[rules-users] activationCancelled() not being executed?

Fermion henss at physik.uni-wuppertal.de
Thu Aug 30 04:29:49 EDT 2007


Hi!

I'm using a JTable to display rules that have been activated.

My goal is to have the table display a set of activations ordered by their
salience. The user should then choose which one of them to fire (if you want
to know why, be invited to read the background).

Of course this makes only sense as long as the activations are valid. Rules
whose activation has been cancelled should still be displayed, but in a
different style (like greyed out).

In order to accomplish this, I want to use an implementation of the
AgendaEventListener-interface, implementing the
activationCancelled()-method.
The Listener itself works, as I use the activationCreated()-method to add
the rule as a row to my table (which works fine).

Unfortunately the activationCancelled()-method doesn't seem to be executed
at all!


I assume that I have a fundamental misunderstanding of what should trigger
an activationCancelled() event?


Background: (just if you're curious...)
I'm working as a PhD student in physics at the CERN international
high-energy physics laboratory, for the ATLAS experiment.
As a member of the Detector Control System (DCS) group, I'm going to write
an expert system in order to assist the shift crew with the detector
operation.

The operation of the detector is a difficult task, because more than 70000
parameters (like voltages, currents and temperatures) have to be controlled.
A Finite State Machine (FSM) computes a defined and limited number of states
from the given parameters (like ON, OFF, STANDBY,...).

I'm going to synchronize the expert system application to ERROR states of
the FSM, in order to extract the relevant parameters from the system (as it
would be impossible to feed all parameters into the XPS all the time).
This is handled by quite some control rules that decide which data has to be
requested, released and so on.
Once all necessary data has been received, this might lead to activations of
the (more interesting) user rules.
Those rules have an explanatory character like "The temperature of this XYZ
is too high, so please try ABC."

For a given set of facts I assume more then one rule to be activated. Whilst
the rule engine should take care of the execution (firing) of all control
related rules, the execution of the user rules should be under direct user
control.

Displaying all activations in a GUI will allow the user to pick one (try it)
and rate it (the proposed solution solved the problem "yes/no"). Changing
the rules salience according to the answer, will allow the system to
dynamically reflect the current system status. (Rules that are related to
broken connections / wrongly connected cables are likely to be found at the
beginning of the experiment but hopefully only on rare occasion later on.)

In order to ensure that no information is lost during the absence of DCS
experts (which will not always be around), a log file should be written for
each major FSM-ERROR. At the moment the WorkingMemoryFileLogger seems to be
predestined for this job. This way I hope to collect large amounts of ERROR
data during the initial phase of the experiment that helps to extract rules
for numerous error conditions.
This will become especially handy, as such errors have a tendency to come
back, even if the original detector experts are gone for years...
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