KnowledgeAgent
by Jeffrey Schneller
Can someone explain how to use the knowledge agent when the rules are
stored on the guvnor. I also do not want to use an xml configuration
file [change-set] to specify the url of the guvnor. The url is
retrieved through the code in my case and I can't set it via a
change-set since we don't know what the url is until runtime.
Thanks.
16 years, 3 months
Unable to pipeline Jms TEXT messages
by Adam Sussman
I am getting the following error:
org.apache.activemq.command.ActiveMQTextMessage cannot be cast to
javax.jms.ObjectMessage
at org.drools.runtime.pipeline.impl.JmsUnwrapMessageObject.receive(JmsUnwrapMessageObject.java:18)
at org.drools.runtime.pipeline.impl.BaseEmitter.emit(BaseEmitter.java:31)
at org.drools.runtime.pipeline.impl.StatefulKnowledgeSessionPipelineImpl.insert(StatefulKnowledgeSessionPipelineImpl.java:40)
at org.drools.runtime.pipeline.impl.JmsMessenger$JmsMessengerRunner.run(JmsMessenger.java:133)
at java.lang.Thread.run(Thread.java:619)
When trying to build the following pipeline to take pure TEXT messages
off of a JMS queue and pass them to Smooks for transformation:
KnowledgeRuntimeCommand insertStage =
PipelineFactory.newStatefulKnowledgeSessionInsert();
// Smooks transform
Smooks smooks = new
Smooks(getClass().getResourceAsStream("smooks-config.xml"));
Transformer transformerStage =
PipelineFactory.newSmooksFromSourceTransformer(smooks, "foo");
transformerStage.setReceiver(insertStage);
// Object deserialization
Action unwrapObjectStage = PipelineFactory.newJmsUnwrapMessageObject();
unwrapObjectStage.setReceiver(transformerStage);
// Pipeline entry stage
Pipeline entry =
PipelineFactory.newStatefulKnowledgeSessionPipeline(ksession);
entry.setReceiver(unwrapObjectStage);
// JNDI lookup for the JMS queue is here. Its an ActiveMQ provider
Service messenger = PipelineFactory.newJmsMessenger(entry,
props, "myqueue", null);
Now I know someone will say "just send objects through JMS", but that
won't work here. The endpoint sending the messages is not Java and
can't build java object encodings. In fact, the endpoint is the JMS providers'
own native own C++ library (ActiveMQ), so we are stuck with a pure
text message.
Is there any way to have other kinds of message unwrappers for a Jms pipeline?
I would be happy to roll my own, but I am pretty unclear on how to plug one in.
Any help would be appreciated.
-adam
16 years, 3 months
RuleBase Refresh
by Jeffrey Schneller
I am having issues refreshing my RuleBase. It works in some cases
[small numbers of rules] and doesn't work in others. I am using the
Guvnor to maintain rules and all my rules are in Excel decision table.
To test, I created a simple package that contains 1 excel decision table
which has 1 rule [row] in it. I ran my application. Then rebuilt the
package in the Guvnor and my application refreshed the rule base
correctly.
Then in my actual application, I have other packages which contain many
100 rules if not 1000 rules all based on multiple excel based decision
tables. If I run my application, then rebuild the package in the
Guvnor, my application throws the exception.
RuleAgent(Assembly) EXCEPTION (Fri Feb 26 12:02:32 EST 2010):
java.lang.ClassCastException: org.drools.util.ObjectHashMap cannot be
cast to org.drools.reteoo.BetaMemory. Stack trace should follow.
org.drools.RuntimeDroolsException: java.lang.ClassCastException:
org.drools.util.ObjectHashMap cannot be cast to
org.drools.reteoo.BetaMemory
It appears the problem occurs where there are many rules. Any ideas?
This is going to be a major problem because the rules may need to be
refreshed on a pretty regular basis and restarted the app each time is
not an option.
Thanks.
16 years, 3 months
Call for Participation: CHR Summer School
by Jon Sneyers
- Call for Participation -
First International Summer School on CHR:
Programming and Reasoning with Rules and Constraints
August 30 - September 3 2010
Leuven, Belgium
Website: http://www.cs.kuleuven.be/~dtai/CHR/summerschool
****************************************************************************
* EARLY REGISTRATION DISCOUNT: When registering (including payment) before *
* March 31, the registration fee will be reduced by 20 euro! *
* *
* Additional early registration incentive: *
* The first 7 registrants get a FREE copy of the book *
* "Constraint Handling Rules - Current Research Topics" *
****************************************************************************
The aim of the summer school is to familiarize the participants with
state-of-the-art high-level declarative programming with rules and
constraints as well as providing insights into the analysis of programs
based on these concepts. The courses cover a wide range from theory to
practice.
The summer school will be based on the advanced high-level rule-based
formalism and programming language Constraint Handling Rules (CHR)
http://constraint-handling-rules.org/
Intended Audience:
The summer school provides courses at various levels. It is open to anyone
interested. It aims at Phd. students, but also post-docs, interested
researchers and master students as well as interested parties from
industry. Besides a working knowledge of English, there are no
prerequisites. A basic knowledge of logic and Prolog that is usually
covered in undergraduate classes could be helpful.
Lectures and Courses:
The programming language CHR will be introduced by several lecturers on the
first day of the summer school.
- Slim Abdennadher, GUC, Egypt
Analysis of CHR Solvers
- Henning Christiansen, U. Roskilde, Denmark
Abduction and language processing with CHR
- Thom Fruehwirth, University Ulm, Germany
CHR - a common platform for rule-based approaches
- Jon Sneyers, K.U.Leuven, Belgium
Computability and Complexity of CHR
- Peter Van Weert, K.U.Leuven, Belgium
Implementation of CHR Systems
A final evaluation for each course is possible through a final exam or
project as determined by the instructor. The daily schedule admits
laboratory, recitation or working group activities to be organized in
addition to lectures.
Registration:
The registration fee for the School is 300 euro and includes teaching
material with book, as well as accomodation and coffee breaks. Meals are
not included. Attendance is limited to 20 students and will be allocated
on a first-come- first-served basis. Without accommodation the
registration fee is reduced to 200 euro.
Location:
Leuven is a lively student town in Belgium with a very high density of
pubs offering hundreds of types of local beers.
Organization:
Thom Fruehwirth, University of Ulm, Germany
Jon Sneyers, K.U. Leuven, Belgium
Peter Van Weert, K.U. Leuven, Belgium
Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
16 years, 3 months
