[rules-users] Re: drools-solver - magic name of scoreCalculator => Solution has a Sore and is inserted into the working memory

Sun, 15 Feb 2009 07:08:17 -0800

I am actually considering a couple of designs, which also happens to solve the problem of the magic name of the scoreCalculator.
1) a score will no longer be a double, but an instance of a new interface Score. This will means that a score of an int hard and int soft will be represented as it should be: an int hard and an int soft. That has 2 advantages: - you could use implement their own Score, if the out-of-the-box types don't suffice, say int hard, BigDecimal soft, double verySoft. - it would be possible to decide the step, not on a normal compareTo, where hard is always higher then soft, but on (hard * hardAsSoftWeight + soft), where hardAsSoftWeight changes: it's normally very high, but when no hard constraints are broken in a long time, it temporarily goes down. This allows the local search to take steps that break a hard constraints for a while, passing through hard barriers. Experiments have proven that this gives better results. 

2) a Solution has a Score. That Score can be uninitialized or dirty.
A Solution is also inserted into the working memory (along with it's facts).

Every changing fact (Queen, Lesson, Exam, ...) will also need to hold a 
reference to it's Solution.

That way every ConstraintOccurrence can hold a reference to it's Solution.

Then the calculateScore rule will update the score in a solution, 
instead of putting it into a global. The solver still has a reference to 
the solution, so it can retrieve the score.
This allows for multiple solution instances to be put into same working 
memory and there's no magic scoreCalculator.


What do you think? Criticism welcome :)


Of course, backward compatibility will be broken (as stated in the 
manual), but everything will be documented into an upgradeRecipe.txt,

so it shouldn't be to hard to upgrade to a newer version.

With kind regards,
Geoffrey De Smet


Greg Barton schreef:

Actually, I was wishing for something similar last night, but for the names of 
entry-points.  I think it would be nice if you could specify the names of 
things in DRL from the values of public static final Strings. (i.e. constants)  
Do you dev folk think that's possible enough to make a jira request for it?

--- On Fri, 2/13/09, Geoffrey De Smet <ge0ffrey.s...@gmail.com> wrote:


From: Geoffrey De Smet <ge0ffrey.s...@gmail.com>
Subject: [rules-users] Re: drools-solver - magic name of scoreCalculator
To: rules-users@lists.jboss.org
Date: Friday, February 13, 2009, 9:37 AM
Yes, it's not that good that it's a magic name.
However, I don't know any other way to do it.
Feel free to make a jira for it, especially if you know a
better way to do it :)

With kind regards,
Geoffrey De Smet


Andrew Waterman schreef:

Thanks Geoffrey!  I patched this yesterday with

slf4j-jcl and slf4j-nop for no loging.  I'll post the
mavne dependencies later this morning in case others wish to
use non-log4j implementations. :)  I did noticeas well  that
the "scoreCalculator" global is referenced by name
from the solver.  Want me to file a jira issue on that?  It
seems strange that the variable name shoudl be static like
that to me.

best wishes,

Andrew

On Fri, Feb 13, 2009 at 7:55 AM, Geoffrey De Smet

<ge0ffrey.s...@gmail.com
<mailto:ge0ffrey.s...@gmail.com>> wrote:

    Adding the slf4j-log4j12 dependency to your

pom.xml should fix it :)

           <dependency>

              

<groupId>org.slf4j</groupId>

              

<artifactId>slf4j-log4j12</artifactId>

               <scope>runtime</scope>
           </dependency>

    Not sure how changing anything in

drools-solver-examples could fix

    it, normally your project wouldn't depend on

it, only on

    drools-solver-core.


    With kind regards,
    Geoffrey De Smet


    Greg Barton schreef:

        I was getting the error below running the

benchmarkNQueens.sh

        script in drools-solver-examples.  I got

around it by taking the

        "<scope>runtime</scope>"

line out of the slf4j-log4j12

        dependency in drools-solver-examples/pom.xml. 

Not sure if

        that's the right way to get around it, but

it worked. :)

        --- On Fri, 2/13/09, Geoffrey De Smet

<ge0ffrey.s...@gmail.com

        <mailto:ge0ffrey.s...@gmail.com>>

wrote:

            From: Geoffrey De Smet

<ge0ffrey.s...@gmail.com

            <mailto:ge0ffrey.s...@gmail.com>>
            Subject: [rules-users] Re: drools-solver

-- logger error

            (slf4j binding)?
            To: rules-users@lists.jboss.org
            <mailto:rules-users@lists.jboss.org>
            Date: Friday, February 13, 2009, 1:04 AM
            drools-score (like hibernate and many

other lib projects)

            just depends on sl4j-api, which is a

logging interface.

            It's up to the end-use product to

decide which logging

            implementation to use under that and how

to configure the

            logging (where to log to, how much to log,

...).

            In the drools solver examples I 've

put slf4j-log4j

            underneat it, because I am familiar with

log4j's

            configuration, take a look at their

log4j.xml files. However

            they say that the logback implementation

is better these

            days.


            PS: I 'll take a look at the other

discussions this

            afternoon.

            With kind regards,
            Geoffrey De Smet

            Andrew Waterman schreef:

                Hi,

                I'm using the drools-solver.M5

build through Maven

            and have gotten the following error while

running my

            project:

                SLF4J: Failed to load class


           

"org.slf4j.impl.StaticLoggerBinder".

                SLF4J: See


           

http://www.slf4j.org/codes.html#StaticLoggerBinder for

            further details.

                I've checked my dependency graph,

and

            drools-solver references the sl4j-api, but

no

            implementation.  I checked the

mvnrepository, and there are

            several other slf4j related projects. 

What is the preferred

            binding for JDK1.6?

                best wishes,

                Andrew

                ---------------------------------
                Andrew Waterman
                San Cristóbal de las Casas, Chiapas,

Mexico

                +52 1 967 107 5902
                +1 510 342 5693










               

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