How to Build a UDF and/or UDAF in ksqlDB 5.0 | Confluent

This post introduces the official API for creating User-Defined Functions (UDFs) and User-Defined Aggregate Functions (UDAFs) in ksqlDB 5.0. It details the motivation for UDFs/UDAFs, the process of writing a Java class with specific annotations (@UdfDescription, @Udf), and the deployment steps involving building an uber JAR and placing it in the ksqlDB extension directory. An advanced example of a deep-learning UDF for anomaly detection is provided, showcasing how to embed external dependencies. Potential development and testing issues are also discussed.