Configure the CData JDBC Driver for Azure Data Lake Storage in a Connection Pool in Tomcat

The CData JDBC Drivers support standard JDBC interfaces to integrate with Web applications running on the JVM. This article details how to connect to Azure Data Lake Storage data from a connection pool in Tomcat.

Connect to Azure Data Lake Storage Data through a Connection Pool in Tomcat

1. Copy the CData JAR and CData .lic file to $CATALINA_HOME/lib. The CData JAR is located in the lib subfolder of the installation directory.
2. Add a definition of the resource to the context. Specify the JDBC URL here.

   Authenticating to a Gen 1 DataLakeStore Account

   Gen 1 uses OAuth 2.0 in Entra ID (formerly Azure AD) for authentication.

   For this, an Active Directory web application is required. You can create one as follows:

   1. Sign in to your Azure Account through the
   2. Select "Entra ID" (formerly Azure AD).
   3. Select "App registrations".
   4. Select "New application registration".
   5. Provide a name and URL for the application. Select Web app for the type of application you want to create.
   6. Select "Required permissions" and change the required permissions for this app. At a minimum, "Azure Data Lake" and "Windows Azure Service Management API" are required.
   7. Select "Key" and generate a new key. Add a description, a duration, and take note of the generated key. You won't be able to see it again.

   To authenticate against a Gen 1 DataLakeStore account, the following properties are required:

   • Schema: Set this to ADLSGen1.
   • Account: Set this to the name of the account.
   • OAuthClientId: Set this to the application Id of the app you created.
   • OAuthClientSecret: Set this to the key generated for the app you created.
   • TenantId: Set this to the tenant Id. See the property for more information on how to acquire this.
   • Directory: Set this to the path which will be used to store the replicated file. If not specified, the root directory will be used.

   Authenticating to a Gen 2 DataLakeStore Account

   To authenticate against a Gen 2 DataLakeStore account, the following properties are required:

   • Schema: Set this to ADLSGen2.
   • Account: Set this to the name of the account.
   • FileSystem: Set this to the file system which will be used for this account.
   • AccessKey: Set this to the access key which will be used to authenticate the calls to the API. See the property for more information on how to acquire this.
   • Directory: Set this to the path which will be used to store the replicated file. If not specified, the root directory will be used.

   Built-in Connection String Designer

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

   java -jar cdata.jdbc.adls.jar
   

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

   👁 Using the built-in connection string designer to generate a JDBC URL (Salesforce is shown.)
   

   You can see the JDBC URL specified in the resource definition below.

   <Resource name="jdbc/adls" auth="Container" type="javax.sql.DataSource" driverClassName="cdata.jdbc.adls.ADLSDriver" factory="org.apache.tomcat.jdbc.pool.DataSourceFactory" url="jdbc:adls:Schema=ADLSGen2;Account=myAccount;FileSystem=myFileSystem;AccessKey=myAccessKey;InitiateOAuth=GETANDREFRESH;" maxActive="20" maxIdle="10" maxWait="-1" />
   

   To allow a single application to access Azure Data Lake Storage data, add the code above to the context.xml in the application's META-INF directory.

   For a shared resource configuration, add the code above to the context.xml located in $CATALINA_BASE/conf. A shared resource configuration provides connectivity to Azure Data Lake Storage for all applications.

3. Add a reference to the resource to the web.xml for the application.

    Azure Data Lake Storage data JSP
    jdbc/ADLS
    javax.sql.DataSource
    Container
   
   

4. Initialize connections from the connection pool:

   Context initContext = new InitialContext();
   Context envContext = (Context)initContext.lookup("java:/comp/env");
   DataSource ds = (DataSource)envContext.lookup("jdbc/ADLS");
   Connection conn = ds.getConnection();
    

More Tomcat Integration

The steps above show how to connect to Azure Data Lake Storage data in a simple connection pooling scenario. For more use cases and information, see the JNDI Datasource How-To in the Tomcat documentation.