Register and query an Iceberg table through the Unity Catalog OSS REST API

Steps

1. Start the Unity Catalog OSS server (base URL defaults to http://localhost:8080); the server exposes its REST API at /api/2.1/unity-catalog — no authentication is required in the default OSS configuration but production deployments should add an auth layer
2. Create a catalog via POST /api/2.1/unity-catalog/catalogs with body {"name": "my_catalog", "comment": "..."}; then create a schema within it via POST /api/2.1/unity-catalog/schemas with {"catalog_name": "my_catalog", "name": "my_schema"}
3. Register a table via POST /api/2.1/unity-catalog/tables with a payload specifying catalog_name, schema_name, name, table_type (EXTERNAL), data_source_format (DELTA or PARQUET), columns array, and storage_location pointing to the file path
4. List tables in a schema via GET /api/2.1/unity-catalog/tables?catalog_name=my_catalog&schema_name=my_schema; retrieve a specific table's metadata via GET /api/2.1/unity-catalog/tables/{full_name} where full_name is catalog.schema.table
5. Connect a query engine that supports Unity Catalog (e.g., Apache Spark with the unitycatalog-spark connector) by pointing its catalog configuration to the UC OSS REST endpoint; engines read table metadata from UC and access data files at the storage_location