What Dataflow concept determines when a Window’s contents should be output based on certain criteria being met?

What Dataflow concept determines when a Window’s contents should be output based on certain criteria being met?
A . Sessions
B . OutputCriteria
C . Windows
D . Triggers

View Answer

Answer: D

Explanation:

Triggers control when the elements for a specific key and window are output. As elements arrive, they are put into one or more windows by a Window transform and its associated WindowFn, and then passed to the associated Trigger to determine if the Windows contents should be output.

Reference: https://cloud.google.com/dataflow/java-sdk/JavaDoc/com/google/cloud/dataflow/sdk/transforms/windowing/Trigger