Understanding terms iTwin, iTwin Plaform, iModelHub, iModel, Briefcases, and Changesets

When working with iTwin.js, it’s essential to grasp few core concepts that form the foundation of digital twin ecosystem. In this post, we’ll explore six fundamental terms: iTwin, iTwin Platform, iModelHub, iModel, Briefcases, and Changesets.

1. What is an iTwin?

An iTwin is Bentley’s standard for infrastructure digital twins. It is a digital representation of a physical asset or system, such as a building, bridge, or rail network. An iTwin enables collaboration by aggregating data from multiple sources, including design applications, IoT sensors, and reality data etc.

Think of an iTwin as a collection or list of data sources relevant to a project. Some of these data sources, are hosted on the iTwin Platform, while others may reside in external systems.

2. What is the iTwin Platform?

The iTwin Platform is a cloud-based ecosystem of APIs, tools, and services designed to create and manage digital twins, known as iTwins. The iTwin Platform helps you unlock the full potential of your asset’s digital twin.

3. What is an iModel?

An iModel is a distributed relational database, designed to support a common cloud format with a schema defined by **BIS (Base Infrastructure Schema)**. It is designed to hold information about a single infrastructure asset. Unlike traditional CAD or BIM files, iModels support incremental updates and enable collaborative workflows.

iModel — data sync from different sources/formats

Key features of iModels:

• Lightweight and efficient: Designed for optimal cloud storage and retrieval.
• Immutable history: Every modification is recorded as a versioned change, maintaining a comprehensive audit trail.

4. What is iModelHub?

iModelHub is a cloud service that serves as the backbone for iTwin.js applications. It coordinates concurrent access to iModels and manages changes through a system of Changesets, ensuring data integrity and facilitating collaborative workflows. It is the control center for iModels.

iModelHub — Image courtesy of iTwin.js org

5. What is a Briefcase?

A Briefcase is a local copy of an iModel that users can acquire to work with the iModel. Users can make changes to their copy of the iModel and then push them as a single Changeset file into iModelHub.

6. What is a Changeset?

A Changeset is a recorded set of modifications made to an iModel in a Briefcase. It contains incremental changes such as new elements, property updates, and deletions. Changesets form a linear timeline of iModel changes, ensuring a structured and traceable history.

Wrapping Up

Understanding iTwin, iTwin Platform, iModelHub, iModel, Briefcases, and Changesets is crucial when developing applications with iTwin.js. These concepts form the backbone of Bentley’s iTwin ecosystem, enabling seamless collaboration, version-controlled updates, and efficient digital twin management.

If you’re just starting with iTwin.js, exploring how these components interact in real-world workflows will help you build scalable and high-performance digital twin applications.

Do you have any questions or specific topics you’d like to explore further? Let’s discuss in the comments!