Window apply problem

[Marcela Charfuelan <ch...@tu-berlin.de>]

hello,

I want to make a function for counting items (per type) in windows of 
size N; For example for N=5 and the stream:
1 2 4 3 4 3 4 5 4 6 7 3 3 6 1 1 3 2 4 6

I would like to generate the tuples:
w(1 2 4 3 4) -> (1,1)(2,1)(4,2)(3,1)
w(3 4 5 4 6) -> (1,1)(2,1)(4,4)(3,2)(5,1)(6,1)
w(7 3 3 6 1) -> (1,2)(2,1)(4,4)(3,4)(5,1)(6,2)(7,1)
w(1 3 2 4 6) -> (1,3)(2,2)(4,5)(3,5)(5,1)(6,3)(7,1)

I am trying to apply my own function with "Window apply", something like:

items
.windowAll(GlobalWindows.create())
.trigger(CountTrigger.of(5))
.apply(new MyWindowfunction())

but in this case there is a parameters mismatch with apply and 
WindowFunction, so I am not sure if it is not possible here. any suggestion?

Looking at the streaming java examples, the (commented) apply example 
shown in GroupedProcessingTimeWindowExample()
which is applied to a timeWindow, does not work either:

.keyBy(new FirstFieldKeyExtractor<Tuple2<Long, Long>, Long>())
.timeWindow(Time.of(2500, MILLISECONDS), Time.of(500, MILLISECONDS))
.apply(new SummingWindowFunction())

So what I am missing here? any help is appreciated.

Regards,
Marcela.