[FLINK-9959] Add JoinWindowFunction to allow access Window

• Type: Improvement
• Status: Open
• Priority: Not a Priority
• Resolution: Unresolved
• Affects Version/s: 1.5.1, 1.6.0
• Component/s: API / DataStream
• Labels: auto-deprioritized-major auto-deprioritized-minor auto-unassigned
• Assignee: Unassigned
• Reporter: Bowen Li
• Created: 25/Jul/18 17:35
• Updated: 28/Dec/21 22:38

Description

e.g. currently, a windowed join looks like this, and the JoinFunction doesn't have access to the Window it runs against.

A.join(B)
	.where(...)
	.equalTo(...)
	.window(...)
	.apply(new JoinFunction<IN1, IN2, OUT>() {});

We can allow users to query window information by having

A.join(B)
	.where(...)
	.equalTo(...)
	.window(...)
	.apply(new JoinWindowFunction<IN1, IN2, OUT, Window>() {});