## Window Accumulation Mode

When you specify a trigger, you must also set the the window’s accumulation mode. When a trigger fires, it emits the current contents of the window as a pane. Since a trigger can fire multiple times, the accumulation mode determines whether the system accumulates the window panes as the trigger fires, or discards them.

Kata: Given that events are being generated every second and a fixed window of 1-day duration, please implement an early trigger that emits the number of events count immediately after new element is processed in accumulating mode.

Use accumulatingFiredPanes() to set a window to accumulate the panes that are produced when the trigger fires.
Use withEarlyFirings to set early firing triggers.
Use FixedWindows with 1-day duration using AfterWatermark.pastEndOfWindow() trigger.
Set the allowed lateness to 0.
Use Combine.globally and Count.combineFn to calculate the count of events.
Refer to the Beam Programming Guide "Event time triggers" section for more information.