Use SAP HANA as the Database for a CAP Java Application

1. In SAP Business Application Studio, open a terminal by choosing Terminal → New Terminal from the main menu.

2. Authenticate using your login credentials using the following command in the terminal:

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   cf login
   

   Should you need to specify the <CF_API_ENDPOINT> again, use the actual value you obtained in the previous tutorial.

Add an additional Maven dependency to your project. The dependency brings the ability to read SAP HANA service bindings and configure the SAP HANA connectivity.

In a previous tutorial, you already added the cds-starter-cloudfoundry dependency in your srv/pom.xml. In this case you can skip the following and go to the next step.

1. Navigate back to the File Explorer by clicking on the corresponding icon.

2. Edit the pom.xml in the srv directory (not the pom.xml file located in the root project folder) and add the following dependency under the <dependencies> tag and make sure you Save the file:

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   <dependency>
       <groupId>com.sap.cds</groupId>
       <artifactId>cds-feature-hana</artifactId>
   </dependency>
   

Assuming you don’t want to use the same service instance as you created during your deployment, you’re creating a new service instance with the same data for your hybrid test cycles here. If you want to use the recently deployed one, use bookstore-db instead of bookstore-hana in the following.

1. Go back to the terminal of SAP Business Application Studio and make sure that you are in the root of the bookstore project:

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   cd ~/projects/bookstore
   

2. Add the following configuration in the file .cdsrc.json in the root folder of your bookstore project:

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   {
     "hana" : {
       "deploy-format": "hdbtable"
     }
   }
   

   

3. Ensure your SAP HANA Cloud instance is started.

4. Create an SAP HANA service instance and implicitly push all artifacts to the database using:

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   cds deploy --to hana:bookstore-hana --store-credentials
   

   As an effect, .hdbtable and .hdbview files are generated in the (gen/)db/src/gen/ folder.

   In addition, the command initialized the database schemas inside the SAP HANA HDI container.

Aside from initializing the SAP HANA database, the cds deploy command created a file with the name default-env.json in your bookstore root folder. This file contains a set of credentials to connect to the SAP HANA HDI container, that was created by the command. CAP Java is able to automatically pick up the SAP HANA credentials from this file and configure the application running locally to use the SAP HANA HDI container as the database.

When deploying the application to the cloud, Cloud Foundry will provide the credentials as a service binding to the application through the Open Service Broker API. Also in this case, CAP Java will automatically pick up the SAP HANA credentials and configures the application for you as you will see in the next tutorial.

1. Before starting your application, make sure that you stop any running instances in the terminal or debug side panel.

2. Let’s test the SAP HANA connectivity. Start your application by running:

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   mvn spring-boot:run -Dspring-boot.run.profiles=cloud
   

   The Java system property -Dspring-boot.run.profiles=cloud ensures that the default configuration using H2 as the database, which is still defined in the application.yaml, doesn’t get activated.

   You can observe the log line Registered DataSource 'ds-bookstore-hana', which indicate that the SAP HANA configuration was picked up.

3. Open the file requests.http and execute one of the requests that create an order, by choosing Send Request above it.

4. Restart your application with the same command and browse to the Orders entity on the Welcome Page. You can see that the entries are persisted.

Congratulations!

You have successfully deployed your database schema to SAP HANA and connected your application, which is running locally. In the following tutorial, you will run the application on the SAP BTP, Cloud Foundry environment, using the SAP HANA service instance that was created in this tutorial.