- From: Thomas Passin <list1@t...>
- To: xml-dev@l...
- Date: Wed, 21 Dec 2022 14:05:03 -0500
How has time been eliminated? You check something now, and you check it
later to see if it has changed. If it has changed, you do some
processing to figure it out, if not or the results are not conclusive,
you check it later again. You are describing some kind of work flow to
accomplish this.
Since you are looking at enemy aircraft (oh, all right, possibly stolen
cars), it would seem that an alert-driven system would be preferable to
a polling-based system. Either way, time (or at least its passage) is
intimately involved.
On 12/21/2022 11:02 AM, Roger L Costello wrote:
Hi Peter,
You don't like my fictitious Car.xml/PoliceReport.xml example? Bummer.
Okay, then here's an actual, real-world example. It is an exact analog of the Car.xml/Police.xml example, albeit a bit more complex.
A radar scans the sky and detects an object. The radar saves the information about the object to an XML file and stores the file in a folder (along with other files that it has stored for other objects):
<Object id="XYZ">
<Location>
<Latitude>10</Latitude>
<Longitude>20</Longitude>
<Elevation>100</Elevation>
</Location>
<DateTime>...</DateTime>
-- other info --
</Object>
At some point a program reads in that XML document and begins processing it. The objective of processing is to output an alert if the object represents an enemy aircraft and "" (benign object) otherwise. However, the program determines that the document does not contain sufficient information to make a decision. The information to make the decision arrives some time later, in another document (the radar has subsequently collected additional information about the object):
<UpdatedInfo>
<Object id="XYZ">
<FlightProfile>......<FlightProfile>
</Object>
</PoliceReport>
So the desired processing behavior is this:
Read the next XML document.
If the XML document contains data about an object and there is insufficient information to process it then
Wait until more info about the object arrives ....
.......... time elapses ........... the updated
info arrives: analyze the new info and
if it indicates the object is an enemy aircraft then
output an alert message else output ""
That algorithm involves dealing with time.
Here's how to eliminate time from the equation.
-- As I described earlier --
/Roger
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