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Counting the Frequency of Values with BottomK

Purpose:

This application demonstrates how to use the siddhi-execution-extrema extension with the bottomK function.

Before you begin:

Save the sample Siddhi application in Streaming Integrator Tooling.

Executing the Sample

To execute the sample open the saved Siddhi application in Streaming Integrator Tooling, and start it by clicking the Start button (shown below) or by clicking Run => Run.

Start button

If the Siddhi application starts successfully, the following message appears in the console.

ExtremaBottomK.siddhi - Started Successfully!

Testing the Sample

The ExtremaBottomK Siddhi application can be tested in three ways as follows.

Option 1: Publish events via CURL

You can publish events in the JSON format to the HTTP endpoint via CURL commands. The CURL commands should be in the format of the example given below. The values for name and amount parameters can change.

curl -X POST -d "{\"event\": {\"name\":\"sugar\",\"amount\": 20}}" http://localhost:8006/productionStream --header "Content-Type:application/json"

Option2: Publish events with Postman

  1. Install the Postman application from Chrome web store.

  2. Launch the application.

  3. Make a POST request to the http://localhost:8006/productionStream endpoint. Set the Content-Type to application/json and set the request body in JSON format as follows.

        {
           "event":{
              "name":"sugar",
              "amount":20
           }
        }
  4. Send some more events in the same format, with different values for the name and amount parameters.

Option3: Publish events with http sample client

Navigate to the <WSO2SIHome>/samples/sample-clients/http-client directory and run the following command.

ant -Dtype=json -DfilePath={WSO2SIHome}/samples/artifacts/ExtreamBottomK/ExtremaBottomKEvents.txt -DeventDefinition='{"event":{"name":"{0}","amount":{1}}}' -Durl=http://localhost:8006/productionStream

Viewing the Results

The output is logged in the Streaming Integrator Tooling console as follows.

INFO {io.siddhi.core.stream.output.sink.LogSink} - ExtremaBottomK : outputStream : [Event{timestamp=1529498254202, data=[sugar, 20, sugar, 1, null, null, null, null], isExpired=false}, Event{timestamp=1529498254202, data=[cake, 10, cake, 1, sugar, 1, null, null], isExpired=false}]<br/><br/>
INFO {io.siddhi.core.stream.output.sink.LogSink} - ExtremaBottomK : outputStream : [Event{timestamp=1529498262769, data=[cake, 10, cake, 1, sugar, 1, null, null], isExpired=false}, Event{timestamp=1529498262769, data=[toffee, 65, toffee, 1, cake, 1, sugar, 1], isExpired=false}]<br/><br/>
INFO {io.siddhi.core.stream.output.sink.LogSink} - ExtremaBottomK : outputStream : [Event{timestamp=1529498270897, data=[toffee, 65, toffee, 1, cake, 1, sugar, 1], isExpired=false}, Event{timestamp=1529498270897, data=[cake, 74, toffee, 1, sugar, 1, cake, 2], isExpired=false}]<br/><br/>
INFO {io.siddhi.core.stream.output.sink.LogSink} - ExtremaBottomK : outputStream : [Event{timestamp=1529498278304, data=[cake, 74, toffee, 1, sugar, 1, cake, 2], isExpired=false}, Event{timestamp=1529498278304, data=[toffee, 25, sugar, 1, toffee, 2, cake, 2], isExpired=false}]
Click here to view the sample Siddhi application.
@App:name("ExtremaBottomK")
@App:Description('Demonstrates how to use the siddhi-execution-extrema with bottomK function')


@Source(type = 'http', receiver.url='http://localhost:8006/productionStream', basic.auth.enabled='false',
    @map(type='json'))
define stream inputStream (name string, amount long);

@sink(type='log')
define stream outputStream(name string, amount long, bottom1Element string, bottom1Frequency long, bottom2Element string, bottom2Frequency long, bottom3Element string, bottom3Frequency long);

from inputStream#extrema:bottomK(name, 3)
insert all events into outputStream;
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