CODEWITHSUNDEEP
apache-flinkflink-streamingcomplex-event-processingflink-cep
Amarjit Dhillon
Amarjit Dhillon

Reputation: 2816

warnings.print() prints events in reverse order(last event first ) excepts first event in Apache Flink CEP

I am trying to filter all temp events that are > 10 in Flink using below pattern,

Pattern<MonitoringEvent, ?> warningPattern = Pattern.<MonitoringEvent>begin("first")
                .subtype(TemperatureEvent.class)
                .where(new FilterFunction<TemperatureEvent>() {
                    @Override
                    public boolean filter(TemperatureEvent temperatureEvent) throws Exception {
                        return temperatureEvent.getTemperature() > 50;
                    }
                });

Input is a text file , which is parsed to stream by an input function, Contents of input file are:-

1,98
2,33
3,44
4,55
5,66
6,88
7,99
8,76

Here first value is Rack_id and second is Temperature

I have issued print() on both input-stream and WarnigsStream as shown below

inputEventStream.print();
warnings.print();

Now, comes the issue, The output of Flink CEP is shown below

08/10/2017 23:43:15 Job execution switched to status RUNNING.
08/10/2017 23:43:15 Source: Custom Source -> Sink: Unnamed(1/1) switched to SCHEDULED 
08/10/2017 23:43:15 Source: Custom Source -> Sink: Unnamed(1/1) switched to DEPLOYING 
08/10/2017 23:43:15 AbstractCEPPatternOperator -> Map -> Sink: Unnamed(1/1) switched to SCHEDULED 
08/10/2017 23:43:15 AbstractCEPPatternOperator -> Map -> Sink: Unnamed(1/1) switched to DEPLOYING 
08/10/2017 23:43:15 AbstractCEPPatternOperator -> Map -> Sink: Unnamed(1/1) switched to RUNNING 
08/10/2017 23:43:15 Source: Custom Source -> Sink: Unnamed(1/1) switched to RUNNING 
Rack id = 1 and temprature = 98.0)
Rack id = 2 and temprature = 33.0)
Rack id = 3 and temprature = 44.0)
Rack id = 4 and temprature = 55.0)
Rack id = 5 and temprature = 66.0)
Rack id = 6 and temprature = 88.0)
Rack id = 7 and temprature = 99.0)
Rack id = 8 and temprature = 76.0)
08/10/2017 23:43:16 Source: Custom Source -> Sink: Unnamed(1/1) switched to FINISHED 
Rack id = 1 and temprature = 98.0)
Rack id = 8 and temprature = 76.0)
Rack id = 7 and temprature = 99.0)
Rack id = 6 and temprature = 88.0)
Rack id = 5 and temprature = 66.0)
Rack id = 4 and temprature = 55.0)
08/10/2017 23:43:16 AbstractCEPPatternOperator -> Map -> Sink: Unnamed(1/1) switched to FINISHED 
08/10/2017 23:43:16 Job execution switched to status FINISHED.

Process finished with exit code 0

As we can see, the first Complex event(Rack id = 1 and temperature = 98.0)) is printed in same order, but after this, all the other complex events having temp > 50 are getting printed in opposite order with respect to the input stream. 

My questions are :-

1. Any idea why events are getting printed in reverse order?
2. Is there a custom way to print values{w/o using warnings.print()} of 
   warning stream, like can I print only temperature, rather than rack-id ?

Thanks in Advance

Upvotes: 0

Views: 66

Answers (1)

Amarjit Dhillon
Amarjit Dhillon

Reputation: 2816

This issue was solved by assigning Timestamps and Watermarks to inputStream shown as below 

// Input stream of monitoring events
        DataStream<MonitoringEvent> inputEventStream = env
                .addSource(new InputStreamAGenerator()).assignTimestampsAndWatermarks(new IngestionTimeExtractor<>());

Output Generated is shown below

 08/11/2017 00:45:09    Job execution switched to status RUNNING.
    08/11/2017 00:45:09 Source: Custom Source -> Timestamps/Watermarks(1/1) switched to SCHEDULED 
    08/11/2017 00:45:09 Source: Custom Source -> Timestamps/Watermarks(1/1) switched to DEPLOYING 
    08/11/2017 00:45:09 AbstractCEPPatternOperator -> Map -> Sink: Unnamed(1/1) switched to SCHEDULED 
    08/11/2017 00:45:09 AbstractCEPPatternOperator -> Map -> Sink: Unnamed(1/1) switched to DEPLOYING 
    08/11/2017 00:45:09 Source: Custom Source -> Timestamps/Watermarks(1/1) switched to RUNNING 
    08/11/2017 00:45:09 AbstractCEPPatternOperator -> Map -> Sink: Unnamed(1/1) switched to RUNNING 
    Rack id = 1 and temprature = 98.0)
    Rack id = 4 and temprature = 55.0)
    Rack id = 5 and temprature = 66.0)
    Rack id = 6 and temprature = 88.0)
    Rack id = 7 and temprature = 99.0)
    Rack id = 8 and temprature = 76.0)
    08/11/2017 00:45:10 Source: Custom Source -> Timestamps/Watermarks(1/1) switched to FINISHED 
    08/11/2017 00:45:10 AbstractCEPPatternOperator -> Map -> Sink: Unnamed(1/1) switched to FINISHED 
    08/11/2017 00:45:10 Job execution switched to status FINISHED.

Upvotes: 1

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