Viewpoints

Viewpoints are one of Jjodel’s most powerful features. A viewpoint defines a perspective on a model — how elements look, how they behave, what constraints they must satisfy, and what artifacts they generate. The same model can have multiple viewpoints, each tailored to a different audience or purpose.

Types of Viewpoints

Jjodel supports four categories of viewpoints:

Syntax Viewpoints (Concrete Syntax)

Syntax viewpoints define the visual or textual representation of model elements. They map abstract metamodel concepts to concrete graphical or textual forms.

Visual Viewpoints

Visual viewpoints use shapes, colors, icons, and connectors to render model elements as diagrams. For each metamodel class, you define a view that specifies:

• Shape — rectangle, ellipse, diamond, custom SVG, etc.
• Label — which attribute(s) to display as text
• Color and style — fill, border, font, opacity
• Compartments — subdivisions within a shape (e.g., showing attributes inside a class box)
• Edge style — for references: line type, arrowheads, routing (Manhattan or direct)

Textual Viewpoints

Textual viewpoints define a text-based syntax for model elements. Instead of graphical shapes, elements are rendered as structured text following a grammar you define. This enables blended modeling — switching between graphical and textual representations of the same model.

Validation Viewpoints

Validation viewpoints enforce constraints and rules that model instances must satisfy. They are used to check model consistency, enforce naming conventions, verify structural integrity, and apply domain-specific business rules.

Validation rules produce notifications that guide the modeler toward restoring model validity. Notifications can be informational, warnings, or errors.

Code Generation Viewpoints

Code generation viewpoints transform model elements into executable artifacts — source code, configuration files, documentation, or any textual output. You define templates that map metamodel classes to code patterns, enabling automated generation from your models.

Viewpoint Configuration

Each viewpoint is configured through a set of tabs in the Properties Panel:

Applied To

Defines which metamodel classes and model elements the viewpoint applies to. You can use OCL or JavaScript constraints to filter which instances should be rendered by this viewpoint.

Template

Specifies the visual template for the view — the shape, layout, and content of each rendered element. Templates use JSX-like expressions for dynamic content.

Style

Controls the appearance properties: colors, borders, fonts, sizes, spacing, and opacity. Styles can be static or computed dynamically based on element properties.

Events

Defines interactive behavior: what happens when the user clicks, drags, resizes, or hovers over a model element. Events enable custom interaction logic through JavaScript handlers.

Options

Additional configuration for layout, alignment, connection routing, and rendering behavior.

Default Viewpoints

When you create a new metamodel, Jjodel automatically generates default viewpoints that provide a basic visual representation for each class. These defaults use simple rectangles with the class name as a label. You can customize or replace them with your own viewpoint definitions.

Multi-View Modeling

Jjodel’s viewpoint system enables true multi-view modeling: the same underlying model can be visualized through multiple viewpoints simultaneously. For example, a software architecture model might have:

• A structural viewpoint showing classes and relationships
• A deployment viewpoint showing servers and connections
• A validation viewpoint highlighting constraint violations
• A documentation viewpoint generating API documentation

Each viewpoint presents a different perspective without modifying the underlying model data.

Viewpoints are not models

Viewpoints define how to render models — they do not contain model data themselves. Modifying a viewpoint changes the visualization, not the model structure.