Re: Metadata and EGL

<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