[rules-users] modify and update is not working in the rule file

[Stephen Masters]

It's worth thinking about it differently. A rule does not fail. It just defines the conditions under which it will activate.

If you wish to perform an action whether the condition is true or false, you have 2 options:

A positive and a negative condition:
when 
	test(a == "b")
then
	...
when 
	test(a != "b")
then
	…

A condition which is always true:
when
	test()
then
	if (a.equals("b")) {
		...
	} else {
		...
	}

To be honest whether you write 1 or 2 rules should not be a 'business' decision. Why does anybody think there should not be 2 rules?

It's probably worth considering what you're trying to achieve. Does logging of a fact value really need to be part of a rule?

For instance, if you're actually just looking for an audit trail, you can have a WorkingMemoryEventListener, which can listen for all of the fact insertions, updates and retractions. It can log them all as they happen. Combined with an AgendaEventListener, you can log what rules have activated and what the values of facts were at the time. Use an asynchronous logger and this will have very little impact on rules processing performance.

Alternatively if the business are writing rules, and only wish to write the positive match, then maybe you can create a DSL which generates the both the positive and negative rules behind the scenes.

A few ideas there for you to try...

Steve




On 17 Aug 2012, at 15:49, Rana <ven12344 at yahoo.com> wrote:

> That's what our Business doesn't want me to do to write negative rules. In
> this way there will be 2 rules to be written for 1 business rule.
> 
> Thanks.
> 
> 
> 
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