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   Re: [xml-dev] Why datatypes?

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"Rick Jelliffe" <ricko@allette.com.au> wrote:

| But many other users do want datatyping, because they want to perform
| QA on outgoing data or QC on incoming data. 

Yes, but this is invariably application-specific.  If you and I exchange
farglebarps, then we'll QA the farglebarps we send and QC the farglebarps
we receive, according to our agreements.  But why does the rest of the
universe need to have validation of farglebarps built in to their systems?

| So you can see that there are actually categories of datatyping:
|   * value-constraining
|   * storage aligned
|   * semantic
| and that there is no universal agreement (or reason to expect or
| want one) one which is better or best or appropriate or wrong.
| Even the issue of "should these be separate layers or should
| these be mixed?" has no concensus.

That's why datatyping in something like XML Schema is fundamentally
misconceived.  The lack of consensus becomes the excuse to force a
political settlement, where the back room boys with seats at the table
win, and the rest lose.  

| People who favour the proscriptive approach tend to feel that users 
| are always shielded from actual XML values by user interfaces, so in
| a sense a lot of the value comes from everyone standardizing on the 
| same set of types rather than from the completeness of the types 
| themselves.

Which is also why people who favor the proscriptive approach also favor
the Back Room Boys approach to "standardization" for um, "everyone".  Such
one-size-fits-all procrustean "standardizations" are not enabling; they
are crippling - only X (<<100%) of needs are supported by a "standard" in
which Y (>>0%) of the facilities are useless.  The downstream systemic
effect is cost transfer by fiat - onto those for whom the standard was not
written.  Poor show.  Beastly luck, old chap.

There is no value in standardizing the unstandardizable.

| (The presence non-tag structure is actually built into ISO SGML:
| you can, inside an element, declare a map which recognizes
| certain strings as delimiters that introduce or separate structures.
| So this is not some fancy wishful thinking, but something that
| XML gave up for parsing simplicity.  I am not trying to
| reintroduce SHORTREF into XML!

How about elaborating the use of data content notations?  With a notation
for farglebarps, anyone can share our understanding of farglebarps if they
want or need to, and the rest of the universe doesn't even have to care.

I thinkit's time to give up on the utopian belief that every XML system in
the universe must be innately capable of meaningfully grokking every XML

| But there is data that has structure that we want to validate but not 
| split into different information units: dates and URLs are good examples.)

Validating URLs is even more non-trivial than validating dates.  See eg


(and the full thread for some corrections.)


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