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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:

  1. 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.
  2. Save this sample.
  3. 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 follwing 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:

  1. Navigate to {KafkaHome} and start zookeeper node using following command.
    bin/zookeeper-server-start.sh config/zookeeper.properties
  2. Navigate to {KafkaHome} and start kafka server node using following command.
    bin/kafka-server-start.sh config/server.properties
  3. Navigate to {WSO2SIHome}/samples/sample-clients/kafka-consumer and run ant command with following arguments.
    ant -DisBinaryMessage=true -DtopicList=kafka_result_topic -Dtype=binary
  4. Start the Siddhi application by clicking on 'Run'.
  5. 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:
  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: PublishKafkaInBinaryFormat
    • Stream Name: SweetProductionStream
  3. In the batchNumber field and lowTotal fields, enter '1', '85.5' respectively and then click Send to send the event.
  4. 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:
  1. Install 'Postman' application from Chrome web store.
  2. Launch the application.
  3. 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]}
  4. 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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