can
define not just the data characteristics of a field (type, length, and
description) as you would in a field reference file, but also
higher-level abstractions, such as prompt, validation, editing, and
external characteristics such as whether a field is read-only.
Some of these things are available in DDS. Technically the COLHDG field
provides you with prompt information, and some basic editing can be done
with things like edit codes or the VALUES/RANGE keywords. But with EGL,
editing and validation is much broader. There are intrinsic
capabilities for everything from money to hexadecimal, while at the same
time you can validate against ranges, lists, data tables (!) or even
specify an editing function. All of this can be done at the data item
level, and then when a field is defined based on that data item, all
those characteristics are brought with.
The other types of metadata include the ability to specify fields to be
read only or, my favorite, non-persistent. A non-persistent field ina
record is one that is not read from nor written to the database. It's
simply for the user interface. For example, you might have a checkbox
that you include in a table of records. The checkbox isn't in the table
itself, but you can include it in the record. That way, any generated
SQL will ignore the checkbox, but when you drop the record on the page
the checkbox will be painted. Anyway, that's another category of metadata.
If you have more specific questions on how EGL does things, I'm going to
cross-post this to the new EGL list, and I'll answer there. For my
part, as far as this list goes I'd be interested in hearing how many of
these features are found in a data warehouse, because that's the sort of
information that makes creating web interfaces of any kind easier. The
more information you have on the field the easier it is to generate a UI
for it.
Joe
midrange.com
