Re: [rules-users] [planner] Questions about employee shift rostering example
by Geoffrey De Smet
[CC'd to the user list]
Hi Samuel,
> Happy new year and all the best for you and your family.
Happy new year too :)
> As you can see below, I tried posting a message on the mailing list but
> unfortunately I am not authorized.
If that doesn't work out (it should!), try the nabble.com forum or the
gmane.org newsgroup:
http://n3.nabble.com/Drools-User-f47000.html
I use gmane.org myself from Thunderbird.
> Geoffrey, I saw a paper on the trunk of drools planner where you address
> the issue about employee shift rostering.
> There is no source, I don't know what level of thinking you're in, but I
> have two questions:
>
I haven't made an example of employee shift rostering (or bin packaging
or vehicle routing) yet.
Employee shift rostering is closely related too curriculum course
scheduling,
so I advice to get to know the curriculum course example inside and out :)
Drools (Planner) is kinda like JPA:
you can model your domain pretty much how you like,
but how you model your domain can impact the complexity of your rules (~
JPA-QL's).
Don't make your domain too smart to help your first rules,
because it will strangle rules (and even moves) you implement later.
Keep your domain on low level details.
> "Each shift has for each specialism a minimal staff size"
> how do you manage the team size ?
> Is there a list of people in the Shift object ? Or an accumulate function
> in the rule ?
>
I'd say: experiment with both and let me know which works best :)
Until now, I 've always gone for the "accumulate function in a rule" manner.
I strongly believe in keeping the domain diagram very simple:
http://beta.parleys.com/#id=1714&st=5&sl=14
So only one "red class".
Only one class that the moves change, only one class that you need to
tell the working memory that has changed.
I believe (and I think I 've seen) that this improves delta based score
calculation.
The problem is that some rules, require to check the sum of thing and
you need an accumulate,
like this rule in examinationScoreRules.drl:
rule "roomCapacityTooSmall" // TODO improve performance, as it takes 50%
of the performance
when
$period : Period();
$room : Room($capacity : capacity);
$totalStudentSize : Number(intValue > $capacity) from accumulate(
Exam(period == $period, room == $room, $studentSize :
topicStudentSize),
sum($studentSize) // Vote for
http://jira.jboss.com/jira/browse/JBRULES-1075
);
...
And Drools 5.0's forward chaining becomes backward chaining once you do
this.
Forward chaining = delta based score calculation.
Backward chaining = NO delta based score calculation.
The answer is "true modify", which mark is working on, but probably
won't make 5.1 I fear.
http://blog.athico.com/2010/01/rete-and-true-modify.html
https://jira.jboss.org/jira/browse/JBRULES-2240
Despite that, I still go for "accumulate function in a rule" each time
and take the performance hit.
Meanwhile I poke Mark :)
Remember: StartingSolutionInitializer and
relativeSelection/absoluteSelection bring far greater peformance rewards.
The "a list of people in the Shift object" approach might be better
untill "true modify"'s been solved,
but I believe it hurts your design in the long run.
But do experiment with both approaches, I 'd love to get some feed-back
on this.
> "minimal 35 hours rest each week"
> How do you check that constraint ? Is there a week object that you parse to
> check that there are 2 consecutive days each week? Or is that the generated
> movements already meet this hard constraint ?
>
How do you define a week? From monday to monday or any 7 days in a row?
In either case, just search for a pattern where that does _not_ happen.
It does depend on how you modeled your domain, I 'd have to see the code
in detail.
Take a look at this rule:
// CurriculumCompactness: Lectures belonging to a curriculum should be
adjacent
// to each other (i.e., in consecutive periods).
// For a given curriculum we account for a violation every time there is
one lecture not adjacent
// to any other lecture within the same day.
// Each isolated lecture in a curriculum counts as 2 points of penalty.
rule "curriculumCompactness"
when
$curriculum : Curriculum();
$lecture : Lecture(curriculumList contains $curriculum,
$day : day, $timeslotIndex : timeslotIndex
);
not Lecture(curriculumList contains $curriculum,
day == $day, timeslotIndex == ($timeslotIndex - 1)
);
not Lecture(curriculumList contains $curriculum,
day == $day, timeslotIndex == ($timeslotIndex + 1)
);
then
insertLogical(new
IntConstraintOccurrence("curriculumCompactness",
ConstraintType.NEGATIVE_SOFT,
2,
$lecture, $curriculum));
end
PS: next week I 'll be presenting Drools Planner in a Lille JUG.
With kind regards,
Geoffrey De Smet
Samuel Deballon schreef:
> Hello Geoffrey,
>
> Happy new year and all the best for you and your family.
>
> As you can see below, I tried posting a message on the mailing list but
> unfortunately I am not authorized.
>
> I sent an email to the administrator, but until you can answer questions in
> the email below.
>
> Note : I'll post the discussion once I have access.
> Do not worry I understand if you do not respond (I have not forgotten the
> remarks in your previous mail)
>
> If my questions aren't specific enough, let me know.
>
> In any case, thank you in advance for your response..
>
> With kind regards,
>
> Samuel Deballon
>
> CSC • This is a PRIVATE message. If you are not the intended recipient,
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> Le Balzac, 10 Place des Vosges, 92072 Paris La Défense Cedex, France •
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> ----- Forwarded by Samuel Deballon/FRA/CSC on 14/01/2010 16:30 -----
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> |Samuel Deballon/FRA/CSC@CSC |
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> >--------------------------------------------------------------------------------------------------------------------------------------------------|
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> |[Drools-planner] : Questions about employee shift rostering example |
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
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>
>
>
> You are not allowed to post to this mailing list, and your message has
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> ----- Message from Samuel Deballon <sdeballon(a)csc.com> on Thu, 14 Jan 2010
> 10:26:06 +0100 -----
>
> To: rules-users(a)lists.jboss.org
>
> Subject: [Drools-planner] : Questions about employee shift
> rostering example
>
>
>
> Hi all, Hi Geoffrey,
>
> Geoffrey, I saw a paper on the trunk of drools planner where you address
> the issue about employee shift rostering.
> There is no source, I don't know what level of thinking you're in, but I
> have two questions:
>
> "Each shift has for each specialism a minimal staff size"
> how do you manage the team size ?
> Is there a list of people in the Shift object ? Or an accumulate function
> in the rule ?
>
> "minimal 35 hours rest each week"
> How do you check that constraint ? Is there a week object that you parse to
> check that there are 2 consecutive days each week? Or is that the generated
> movements already meet this hard constraint ?
>
> Thanks in advance for your answer,
>
> Samuel
>
>
> CSC • This is a PRIVATE message. If you are not the intended recipient,
> please delete without copying and kindly advise us by e-mail of the mistake
> in delivery. NOTE: Regardless of content, this e-mail shall not operate to
> bind CSC to any order or other contract unless pursuant to explicit written
> agreement or government initiative expressly permitting the use of e-mail
> for such purpose • CSC Computer Sciences SAS • Registered Office: Immeuble
> Le Balzac, 10 Place des Vosges, 92072 Paris La Défense Cedex, France •
> Registered in France: RCS Nanterre B 315 268 664
>
>
16 years, 3 months
Weblogic rules to Drools rules.
by kashif10
Hi,
We have a product using weblogic server & weblogic rules.
We are planning to move our application to jboss As using drool rules.
Brief intro of our rules:
Currently we have around 20K rules in our databse. We load all those rules
form our database in to weblogic Rule Manger. All those rules loaded in to
Rule manger with rule ID as key & Rule Data as values. we can simply add
new ruels on run time we can remove any rule form RuleMnager at runtime.
Then we have catalogs in out databse pointing those rules.
So whenever user inputs some data & ask to evaluate that data with some
catalog.
Then we simply add user data in WM & get rules from Rule manager one by one
& evaliate the rule on the basisi of WM. In the end we send the
alerts/result to user.
My questions:
i) Is there a rule manger Api in drools to whoch we provide rule Id along
with rule data to load rules in memory.
& we can remove & add furtgur rules in to it.
Also how effecient is it to load & evaluate more than 20K rules.
ii) I don't find RuleSet in ApI, whats the replacement of it?
iii) Any link having good example to load rules & then evaluate a set from
this a caalog type of case.
I hope your precious answers will help us a lot to make the decision.
Thanks.
--
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16 years, 4 months
Stateless Vs Stateful Sessions in Webtier
by Pritam
It isn't clear from the documentation and examples on the recommended usage
of knowledge sessions. From Michael Bali's book, it is highly recommended to
use StatelessKnowledgeSession, since it's threadsafe, but a quick look at
the API shows that it doesn't support many of the features of stateful
ksession.
-- cannot pass agendaFilter
-- cannot use agenda-group, activation-group or ruleflow-group in statelss
ksession
-- It looks like one cannot get Agenda from a statelss ksession and hence
cannot use clear() or setFocus()
...
Drools says, for rules itself, "it doesn't matter whether you use stateless
or stateful ksession ..." then why is that an entire set of metadata like
grouping and ordering is ignored?
If statefulknowledge session isn't threadsafe, then what are the best
practices and considerations for making it threadsafe?
--
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16 years, 4 months
prevent infinite loops
by Garner, Shawn
Is there a good way to globally prevent infinite loops.
I had rule A and rule B and they both have FactA on the condition.
They also both modify FactA.
I tried no-loop and it prevents a loop of repeating RuleA over and over.
However it then goes from Rule A back to Rule B back to Rule A.
I fixed it by lock-on-active instead of no-loop.
However I was wondering if there was either a timeout feature or a maximum number of times you could set a rule to be executed to error out on infinite loops.
Any guidance would be appreciated.
Thanks,
SDG
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16 years, 4 months
Checking in one rule the "result" of another rule
by orchid
Hi All,
I have "rule1" and "rule2", very simple rules. I would like in "rule3" to
check one of the following:
"rule1" AND "rule2" (i.e. if both rule1 and rule2 were fired)
"rule1" OR "rule2" (rule1 or rule2 was fired)
How can I achieve this? Does the "extends" keyword might help here?
I achieved that buy defining a list, to which rule1 and rule2 in the RHS
inserted some value. In rule3 I checked the values of that list. I would
like to ask if there are some prettier solutions.
Thanks in advance.
Any help would be appreciated.
--
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16 years, 4 months
Re: [rules-users] newbie, Expressing a rule in different ways
by rouvas＠di.uoa.gr
Wolfgang Laun wrote:
> 2010/1/31 <rouvas(a)di.uoa.gr>
>
>> Wolfang,
>>
>> thank you very much for your reply.
>>
>> Your assumptions are correct and your explanation makes sense.
>> Unfortunately, I cannot understand why this happens.
>>
>>
> It may very well be an implementation restriction; whether it can be
> removed easily I'm not prepared to say. (@Edson?)
Fair enough.
>
>
>> The IUEcop has the following structure (in rough terms)
>> IUEcop
>> +- (various objects as properties)
>> +- list of traderAuthorisation
>> +- list of warehouseAuthorisation
>> +- list of temporaryAuthorisation
>>
>>
>> A more general issue with my understanding has to do with handling of
>> deeply nested objects. In my case, the "traderAuthorisation" object has
>> itself another set of object properties and lists that I would like to
>> refer to in my rules. Are you aware of any relevant documentation?
>>
>
> Nested objects that are not facts but shared between fact objects should
> not
> cause any problems; especially the MVEL syntax is provided for easy
> access to properties of a property.
>
> If such an object is shared among several fact objects, you'll have a
> problem whenever such a shared object is updated by code on a RHS:
> To trigger reevaluation of rules, the engine would have to be
> notified about all objects referring to the shared object as being
> updated.
Although in my case the objects are not shared, I understand the issues
involved.
>
> Lists is adding another twist, even though the "from" CE appears
> to simplify handling of Iterable properties and works well enough.
> The recommended (see Drools Expert, section 4.8.2.8, Conditional
> Element "from") alternative is to add List elements as WM elements
> of their own,
I was hoping to avoid this.
This is how I was doing things in Prolog, but I was hoping that
object-orientation would help tackling this issue.
Anyway, thanks a lot for your help.
-Stathis
> even though this may require the addition of linking
> information to the list elements. (In your case: a TraderAuthorisation
> would have to contain a reference to the IUEcop object it belongs
> to.) You'll have to balance the additionally required coding effort
> for this against the greater complexity of rules using "from".
>
> -W
>
>
>> Thank you very much for your time,
>> -Stathis
>>
>>
>
16 years, 4 months
newbie, Expressing a rule in different ways
by rouvas＠di.uoa.gr
Can you please explain why the second form of the same (as it seems to me)
rule does not work?
This works:
rule "takeTwo"
when
$c : CD713AType(
Body.incrementalUpdateOfEconomicOperators.traderAuthorisation.size !=
0 )
$t : TraderAuthorisationType ( $t.OperatorRole.size == 0) from
$c.Body.incrementalUpdateOfEconomicOperators.traderAuthorisation
then
stdout(drools.getRule().getName()+"
"+$c.getHeader().getMessageIdentifier());
end
and this fails to compile:
rule "take3"
when
$c : CD713AType( $i : this.Body.incrementalUpdateOfEconomicOperators )
$t : TraderAuthorisationType ( $t.OperatorRole.size !=0 ) from
$i.traderAuthorisation
then
stdout(drools.getRule().getName()+"
"+$c.getHeader().getMessageIdentifier());
end
with the message:
Unable to build expression for 'from' : Failed to compile: 1 compilation
error(s):
- (1,22) unqualified type in strict mode for: traderAuthorisation
'$i.traderAuthorisation' : [Rule name='take3']
Pretty new to Drools and try to figure out how things work.
In the second form of the rule I am trying to use the $i variable as a
shortcut for the "Body.incrementalUpdateOfEconomicOperators" locator.
"stdout" is just a function that print to System.out
Thank you for your time,
-Stathis
16 years, 4 months
Drools and Persistence How much Reliable and Secure
by KiranP
i m a Novice level user of drools and i want to use drools for our firms new
projects
so, i m evaluating the Drools 5.0 and 5.1 versions so that i can rely on
some thing very reliable and secure
i have worked out with the Drools5.1 variable persistence strategy and also
worked out some examples and i think it is also good to work with a
plugabble version of Persistence
So now my problem is what to use My own Persistence Mechanism in Drools5.0
or to use Drools5.1 with its provided plugabble Persistence Mechanism ???
one more thing can somebody tell me which books or online documents to refer
while using drools 5.1 ???
Thanks in advance......
yours always thankfullllll
KiranP
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16 years, 4 months
