RE: [rules-users] Design Question (hashCode/equals/fact maintenance)
I just realized I could use the "from" CE to avoid this entire mess.
-----Original Message-----
From: rules-users-bounces(a)lists.jboss.org
[mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Fenderbosch,
Eric
Sent: Tuesday, July 15, 2008 10:38 AM
To: rules-users(a)lists.jboss.org
Subject: [rules-users] Design Question (hashCode/equals/fact
maintenance)
I'm just looking for a bit of verification that this is a reasonable
solution. This just feels like a hack and there's probably a better way
that I'm just not seeing. Alternate ideas are welcome and appreciated.
Thanks in advance.
The objective is to find the best workers for a job:
Jobs have a location.
Workers have a location.
Scores are calculated based on miles and minutes of a route from the
worker to a job.
When a job or worker location changes, then the route should be
recalculated so that scores can be recalculated. It is possible for a
location to get re-inserted that might be the functionally the same as a
previous location for a job/worker, but a different instance. In this
case, the route should not be recalculated and the old scores should
remain.
assert behavior = equality
logical override = discard
maintain tms = true
remove identies = true
shadow proxies are enabled
public class JobLatitudeLongitude {
private String jobId;
private double latitude;
private double longitude;
private long timestamp = System.currentTimeMillis();
// getters & setters omitted for brevity
public int hashCode() {
return jobId.hashCode();
}
public boolean equals(Object obj) {
// not null or type safe, just simple version for
brevity
JobLatitudeLongitude other = (JobLatitudeLongitude) obj;
return this.jobId.equals(other.jobId) && this.timestamp
== other.timestamp;
// would "return false;" work ???
}
}
rule "retract redundant job latitude/longitude facts"
// if more than one lat/long with same position for a job, keep the
oldest
salience 600
when
older : JobLatitudeLongitude()
newer : JobLatitudeLongitude(jobId == older.jobId,
latitude == older.latitude, longitude == older.longitude, timestamp >=
older.timestamp)
then
retract(newer);
end
rule "retract old job latitude/longitude facts"
// if more than one lat/long with different position for a job, keep the
newest
salience 600
when
older : JobLatitudeLongitude()
newer : JobLatitudeLongitude(jobId == older.jobId,
latitude != older.latitude, longitude != older.longitude, timestamp >=
older.timestamp)
then
retract(older);
end
rule "add Route fact"
salience 450
when
jobLatitudeLongitude : JobLatitudeLongitude()
workerLatitudeLongitude : WorkerLatitudeLongitude()
then
// calculateRoute is an imported function
Route route = calculateRoute(workerLatitudeLongitude,
jobLatitudeLongitude);
insertLogical(route);
end
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