> ## Documentation Index
> Fetch the complete documentation index at: https://lightdash-mintlify-3eb36d6a.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Apache Ossie support

> Lightdash will support Apache Ossie (Incubating), formerly the Open Semantic Interchange (OSI) — the open specification for semantic layer and ontology interchange.

<Note>
  Apache Ossie is currently incubating at the Apache Software Foundation and its spec is pre-1.0. Support in Lightdash is planned — this page describes what we intend to support and how it relates to the Lightdash semantic layer today. Timelines will follow the spec's stabilization.
</Note>

## What is Apache Ossie?

[Apache Ossie (Incubating)](https://ossie.apache.org) — formerly known as the Open Semantic Interchange (OSI) — is an open, vendor-neutral specification for exchanging semantic models between tools. It defines a shared, machine-readable format for describing datasets, relationships, fields (dimensions), and metrics — plus the business context around them — so that any tool in a data stack can produce or consume semantic definitions without losing meaning.

The project sits under the Apache Software Foundation, is developed in the open on GitHub, and is backed by a coalition of data and analytics vendors. Its goal is to make a business concept like "Monthly Active Users" resolvable consistently across warehouses, BI tools, and AI agents, regardless of where it was originally defined.

## How Ossie relates to the Lightdash semantic layer

The [Lightdash semantic layer](/guides/lightdash-semantic-layer) already models the same core building blocks Ossie standardizes:

| Ossie concept     | Lightdash equivalent                                                                    |
| ----------------- | --------------------------------------------------------------------------------------- |
| Semantic model    | A Lightdash project's models and their [YAML](/guides/lightdash-yaml) / dbt definitions |
| Dataset           | A [table / model](/get-started/develop-in-lightdash/adding-tables-to-lightdash)         |
| Relationship      | [Joins](/references/joins) between models                                               |
| Field (dimension) | [Dimensions](/references/dimensions)                                                    |
| Metric            | [Metrics](/references/metrics)                                                          |

## Following Ossie's roadmap

The Ossie community is actively working on a few directions that will directly benefit Lightdash users as they land:

* A more expressive core model, with richer metric semantics, explicit grain and entity modeling, and more capable relationships.
* A standardized semantic query language and reference engine, so BI tools, AI agents, and APIs can query any Ossie-compatible semantic layer through a consistent interface.
* Catalog and ontology integration, so semantic models are discoverable and governable at the platform layer and can describe business concepts independently of physical tables.

We plan to support Apache Ossie as an interchange format for the Lightdash semantic layer, and will evolve that support in step with the spec as it stabilizes.

## Where to learn more

* Apache Ossie project site: [ossie.apache.org](https://ossie.apache.org)
* Source and spec: [github.com/apache/ossie](https://github.com/apache/ossie)
* Lightdash semantic layer: [Lightdash semantic layer](/guides/lightdash-semantic-layer)

If you're evaluating Ossie for your stack and want to talk through how it will fit with Lightdash, [get in touch](/contact/contact-info).