Drools 5 PseudoClock with StatelessKnowledgeSession
by Ben Scott
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I'm wanting to use the date-effective and date-expiry rule metadata to add date specific rule variants within my app. To test these I was planning on using the pseudo clock and setting the expected date prior to executing the rules within a StatelessKnowledgeSession. I can set the clock easily enough, but can't understand why the getSessionClock() method is missing? It's on the StatefulKnowledgeSession, but not on the Stateless.
I'm initialising the session like this:
SessionConfiguration sessionConfiguration = new SessionConfiguration();
sessionConfiguration.setClockType( ClockType.PSEUDO_CLOCK );
StatelessKnowledgeSession session = _testKnowledgeBase.newStatelessKnowledgeSession(sessionConfiguration);
The only thing I could think of to set the pseudo clock was to write a command something like:
private static class SetPseudoClockCommand implements org.drools.process.command.Command<Boolean> {
public Boolean execute(ReteooWorkingMemory session) {
// Set the clock to the current date
pseudoSessionClock.advanceTime(new DateTime().getMillis(), TimeUnit.MILLISECONDS);
// Add a couple of days
pseudoSessionClock.advanceTime(2, TimeUnit.DAYS);
return true;
}
}
But this doesn't appear to take any effect whilst rules are running.
Is there another way to get programmatic access to the session clock, or some better way of changing the underlying date prior to rule execution?
Ben.
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13 years, 2 months
Date validation in Guvnor
by mick00
Hi,
I want to validate the date format in my rule. I just want to check whether
my date is in the given format(yyyy-mm-dd) in my rule in Guvnor. Is it
possible to do such validation in Guvnor? I tried the same but got an
exception stating that the date is not in the given format(dd-MMM-yyyy). Can
someone suggest a solution as to how to validate the date in Guvnor?
Thanks,
mick
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13 years, 2 months
Fusion and open-ended intervals?
by Barry Kaplan
A fusion design question:
I have events that represent intervals. Initially the intervals are
open-ended (kind a like the current state of an entity). Other events are
matched "during" the interval and correlated. At some point the interval
will be closed (eg, a specific downtime interval is closed because the
device is no online again).
All the events in this system are immutable -- so if some property of an
event changes, it is cloned and modified in working-memory. For the case of
the interval events, initially the interval is inserted open-ended, and at
some point later closed and then modified.
This does not work with fusion however, since an event's duration is
maintained by the fact-handle not the event itself. Hence a modify with a
now closed interval (ie, a finite @duration) has no effect. I'm guessing the
temporal values are maintained the handle to ensure stable values for the
behaviors that trigger based on temporal values, which is reasonable.
So I'm looking for alternative designs. Some are:
1) Modeled the intervals as begin/end events, but that gets messy real
fast (have to correlate
the begin/end events somehow, can't use evaluators like 'includes' or
'during', etc).
2) Retract the interval event when it is closed (this way closed intervals
no longer correlate
with other incoming events). But then we really have a manually
maintained state machine
using only facts, and there can be no reasoning over a series these
interval events.
(eg, 3 downtimes longer than 2 minutes in the last hour).
Opinions?
-barry
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13 years, 2 months
Persistence of events
by Maciej Prochniak
Hello,
Is it possible to persist events (from drools fusion) with default jpa
mechanism? When I try to do this 'just like that' I get exception
like
org.drools.common.DefaultFactHandle incompatible with
org.drools.common.EventFactHandle
It seems that session marshaller is not really aware of certain objects
being events, not facts.
The code I try is more or less like:
UserTransaction ut = ...
StatefulKnowledgeSession session = JPAKnowledgeService
.newStatefulKnowledgeSession(kbase, null, env);
ut.begin()
session.insert(e1);
ut.commit();
StatefulKnowledgeSession sessionPersisted =
JPAKnowledgeService.loadStatefulKnowledgeSession( session.getId(),
kbase, null, env );
ut.begin()
sessionPersisted.insert(e2); (*) <- fails
ut.commit();
When I use session instead of sessionPersisted - it works fine, when
e2 is a fact, not an event - it also works
I know that it may be awkward to persist events which have time
limitations, but I want to use time limits in rules which are like few
days - so I want to have some persistence in case of server shutdown.
I would be grateful for any comment,
br,
maciek prochniak
13 years, 2 months
Log4j in the rules?
by granz＠MIT.EDU
Hi,
Is it possible to use Log4j inside the rules (RHS)?? (drl file)
Thanks,
Fabrice
13 years, 2 months
Drools-Fusion : Inserting an Event in to an "entry-point" stream in the RHS of a rule?? Pls help
by Chetan Mahadev
Hi
Can we insert an Event in the RHS part of a rule to an entry-point?
basically i am trying to do this. Pls let me know if this is possible? if
not any alternative approaches? Any example would be useful pls
declare TransactionEvent
@role( event )
end
$tmp : TestClass()
$tmp.message == "TRUE"
then
TransactionEvent ev1 = new TransactionEvent (); // This should be
inserted in to an entry-pont "Temporal Reasoning" stream
ev1.setMessage("Temporal Reasoning")
insert (ev1) to entry-point "Temporal Reasoning"
end
rule "Temporal Reasoning"
$tmp : TransactionEvent ( message== "Temporal Reasoning") from entry-point
"Temporal Reasoning"
then
System.out.println("Rule fired due to entry point ");
end
Regds
Chetan
13 years, 3 months
How to Access and Execute Rules from Database
by Ashish Soni
Hi All ,
I am able to configure oracle database in drools but now i am not able to
find how can i load rules from the DB and execute them , I gone through the
documentation but not able to get much information or might be i am missing
something.
If any one can provide me a example or some pointer ,hints then it would be
helpful.
Regards,
Ashish
13 years, 4 months
unable to determine operator for symbol [before]
by vladimiro
Hi all,
I'm building a KnowledgeBase with KnowledgeAgent and a precompiled
rule package. When the package contains a rule using temporal operators
such "after" or "before" I get the exception listed at the end of this
message.
I'm using the latest version of drools 5 and my runtime configuration
includes the following libraries:
* drools-core - the rule engine itself.
* drools-api
* mvel2-2.0.10
* joda-time-1.6
the rule causing such a behaviour is:
rule 'Test2'
dialect 'mvel'
when
u1:UserType( firstName=="UserA" )
lie:UserEventType( event=="Login", user.id==u1.id)
loe:UserEventType(event=="Logout", user.id==u1.id, this before lie)
then
Message msg = new Message();msg.setText("Test2
fired");driver.getMessages().add(msg);
end
java.lang.RuntimeException: KnowledgeAgent exception while trying to
deserialize KnowledgeDefinitionsPackage
at
org.drools.agent.impl.KnowledgeAgentImpl.rebuildResources(KnowledgeAgentImpl.java:418)
at
org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(KnowledgeAgentImpl.java:120)
at
org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(KnowledgeAgentImpl.java:109)
at
info.vladimiro.tesi.peservice.KnowledgeBaseService.<init>(KnowledgeBaseService.java:94)
at
info.vladimiro.tesi.peservice.KnowledgeBaseService.getInstance(KnowledgeBaseService.java:65)
at
info.vladimiro.tesi.peservice.PEListener$KBTask.run(PEListener.java:35)
at java.util.TimerThread.mainLoop(Timer.java:512)
at java.util.TimerThread.run(Timer.java:462)
Caused by: org.drools.RuntimeDroolsException: unable to determine
operator for symbol [before]
at
org.drools.base.evaluators.Operator.determineOperator(Operator.java:71)
at org.drools.base.evaluators.Operator.readResolve(Operator.java:106)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at
java.io.ObjectStreamClass.invokeReadResolve(ObjectStreamClass.java:1033)
at
java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1728)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1305)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:348)
at org.drools.base.BaseEvaluator.readExternal(BaseEvaluator.java:53)
at ...
Can someone help? Thanks in advance.
Vladimiro Corsi
13 years, 6 months
KnowledgeAgent and Guvnor restart
by Gerret Hansper
Hello,
I have got an issue with the KnowledgeAgent that seems not to survive a Guvnor
restart. The scenario is as follows:
* We use Drools 5.0
* On our application server we create a KnowledgeAgent
applying a ChangeSet that points to a package binary on a separate Guvnor server
like so:
SystemEventListenerFactory.setSystemEventListener(new
SystemEventLogger());
ResourceFactory.getResourceChangeNotifierService().start();
ResourceFactory.getResourceChangeScannerService().start();
KnowledgeAgent agent =
KnowledgeAgentFactory.newKnowledgeAgent(workflowName);
agent.applyChangeSet(changeSet);
* Creating the kbase, registering globals and running sessions works fine.
* We shut down Guvnor (or the connection goes down, this was how we spotted the
problem) and restart it after a minute
* We then try to run sessions from the
same agent as above via
kagent.getKnowledgeBase().newStatefulKnowledgeSession();
which returns a ksession, but then setting a global we get
java.lang.RuntimeException: Unexpected global [log]
at
org.drools.common.AbstractWorkingMemory.setGlobal(AbstractWorkingMemory.java:5
50)
at
org.drools.impl.StatefulKnowledgeSessionImpl.setGlobal(StatefulKnowledgeSessio
nImpl.java:284)
>From the debugger I can see that indeed the ruleBase's globals map is empty. The
SystemEventLogger indicates that the KnowledgeAgent unsubscribes from its
resource when Guvnor is down and rebuilds its kbase. Also, it stops scanning the
resource and does not find it once Guvnor is up again. (See log snippet below).
Wouldn't it be better in these cases to keep the resource as is in memory and
try to rescan? I figure that as long as the resource is specified in the
changeSet it should be considered part of the kbase and not be removed if it
cannot be found.
For the time being, does anyone have a suggestion how to avoid these problems?
We could catch the RuntimeException and recreate the KnowledgeAgent, but perhaps
there is a better way?
Thanks, Gerret
-- SystemEventLog --
# Guvnor is up here
07:58:01,881 ResourceChangeScanner attempt to scan 1 resources
07:58:02,209 ResourceChangeScanner thread is waiting for 60
07:58:15,067 ResourceChangeScanner attempt to scan 1 resources
# Guvnor goes down here
07:58:16,738 ResourceChangeScanner removed resource=[UrlResource
path='http://localhost:7080/drools-
guvnor/org.drools.guvnor.Guvnor/package/com.foo.bar/LATEST']
07:58:16,738 ResourceChangeNotification received ChangeSet notification
07:58:16,738 ResourceChangeScanner thread is waiting for 60
07:58:16,738 ResourceChangeNotification processing ChangeSet
07:58:16,738 ResourceChangeNotification ChangeSet removed resource=[UrlResource
path='http://localhost:7080/drools-
guvnor/org.drools.guvnor.Guvnor/package/com.foo.bar/LATEST'] for
listener=org.drools.agent.impl.KnowledgeAgentImpl@1053d6d
07:58:16,738 ResourceChangeNotification ChangeSet removed resource=[UrlResource
path='http://localhost:7080/drools-
guvnor/org.drools.guvnor.Guvnor/package/com.foo.bar/LATEST'] for
listener=org.drools.agent.impl.KnowledgeAgentImpl@b71c17
07:58:16,738 KnowledgeAgent received ChangeSet changed notification
07:58:16,738 KnowledgeAgent received ChangeSet changed notification
07:58:16,738 KnowledgAgent applying ChangeSet
07:58:16,738 ResourceChangeNotification thread is waiting for queue update
07:58:16,738 KnowledgAgent applying ChangeSet
07:58:16,738 KnowledgeAgent unsubscribing from resource=[UrlResource
path='http://localhost:7080/drools-
guvnor/org.drools.guvnor.Guvnor/package/com.foo.bar/LATEST']
07:58:16,738 ResourceChangeNotification unsubscribing
listener=org.drools.agent.impl.KnowledgeAgentImpl@1053d6d to
resource=[UrlResource path='http://localhost:7080/drools-
guvnor/org.drools.guvnor.Guvnor/package/com.foo.bar/LATEST']
07:58:16,738 KnowledgeAgent rebuilding KnowledgeBase using ChangeSet
07:58:16,738 KnowledgeAgent unsubscribing from resource=[UrlResource
path='http://localhost:7080/drools-
guvnor/org.drools.guvnor.Guvnor/package/com.foo.bar/LATEST']
07:58:16,738 ResourceChangeNotification unsubscribing
listener=org.drools.agent.impl.KnowledgeAgentImpl@b71c17 to
resource=[UrlResource path='http://localhost:7080/drools-
guvnor/org.drools.guvnor.Guvnor/package/com.foo.bar/LATEST']
07:58:16,738
KnowledgeAgent rebuilding KnowledgeBase using ChangeSet
07:58:16,738 KnowledgeAgent new KnowledgeBase now built and in use
07:58:16,738 KnowledgeAgent new KnowledgeBase now built and in use
07:59:02,202 ResourceChangeScanner attempt to scan 0 resources
07:59:02,202 ResourceChangeScanner thread is waiting for 60
# Guvnor back up here
07:59:16,731 ResourceChangeScanner attempt to scan 0 resources
07:59:16,731 ResourceChangeScanner thread is waiting for 60
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13 years, 7 months
