Receiving JSON Events via TCP

Purpose

This application demonstrates how to configure WSO2 Integrator: SI to receive events to the SweetProductionStream via TCP transport in JSON format using default mapping and log the events in LowProductionAlertStream to the output console.

Prerequisites

• Install the tcp Siddhi extension. For instructions, see Downloading and Installing Siddhi Extensions.
• A TCP client capable of producing events in the siddhi-io-tcp wire format. For the framing details, see the siddhi-io-tcp documentation.

Try it out

1. Start the Siddhi application by clicking Run. The following messages appear in the console:

   Tcp Server started in 0.0.0.0:9892
   ReceiveTCPinJSONFormat - Started Successfully!
   

   Port already in use?

   If Tcp Server started in 0.0.0.0:9892 does not appear, the port 9892 may already be in use by another program. Stop the application, change the port in the source configuration to an unused one, and start it again.

2. Send JSON-encoded sweet production events to tcp://localhost:9892 with context SweetProductionStream using your TCP client. Each event payload should be in the form:

   {"event":{"name":"<name>","amount":<amount>}}
   

3. The console logs the received events. A sample output looks like the following:

   INFO {io.siddhi.core.stream.output.sink.LogSink} - ReceiveTCPinJSONFormat : LowProductionAlertStream : Event{timestamp=1513049050858, data=[Gingerbread, 6664.0], isExpired=false}
   INFO {io.siddhi.core.stream.output.sink.LogSink} - ReceiveTCPinJSONFormat : LowProductionAlertStream : Event{timestamp=1513049051858, data=[Cream Sandwich, 6190.0], isExpired=false}
   INFO {io.siddhi.core.stream.output.sink.LogSink} - ReceiveTCPinJSONFormat : LowProductionAlertStream : Event{timestamp=1513049052859, data=[Gingerbread, 9725.0], isExpired=false}
   INFO {io.siddhi.core.stream.output.sink.LogSink} - ReceiveTCPinJSONFormat : LowProductionAlertStream : Event{timestamp=1513049053859, data=[Donut, 7777.0], isExpired=false}
   INFO {io.siddhi.core.stream.output.sink.LogSink} - ReceiveTCPinJSONFormat : LowProductionAlertStream : Event{timestamp=1513049054860, data=[Honeycomb, 8818.0], isExpired=false}
   

Siddhi application

@App:name("ReceiveTCPinJSONFormat")
@App:description('Receive events via TCP transport in JSON format with default mapping and view the output on the console.')

@Source(type = 'tcp',
        context='SweetProductionStream',
        @map(type='json'))
define stream SweetProductionStream (name string, amount double);

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

-- passthrough data in the SweetProductionStream into LowProductionAlertStream
@info(name='query1')
from SweetProductionStream
select *
insert into LowProductionAlertStream;

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Last update: May 14, 2026