Jjodel Definition Language

The Jjodel Definition Language provides a textual notation for defining metamodels, viewpoints, and expressions. While Jjodel’s graphical editors are the primary interface for most users, the definition language offers a compact, code-oriented alternative that is especially useful for advanced users, automation, and version control.

Expression Languages

Jjodel includes three specialized languages:

JjEL — Jjodel Expression Language

JjEL is used for navigating models, accessing properties, and defining computed values. It appears in viewpoint templates, validation constraints, and the Console.

// Navigate from an object to its metaclass
self.instanceOf.name

// Access an attribute
self.name

// Collection operations
Person.allInstances.filter(p => p.age > 18)
Person.allInstances.map(p => p.name)

JjTL — Jjodel Transformation Language

JjTL is Jjodel’s model-to-model transformation language. It defines mappings between source and target metamodels, enabling systematic model transformations.

JjTL serves a dual purpose: it is both a user-facing language for defining transformations and the core intermediate representation for future interoperability with other transformation languages (ATL, ETL).

JjScript

JjScript provides a scripting interface for programmatic manipulation of metamodels and models. It extends JavaScript with Jjodel-specific APIs for creating, modifying, and querying model elements.

Jjodel uses JSX-like expressions in viewpoint templates to define dynamic content. These expressions are evaluated at render time and can access the current model element, its properties, and its relationships.

// A simple template for rendering a class
<rect>
  <text>{self.name}</text>
  {self.attributes.map(a =>
    <text>{a.name}: {a.type}</text>
  )}
</rect>