Sessions (Google Cloud Dataflow SDK 1.9.1 API)

Google Cloud Dataflow SDK for Java, version 1.9.1

Warning: Dataflow SDK 1.x for Java is unsupported as of October 16, 2018. After August 12, 2020, Dataflow will not run jobs using Dataflow 1.x and below. See Migrating from Dataflow SDK 1.x for Java for migration guidance.

Note: If you are using Cloud Dataflow SDK version 2.x, see the Apache Beam API reference documentation.

com.google.cloud.dataflow.sdk.transforms.windowing

Class Sessions

• java.lang.Object
• • com.google.cloud.dataflow.sdk.transforms.windowing.WindowFn<Object,IntervalWindow>
  • • com.google.cloud.dataflow.sdk.transforms.windowing.Sessions

• All Implemented Interfaces:

  HasDisplayData, Serializable

  ---

  
  

  public class Sessions
  extends WindowFn<Object,IntervalWindow>

  A WindowFn windowing values into sessions separated by gapDuration-long periods with no elements.

  For example, in order to window data into session with at least 10 minute gaps in between them:

   
   PCollection<Integer> pc = ...;
   PCollection<Integer> windowed_pc = pc.apply(
     Window.<Integer>into(Sessions.withGapDuration(Duration.standardMinutes(10))));
    

  See Also:

  Serialized Form

• • Nested Class Summary

    • Nested classes/interfaces inherited from class com.google.cloud.dataflow.sdk.transforms.windowing.WindowFn

      WindowFn.AssignContext, WindowFn.MergeContext

  • Method Summary

    All Methods Static Methods Instance Methods Concrete Methods 

    Modifier and Type	Method and Description
    Collection<IntervalWindow>	assignWindows(WindowFn.AssignContext c) Given a timestamp and element, returns the set of windows into which it should be placed.
    boolean	equals(Object object)
    Duration	getGapDuration()
    OutputTimeFn<? super IntervalWindow>	getOutputTimeFn() Provides a default implementation for WindowingStrategy.getOutputTimeFn().
    IntervalWindow	getSideInputWindow(BoundedWindow window) Returns the window of the side input corresponding to the given window of the main input.
    int	hashCode()
    boolean	isCompatible(WindowFn<?,?> other) Returns whether this performs the same merging as the given WindowFn.
    void	mergeWindows(WindowFn.MergeContext c) Does whatever merging of windows is necessary.
    void	populateDisplayData(DisplayData.Builder builder) Register display data for the given transform or component.
    Coder<IntervalWindow>	windowCoder() Returns the Coder used for serializing the windows used by this windowFn.
    static Sessions	withGapDuration(Duration gapDuration) Creates a Sessions WindowFn with the specified gap duration.

    • Methods inherited from class com.google.cloud.dataflow.sdk.transforms.windowing.WindowFn

      assignsToSingleWindow, getOutputTime, isNonMerging

    • Methods inherited from class java.lang.Object

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

• • Method Detail

    • withGapDuration

      public static Sessions withGapDuration(Duration gapDuration)

      Creates a Sessions WindowFn with the specified gap duration.

    • assignWindows

      public Collection<IntervalWindow> assignWindows(WindowFn.AssignContext c)

      Description copied from class: WindowFn
      Given a timestamp and element, returns the set of windows into which it should be placed.

      Specified by:

      assignWindows in class WindowFn<Object,IntervalWindow>

    • mergeWindows

      public void mergeWindows(WindowFn.MergeContext c)
                        throws Exception

      Description copied from class: WindowFn
      Does whatever merging of windows is necessary.

      See MergeOverlappingIntervalWindows.mergeWindows(com.google.cloud.dataflow.sdk.transforms.windowing.WindowFn<?, com.google.cloud.dataflow.sdk.transforms.windowing.IntervalWindow>.MergeContext) for an example of how to override this method.

      Specified by:

      mergeWindows in class WindowFn<Object,IntervalWindow>

      Throws:

      Exception

    • windowCoder

      public Coder<IntervalWindow> windowCoder()

      Description copied from class: WindowFn
      Returns the Coder used for serializing the windows used by this windowFn.

      Specified by:

      windowCoder in class WindowFn<Object,IntervalWindow>

    • isCompatible

      public boolean isCompatible(WindowFn<?,?> other)

      Description copied from class: WindowFn
      Returns whether this performs the same merging as the given WindowFn.

      Specified by:

      isCompatible in class WindowFn<Object,IntervalWindow>

    • getSideInputWindow

      public IntervalWindow getSideInputWindow(BoundedWindow window)

      Description copied from class: WindowFn
      Returns the window of the side input corresponding to the given window of the main input.

      Authors of custom WindowFns should override this.

      Specified by:

      getSideInputWindow in class WindowFn<Object,IntervalWindow>

    • getOutputTimeFn

      @Experimental(value=OUTPUT_TIME)
      public OutputTimeFn<? super IntervalWindow> getOutputTimeFn()

      Description copied from class: WindowFn
      Provides a default implementation for WindowingStrategy.getOutputTimeFn(). See the full specification there.

      If this WindowFn doesn't produce overlapping windows, this need not (and probably should not) override any of the default implementations in OutputTimeFn.Defaults.

      If this WindowFn does produce overlapping windows that can be predicted here, it is suggested that the result in later overlapping windows is past the end of earlier windows so that the later windows don't prevent the watermark from progressing past the end of the earlier window.

      For example, a timestamp in a sliding window should be moved past the beginning of the next sliding window. See SlidingWindows.getOutputTimeFn().

      Overrides:

      getOutputTimeFn in class WindowFn<Object,IntervalWindow>

    • getGapDuration

      public Duration getGapDuration()

    • populateDisplayData

      public void populateDisplayData(DisplayData.Builder builder)

      Description copied from class: WindowFn
      Register display data for the given transform or component.

      populateDisplayData(DisplayData.Builder) is invoked by Pipeline runners to collect display data via DisplayData.from(HasDisplayData). Implementations may call super.populateDisplayData(builder) in order to register display data in the current namespace, but should otherwise use subcomponent.populateDisplayData(builder) to use the namespace of the subcomponent.

      By default, does not register any display data. Implementors may override this method to provide their own display data.

      Specified by:

      populateDisplayData in interface HasDisplayData

      Overrides:

      populateDisplayData in class WindowFn<Object,IntervalWindow>

      Parameters:

      builder - The builder to populate with display data.

      See Also:

      HasDisplayData

    • equals

      public boolean equals(Object object)

      Overrides:

      equals in class Object

    • hashCode

      public int hashCode()

      Overrides:

      hashCode in class Object