Announcing Overlays Capture Architecture (OCA) 2.0.0: Unlocking Semantic Interoperability with Community-Driven Flexibility

28 Mar

We are thrilled to announce the official release of Overlays Capture Architecture (OCA) 2.0.0, marking a significant milestone in our journey toward a dynamic, interoperable, and verifiable data economy. This release is the culmination of extensive community feedback and testing of new paradigms in semantic flexibility.

Version 2.0.0 is not just an update; it is a fundamental leap forward. It transforms OCA into a more modular, extensible, and community-centric architecture, empowering non-technical users and entire ecosystems to define, share, and validate data structures with unprecedented ease and cryptographic integrity.

What’s New in OCA 2.0.0?

The core theme of this release is semantic flexibility, achieved through a host of new features and improvements designed for real-world application across science, compliance, supply chain, and beyond.

Introducing OCAFILE, OVERLAYFILE and Community Overlays

The centerpiece of OCA 2.0 is the introduction of Community Overlays, empowering any group—from a research consortium to a regulatory body—to create and govern their own overlay definitions without deep technical barriers. This is made possible through a two-layered DSL approach. OCAFile serves as the Domain-Specific Language (DSL) for creating individual overlays, while OVERLAYFILE is the higher-level DSL that defines the types of overlays a community can use, enabling the creation of reusable overlay definitions in .overlayfile documents. If you are familiar with programming, think of .overlayfile as a header (.h) file that declares the structure and meaning of your data. For non-technical users, it represents the exact, validated structure that a team, department, or entire community has approved for use. By separating overlay definitions from their usage, this dual-layer approach enables clear governance, cryptographic assurance of validation, and seamless reusability across projects.

OCA Bundle as single object

We are replacing the legacy `.zip` format with a new, streamlined JSON-based OCA Bundle. This simplification makes it easier to transmit, parse, and integrate OCA bundles within tooling and applications, a change that has been battle-tested in our reference implementation.

Enhanced Modularity and Validation

Overlays can now define their own schemas, enabling robust tooling validation against community-defined rules. This drastically reduces errors and increases trust in the data structures being used.

Major Specification Upgrades

The OCA Specification v2.0.0 introduces several key enhancements:

- Sensitive Overlay: Replaces the old PII flagging in the Capture Base, offering a more nuanced and powerful approach to managing privacy and risk flags directly in the schema.

- Separation of Concerns: Categories have moved from the Label overlay to the Presentation layer, strictly enforcing the distinction between a data's inner structure and its visual presentation.

- Community-Nominated Overlays: Several previously “core” overlays are now upgraded to first-class Community Overlays, fostering a repository-driven ecosystem for sharing:

- Information
- Transformation
- Presentation
- Layout
- Conditional
- Unit Mapping

- SemVer for All Objects: All OCA objects now support Semantic Versioning (SemVer), enabling better lifecycle management.

- Enhanced Language Support: Added support for ISO 639-1 and 639-3 language codes.

- Namespacing: Introduced support for namespacing in overlay names, allowing for better organization and preventing collisions.

Get Started with OCA 2.0.0

The official OCA Specification v2.0.0 is now released and ready for adoption. The reference implementation, `oca-rs`, has been updated to support all new features and is the best place to see the architecture in action.

- Read the Specification: https://oca.colossi.network/specification/

- Explore the Reference Implementation: https://github.com/THCLab/oca-sdk-rs

- Browse and Build Community Overlays: https://oca.colossi.network/ecosystem/overlay-registry.html

Join the Movement

This release is the result of the hard work and vision of the Human Colossus Foundation’s Technology Council and the broader OCA community. We invite developers, data architects, and organizations to explore OCA 2.0.0 and contribute to this open, extensible semantic ecosystem.

Let’s build a more interoperable and trustworthy data future together.

HCF News

Robert Mitwicki

Robert is the Head of the Human Colossus Foundation Technology Council. He is a highly experienced software architect and developer whose recent focus has been engaged in decentralised identity and user-centric data initiatives.

Capitalising on a wealth of experience in software design, quality assurance, software engineering and DevOps practices, and with expertise in mobile and web development, Robert is currently working on digital-self to allow people to participate in this new interoperable and fair dynamic data economy.