Expression Languages

This is where the rubber hits the road and all of the work that has been done at a level of the Decision Requirements diagram will need to be embellished with the expressions that express the logic of decisions. As with many aspects of design, things start simple but inevitably can become quite complex. It is important at this point in the Decision Model Definition to remember that the purpose of the models is to ensure that the decisions are decomposed into understandable chunks that make sense to the business, engineering or scientific stakeholders. For many applications the logic and the accompanying expressions will be simple enough for most stakeholders to understand. The value expressions that are used in the various expression types are written in the Friendly Enough Expression Language or FEEL for short. The next sections will detail the fundamental aspects of the language and how it is supported by Enterprise Architects code editor and Validator.

The expressions consist of both literal values (e.g. 20, 'Approved') and variables (Credit Rating, Price) in addition to FEEL language constructs (e.g. not([10..35]), date and time("2022-02-04T07:42:00")).