Authoring JBoss Drools rules using UI

Question

We're using JBoss Drools to externalise some particularly prone to change business logic in some services we are building.

Where these rules can be created and maintained by our developers this is working very well and we have a good level of integration and integrated workflow.

We are looking to expand its use to a new service that has a very high level of customisation required. Essentially an "expert user" needs to be able to setup rules of two different kinds:

1. "standard" rules - these are almost implicit rules that we know are common requirements and which we could build UI for to set e.g. only allowing certain operations to take place between two dates etc.

2. "custom" rules - completely off the wall requests that whilst we could try and anticipate we'd rather just let people write and test their own rules against :)

My question is, is it possible (and indeed is there anything out there as an example) of using Drools for both 1 & 2? Basically, to have a fixed UI application author Drools rules effectively AND have a "free text" rule editor embedded in our UI?

Any suggestions appreciated!

Answer 1

You have a few options.

For (2), you can simply embed the rules editor from Guvnor in your web application. All editors in Guvnor are embeddable components, so you can choose what you want to use and what you don't. The problem that I see in this approach is that you might be giving too much power to the users :). In other words, the ability to write any rules based on the model requires disciplines that are typically only known to technical users. For instance, writing tests to validate the rules. Some business users have enough technical knowledge for that, but I would say it is probably the exception, not the rule.

What I prefer and recommend most of the time is to develop your own domain specific GUI, that uses/exposes concepts and terminology that are familiar to the business users and a way to write rules that "makes sense" for their specific job. Sometimes, they will not even know they are writing "rules", but they will. Behind the scenes, your application takes the input from the Domain Specific GUI and generates the rules dynamically, either using the drools API or a string based template. This solves your (1) requirement, but might be powerful enough to solve (2) as well.