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//Creating a window of ten items 

WindowedStream<ObservationEvent,Tuple,GlobalWindow> windowStream = inputStream.keyBy("rackId").countWindow(10);

// Applying a Window Function , adding some custom evaluating all the values in the window 

DataStream<ObservationEvent> inactivityStream = windowStream.apply(new WindowFunction<ObservationEvent, ObservationEvent , Tuple , GlobalWindow>() { 

                        @Override 
                        public void apply(Tuple tuple, GlobalWindow timeWindow, Iterable<ObservationEvent> itr, Collector<ObservationEvent> out) 
                                //custom evaluation logic 
                                out.collect(new ObservationEvent(1,"temperature", "stable")); 
                        } 
                });

//Defining Simple CEP Pattern 

 Pattern<ObservationEvent, ?> inactivityPattern = Pattern.ObservationEvent>begin("first") 
                                .subtype(ObservationEvent.class) 
                                .where(new FilterFunction<ObservationEvent>() { 

                                        @Override 
                                        public boolean filter(ObservationEvent arg0) throws Exception { 
                                                System.out.println( arg0 );  //This function is not at all called
                                                return false; 
                                        } 
                });



PatternStream<ObservationEvent> inactivityCEP = CEP.pattern(inactivityStream.keyBy("rackId"), inactivityPattern);

When I run this code, the filter function inside the where clause is not at all getting called. I have printed the inactivityStream.print() and I can see the matching value.

Now, when I plug in the inputStream directly without applying a window. The pattern is matching

I printed inputStream and WindowedStream and I can see they both send similar kind of data.

What am I missing

madhairsilence
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1 Answers1

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The FilterFunction should be getting called eventually but you are going to have to wait for 10 events for the SAME key before you see your FilterFunction called for the first time. Could it be that you are just not waiting long enough in your windowing test?

Keep in mind that if you have many unique keys this implies you will have to wait well more than 10 times as long in the window test before you'll see your filter function called.

Jamie Grier
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  • Why do I have to wait ?. Moreover the mock up data has only one key. The window prints immediately but the filter function is not gettting called. Sorry but I don't get the "Waiting" part. – madhairsilence Jan 07 '17 at 03:15
  • You have to wait simply because there will be no output from the window function for a given key until you've seen 10 elements for that key. Can you post an entire working example so I can comment further? It's hard to see what might be causing your issue without a full code sample. – Jamie Grier Jan 09 '17 at 15:47