Authoring Java SDK Tasks

The Airflow Java SDK implements the language-SDK model for the JVM: your DAG stays in Python, and each task instance runs in a short-lived JVM subprocess. This skill covers the Java-specific native API. The shared model — the Python @task.stub pattern, ID matching, and the XCom-as-JSON contract — lives in authoring-language-sdk-tasks; read that first if you're new to language SDKs.

Experimental. The Java SDK is in preview. Artifact coordinates and APIs may change.

Related skills: authoring-language-sdk-tasks (shared Python stub + concepts), configuring-airflow-language-sdks (route the queue to JavaCoordinator), deploying-java-sdk-bundles (compile and ship the JAR).

Recap: the Python side

Java tasks are paired with Python stubs that carry no logic — they declare the task, queue, dependency graph, and retries. IDs must match the Java annotations exactly, and an upstream argument on a stub only declares the dependency (the value is fetched in Java). Full rules are in authoring-language-sdk-tasks; the minimal shape:

from airflow.sdk import dag, task