In our application we have some formulae to be used. But we don't want this code to be inside java because these formulae are subject to change with time. So we want to externalize this code. I heard that we need to use some Rules engine for the same. My question is will Drools engine meet my requirement? Kindly reply at the earliest.
Rules based engines are great for what they do. Meaning if you have say a product that has different configurations and certain parts won't work with other parts, and others must have other parts, and these rules change with new products, or changes in time, then a Rules based engine is what you really want. That is an example of a great reason to use a Rules based engine. You can try Jess, or JRules for JBoss to find the one that you like the best, both are really good.
If these are purely mathematical formulas (as opposed to logical rules which Mark talked about), you might look into packages like JEP which interpret Strings as formulas and calculate their value based on a set of variables. [ June 22, 2006: Message edited by: Ulf Dittmer ]