In two of the three cases you mention the encoded data
binds to a physical object or a collection of physical
objects.
In the third case the encoded data is a time
stamp.
What is common in all these cases is after assignment if
the ID is NEVER EVER changes.
Meeting that condition in most systems is very hard. I
have had conversations like this dozens of times
Wouldnt it be cool to have the
Region of the salesmen encoded in his ID?
Sure, but what happens when he
move to a different region?
Do we change the ID of the
salesmen and orphan all his old records?
Or do we keep his old ID which
makes the region encoding a lie?
Encoding data into ID violates one of Dr. Codds design
rules. It makes the key a functionally related to other facts in the
record.
Vet very carefully any proposal to have encoding in ID
values. If the business representatives cannot swear a blood oath that the
encoded fact will never change use something else.
-----Original Message-----
From: Costello, Roger L.
[mailto:costello@m...]
Sent: Friday, March 05, 2010 3:58 PM
To:
xml-dev@l...
Subject: Should information be encoded into
identifiers?
Hi Folks,
Should identifiers be dumb? That is, no meaning can be
ascribed to identifiers; they are completely
random.
Or, should information be encoded into identifiers? What
information should be encoded into them?
There are precedents for encoding information into
identifiers:
1. In the U.S. each auto is identified by a
Vehicle Identification Number (VIN). Encoded within each VIN is a wealth of
information, including the make and model of the auto, the plant where it was
manufactured, and the vehicle's options.[1]
2. Books are identified by ISBNs. Encoded within each
ISBN is a wealth of information, including the country, publisher, and the
relative size of the publisher.[2]
3. UUIDs are used in many applications. Encoded within
some UUIDs are the date/time stamp of when the UUID was created, and the network
address of the machine which created the UUID.[3]
I suspect there are other examples of identifiers that
have information encoded into them.
What are the advantages of encoding information into an
identifier? What are the disadvantages?
/Roger
[1] Format of VIN:
http://en.wikipedia.org/wiki/VIN
[2] Format of ISBN:
http://www.xfront.com/isbn.xsd
[3] Fomat of UUID:
http://www.ietf.org/rfc/rfc4122.txt
_______________________________________________________________________
XML-DEV is a publicly archived, unmoderated list hosted
by OASIS
to support XML implementation and development. To
minimize
spam in the archives, you must subscribe before
posting.
[Un]Subscribe/change address:
http://www.oasis-open.org/mlmanage/
Or unsubscribe:
xml-dev-unsubscribe@l...
subscribe:
xml-dev-subscribe@l...
List archive:
http://lists.xml.org/archives/xml-dev/
List Guidelines:
http://www.oasis-open.org/maillists/guidelines.php
Cart
