Apache Spark vs Kafka Streams

Apache Spark is a free, open-source engine for large-scale data analytics. It processes batches and real-time streams using Python, SQL, Scala, Java, or R. Spark SQL runs distributed ANSI SQL queries on structured tables and unstructured data such as JSON or images; MLlib provides machine-learning algorithms for local use or cluster scale. The project also describes exploratory analysis on petabyte-scale data without downsampling. Listed ecosystem components include pandas, TensorFlow, PyTorch, scikit-learn, Apache Kafka, Kubernetes, Delta Lake, and Apache Iceberg. Deployment options include standalone, Hadoop YARN, and Kubernetes. Spark runs on Windows and UNIX-like systems, including Linux and macOS, when a supported Java version is available. The 4.2.0 documentation lists Java 17, 21, or 25, Scala 2.13, Python 3.10+, and R 4.0+ (deprecated). Spark Connect separates client applications from clusters for remote access. Security is not enabled by default; Spark supports TLS for RPC connections and encryption of temporary local-disk data. The project is licensed under Apache License, Version 2.0.

Kafka Streams is a free client library for building applications and microservices that use data stored in Kafka clusters. It processes Kafka data with event-time handling, windowing, and real-time queries of application state. The Streams DSL provides operations such as mapping, filtering, joins, and aggregations, while the Processor API supports custom processors and state stores. Fault-tolerant local state supports stateful work such as windowed joins and aggregations, and the library offers exactly-once processing semantics. Applications can run on one machine or scale across multiple machines, and can be deployed in containers, virtual machines, on bare metal, or in cloud environments. Kafka Streams uses Kafka as its internal messaging layer and does not require a separate processing cluster. It supports Java and Scala and integrates with Kafka security features for encryption in transit, client authentication, and authorization. The software is licensed under Apache License 2.0. The Apache Software Foundation says it does not sell its software or provide formal or commercial support for its packages; project communication is available through community mailing lists.