11:25 a.m.
5.2.0.Final
consider this simplified example, which has RMI calls to a service to
getLocation()
rule "example"
when
$p : Product( location != remoteService.getLocation("A") )
then
$p.setLocation( remoteService.getLocation("A") );
end
the above rule calls the remote method twice, once in the LHS to compare to
a current value, and again in the RHS to set the value. I would like to
capture the return value of the LHS call, to avoid making the call twice. I
haven't been able to figure out the syntax to do this within the pattern.
Here's one example of what I have tried:
rule "example"
when
$p : Product( location != $loc : remoteService.getLocation("A") )
then
$p.setLocation( $loc );
end
Does anyone know the correct syntax to accomplish this? Or am I trying to
do the impossible?
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1:13 p.m.
See below.
On 22 March 2012 17:25, lhorton <LHorton(a)abclegal.com> wrote:
5.2.0.Final
consider this simplified example, which has RMI calls to a service to
getLocation()
rule "example"
when
$p : Product( location != remoteService.getLocation("A") )
then
$p.setLocation( remoteService.getLocation("A") );
end
the above rule calls the remote method twice, once in the LHS to compare to
a current value, and again in the RHS to set the value. I would like to
capture the return value of the LHS call, to avoid making the call twice.
I
haven't been able to figure out the syntax to do this within the pattern.
Here's one example of what I have tried:
rule "example"
when
$p : Product( location != $loc : remoteService.getLocation("A") )
then
$p.setLocation( $loc );
end
Does anyone know the correct syntax to accomplish this? Or am I trying to
do the impossible?
With a single rule: yes, I think. However:
1. At the outset, you know that a comparison with Location A is required.
2. If you have that firmly in your WM, you can compare and it's possible
to use it on the RHS.
This is reflected by the following rules:
rule example1
when
$p : Product( $mli: missingLocationId ) // that would be "A"
not Location( id == $mli ) // haven't RMI'd this yet
then
Location loc = remoteService.getLocation( $mli );
insert( loc );
end
rule example2
when
$p : Product( $mli: missingLocationId )
$loc: Location( id == $mli )
then
$p.setLocation( $loc );
end
The idea here is to let a RHS execution intervene to do the RMI once.
-W
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1:45 p.m.
That would be a good approach for one location. My real world rules are 24
rules for 24 different locations. If I used your approach, I think I would
have to look up and insert all 24 locations for each session execution (we
use stateless sessions) in order to have the 24 setter rules work.
I am trying to avoid too many calls to the RMI service (remote database
reads), which is why I was trying to put all the work into the one rule
pattern. in my real-world rules, there are more conditions in the pattern
than just the RMI lookup, so that only one of the setter rules will fire for
each session execution.
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1:54 p.m.
You might also consider some sort of caching approach that would make the
second call to remoteService.getLocation() cheap.
-W
On 22 March 2012 19:45, lhorton <LHorton(a)abclegal.com> wrote:
That would be a good approach for one location. My real world rules
are 24
rules for 24 different locations. If I used your approach, I think I would
have to look up and insert all 24 locations for each session execution (we
use stateless sessions) in order to have the 24 setter rules work.
I am trying to avoid too many calls to the RMI service (remote database
reads), which is why I was trying to put all the work into the one rule
pattern. in my real-world rules, there are more conditions in the pattern
than just the RMI lookup, so that only one of the setter rules will fire
for
each session execution.
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Wolfgang Laun