Using Javascript Functions in Siddhi Applications

Purpose

This sample demonstrates how javascript functions can be used in Siddhi Applications.

Prerequisites

1. Save this sample.

Executing the Sample

1. Start the Siddhi application by clicking on 'Run'.
2. If the Siddhi application starts successfully, the following messages would be shown on the console.

   * Script-js-sample.siddhi - Started Successfully!
   

Testing the Sample

1. To open event simulator by clicking on the second icon or press Ctrl+Shift+I.
2. In the Single Simulation tab of the panel, select values as follows:
   • Siddhi App Name: Script-js-sample
   • Stream Name: sweetProductionStream
3. In the name field and amount fields, enter 'toffee', '45.25' respectively and then click Send to send the event.
4. Send some more events.

Viewing the Results

See the output on the console. Description of the raw material with the passed details are shown in the logger. You will get the output as follows:

[2017-12-20_14-26-03_120] INFO {io.siddhi.core.stream.output.sink.LogSink} - Script-js-sample : logStream : Event{timestamp=1513760163112, data=[toffee, 45.25, There are 45.25kg of toffee in the store], isExpired=false}

Notes: If you need to edit this application while it is running, then Save -> Start.

@App:name('Script-js-sample')
@App:Description('Demonstrate how javascript functions can be used in Siddhi Applications.')


define stream sweetProductionStream (name string, amount double);

@sink(type='log')
define stream logStream (name string, amount double, itemDescription string);

define function detailedMaterial[JavaScript] return string {
     var name = data[0];
     var amount = data[1];
     var res = "There are "+amount+"kg of "+name+ " in the store";
     return res;
};

from sweetProductionStream select name , amount, detailedMaterial(name,amount) as itemDescription
insert into detailedProductionstream;

from detailedProductionstream
select *
insert into logStream;

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Last update: May 14, 2026