I noticed the recent introduction of the concept of Shadow Variables in the Optaplanner. I'm wondering if someone could help me understand the difference between Shadow Variables and inserting facts with insertLogical()? Each are described a little bit in the manual and it seems that there is a similar use case but I'm not sure I understand the implications of using one over the other? I see that some of the examples still use insertLogical so I'm assuming that shadow variables are not a replacement in every case. To help frame the answer, consider the following toy problem which maps to my domain fairly well: Say my problem is creating purchase orders of raw materials for my factory from various vendors. The input states how many of each raw material I need. Obviously I would want to minimize cost but I also have no capacity to store extra raw materials so any extra that I buy will be waste. Therefore, I'll want to create a list of orders that obtains exactly the required number of each if possible. Each vendor offers package deals that include different combinations of raw materials in different amounts. There would clearly be other optimizations such as reducing the number of vendors used but those would likely be secondary to the cost and waste optimizations. The domain model for this problem would include a Planning Value for each individual raw material item as well as one for each package combo offered by a vendor (essentially anything with a price). So, for a problem space like this, I'll want rules which count the number of each raw material type across all of the different packages purchased from different vendors and make sure it meets the needs of the particular provided problem. Currently I am using a rule that fires for each raw material type and counts the number of units ordered for that type using an accumulator over Planning Entities. I am currently experiencing score corruption which I believe may be due to this approach so I am looking to redesign. Would Shadow Variables or calls to insertLogical() be more appropriate/efficient for this use? Thanks in advance, Jon -- View this message in context: http://drools.46999.n3.nabble.com/Optaplanner-Shadow-Variables-vs-insertL... Sent from the Drools: User forum mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users

ge0ffrey wrote > But the first question is why you're getting score corruption the first > place. Of course I'm not sure of the cause of the score corruption. I assume that it is due to my rules using an accumulator over Planning Entities in the When portion of the rule and that somehow confusing the delta score calculations.

I hoped that a rule redesign based on Shadow Variables or insertLogical rather than accumulators would be more efficient and not result in score corruption. Jon -- View this message in context: http://drools.46999.n3.nabble.com/Optaplanner-Shadow-Variables-vs-insertL... Sent from the Drools: User forum mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users

It turns out that the score corruption was caused by something unrelated. In fact, a rule that will be removed in the re-design I am asking about. If I see a similar problem after the re-design I'll pursue your suggestions to determine the reason.

However I was wondering if you had more insight into the Shadow Variable vs insertLogical() question for my domain. I imagine that the insertLogical() approach would fire for each line of an order (Planning Entity) and insert a fact for each type of raw material in the order where each fact contains the number of that type of raw material. Then, a rule with a different salience would accumulate all of these facts to produce total counts of each type across all orders. Is this an appropriate approach?

Does this approach break the delta score calculation?

Will the creation, (automated) retraction, and accumulation of these facts create a slowdown or is this an intended use?

I imagine that the Shadow Variable approach would update a similar set of total count variables but instead do so appropriately when the Planning Variable changes. Would the classes representing the raw material types themselves become Planning Entities in this case?

Is this the intended use?

Thanks, Jon -- View this message in context: http://drools.46999.n3.nabble.com/Optaplanner-Shadow-Variables-vs-insertL... Sent from the Drools: User forum mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users