FAQ
General
Section titled “General”What is Jjodel?
Section titled “What is Jjodel?”Jjodel is a cloud-native, reflective modeling platform for defining, visualizing, and evolving Domain-Specific Modeling Languages (DSLs) directly in the browser. It provides an integrated environment where metamodels, models, and viewpoints coexist and co-evolve in real time, without code generation or tool recompilation.
Who develops Jjodel?
Section titled “Who develops Jjodel?”Jjodel is developed and maintained by the Software Engineering (SWEN) Research Group at the University of L’Aquila (Italy), with collaborations across Europe. It is part of the AIM-PRO European research project.
Is Jjodel open source?
Section titled “Is Jjodel open source?”Yes. Jjodel is released under the MIT License, which allows free use, modification, and redistribution. The source code, documentation, and examples are available on GitHub.
What makes Jjodel different from other modeling tools?
Section titled “What makes Jjodel different from other modeling tools?”Three key differentiators set Jjodel apart:
- Live co-evolution — metamodel changes propagate instantly to models, editors, and viewpoints without regeneration or redeployment
- Cloud-native — no installation required, real-time collaboration built in
- Reactive and reflective architecture — the tool observes its own structure and synchronizes all components automatically
Access and Setup
Section titled “Access and Setup”How do I access Jjodel?
Section titled “How do I access Jjodel?”Visit app.jjodel.io in your browser. Registration is free.
Do I need to install anything?
Section titled “Do I need to install anything?”No. Jjodel runs entirely in the browser. For local development or offline use, you can optionally install Jjodel via Docker or build from source — see Installation.
Can I use Jjodel offline?
Section titled “Can I use Jjodel offline?”The cloud version requires an internet connection. For offline use, you can run Jjodel locally using Docker, though this setup does not include shared storage or real-time synchronization.
Which browsers are supported?
Section titled “Which browsers are supported?”Google Chrome and Microsoft Edge (latest versions) are recommended. Other Chromium-based browsers are generally supported.
Modeling
Section titled “Modeling”What kinds of models can I create?
Section titled “What kinds of models can I create?”Jjodel supports any domain-specific or general-purpose modeling language. You define the metamodel (abstract syntax), and Jjodel lets you create models conforming to it. Common examples include UML class diagrams, entity-relationship diagrams, state machines, process models, and custom DSLs.
How does live co-evolution work?
Section titled “How does live co-evolution work?”Every change to a metamodel is immediately reflected across all related models, viewpoints, and editors. This is possible because Jjodel interprets metamodels at runtime (rather than generating code from them) and uses a reactive architecture that propagates changes automatically.
Can I import or export models?
Section titled “Can I import or export models?”Ecore and XMI import/export is planned for a future release. The team is also exploring participation in the LionWeb initiative for cross-tool interoperability.
Collaboration
Section titled “Collaboration”Does Jjodel support collaborative editing?
Section titled “Does Jjodel support collaborative editing?”Yes. Multiple users can work simultaneously on the same models or metamodels. All actions are propagated in real time through a cloud-based publish-subscribe infrastructure.
Can Jjodel be integrated with other tools?
Section titled “Can Jjodel be integrated with other tools?”Jjodel can interoperate with external tools through REST APIs. Its React-based editors can also be embedded in other web applications.
Technical
Section titled “Technical”Does Jjodel support version control?
Section titled “Does Jjodel support version control?”Jjodel includes an operation recorder but does not currently provide built-in version control. Projects are stored in the cloud with operational history.
Does Jjodel support metamodel evolution?
Section titled “Does Jjodel support metamodel evolution?”Yes — this is one of Jjodel’s core strengths. Metamodel changes are propagated instantly, with no recompilation needed.
Learning and Support
Section titled “Learning and Support”Where can I find tutorials?
Section titled “Where can I find tutorials?”See the Tutorials section for step-by-step guides, and the Video Pills page for recorded introductions and demonstrations.
Is Jjodel used in teaching or research?
Section titled “Is Jjodel used in teaching or research?”Yes. Jjodel is used in MDE courses, software modeling laboratories, and European research projects (AIM-PRO). It serves as an open, reflective environment for experimentation, prototyping, and education.
How can I contribute?
Section titled “How can I contribute?”Visit the GitHub repository to report issues, propose features, or contribute code. Look for issues labeled good first issue to get started.