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Sending Custom JSON Events via HTTP¶

Purpose¶

This application demonstrates how to configure the Streaming Integrator to send sweet production events via HTTP transport in JSON format using custom mapping.

Before executing the sample:

Save the sample Siddhi application. Is there is no syntax error, the following message appears in the console.
- Siddhi App PublishHTTPInJsonFormatWithCustomMapping successfully deployed.

Executing the Sample¶

Start the Siddhi application by clicking Run => Run.
If the Siddhi application starts successfully, the following messages are shown on the console.
- PublishHTTPInJsonFormatWithCustomMapping.siddhi - Started Successfully!
- 'http' sink at 'LowProductionAlertStream' has successfully connected to http://localhost:8080/abc

Testing the Sample¶

Open a terminal and navigate to <SI_HOME>/samples/sample-clients/http-server. Then run the ant command without any arguments.
To send events, follow one or more of the following methods.
- Send events with http server through the event simulator:
  
  a. Open the event simulator by clicking on the second icon or pressing Ctrl+Shift+I.
  
  b. In the Single Simulation tab of the panel, specify the values as follows.
```
- Siddhi App Name`: `PublishHttpInJsonFormatWithCustomMapping
- Stream Name`: `SweetProductionStream
```
  c. In the id and amount fields, enter toffees and 123.5 respectively and then click Send to send the event.
  
  d. Send more events as required.
- Send events to the http endpoint defined by 'publish.url' in the Sink configuration through the curl command:
  
  a. Open a new terminal and issue the following command
```
curl -X POST -d '{"streamName": "SweetProductionStream", "siddhiAppName": "PublishHTTPInJsonFormatWithCustomMapping","data": ['toffees', 123.5]}' http://localhost:9390/simulation/single -H 'content-type: text/plain'
```
  b. If there is no error, the following message appears in the terminal.
```
{"status":"OK","message":"Single Event simulation started successfully"}
```
- Publish events with Postman:
  
  a. Install the 'Postman' application from Chrome web store.
  
  b. Launch the application.
  
  c. Make a 'Post' request to the 'http://localhost:9390/simulation/single' endpoint. Set the Content-Type to 'text/plain' and set the request body in text as follows.
```
{"streamName": "SweetProductionStream", "siddhiAppName": "PublishHTTPInJsonFormatWithCustomMapping","data": ['toffees', 75.6]}
```
  d. Click Send. If there is no error, the following messages appear in the terminal.
```
* "status": "OK"

* "message": "Single Event simulation started successfully"
```

Viewing the Results¶

See the output on the terminal:

[java] [org.wso2.si.http.server.HttpServerListener] : Event Name Arrived: {"event":{"id":"toffees","amount":123.5}}
[java] [org.wso2.si.http.server.HttpServerMain] : Received Event Names:{"event":{"id":"toffees","amount":123.5}} ,
[java] [org.wso2.si.http.server.HttpServerMain] : Received Event Headers key set:[Http_method, Content-type, Content-length]
[java] [org.wso2.si.http.server.HttpServerMain] : Received Event Headers value set:[[POST], [application/json], [43]]

Note

If the message "'HTTP' sink at 'LowProductionAlertStream' has successfully connected to http://localhost:8080/abc" does not appear, it could be due to port 8080 defined in the Siddhi application is already being used by a different program. To resolve this issue, do the following:
1. Stop this Siddhi application (Click 'Run' on menu bar -> 'Stop').
2. In this Siddhi application's source configuration, change the port from 8080 to an unused port.
3. Start the application and check whether the specified messages appear on the console.

Click here to view the complete sample Siddhi application

@App:name("PublishHTTPInJsonFormatWithCustomMapping")

@App:description('Send events via HTTP transport in JSON format with custom mapping.')


define stream SweetProductionStream (id string, amount double);

@sink(type='http', publisher.url='http://localhost:8080/abc',
@map(type='json' , @payload( "{'name': {{id}}, 'amount': {{amount}}}")))
define stream LowProductionAlertStream (id string, amount double);

@info(name='query1')
from SweetProductionStream
select *
insert into LowProductionAlertStream;

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