OptaPlanner deprecates score DRL

As I was starting with OptaPlanner more than a decade ago, score DRL was there, promising easy and fast score calculation. It wasn’t as fast as the Incremental Java calculator, but it also wasn’t as hard to write while still getting better results than the Easy Java calculator. On the other hand, it required me to learn a new programming language.

When I joined the OptaPlanner core team several years ago, I decided that we can do better. With the help of many other people, we introduced the Constraint Streams API. Constraint Streams, while still implemented using Drools under the hood, is a well-performing pure Java API for writing score constraints in OptaPlanner. Since its introduction in 2020, we kept improving it until it reached a full feature set in 2021 and has become the new default. Now, a further full year later, we are finally ready to announce the deprecation of score DRL.

Starting with OptaPlanner 8.23.0.Final, users of score DRL will be getting IDE and logging notifications that score DRL is deprecated, encouraging migration to Constraint Streams. Rest assured that support for score DRL will not be removed in OptaPlanner 8. The next major version of OptaPlanner, however, will no longer support score DRL.

We understand that constraints are a fundamental part of your application, and that refactoring them to Constraint Streams will take time. To make this job as easy as possible, we have prepared a migration guide which explains the most typical use cases and migration patterns.

We believe that, while reading the guide, you will realize that the migration is fairly straight-forward in most cases. In return, you will get fast constraints written in Java that are ready for Quarkus and the cloud, with full IDE support and a comprehensive testing framework.

And as always, if you’re ever stuck, we are here to help. Onwards with Constraint Streams!