Query Kafka Data in ColdFusion

The CData JDBC Driver for Kafka seamlessly integrates connectivity to Kafka data with the rapid development tools in ColdFusion. This article shows how to connect to Kafka data in ColdFusion and query Kafka tables.

Create a JDBC Data Source for Kafka in ColdFusion

The JDBC data source enables you to execute SQL from standard ColdFusion tags like cfquery and CFScript like executeQuery.

1. Copy the driver JAR and .lic file from the installation directory onto the ColdFusion classpath. For example, copy the files into C:\MyColdFusionDirectory\cfusion\wwwroot\WEB-INF\lib. Or, open the Java and JVM page in the ColdFusion Administrator and enter the path to the files in the ColdFusion Class Path box.

   The JAR and license for the driver are located in the lib subfolder of the installation directory.

   Restart the server after this step.

2. Add the driver as a data source:

   From the ColdFusion administrator interface, expand the Data & Services node and click Data Sources. In the Add New Data Source section, enter a name for the data source and select Other in the Driver menu.

3. Populate the driver properties:

   • JDBC URL: Enter connection properties in the JDBC URL. The JDBC URL begins with jdbc:apachekafka: and is followed by the connection properties in a semicolon-separated list of name=value pairs.

     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.

     A typical JDBC URL is below:

     jdbc:apachekafka:User=admin;Password=pass;BootStrapServers=https://localhost:9091;Topic=MyTopic;
   • Driver Class: Enter the driver class. The driver class is cdata.jdbc.apachekafka.ApacheKafkaDriver.
   • Driver Name: Enter a user-defined name for the driver.
   • Username: Enter the username used to authenticate.
   • Password: Enter the password used to authenticate.

You can now test the connection by enabling the CData Kafka data source in the Actions column. After reporting a status of OK, the Kafka data source is ready for use.

Execute Queries

The cfquery tag can pass SQL statements to Kafka, including INSERT, UPDATE, and DELETE.. Use the cfqueryparam tag to create parameterized queries and prevent SQL injection through the query string.

Note: To use the cfquery and cfscript, create a .cfm file. Inside the .cfm file, write the code to execute the query (see below). Place the file directly in the root directory of your web server (e.g., wwwroot in Adobe ColdFusion). Restart the service after placing the file for the changes to take effect.

Below is the equivalent in CFScript:

<cfscript>
result = queryExecute(
  "SELECT * FROM SampleTable_1 WHERE Column2 = ?", 
  [
    { value="100", cfsqltype="cf_sql_varchar" }
  ],
  { datasource="CDataApacheKafka" }
);

writeDump( var= result );
</cfscript> 

You can then make requests to your .cfm like the following: