Connect to Cassandra Data in JRuby

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

Configure a JDBC Connection to Cassandra 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 Cassandra\lib).

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

Set the Server, Port, and Database connection properties to connect to Cassandra. Additionally, to use internal authentication set the User and Password connection properties.

Built-in Connection String Designer

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

java -jar cdata.jdbc.cassandra.jar

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

Below is a typical JDBC connection string for Cassandra:

jdbc:cassandra:Database=MyCassandraDB;Port=7000;Server=127.0.0.1;

Create a JRuby App with Connectivity to Cassandra Data

Create a new Ruby file (for example: CassandraSelect.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 Cassandra 2018/lib/cdata.jdbc.cassandra.jar'

url = "jdbc:cassandra:Database=MyCassandraDB;Port=7000;Server=127.0.0.1;"
conn = java.sql.DriverManager.getConnection(url)
stmt = conn.createStatement
rs = stmt.executeQuery("SELECT City, TotalDue FROM Customer")
while (rs.next) do
 puts rs.getString(1) + ' ' + rs.getString(2)
end

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

jruby -S CassandraSelect.rb

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