DSLs for Decision Services: A Tutorial Introduction to Language-Driven Engineering

Language-Driven Engineering (LDE) is a new paradigm that aims at involving stakeholders, including the application experts, in the system development and evolution process using dedicated domains-specific languages (DSLs) tailored to match the stakeholders’ mindsets. The interplay between the involved DSLs is realized in a service-oriented fashion, with corresponding Mindset-Supporting Integrated Development Environments (mIDEs). This organization eases product line and system evolution, because one can introduce and exchange entire DSLs as if they were services. Using as example a smart email classification system that highlights important emails in the inbox, we model its decision procedure in a tailored graphical domain-specific language based on Binary Decision Diagrams. BDDs are a compact form of the popular decision trees and thus a mindset natural to many application experts. We then evolve this language and its mIDE to meet the new users’ wish to model some uncertainty in the classification. To evolve the language, we first manually adapt its metamodel and code generator. Subsequently we show, how this step can be automated by refining the BDD DSL with a dedicated DSL for defining algebraic structures. As this exchange happens in a service-oriented fashion, it does not impair the optimization potential and nicely follows the successive refinement of the users’ mindset.