org.apache.beam.sdk.transforms

Class DoFn.WindowedContext

java.lang.Object

org.apache.beam.sdk.transforms.DoFn.WindowedContext

Direct Known Subclasses:

DoFn.OnTimerContext, DoFn.OnWindowExpirationContext, DoFn.ProcessContext

Enclosing class:

DoFn<InputT,OutputT>

public abstract class DoFn.WindowedContext
extends java.lang.Object

Information accessible to all methods in this DoFn where the context is in some window.

Constructor Summary

Constructors

Constructor and Description
WindowedContext()

Method Summary

Modifier and Type	Method and Description
abstract PipelineOptions	getPipelineOptions() Returns the PipelineOptions specified with the PipelineRunner invoking this DoFn.
abstract void	output(OutputT output) Adds the given element to the main output PCollection.
abstract <T> void	output(TupleTag<T> tag, T output) Adds the given element to the output PCollection with the given tag.
abstract void	outputWithTimestamp(OutputT output, Instant timestamp) Adds the given element to the main output PCollection, with the given timestamp.
abstract <T> void	outputWithTimestamp(TupleTag<T> tag, T output, Instant timestamp) Adds the given element to the specified output PCollection, with the given timestamp.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

WindowedContext

public WindowedContext()

Method Detail

getPipelineOptions

@Pure
public abstract PipelineOptions getPipelineOptions()

Returns the PipelineOptions specified with the PipelineRunner invoking this DoFn.

output

public abstract void output(OutputT output)

Adds the given element to the main output PCollection.

Once passed to output the element should not be modified in any way.

If invoked from DoFn.ProcessElement, the output element will have the same timestamp and be in the same windows as the input element passed to the method annotated with @ProcessElement.

If invoked from DoFn.StartBundle or DoFn.FinishBundle, this will attempt to use the WindowFn of the input PCollection to determine what windows the element should be in, throwing an exception if the WindowFn attempts to access any information about the input element. The output element will have a timestamp of negative infinity.

Note: A splittable DoFn is not allowed to output from DoFn.StartBundle or DoFn.FinishBundle methods.

outputWithTimestamp

public abstract void outputWithTimestamp(OutputT output,
                                         Instant timestamp)

Adds the given element to the main output PCollection, with the given timestamp.

Once passed to outputWithTimestamp the element should not be modified in any way.

If invoked from DoFn.ProcessElement), the timestamp must not be older than the input element's timestamp minus DoFn.getAllowedTimestampSkew(). The output element will be in the same windows as the input element.

If invoked from DoFn.StartBundle or DoFn.FinishBundle, this will attempt to use the WindowFn of the input PCollection to determine what windows the element should be in, throwing an exception if the WindowFn attempts to access any information about the input element except for the timestamp.

Note: A splittable DoFn is not allowed to output from DoFn.StartBundle or DoFn.FinishBundle methods.

output

public abstract <T> void output(TupleTag<T> tag,
                                T output)

Adds the given element to the output PCollection with the given tag.

Once passed to output the element should not be modified in any way.

The caller of ParDo uses ParDo.SingleOutput.withOutputTags(org.apache.beam.sdk.values.TupleTag<OutputT>, org.apache.beam.sdk.values.TupleTagList) to specify the tags of outputs that it consumes. Non-consumed outputs, e.g., outputs for monitoring purposes only, don't necessarily need to be specified.

The output element will have the same timestamp and be in the same windows as the input element passed to DoFn.ProcessElement).

If invoked from DoFn.StartBundle or DoFn.FinishBundle, this will attempt to use the WindowFn of the input PCollection to determine what windows the element should be in, throwing an exception if the WindowFn attempts to access any information about the input element. The output element will have a timestamp of negative infinity.

Note: A splittable DoFn is not allowed to output from DoFn.StartBundle or DoFn.FinishBundle methods.

See Also:

ParDo.SingleOutput.withOutputTags(org.apache.beam.sdk.values.TupleTag<OutputT>, org.apache.beam.sdk.values.TupleTagList)

outputWithTimestamp

public abstract <T> void outputWithTimestamp(TupleTag<T> tag,
                                             T output,
                                             Instant timestamp)

Adds the given element to the specified output PCollection, with the given timestamp.

Once passed to outputWithTimestamp the element should not be modified in any way.

If invoked from DoFn.ProcessElement), the timestamp must not be older than the input element's timestamp minus DoFn.getAllowedTimestampSkew(). The output element will be in the same windows as the input element.

If invoked from DoFn.StartBundle or DoFn.FinishBundle, this will attempt to use the WindowFn of the input PCollection to determine what windows the element should be in, throwing an exception if the WindowFn attempts to access any information about the input element except for the timestamp.

Note: A splittable DoFn is not allowed to output from DoFn.StartBundle or DoFn.FinishBundle methods.

See Also:

ParDo.SingleOutput.withOutputTags(org.apache.beam.sdk.values.TupleTag<OutputT>, org.apache.beam.sdk.values.TupleTagList)