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Publishing Binary Events via Kafka¶

Purpose:¶

This application demonstrates how to configure WSO2 Streaming Integrator Tooling to send sweet production events via Kafka transport in Binary format.

Prerequisites:¶

Setup Kafka.
- Kafka libs to be added and converted to OSGI from {KafkaHome}/libs are as follows.
  - kafka_2.11-0.10.0.0.jar
  - kafka-clients-0.10.0.0.jar
  - metrics-core-2.2.0.jar
  - scala-library-2.11.8.jar
  - zkclient-0.8.jar
  - zookeeper-3.4.6.jar
- Add the OSGI converted kafka libs to {WSO2SIHome}/lib.
- Add the kafka libs to {WSO2SIHome}/samples/sample-clients/lib.
Save this sample.
If there is no syntax error, the following messages would be shown on the console.
```
Siddhi App PublishKafkaInBinaryFormat successfully deployed.
```

Note:¶

To convert Kafka libs to OSGI, 1. Create a folder (Eg: Kafka) and copy Kafka libs to be added from {KafkaHome}/libs. 2. Create another folder(Eg: Kafka-osgi, This folder will have the libs that converted to OSGI). 3. Navigate to {WSO2SIHome}/bin and issue the following command. * For Linux:

./jartobundle.sh <path/kafka> <path/kafka-osgi>

* For Windows:

./jartobundle.bat <path/kafka> <path/kafka-osgi>

4. If converted successfully then for each lib, following messages would be shown on the terminal.

- INFO: Created the OSGi bundle <kafka-lib-name>.jar for JAR file <absolute_path>/kafka/<kafka-lib-name>.jar

5. You can find the OSGi converted libs in kafka-osgi folder. You can copy that to {WSO2SIHome}/lib.

Executing the Sample:¶

Navigate to {KafkaHome} and start zookeeper node using following command.
```
bin/zookeeper-server-start.sh config/zookeeper.properties
```
Navigate to {KafkaHome} and start kafka server node using following command.
```
bin/kafka-server-start.sh config/server.properties
```
Navigate to {WSO2SIHome}/samples/sample-clients/kafka-consumer and run ant command with following arguments.
```
ant -DisBinaryMessage=true -DtopicList=kafka_result_topic -Dtype=binary
```
Start the Siddhi application by clicking on 'Run'.

If the Siddhi application starts successfully, the following messages would be shown on the console.

- PublishKafkaInBinaryFormat.siddhi - Started Successfully!
- Kafka version : 0.10.0.0
- Kafka commitId : 23c69d62a0cabf06
- Kafka producer created.

Testing the Sample:¶

Send events with kafka server, through event simulator:¶

To open event simulator by clicking on the second icon or press Ctrl+Shift+I.
In the Single Simulation tab of the panel, select values as follows:
- Siddhi App Name: PublishKafkaInBinaryFormat
- Stream Name: SweetProductionStream
In the batchNumber field and lowTotal fields, enter '1', '85.5' respectively and then click Send to send the event.
Send some more events.

Publish events with curl command:¶

Open a new terminal and issue the following command.

curl -X POST -d '{"streamName": "SweetProductionStream", "siddhiAppName": "PublishKafkaInBinaryFormat", "data": [1, 85.5]}' http://localhost:9390/simulation/single -H 'content-type: text/plain'

Publish events with Postman:¶

Install 'Postman' application from Chrome web store.
Launch the application.
Make a 'Post' request to 'http://localhost:9390/simulation/single' endpoint. Set the Content-Type to 'text/plain' and set the request body in json format as follows,
```
{"streamName": "SweetProductionStream", "siddhiAppName": "PublishKafkaInBinaryFormat","data": [1, 85.5]}
```
Click 'send'. If there is no error, the following messages would be shown on the console.
```
"status": "OK",
"message": "Single Event simulation started successfully"
```

Viewing the Results:¶

It will print the results in binary format.

Notes:¶

If the message "'Kafka' sink at 'LowProducitonAlertStream' has successfully connected to 'http://localhost:9092' does not appear, it could be due to port 9092, defined in the Siddhi application is already being used by a different program. To resolve this issue, please do the following, * Stop this Siddhi application (Click 'Run' on menu bar -> 'Stop') * Change the port 9092 to an unused port, in this Siddhi application's source configuration. * Start the application and check whether the specified messages appear on the console.

@App:name("PublishKafkaInBinaryFormat")
@App:description('Send events via Kafka transport using Binary format')


define stream SweetProductionStream (batchNumber long, lowTotal double);

@sink(type='kafka',
      topic='kafka_result_topic',
      bootstrap.servers='localhost:9092',
      is.binary.message='true',
      @map(type='binary'))
define stream LowProductionAlertStream (batchNumber long, lowTotal double);

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

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