Object-Relational Mapping (ORM) with IBM Cloud Object Storage Data Entities in Java

You can use Hibernate to map object-oriented domain models to a traditional relational database. The tutorial below shows how to use the CData JDBC Driver for IBM Cloud Object Storage to generate an ORM of your IBM Cloud Object Storage repository with Hibernate.

Though Eclipse is the IDE of choice for this article, the CData JDBC Driver for IBM Cloud Object Storage works in any product that supports the Java Runtime Environment. In the Knowledge Base you will find tutorials to connect to IBM Cloud Object Storage data from IntelliJ IDEA and NetBeans.

Install Hibernate

Follow the steps below to install the Hibernate plug-in in Eclipse.

1. In Eclipse, navigate to Help -> Install New Software.
2. Enter "http://download.jboss.org/jbosstools/neon/stable/updates/" in the Work With box.
3. Enter "Hibernate" into the filter box.
4. Select Hibernate Tools.

Start A New Project

Follow the steps below to add the driver JARs in a new project.

1. Create a new project. Select Java Project as your project type and click Next. Enter a project name and click Finish.
2. Right-click the project and click Properties. Click Java Build Path and then open the Libraries tab.
3. Click Add External JARs to add the cdata.jdbc.ibmcloudobjectstorage.jar library, located in the lib subfolder of the installation directory.

Add a Hibernate Configuration File

Follow the steps below to configure connection properties to IBM Cloud Object Storage data.

1. Right-click on the new project and select New -> Hibernate -> Hibernate Configuration File (cfg.xml).
2. Select src as the parent folder and click Next.

3. Input the following values:

   • Hibernate version:: 5.2
   • Database dialect: Derby
   • Driver class: cdata.jdbc.ibmcloudobjectstorage.IBMCloudObjectStorageDriver

   • Connection URL: A JDBC URL, starting with jdbc:ibmcloudobjectstorage: and followed by a semicolon-separated list of connection properties.

     Register a New Instance of Cloud Object Storage

     If you do not already have Cloud Object Storage in your IBM Cloud account, follow the procedure below to install an instance of SQL Query in your account:

     1. Log in to your IBM Cloud account.
     2. Navigate to the page, choose a name for your instance and click Create. You will be redirected to the instance of Cloud Object Storage you just created.

     Connecting using OAuth Authentication

     There are certain connection properties you need to set before you can connect. You can obtain these as follows:

     API Key

     To connect with IBM Cloud Object Storage, you need an API Key. You can obtain this as follows:

     1. Log in to your IBM Cloud account.
     2. Navigate to the Platform API Keys page.
     3. On the middle-right corner click "Create an IBM Cloud API Key" to create a new API Key.
     4. In the pop-up window, specify the API Key name and click "Create". Note the API Key as you can never access it again from the dashboard.

     Cloud Object Storage CRN

     If you have multiple accounts, you will need to specify the CloudObjectStorageCRN explicitly. To find the appropriate value, you can:

     • Query the Services view. This will list your IBM Cloud Object Storage instances along with the CRN for each.
     • Locate the CRN directly in IBM Cloud. To do so, navigate to your IBM Cloud Dashboard. In the Resource List, Under Storage, select your Cloud Object Storage resource to get its CRN.

     Connecting to Data

     You can now set the following to connect to data:

     • InitiateOAuth: Set this to GETANDREFRESH. You can use InitiateOAuth to avoid repeating the OAuth exchange and manually setting the OAuthAccessToken.
     • ApiKey: Set this to your API key which was noted during setup.
     • CloudObjectStorageCRN (Optional): Set this to the cloud object storage CRN you want to work with. While the connector attempts to retrieve this automatically, specifying this explicitly is recommended if you have more than Cloud Object Storage account.

     When you connect, the connector completes the OAuth process.

     1. Extracts the access token and authenticates requests.
     2. Saves OAuth values in OAuthSettingsLocation to be persisted across connections.

     Built-in Connection String Designer

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

     java -jar cdata.jdbc.ibmcloudobjectstorage.jar

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

     A typical JDBC URL is below:

     jdbc:ibmcloudobjectstorage:ApiKey=myApiKey;CloudObjectStorageCRN=MyInstanceCRN;Region=myRegion;OAuthClientId=MyOAuthClientId;OAuthClientSecret=myOAuthClientSecret;

Connect Hibernate to IBM Cloud Object Storage Data

Follow the steps below to select the configuration you created in the previous step.

1. Switch to the Hibernate Configurations perspective: Window -> Open Perspective -> Hibernate.
2. Right-click on the Hibernate Configurations panel and click Add Configuration.
3. Set the Hibernate version to 5.2.
4. Click the Browse button and select the project.
5. For the Configuration file field, click Setup -> Use Existing and select the location of the hibernate.cfg.xml file (inside src folder in this demo).
6. In the Classpath tab, if there is nothing under User Entries, click Add External JARS and add the driver jar once more. Click OK once the configuration is done.
7. Expand the Database node of the newly created Hibernate configurations file.

Reverse Engineer IBM Cloud Object Storage Data

Follow the steps below to generate the reveng.xml configuration file. You will specify the tables you want to access as objects.

1. Switch back to the Package Explorer.
2. Right-click your project, select New -> Hibernate -> Hibernate Reverse Engineering File (reveng.xml). Click Next.
3. Select src as the parent folder and click Next.
4. In the Console configuration drop-down menu, select the Hibernate configuration file you created above and click Refresh.
5. Expand the node and choose the tables you want to reverse engineer. Click Finish when you are done.

Configure Hibernate to Run

Follow the steps below to generate plain old Java objects (POJO) for the IBM Cloud Object Storage tables.

1. From the menu bar, click Run -> Hibernate Code Generation -> Hibernate Code Generation Configurations.
2. In the Console configuration drop-down menu, select the Hibernate configuration file you created in the previous section. Click Browse by Output directory and select src.
3. Enable the Reverse Engineer from JDBC Connection checkbox. Click the Setup button, click Use Existing, and select the location of the hibernate.reveng.xml file (inside src folder in this demo).
4. In the Exporters tab, check Domain code (.java) and Hibernate XML Mappings (hbm.xml).
5. Click Run.

One or more POJOs are created based on the reverse-engineering setting in the previous step.

Insert Mapping Tags

For each mapping you have generated, you will need to create a mapping tag in hibernate.cfg.xml to point Hibernate to your mapping resource. Open hibernate.cfg.xml and insert the mapping tags as so:

Execute SQL

Using the entity you created from the last step, you can now search IBM Cloud Object Storage data: import java.util.*; import org.hibernate.Session; import org.hibernate.cfg.Configuration; import org.hibernate.query.Query; public class App { public static void main(final String[] args) { Session session = new Configuration().configure().buildSessionFactory().openSession(); String SELECT = "FROM Objects O WHERE Bucket = :Bucket"; Query q = session.createQuery(SELECT, Objects.class); q.setParameter("Bucket","someBucket"); List<Objects> resultList = (List<Objects>) q.list(); for(Objects s: resultList){ System.out.println(s.getKey()); System.out.println(s.getEtag()); } } }