# ossie | The Apache Software Foundation | Knowledge Base | Instagit

Apache Ossie, industry wide specification effort to standardize how we exchange semantic metadata across analytics, AI and BI platforms, providing a vendor neutral, single source of truth for semantic data

GitHub Stars: 1.1k

Repository: https://github.com/apache/ossie

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## Articles

### [Apache Ossie Roadmap: Future Specification Features and Semantic Data Model Enhancements](/apache/ossie/ossie-roadmap-future-features)

Explore the Apache Ossie roadmap for future Apache Ossie specification features. Discover Dataset Abstraction, Semantic Query Language, AI-Native Semantic Layers, and more.

- Tags: roadmap
- Published: 2026-07-26

### [Naming Rules for Identifiers in Apache OSSIE: Case Sensitivity and Quoting](/apache/ossie/ossie-identifier-naming-rules-case-sensitivity-quoting)

Discover Apache OSSIE identifier naming rules. Learn how case sensitivity and quoting affect your names, following ANSI-SQL conventions for unquoted and double-quoted identifiers.

- Tags: api-reference
- Published: 2026-07-26

### [How Apache Ossie Supports Composite Primary Keys with Multiple Columns](/apache/ossie/ossie-composite-primary-keys-multiple-columns)

Apache Ossie supports composite primary keys using ordered arrays of column names. Learn how Ossie preserves order across relationships and conversions for multi-column keys.

- Tags: how-to-guide
- Published: 2026-07-26

### [How to Contribute New Features or Changes to the Apache Ossie Specification](/apache/ossie/contribute-ossie-specification-features)

Contribute to the Apache Ossie specification by proposing changes on the dev mailing list, submitting a pull request, and getting PPMC approval. Learn the merge process.

- Tags: how-to-guide
- Published: 2026-07-26

### [How to Extend Ossie with New Vendor-Specific Attributes and Extensions](/apache/ossie/ossie-extend-vendor-attributes-extensions)

Extend Ossie's vendor-agnostic core model with proprietary metadata using JSON. Learn how to implement custom extensions and converters for seamless data management.

- Tags: how-to-guide
- Published: 2026-07-26

### [How Ossie Converters Handle Dialect-Specific Transformations: GoodData, Salesforce, and dbt](/apache/ossie/ossie-converters-dialect-specific-transformations)

Explore how Ossie converters like GoodData, Salesforce, and dbt manage dialect-specific transformations, translating SQL dialects for target platforms and ensuring data compatibility.

- Tags: deep-dive
- Published: 2026-07-26

### [How Field Expressions and Calculated Fields Work in the Ossie Expression Language](/apache/ossie/ossie-expression-language-field-calculated-fields)

Understand how Ossie expression language uses field expressions and calculated fields. Learn about SQL fragments, regex patterns, arithmetic operators, and aggregate functions.

- Tags: how-to-guide
- Published: 2026-07-26

### [Best Practices for Organizing Multiple Datasets in an Apache Ossie Semantic Model](/apache/ossie/ossie-organize-multiple-datasets-best-practices)

Organize multiple datasets in Apache Ossie semantic models using best practices. Store data, distinguish types, and validate with JSON schema for a lossless Salesforce roundtrip.

- Tags: best-practices
- Published: 2026-07-26

### [How to Validate Ossie Semantic Models: Tools and Methods Explained](/apache/ossie/ossie-validation-tools-directory)

Discover tools and methods to validate Ossie semantic models. Learn about the Python validator in the Apache Ossie repository for comprehensive checks and specification conformance.

- Tags: how-to-guide
- Published: 2026-07-26

### [Apache Ossie Ontology Specification and Core Logical Layer: Architecture Explained](/apache/ossie/ossie-ontology-vs-logical-layer-relationship)

Explore the Apache Ossie ontology specification and core logical layer architecture. Understand how these layers define business concepts and analytical datasets, linked by ontology mappings.

- Tags: architecture
- Published: 2026-07-26

### [Ossie dbt MSI Conversion Issues: Handling Lossy Transformations Between Formats](/apache/ossie/ossie-dbt-msi-conversion-issues)

Discover Ossie dbt MSI conversion issues. Learn how lossy transformations between formats can impact semantic granularity and explore solutions for accurate data mapping.

- Tags: deep-dive
- Published: 2026-07-26

### [How to Define Metrics with Aggregate Expressions in the Ossie Specification](/apache/ossie/ossie-define-metrics-aggregate-expressions)

Learn how to define metrics using aggregate expressions like SUM and COUNT in the Apache Ossie specification. Master quantitative business calculations across datasets.

- Tags: tutorial
- Published: 2026-07-26

### [How `primary_key` and `unique_keys` Enforce Data Integrity in Apache Ossie Datasets](/apache/ossie/ossie-primary-unique-keys-data-integrity)

Learn how primary_key and unique_keys in Apache Ossie datasets ensure data integrity by enforcing row-level uniqueness across converters, guaranteeing clean data in downstream systems.

- Tags: how-to-guide
- Published: 2026-07-26

### [Complete YAML Structure for an Apache Ossie Semantic Model: Schema, Fields, and Examples](/apache/ossie/ossie-semantic-model-yaml-structure)

Discover the complete YAML structure for Apache Ossie semantic models. Learn about schema, fields, and examples for datasets, relationships, and more to enable cross-platform analytics.

- Tags: schema-reference
- Published: 2026-07-26

### [How the `ai_context` Field Functions for AI Tools Consuming Apache OSSIE Models](/apache/ossie/ossie-ai-context-field-usage)

Discover how the ai_context field in Apache OSSIE models provides AI-specific metadata for LLM converters. Gain fine-grained control over AI behavior without changing converter logic.

- Tags: how-to-guide
- Published: 2026-07-26

### [What Are Custom Extensions in OSSIE? A Complete Guide to Vendor-Specific Attributes](/apache/ossie/ossie-custom-extensions-vendor-attributes)

Understand custom extensions in OSSIE. Learn how this vendor-agnostic mechanism preserves proprietary metadata for lossless round-tripping of vendor specific attributes.

- Tags: how-to-guide
- Published: 2026-07-26

### [How Ossie Defines and Resolves Relationships Between Logical Datasets in a Semantic Model](/apache/ossie/ossie-define-resolve-dataset-relationships)

Learn how Ossie defines and resolves relationships between logical datasets. Explore structured maps, bidirectional resolution, and validation for semantic models.

- Tags: deep-dive
- Published: 2026-07-26

### [Data Types Supported in the Ossie Specification: Complete Vendor Mapping Guide](/apache/ossie/ossie-supported-data-types-vendor-mapping)

Explore Ossie specification's 10 data types like String, Integer, Decimal, and Date. Discover their automatic mapping to vendor-specific types like Snowflake VARCHAR and Iceberg timestamps.

- Tags: api-reference
- Published: 2026-07-26

### [How to Convert dbt MetricFlow Semantic Interface (MSI) Models to Ossie YAML Using the CLI](/apache/ossie/convert-dbt-msi-to-ossie-yaml-cli)

Convert dbt MetricFlow Semantic Interface MSI models to Ossie YAML using the ossie convert dbt-metric-flow CLI command for streamlined data modeling.

- Tags: how-to-guide
- Published: 2026-07-26

### [Ontological Layer vs Logical Layer in Apache Ossie: Architecture Distinctions](/apache/ossie/ossie-ontological-vs-logical-layer)

Understand Apache Ossie's ontological vs logical layer distinctions. Discover how the ontological layer maps business concepts and the logical layer prepares data for analysis.

- Tags: architecture
- Published: 2026-07-26

### [How Apache Ossie Ensures Expression Language Portability Across Snowflake, BigQuery, and Databricks](/apache/ossie/ossie-expression-language-portability-sql-dialects)

Apache Ossie makes SQL portable across Snowflake, BigQuery, and Databricks. It validates expressions using sqlglot parsers, ensuring seamless cross-platform compatibility for your data analysis.

- Tags: deep-dive
- Published: 2026-07-26

### [Where to Find Ossie Semantic Models Examples in the Apache OSSIE Repository](/apache/ossie/where-can-i-find-examples-of-ossie-semantic-models)

Discover Ossie semantic models examples in the Apache OSSIE repository examples directory. Explore TPC-DS and flights datasets to understand OSSIE Core Metadata Specification.

- Tags: getting-started
- Published: 2026-07-24

### [Apache Ossie SQL Dialects: Complete Guide to Expression Language Support](/apache/ossie/which-sql-dialects-are-supported-by-ossie)

Explore Apache Ossie's support for seven SQL dialects including Snowflake BigQuery Databricks MDX Tableau and Maql. Define platform specific expressions with automatic ANSI SQL fallback.

- Tags: deep-dive
- Published: 2026-07-24

### [How Ossie Handles Multiple SQL Dialects: Native Multi-Database Expression Support](/apache/ossie/how-does-ossie-handle-expressions-with-multiple-sql-dialects)

Discover how Apache Ossie supports multiple SQL dialects by storing logical expressions as dialect-specific SQL renderings. It automatically selects variants and falls back to ANSI SQL when necessary.

- Tags: deep-dive
- Published: 2026-07-24

### [How Fields Are Represented in Apache Ossie: A Complete Guide to the Data Model](/apache/ossie/how-are-fields-represented-in-ossie)

Learn how Apache Ossie represents fields using a hierarchical class system. Discover the base Field class and concrete types like StringField and IntegerField for robust data modeling.

- Tags: how-to-guide
- Published: 2026-07-24

### [How to Define Relationships Between Datasets in Apache OSSIE](/apache/ossie/how-are-relationships-defined-between-datasets-in-ossie)

Learn how Apache OSSIE defines dataset relationships using Relationship objects in the semantic model. Discover how join columns and parsing ensure seamless data integration with platforms like Salesforce.

- Tags: how-to-guide
- Published: 2026-07-24

### [How Apache Ossie Solves Semantic Fragmentation: Hub-and-Spoke Architecture Explained](/apache/ossie/how-does-apache-ossie-solve-semantic-fragmentation)

Apache Ossie solves semantic fragmentation with its vendor-agnostic hub-and-spoke architecture. Get a single definition for models and metrics, avoiding complex integrations.

- Tags: architecture
- Published: 2026-07-24

### [Apache OSSIE Performance Considerations: 6 Optimization Strategies for Semantic Models](/apache/ossie/what-are-the-performance-considerations-for-apache-ossie)

Optimize Apache OSSIE semantic models with 6 performance strategies. Learn how to boost performance with scalar-only expressions, approximate aggregations, and declarative converters.

- Tags: performance
- Published: 2026-07-23

### [What Is the Release Cycle of Apache OSSIE? Two-Stage Voting Explained](/apache/ossie/what-is-the-release-cycle-of-apache-ossie)

Understand the Apache OSSIE release cycle. Discover the two-stage voting process involving PMC and Incubator PMC approvals for every release.

- Tags: internals
- Published: 2026-07-23

### [Where to Find Example Ossie Semantic Models in Apache Ossie](/apache/ossie/ossie-example-semantic-models-location)

Discover example Ossie semantic models in the Apache Ossie repository's examples directory. Explore TPC-DS retail and minimal Flights models for your projects.

- Tags: how-to-guide
- Published: 2026-07-19

### [How to Translate Between Ossie and Other Semantic Model Formats (OBML, Snowflake, GoodData, DBT)](/apache/ossie/ossie-format-translation)

Easily translate between Ossie and other semantic model formats like OBML, Snowflake, GoodData, and DBT. Use bidirectional converters with CLI commands and Python APIs for lossless conversions.

- Tags: how-to-guide
- Published: 2026-07-19

### [How to Configure AI Synonyms for Ossie Fields: A Complete Guide](/apache/ossie/ossie-field-ai-synonyms-configuration)

Configure AI synonyms for Ossie fields using the ai_context attribute with a synonyms array in the OSIField model. Enhance AI tool references with this guide.

- Tags: how-to-guide
- Published: 2026-07-19

### [Structure for Defining Fields in Apache Ossie: The OSIField Model Guide](/apache/ossie/ossie-field-definition-structure)

Learn the OSIField model structure for defining fields in Apache Ossie. Discover name, expression, time dimensions, AI context, labels, and extensions.

- Tags: guide
- Published: 2026-07-19

### [How to Define a Metric with Multi-Dialect SQL Expressions in Apache Ossie](/apache/ossie/ossie-define-metric-multi-dialect-sql)

Learn how to define metrics with multi-dialect SQL expressions in Apache Ossie. Achieve cross-platform portability and graceful fallback for BI tools and AI engines.

- Tags: how-to-guide
- Published: 2026-07-19

### [How to Define Relationships Between Datasets in Ossie: YAML and Java Guide](/apache/ossie/ossie-define-dataset-relationships)

Learn how to define relationships between datasets in Ossie using YAML or Java. Declare relationships in the semantic model or construct them via the OsiModel API for seamless data integration.

- Tags: how-to-guide
- Published: 2026-07-19

### [How Custom Extensions Work in Ossie Datasets: Bidirectional Conversion Guide](/apache/ossie/ossie-dataset-custom-extensions-usage)

Learn how custom extensions work in Ossie datasets. Easily store vendor-specific fields and leverage bidirectional conversion for seamless data management.

- Tags: how-to-guide
- Published: 2026-07-19

### [Understanding Primary and Unique Keys in Ossie Datasets: A Complete Guide](/apache/ossie/ossie-dataset-primary-unique-keys)

Learn about primary and unique keys in Ossie datasets. Discover how Ossie uses column arrays to define main row identifiers and enforce additional uniqueness constraints.

- Tags: how-to-guide
- Published: 2026-07-19

### [Ossie Dataset Definition Structure: Complete Guide to Schema Modeling](/apache/ossie/ossie-dataset-definition-structure)

Understand the Ossie dataset definition structure. Learn about schema modeling with name, source, primaryKey, uniqueKeys, description, fields, and customExtensions defined in OsiModel.

- Tags: deep-dive
- Published: 2026-07-19

### [Ossie Semantic Model: Key Properties and Implementation Guide](/apache/ossie/ossie-semantic-model-key-properties)

Explore the Ossie semantic model with its five key properties name description datasets relationships and metrics Understand how Ossie models translate business data for analytics platforms.

- Tags: how-to-guide
- Published: 2026-07-19

### [Which SQL Dialects Does Apache Ossie Support? Complete Guide](/apache/ossie/ossie-supported-sql-dialects)

Apache Ossie supports seven SQL dialects including Snowflake MDX Tableau Databricks Maql and BigQuery. Define platform specific expressions with ANSI SQL fallback.

- Tags: complete-guide
- Published: 2026-07-19

### [How to Validate Ossie Semantic Models: The Complete Python Validation Toolkit](/apache/ossie/ossie-semantic-model-validation-tools)

Explore the Python validation toolkit for Ossie semantic models. Validate schema compliance, uniqueness, referential integrity, and SQL syntax efficiently.

- Tags: how-to-guide
- Published: 2026-07-19

### [How Python Pydantic Models Work in Apache Ossie: Schema Validation and Serialization](/apache/ossie/ossie-python-pydantic-models-usage)

Discover how Python Pydantic models integrate with Apache Ossie for robust schema validation and seamless serialization. Convert YAML/JSON to type-safe Python objects efficiently.

- Tags: how-to-guide
- Published: 2026-07-19

### [Where to Find Reference Implementations for Ossie Converters in Apache Ossie](/apache/ossie/ossie-converters-reference-implementation-location)

Find Ossie converters reference implementations in the converters/ directory of the Apache Ossie repository. Explore vendor subfolders for translation logic between OSI and vendor formats.

- Tags: reference-implementation
- Published: 2026-07-19

### [Machine-Readable Schemas for Ossie Validation: JSON Schema Reference](/apache/ossie/ossie-validation-schemas)

Discover machine-readable schemas for Ossie validation. Ossie enforces data compliance using JSON Schema definitions and the SchemaValidator class. Learn more.

- Tags: api-reference
- Published: 2026-07-19

### [Where to Find the Core Specification Document for Apache Ossie](/apache/ossie/ossie-core-specification-document-location)

Locate the core specification document for Apache Ossie within the 'core-spec/' directory. Find the human-readable spec.md and machine-readable spec.yaml for clear definitions.

- Tags: api-reference
- Published: 2026-07-19

### [Layers of Apache Ossie Architecture: The Semantic Stack Explained](/apache/ossie/apache-ossie-architecture-layers)

Explore the five semantic layers of Apache Ossie architecture: Semantic Hub Ontology Logical Physical and Mapping. Understand how Ossie separates business meaning from physical storage.

- Tags: architecture
- Published: 2026-07-19

### [What is Apache Ossie and How It Solves Semantic Fragmentation in Modern Data Stacks](/apache/ossie/what-is-apache-ossie-problem-solved)

Explore Apache Ossie, an open source solution unifying KPI definitions across BI, AI, and analytics platforms. Solve semantic fragmentation and eliminate vendor lock-in.

- Tags: deep-dive
- Published: 2026-07-19

### [Cross-Dialect Compatibility for Expressions in Apache Ossie: A Complete Guide](/apache/ossie/cross-dialect-compatibility-for-expressions-in-ossie)

Master cross-dialect expression compatibility in Apache Ossie. Learn how Ossie's portable expression language automatically adapts to your target database, defaulting to ANSI SQL for seamless integration.

- Tags: how-to-guide
- Published: 2026-07-17

### [How to Handle Column-Level Lineage for Metrics in Ossie](/apache/ossie/how-to-handle-column-level-lineage-for-metrics-in-ossie)

Learn how Ossie handles column-level lineage for metrics by parsing SQL expressions and mapping columns to their originating field definitions in the semantic model.

- Tags: how-to-guide
- Published: 2026-07-17