Angel \”Java\” Lopez on Blog

February 25, 2012

AjRools (1) Rule Engine in C#

Filed under: .NET, AjRools, Open Source Projects, Rule Engine — ajlopez @ 6:50 pm

Since last year, I was conducting a bit of research about rule engines, specially in Java:

http://delicious.com/ajlopez/ruleengine

I reviewed JBoss Drools Expert (see http://delicious.com/ajlopez/drools). Past December, I assisted to Buenos Aires JBoss Meetup (see Spanish post)

In the old eighties, I met Rete Algorithm (see The Rete Matching Algorithm, Dr.Dobb’s). After all that, I decide to implement my own rule engine, in C#. You can check my progress at:

https://github.com/ajlopez/AjRools

This is the current solution:

As usual, it was coded using TDD.

I have facts, that are asserted, like Temperature = 38. And rules, that based on the asserted facts, produce other asserted facts (I plan to add actions, too, beyond fact assertions). A rule example:

# Rules example
rules
# Rule for Child Fever
rule
	when
		Temperature > 38
		Age <= 12
	then
		HasFever is true
end
# Rule for Adult Fever
rule
	when
		Temperature > 37
		Age > 12
	then
		HasFever is true
end
end

I have ideas to extend the rule engine to support objects with properties, not only variables:

rule
when
	p is_a Patient
	p.Temperature is 39
then
	p.HasFever is true
end

but this feature is still in progress. I didn’t adopt the Rete algorithm, yet, or something similar. I want to have a running implementation, with tests. Then, changing internal algorithm is like an exercise on refactoring.

Pending work: more object+properties support, session (client use of the internal implementation), etc.

Keep tuned!

Angel “Java” Lopez

http://www.ajlopez.com

http://twitter.com/ajlopez

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