Github user aljoscha commented on a diff in the pull request:
https://github.com/apache/flink/pull/3191#discussion_r97827894
--- Diff: docs/dev/windows.md ---
@@ -622,133 +690,138 @@ input
</div>
</div>
-## Dealing with Late Data
+## Triggers
-When working with event-time windowing it can happen that elements arrive
late, i.e the
-watermark that Flink uses to keep track of the progress of event-time is
already past the
-end timestamp of a window to which an element belongs. Please
-see [event time](./event_time.html) and especially
-[late elements](./event_time.html#late-elements) for a more thorough
discussion of
-how Flink deals with event time.
+A `Trigger` determines when a window (as formed by the `WindowAssigner`)
is ready to be
+processed by the *window function*. Each `WindowAssigner` comes with a
default `Trigger`.
+If the default trigger does not fit your needs, you can specify a custom
trigger using `trigger(...)`.
-You can specify how a windowed transformation should deal with late
elements and how much lateness
-is allowed. The parameter for this is called *allowed lateness*. This
specifies by how much time
-elements can be late. Elements that arrive within the allowed lateness are
still put into windows
-and are considered when computing window results. If elements arrive after
the allowed lateness they
-will be dropped. Flink will also make sure that any state held by the
windowing operation is garbage
-collected once the watermark passes the end of a window plus the allowed
lateness.
+The trigger interface provides five methods that react to different
events:
--- End diff --
I think it doesn't "provide" the methods, maybe write "The trigger
interface has five methods that allow a Trigger to react to different events"
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