Should I use Drools in this situation?

Question

I\'ll use a university\'s library system to explain my use case. Students register in the library system and provide their profile: gender, age, department, previously completed

Answer 1

My experience with Drools (or a rules engine in general) is that it is a good fit if user visibility into the rules are important, or if fast changes to the rules without making it a coding project is important, or if the set of rules is very large making it hard to manage, think about and analyze in code (so you would have business people asking technical people to go read the code and tell them what happens in situation X).

That being said, rules engines can be a bottleneck. They don't run anything close to the performance of code, so you do need to manage that up front architecturally. In this specific case there is certainly a database behind this, and you can add to the performance issues that the database will return a query a whole lot faster than you can analyze the whole set in code.

I would absolutely not implement that by making a million rules objects, rather I would make a book type that multiple books can be assigned to, and run the rules against the book types, and then only show books that are in an allowed type. This way you could load the types, pass them through the rules engine, and then push the allowed types to a query on the database end that pulls the list of books in the allowed types.

Types get a bit complicated by the fact it will be likely that in practice a book may be of two types (allowed if you are taking a certain course, or in general if you are part of the department), but the approach should still hold.