Google Cloud Dataflow SDK for Java
Google Cloud Dataflow provides a simple, powerful programming model for building both batch and streaming parallel data processing pipelines. This repository hosts the open-sourced Cloud Dataflow SDK for Java, which can be used to run pipelines against the Google Cloud Dataflow Service.
General usage of Google Cloud Dataflow does not require use of this repository. Instead:
<dependency> <groupId>com.google.cloud.dataflow</groupId> <artifactId>google-cloud-dataflow-java-sdk-all</artifactId> <version>version_number</version> </dependency>
download the example pipelines from the separate DataflowJavaSDK-examples repository.
However, if you'd like to contribute to the SDK, write your own PipelineRunner, or just dig in for the fun of it, please stay with us here!
Both the SDK and the Dataflow Service are generally available, open to all developers, and considered stable and fully qualified for production use.
The key concepts in this programming model are:
PCollection: represents a collection of data, which could be bounded or unbounded in size.
PTransform: represents a computation that transforms input PCollections into output PCollections.
Pipeline: manages a directed acyclic graph of PTransforms and PCollections that is ready for execution.
PipelineRunner: specifies where and how the pipeline should execute.
We provide three PipelineRunners:
DirectPipelineRunnerruns the pipeline on your local machine.
DataflowPipelineRunnersubmits the pipeline to the Dataflow Service, where it runs using managed resources in the Google Cloud Platform (GCP).
BlockingDataflowPipelineRunnersubmits the pipeline to the Dataflow Service via the
DataflowPipelineRunnerand then prints messages about the job status until the execution is complete.
The SDK is built to be extensible and support additional execution environments
beyond local execution and the Google Cloud Dataflow Service. In partnership
with Cloudera, you can run Dataflow pipelines on
an Apache Spark backend using the
Additionally, you can run Dataflow pipelines on an
Apache Flink backend using the
This repository consists of the following parts:
sdkmodule provides a set of basic Java APIs to program against.
examplesmodule provides a few samples to get started. We recommend starting with the
contribdirectory hosts community-contributed Dataflow modules.
The following command will build both the
example modules and
install them in your local Maven repository:
mvn clean install
You can speed up the build and install process by using the following options:
To skip execution of the unit tests, run:
mvn install -DskipTests
While iterating on a specific module, use the following command to compile and reinstall it. For example, to reinstall the
mvn install -pl examples
Be careful, however, as this command will use the most recently installed SDK from the local repository (or Maven Central) even if you have changed it locally.
After building and installing, you can execute the
WordCount and other
example pipelines by following the instructions in this
We welcome all usage-related questions on Stack Overflow
Please use issue tracker on GitHub to report any bugs, comments or questions regarding SDK development.