I am somewhat new to rules-based programming, so I thought I'd ask if my approach to our problem seems valid (or if there are any better ways of doing it). Basically, we have a bunch of data from public sources. Let's call them public records. I am going to assert those into the working memory. Then, we have summary objects that are supposed to summarize everything we know from the public sources about a specific item. The summary objects have properties that are to be populated from the related public record objects. Now, we trust records from some public sources more than others. So, we would use the values from those public records first to populate the properties. Anyway, here's my thoughts on my approach: 1. Assert the public records into the working memory. 2. Find the corresponding summary object and assert that into working memory. 3. Insert RequiredProperty objects (they will have a propertyName field) for all properties on the summary object that need to be populated. 4. Write my rules based on the existence of a RequiredProperty objects (and the summary object of course) with a specified propertyName. So, when my rule fires that sets a property, I'll remove the RequiredProperty object from working memory so that other rules that try to set the same property from less trusted public sources won't fire anymore. We'll use salience to give the rules priority based on our preferences. Does this sound feasible? Is this the "drools way"? James Carman