DoFn Additional Parameters

In addition to the element and the OutputReceiver, Beam will populate other parameters to your DoFn’s @ProcessElement method. Any combination of these parameters can be added to your process method in any order.

• Timestamp: To access the timestamp of an input element, add a parameter annotated with @Timestamp of type Instant
• Window: To access the window an input element falls into, add a parameter of the type of the window used for the input PCollection.
• PaneInfo: When triggers are used, Beam provides a PaneInfo object that contains information about the current firing. Using PaneInfo you can determine whether this is an early or a late firing, and how many times this window has already fired for this key.
• PipelineOptions: The PipelineOptions for the current pipeline can always be accessed in a process method by adding it as a parameter.

Refer to the Beam Programming Guide “Accessing additional parameters in your DoFn” section for more information.