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Connect to Kafka Data in JRuby


Create a simple JRuby app with access to live Kafka data.

JRuby is a high-performance, stable, fully threaded Java implementation of the Ruby programming language. The CData JDBC Driver for Kafka makes it easy to integrate connectivity to live Kafka data in JRuby. This article shows how to create a simple JRuby app that connects to Kafka data, executes a query, and displays the results.

Configure a JDBC Connection to Kafka Data

Before creating the app, note the installation location for the JAR file for the JDBC Driver (typically C:\Program Files\CData\CData JDBC Driver for Kafka\lib).

JRuby natively supports JDBC, so you can easily connect to Kafka and execute SQL queries. Initialize the JDBC connection with the getConnection function of the java.sql.DriverManager class.

Set BootstrapServers and the Topic properties to specify the address of your Apache Kafka server, as well as the topic you would like to interact with.

Authorization Mechanisms

  • SASL Plain: The User and Password properties should be specified. AuthScheme should be set to 'Plain'.
  • SASL SSL: The User and Password properties should be specified. AuthScheme should be set to 'Scram'. UseSSL should be set to true.
  • SSL: The SSLCert and SSLCertPassword properties should be specified. UseSSL should be set to true.
  • Kerberos: The User and Password properties should be specified. AuthScheme should be set to 'Kerberos'.

You may be required to trust the server certificate. In such cases, specify the TrustStorePath and the TrustStorePassword if necessary.

Built-in Connection String Designer

For assistance in constructing the JDBC URL, use the connection string designer built into the Kafka JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.

java -jar cdata.jdbc.apachekafka.jar

Fill in the connection properties and copy the connection string to the clipboard.

Below is a typical JDBC connection string for Kafka:

jdbc:apachekafka:User=admin;Password=pass;BootStrapServers=https://localhost:9091;Topic=MyTopic;

Create a JRuby App with Connectivity to Kafka Data

Create a new Ruby file (for example: ApacheKafkaSelect.rb) and open it in a text editor. Copy the following code into your file:

require 'java' require 'rubygems' require 'C:/Program Files/CData/CData JDBC Driver for Kafka 2018/lib/cdata.jdbc.apachekafka.jar' url = "jdbc:apachekafka:User=admin;Password=pass;BootStrapServers=https://localhost:9091;Topic=MyTopic;" conn = java.sql.DriverManager.getConnection(url) stmt = conn.createStatement rs = stmt.executeQuery("SELECT Id, Column1 FROM SampleTable_1") while (rs.next) do puts rs.getString(1) + ' ' + rs.getString(2) end

With the file completed, you are ready to display your Kafka data with JRuby. To do so, simply run your file from the command line:

jruby -S ApacheKafkaSelect.rb

Writing SQL-92 queries to Kafka allows you to quickly and easily incorporate Kafka data into your own JRuby applications. Download a free trial today!

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