Apache Polaris is a production-grade, multi-tenant Iceberg REST catalog server built on Quarkus. It provides a REST API for catalog management (namespaces, tables, views), credential vending for cloud storage (S3, GCS, Azure), fine-grained authorization via built-in RBAC or external OPA/Ranger, and event publishing (Kafka, CloudWatch). The system supports two persistence backends: a legacy relational JDBC (PostgreSQL, H2) and a new NoSQL abstraction with custom indexing, caching, and distributed invalidation. Multi-tenancy is implemented via isolated realms, each with its own configuration and persisted state. Key entry points are the Quarkus server (`polaris-server`), a CLI admin tool, and a Python client. External dependencies include Iceberg libraries, Quarkus, Jackson, Testcontainers, and optional integrations like Open Policy Agent, Apache Ranger, and Kafka. The architecture is modular with clear SPI boundaries, making extensions (persistence, auth, federation) pluggable.
Apache Iceberg is a high-performance table format for analytic data lakes, providing ACID transactions, snapshot isolation, schema evolution, and time travel. The repository contains the Java reference implementation, including core libraries for table metadata management, file format support (Parquet, ORC, Avro, Arrow), expression evaluation, encryption, and a REST catalog protocol. It integrates deeply with Spark (versions 3.5, 4.0, 4.1, 4.2), Flink (1.20, 2.2, 2.3), Kafka Connect, Hive, and cloud object stores (AWS S3, Azure ADLS, Aliyun OSS, GCS). The architecture is modular: the `api` module defines public interfaces (Table, Catalog, Scan, FileIO), `core` provides implementations and utilities, and separate modules handle engine-specific integrations and cloud backends. Key entry points include the Table interface for DDL/DML operations, Scan for query planning, FileIO for storage access, and the REST catalog client for remote metadata management. Data flows involve reading/writing manifest files, applying expressions for predicate pushdown, and coordinating commits via optimistic concurrency control. External dependencies include Apache Parquet, ORC, Avro, Arrow, and various cloud SDKs, but the core is designed to be lightweight and extensible.
Elyra is a JupyterLab extension suite that provides a visual pipeline editor for building, validating, and executing multi-step AI/ML workflows on Kubeflow Pipelines, Apache Airflow, or locally. It includes enhanced script editors (Python, R, Scala) with kernel management and debugging, a code snippet manager, and a metadata-driven system for runtime configurations, runtime images, and component catalogs. The backend (Python) handles pipeline parsing, validation, code generation via Jinja2 templates, and submission to remote orchestrators, while the frontend (TypeScript/React) delivers a rich UI with drag-and-drop, property editing, and real-time validation. The architecture is modular with pluggable runtime processors, component catalog connectors, and metadata storage backends, making it extensible for custom runtimes and data sources. Although primarily an application, it serves the MLOps domain by orchestrating data science notebooks and scripts as reproducible pipelines.
Masader is a metadata catalog for Arabic NLP datasets, providing structured information about over 100 datasets including their tasks, dialects, sources, volumes, and licensing. The repository combines a Jekyll-based static site with a modular JavaScript frontend to enable dataset discovery through search, filtering, statistics visualization, and a natural language chatbot interface. While the core asset is the dataset metadata (JSON files in /datasets/), the web interface and associated tools (annotation, migration, validation scripts) form an application layer that makes the catalog usable and maintainable. The system supports dataset exploration via faceted search, demographic charts, and embedding-based clustering, with a chatbot for conversational queries. Metadata is kept up-to-date through migration scripts that handle schema evolution and validation checks that ensure consistency with external sources like venue links and volume totals.