NxBRE DSL, aka NxDSL, main goal is to allow rules authors to use their own natural language to write executable rules. Technically this feature is based on:

• a language-specific ANTLR grammar that strictly enforces the structure of a rule file: this file is not supposed to be edited by the implementer,
• a custom definition file that translates statements into RuleML atoms: this file must be created by the implementer to capture, with regular expressions, the natural language fragments and how they translate in RuleML atoms.

In the following example, the words in bold are parsed by ANTLR while the other ones are matched by the regular expression from the definition file.

rule "Discount for regular products"
if
The customer is rated premium
and
The product is a regular product
then deduct
The discount on this product for the customer is 5.0 %

The terms in italic are captured by ANTLR and the regular expressions to get values for labels, implication actions and atom values. As you can see, the ANTLR grammar defines and enforces the structure of the rulebase, i.e. the skeleton of the rules, logical blocks and statements.

NxDSL comes with a grammar that allows using French terms for defining the rule structure, thus opening the door to consistently write the body of the rules in the same language, as shown hereafter:

règle "Remise pour les produits standard"
si
Le client est en catégorie premium
et
Le produit est de type standard
alors déduis
La remise pour ce produit pour ce client est de 5.0 %