RE: [xml-dev] RE: ANN: Portable Data Component -- start/end

["David Lee" <dlee@calldei.com>]

I don't believe anything can be truly portable.
There is always a context.   This is not limited to XML but to everything.
But even if we limit ourselves to say language or data representations,  
there is always  a context by which the words or datum are interpreted and
their meaning inferred.
So asking  for "absolute portability" is meaningless or impossible depending
on how you think of it.
Even then one must consider (or define) in what space things are being
"ported".   That is, what is the agreed on set of global context which need
not be specified in the datum.
Also many measurements of  portability are relative.    One might naively
attempt to assign a single number to the concept of "portability"
so that you could then compare one representation against another, but I
think that is not accurate.
There are many aspects of portability that are not comparable against each
other or depend on the environment.

The namespaces example is a good one.   It is not definitive if namespaces
add or remove portability.
The movie case may be better implemented using a start+duration instead of a
start+end ... and these could both be time only, in which case
the datum is portable across days.   If you used a datetime for start, then
the data is not portable across days.
So which is "more portable" ... It would depend on what you want it to mean
(single movie or occurrence) and what space you are trying to port (apps or
time ).





----------------------------------------
David A. Lee
dlee@calldei.com
http://www.xmlsh.org

-----Original Message-----
From: Stephen D Green [mailto:stephengreenubl@gmail.com] 
Sent: Tuesday, April 19, 2011 5:58 AM
To: Costello, Roger L.
Cc: xml-dev@lists.xml.org
Subject: Re: [xml-dev] RE: ANN: Portable Data Component -- start/end


Sorry, I'd better elaborate or it just sounds wrong:

If the context includes the namespace then the component isn't portable
by the principle that portability requires context-independence. Instead,
though, the component, if it had a namespace, could have a context-
independant namespace by moving it into a separate schema module
and assigning a namespace to that module then either including it if
the referencing schema has the same namespace or importing it if the the
referencing schema has a different namespace. You then lose the use
case of simple copy and paste though, don't you?
----
Stephen D Green



On 19 April 2011 10:48, Stephen D Green <stephengreenubl@gmail.com> wrote:
> If this is the case, that context-dependence violates portability,
> then do namespaces violate portability too?
> ----
> Stephen D Green
>
>
>
> On 19 April 2011 10:05, Costello, Roger L. <costello@mitre.org> wrote:
>> David Lee wrote:
>>
>>> Time alone assumes a date is present in the context
>>
>> Ah, excellent point David.
>>
>> And, by definition, a portable data component does not depend on context.
Therefore, specifying the movie using only time values violates the
principle of portability. Do you agree?
>>
>> /Roger
>>
>>
>> -----Original Message-----
>> From: David Lee [mailto:dlee@calldei.com]
>> Sent: Monday, April 18, 2011 3:27 PM
>> To: Costello, Roger L.; xml-dev@lists.xml.org
>> Subject: RE: [xml-dev] RE: ANN: Portable Data Component -- start/end
>>
>> "Who's at fault"
>> Anyone who thinks using Time values instead of datetime values for actual
>> instances of a temporal point is at fault.
>> Time alone assumes a date is present in the context (either explicitly,
or
>> as an occurrence etc).
>> Time alone can never specify a temporal point anymore more than an "x"
value
>> alone can specify a point in 2D space or a fraction can specify a
decimal.
>>
>>
>>
>>
>>
>>
>>
>> ----------------------------------------
>> David A. Lee
>> dlee@calldei.com
>> http://www.xmlsh.org
>>
>> -----Original Message-----
>> From: Costello, Roger L. [mailto:costello@mitre.org]
>> Sent: Monday, April 18, 2011 2:19 PM
>> To: xml-dev@lists.xml.org
>> Subject: [xml-dev] RE: ANN: Portable Data Component -- start/end
>>
>>
>> Hi Folks,
>>
>> Suppose that a person records the start time and end time of a movie,
which
>> starts at 11pm and ends at 1am the next day:
>>
>>    <movie>
>>        <start>23:00:00</start>
>>        <end>01:00:00</end>
>>    </movie>
>>
>> Validating that against the portable start/end data component (see below)
>> results in this error: "movie does not match the assertion".
>>
>> Had the movie times been specified using dateTime:
>>
>>    <movie>
>>        <start>2011-04-16T23:00:00</start>
>>        <end>2011-04-17T01:00:00</end>
>>    </movie>
>>
>> then there would be no error.
>>
>> QUESTION
>>
>> Who's at fault?
>>
>>    - The person who specified the movie times using just time values?
>>    - Or, the portable start/end data component for throwing an error on
>> perfectly good movie times?
>>
>> /Roger
>>
>> P.S. Here's the portable start/end data component:
>>
>>    <xs:complexType name="start-end-date-time">
>>        <xs:sequence>
>>            <xs:element name="start">
>>                <xs:simpleType>
>>                    <xs:union memberTypes="xs:date xs:time
>>                                           xs:dateTime" />
>>                </xs:simpleType>
>>            </xs:element>
>>            <xs:element name="end" minOccurs="0">
>>                <xs:simpleType>
>>                    <xs:union memberTypes="xs:date xs:time
>>                                           xs:dateTime" />
>>                </xs:simpleType>
>>            </xs:element>
>>        </xs:sequence>
>>        <xs:assert test="
>>              if (exists(end)) then
>>                  if (start castable as xs:dateTime) then
>>                      xs:dateTime(end) gt xs:dateTime(start)
>>                  else if (start castable as xs:date) then
>>                      xs:date(end) gt xs:date(start)
>>                  else if (start castable as xs:time) then
>>                      xs:time(end) gt xs:time(start)
>>                  else true()
>>              else true()" />
>>    </xs:complexType>
>>
>> Comments welcome.
>>
>> /Roger
>>
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