Re: [rules-users] Web decision tables (Guvnor)
Hi Stephen,
You've made my afternoon ;)
The operation of otherwise is rather dumb. It does not have any
understanding of what groups of rows it is meant to limit it's search of
values to construct the not in part.
As you have discovered, in your case, the Account column has no
significance at all (to the web-guided decision table) although it does to
the business analyst.
The immediate workaround would be to move each group to a different
decision table; i.e. Account=1 and Account=2. I appreciate your example is
probably a simplification of the real problem.
A better solution would be to furnish the otherwise value with the
information it would need to determine it's search range. e.g. define
otherwise with a key column of Account. This is however an enhancement
:(
Feel free to raise a JIRA (for GUVNOR)... no promises as to when I'll get a
chance to do anything about it though :(
More complex requirements exist, for example given:-
Account Qualifier Currency CanTrade
1 A EUR Y
1 A USD Y
1 B IDR Y
1 A Otherwise N
2 A EUR Y
2 B USD Y
2 B Otherwise N
Account=1, Qualifier=A, Otherwise = not in (EUR, USD)
Account=1, Qualifier=B, There is no otherwise
Account=2, Qualifier=A, There is no otherwise
Account=2, Qualifier=B, Otherwise = not in (USD) etc
So Otherwise will need a set of key\group columns.
With kind regards,
Mike
On 10 August 2012 15:50, Stephen Masters stephen.mast...@me.com wrote:
Hi folks,
Given a decision table a bit like this (hopefully the monospaced font lays
it out ok!):
Account Currency CanTrade
1 EUR Y
1 USD Y
1 IDR Y
1 Otherwise N
2 EUR Y
2 USD Y
2 Otherwise N
LHS conditions are generated a bit like this:
account == 1, currency == 'EUR'
account == 1, currency == 'USD'
account == 1, currency == 'IDR'
account == 1, currency not in ('EUR', 'USD', 'IDR')
account == 2, currency == 'EUR'
account == 2, currency == 'USD'
account == 2, currency not in ('EUR', 'USD', 'IDR')
… which has the effect that for account 2, currency IDR, the rule does not
fire. For the business analysts building the rules, this does't make a lot
of sense, as they're expecting it to mean:
account == 2, currency not in ('EUR', 'USD')
Unfortunately this means that if a currency is permitted for one account,
then a row must be added for every other account, indicating that the
currency is not permitted.
I'm trying to achieve a sensible default (fire the rule to reject the
trade) unless the currency is explicitly permitted.
Is there a decent mechanism for achieving this in a decision table?
One alternative I can think of is to create a technical rule which
logically inserts a rejection which exists as long as this rule hash't
fired. But I would really prefer to avoid doing anything like that, as I
reckon it would be something of a maintenance nightmare.
Any thoughts?
Cheers,
Steve
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Re: [rules-users] Web decision tables (Guvnor)
Hi
I was wondering why you need the otherwise here.
May be it is only because you have simplified your sample, but the table you
sent is like a truth-table telling what currency can be converted for a
particular account.
So, as you have a 2 state answer, you can simply add rules to specify the
true answer, by modifying the answer flag that is set to false initially. In
other words, you cannot convert the currency unless a rule have triggered to
set the flag to true. Or if you use a fact to store the answer, if the fact is
there you can convert, if not (because no rule had triggered) you can't convert.
This way, your table becomes quite simple, but I don't know if my assumption is
generalizable to your whole application.
- Original Message -
From: Michael Anstis michael.ans...@gmail.com
To: Rules Users List rules-users@lists.jboss.org
Sent: Friday, August 10, 2012 5:07:54 PM
Subject: Re: [rules-users] Web decision tables (Guvnor)
Hi Stephen,
You've made my afternoon ;)
The operation of otherwise is rather dumb. It does not have any understanding
of what groups of rows it is meant to limit it's search of values to construct
the not in part.
As you have discovered, in your case, the Account column has no significance at
all (to the web-guided decision table) although it does to the business analyst.
The immediate workaround would be to move each group to a different decision
table; i.e. Account=1 and Account=2. I appreciate your example is probably a
simplification of the real problem.
A better solution would be to furnish the otherwise value with the
information it would need to determine it's search range. e.g. define
otherwise with a key column of Account. This is however an enhancement :(
Feel free to raise a JIRA (for GUVNOR)... no promises as to when I'll get a
chance to do anything about it though :(
More complex requirements exist, for example given:-
Account Qualifier Currency CanTrade
1 A EUR Y
1 A USD Y
1 B IDR Y
1 A Otherwise N
2 A EUR Y
2 B USD Y
2 B Otherwise N
Account=1, Qualifier=A, Otherwise = not in (EUR, USD)
Account=1, Qualifier=B, There is no otherwise
Account=2, Qualifier=A, There is no otherwise
Account=2, Qualifier=B, Otherwise = not in (USD) etc
So Otherwise will need a set of key\group columns.
With kind regards,
Mike
On 10 August 2012 15:50, Stephen Masters stephen.mast...@me.com wrote:
Hi folks,
Given a decision table a bit like this (hopefully the monospaced font lays it
out ok!):
Account Currency CanTrade
1 EUR Y
1 USD Y
1 IDR Y
1 Otherwise N
2 EUR Y
2 USD Y
2 Otherwise N
LHS conditions are generated a bit like this:
account == 1, currency == 'EUR'
account == 1, currency == 'USD'
account == 1, currency == 'IDR'
account == 1, currency not in ('EUR', 'USD', 'IDR')
account == 2, currency == 'EUR'
account == 2, currency == 'USD'
account == 2, currency not in ('EUR', 'USD', 'IDR')
… which has the effect that for account 2, currency IDR, the rule does not
fire. For the business analysts building the rules, this does't make a lot of
sense, as they're expecting it to mean:
account == 2, currency not in ('EUR', 'USD')
Unfortunately this means that if a currency is permitted for one account, then
a row must be added for every other account, indicating that the currency is
not permitted.
I'm trying to achieve a sensible default (fire the rule to reject the trade)
unless the currency is explicitly permitted.
Is there a decent mechanism for achieving this in a decision table?
One alternative I can think of is to create a technical rule which logically
inserts a rejection which exists as long as this rule hash't fired. But I would
really prefer to avoid doing anything like that, as I reckon it would be
something of a maintenance nightmare.
Any thoughts?
Cheers,
Steve
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Re: [rules-users] Web decision tables (Guvnor)
If any of the positive rules for a Trade (account==N,
currency==XYZ) were to modify or retract the fact a single
low-salience technical rule triggering on the modified or remaining
fact would be sufficient to implement an otherwise for everything.
Which account and which currency is available from the fact itself.
If modifying or retracting is out, consider inserting a Done fact
referring to the Trade, and the low-salience rule is almost as simple.
-W
On 10/08/2012, Stephen Masters stephen.mast...@me.com wrote:
Hi folks,
Given a decision table a bit like this (hopefully the monospaced font lays
it out ok!):
Account Currency CanTrade
1 EUR Y
1 USD Y
1 IDR Y
1 Otherwise N
2 EUR Y
2 USD Y
2 Otherwise N
LHS conditions are generated a bit like this:
account == 1, currency == 'EUR'
account == 1, currency == 'USD'
account == 1, currency == 'IDR'
account == 1, currency not in ('EUR', 'USD', 'IDR')
account == 2, currency == 'EUR'
account == 2, currency == 'USD'
account == 2, currency not in ('EUR', 'USD', 'IDR')
… which has the effect that for account 2, currency IDR, the rule does not
fire. For the business analysts building the rules, this does't make a lot
of sense, as they're expecting it to mean:
account == 2, currency not in ('EUR', 'USD')
Unfortunately this means that if a currency is permitted for one account,
then a row must be added for every other account, indicating that the
currency is not permitted.
I'm trying to achieve a sensible default (fire the rule to reject the trade)
unless the currency is explicitly permitted.
Is there a decent mechanism for achieving this in a decision table?
One alternative I can think of is to create a technical rule which logically
inserts a rejection which exists as long as this rule hash't fired. But I
would really prefer to avoid doing anything like that, as I reckon it would
be something of a maintenance nightmare.
Any thoughts?
Cheers,
Steve
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Re: [rules-users] Web decision tables (Guvnor)
Thanks for the feedback chaps.
Wolfgang / Vincent - The real application is evaluating what products (FX
swaps, options, forwards, etc) a particular account is permitted to trade with
different banks. The example provided was rather simplified, just to
demonstrate the workings of a decision table and what I was hoping to do with
it. The way the system is designed, there should always be a rule within that
table, firing and inserting a new fact into working memory. The system collates
responses from a variety of rules in order to provide detailed responses on why
a particular transaction is permitted or not.
My thinking for now is that I'll break it into separate tables, which as per
Mike's response will at least get the 'otherwise' working in a more readable
manner. An added benefit is that this particular decision table had hit a few
hundred rows, and it's looking like a table-per-account approach will be more
manageable. Somewhat like Wolfgang's idea, I think I may handle the potential
of these rules not firing through a separate technical rule which looks to see
whether a rule response fact has been inserted by one of these rules. It's not
too tricky to do, but I had hoped there might be a neater way to do it within
the decision tables. Where possible I like to keep my rules nicely encapsulated
so that future developers won't be caught out by 'hidden' technical rules,
which are tightly coupled to rules which are managed by the business within
Guvnor.
Mike - I'll have a think on wording a Jira enhancement request. I think it
would be useful, so if it's in Jira, then at least it might get built at some
point in the future in the unlikely case that you find yourself with some time
to kill. ;)
Many thanks all,
Steve
On 10 Aug 2012, at 17:00, Wolfgang Laun wrote:
If any of the positive rules for a Trade (account==N,
currency==XYZ) were to modify or retract the fact a single
low-salience technical rule triggering on the modified or remaining
fact would be sufficient to implement an otherwise for everything.
Which account and which currency is available from the fact itself.
If modifying or retracting is out, consider inserting a Done fact
referring to the Trade, and the low-salience rule is almost as simple.
-W
On 10/08/2012, Stephen Masters stephen.mast...@me.com wrote:
Hi folks,
Given a decision table a bit like this (hopefully the monospaced font lays
it out ok!):
Account Currency CanTrade
1 EUR Y
1 USD Y
1 IDR Y
1 Otherwise N
2 EUR Y
2 USD Y
2 Otherwise N
LHS conditions are generated a bit like this:
account == 1, currency == 'EUR'
account == 1, currency == 'USD'
account == 1, currency == 'IDR'
account == 1, currency not in ('EUR', 'USD', 'IDR')
account == 2, currency == 'EUR'
account == 2, currency == 'USD'
account == 2, currency not in ('EUR', 'USD', 'IDR')
… which has the effect that for account 2, currency IDR, the rule does not
fire. For the business analysts building the rules, this does't make a lot
of sense, as they're expecting it to mean:
account == 2, currency not in ('EUR', 'USD')
Unfortunately this means that if a currency is permitted for one account,
then a row must be added for every other account, indicating that the
currency is not permitted.
I'm trying to achieve a sensible default (fire the rule to reject the trade)
unless the currency is explicitly permitted.
Is there a decent mechanism for achieving this in a decision table?
One alternative I can think of is to create a technical rule which logically
inserts a rejection which exists as long as this rule hash't fired. But I
would really prefer to avoid doing anything like that, as I reckon it would
be something of a maintenance nightmare.
Any thoughts?
Cheers,
Steve
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