Build an SAP CAP Application to Access SAP HANA Cloud, data lake Relational Engine

1. From SAP HANA Cloud Central, open your SAP HANA database in Database Explorer by choosing Open in SAP HANA Database Explorer.

   If you have not previously opened the database in Database Explorer, you will need to login using the DBADMIN credentials specified upon the creation of your HANA database.
   

   

2. Within Database Explorer as DBADMIN, run the following SQL script to create a new user HDB_BOOKSHOP_USER and a relational container BOOKSHOP_CONTAINER in the attached HANA-managed data lake Relational Engine instance owned by HDB_BOOKSHOP_USER. and a new schema BOOKSHOP. This script also grants privileges on the BOOKSHOP SCHEMA to the HDB_BOOKSHOP_USER.

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   -- Create a new user called HDB_BOOKSHOP_USER
   CREATE USER HDB_BOOKSHOP_USER PASSWORD Password1 NO FORCE_FIRST_PASSWORD_CHANGE SET USERGROUP DEFAULT;
   -- Create a Relational Container in the attached HANA-managed HDLRE instance
   CALL SYSHDL.CREATE_CONTAINER('BOOKSHOP_CONTAINER', 'HDB_BOOKSHOP_USER');
   

   

   Then, create a new schema BOOKSHOP, and grant schema privileges on BOOKSHOP schema to the HDB_BOOKSHOP_USER.

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   -- Create a new schema
   CREATE SCHEMA BOOKSHOP;
   -- Grant all BOOKSHOP schema privileges to HDB_BOOK_USER
   GRANT ALL PRIVILEGES ON SCHEMA BOOKSHOP TO HDB_BOOKSHOP_USER WITH GRANT OPTION;
   

   

3. You will now create database objects in the BOOKSHOP schema in the HANA-managed data lake Relational Engine that map to objects in the HANA database. These commands will be executed as the HDB_BOOKSHOP_USER as the owner of the relational container created in the previous step.

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   -- Connect as the HDB_BOOKSHOP_USER
   CONNECT HDB_BOOKSHOP_USER PASSWORD Password1;
   
   -- Create a virtual table in HANA that maps to a table in the attached HANA-managed HDLRE instance, also created here
   CREATE VIRTUAL TABLE BOOKSHOP.BOOK_REVIEWS (
       REVIEW_ID INTEGER PRIMARY KEY,
       BOOK_ID INTEGER NOT NULL,
       RATING INTEGER NOT NULL,
       REVIEW VARCHAR(500) NOT NULL
   ) AT "SYSHDL_BOOKSHOP_CONTAINER_SOURCE"."NULL"."SYSHDL_BOOKSHOP_CONTAINER"."BOOK_REVIEWS" WITH REMOTE;
   
   -- Insert sample data into the virtual table
   INSERT INTO BOOKSHOP.BOOK_REVIEWS(REVIEW_ID, BOOK_ID, RATING, REVIEW) VALUES(1, 1, 5, 'I loved reading this novel since I love mysteries.');
   INSERT INTO BOOKSHOP.BOOK_REVIEWS(REVIEW_ID, BOOK_ID, RATING, REVIEW) VALUES(2, 12, 4, 'This was a good fantasy book, but not as realistic as I had hoped.');
   INSERT INTO BOOKSHOP.BOOK_REVIEWS(REVIEW_ID, BOOK_ID, RATING, REVIEW) VALUES(3, 7, 3, 'This book was slow but an interesting read overall.'); 
   INSERT INTO BOOKSHOP.BOOK_REVIEWS(REVIEW_ID, BOOK_ID, RATING, REVIEW) VALUES(4, 3, 5, 'I could not put this book down. I truly get why this is a classic.');
   INSERT INTO BOOKSHOP.BOOK_REVIEWS(REVIEW_ID, BOOK_ID, RATING, REVIEW) VALUES(5, 12, 3, 'I wish there was more action and less romance.');
   

   

   For additional details consult Creating Virtual Tables

4. Query the local SAP HANA table and the equivalent SAP HANA Cloud, data lake Relational Engine table. Note that both results should be identical.

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   SELECT * FROM BOOKSHOP.BOOK_REVIEWS;
   SELECT * FROM SYSHDL_BOOKSHOP_CONTAINER.BOOK_REVIEWS;
   

   

1. In SAP BTP Cockpit, navigate to the Service Marketplace at the subaccount level.

   

   Search for SAP Business Application Studio and launch the application by clicking the Go to Application button.

   

2. Within Business Application Studio, create a Full Stack Cloud Application dev space with the following three additional SAP Extensions: SAP HANA Calculation View Editor, SAP HANA Performance Tools, SAP HANA Tools.

   

   Your dev space is created instantly and automatically started, which can take a minute or so.

3. Once it is running, click on the name of your dev space to open it.

   

1. Before you create an application, you will need to sign in to Cloud Foundry. Navigate to the Cloud Foundry page using the left menu bar.
   

   

   Expand the Services directory and click the circled arrow icon to open the Cloud Foundry sign in page.

   

   Sign in using SSO and select the correct organization and space where your HANA database is located.

   

   Ensure to click Apply to save your organization and space targets.

   

2. Navigate to the Explorer page using the left menu bar and select Create Project to create a new project using a template.

   

3. Use the CAP Project template and select Start to open the project creation wizard using the CAP template.

   

4. Name your project My_HDL_CAP_Project and ensure your project uses the Node.js runtime environment, all available features, and includes basic sample files. Click Finish to create your project.

   

1. To specify the specific pre-existing SAP HANA database you would like to configure your CAP application with, you will need to provide the instance ID, which can be found in SAP HANA Cloud Central.
   In HANA Cloud Central, copy the Instance ID of your SAP HANA database.

   

2. In your project workspace in Business Application Studio, right click on the mta.yaml file and select Open With….

   

   Select Text Editor.

   

3. Under the resources header, edit the file to add your instance ID from your clipboard.

   

4. Next, you will create the service instance which will connect to our specified HANA database.

   In your project workspace under SAP HANA PROJECTS, select the icon to add a new database connection.

   

5. Create a user-provided service instance and provide the information for the HDB_BOOKSHOP_USER created in a previous step.

   Ensure you use the BOOKSHOP schema since this is where the BOOK_REVIEWS table is located in our HANA database.

   Additionally, check the box to generate hdbgrants file which will give the runtime user the same permissions as HDB_BOOKSHOP_USER in the BOOKSHOP schema.

   

6. Once the service is created and bound, you will be able to see it in the workspace under SAP HANA PROJECTS.

   

7. Next you will create an HDI container within your existing SAP HANA database.

   

   Select Bind to an HDI container and Create a new service instance. Call the container My_CAP_HDI_Container.

   You will receive the following two notifications once your service instance has been created and bound to your project.

8. Create an hdbsynonym by opening the Command Palette.

   

9. Search for SAP HANA: Create SAP HANA Database Artifact. Select the artifact type as Synonym (hdbsynonym) and name the synonym MY_BOOKSHOP_BOOK_REVIEWS_SYNONYM.

   

10. Open the file MY_BOOKSHOP_BOOK_REVIEWS_SYNONYM.hdbsynoym and click on … under the Object Name column.

11. Ensure the connection My_HANA_Connection is selected, and select the BOOKSHOP.BOOK_REVIEWS table.
    
    

12. Open the data-model.cds file and replace the contents with the following code.

    data-model.cds

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    namespace MY.BOOKSHOP;
    
    entity Books {
    key ID : Integer;
    title  : String;
    stock  : Integer;
    }
    
    @cds.persistence.exists
    entity BOOK_REVIEWS_SYNONYM {
    key REVIEW_ID  : Integer;
        BOOK_ID    : Integer;
        RATING     : Integer;
        REVIEW : String(500)
    }
    

    

13. Open the cat-service.cds file and replace the contents with the following code.

    cat-service.cds

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    using MY.BOOKSHOP as my from '../db/data-model';
    
    service CatalogService {
        @readonly entity Books as projection on my.Books;
        @readonly entity BOOK_REVIEWS_SYNONYM as projection on my.BOOK_REVIEWS_SYNONYM;
    }
    

    

14. Deploy the project using the rocket icon.
    

    

15. In the left navigation menu, navigate to Run Configurations and create a new configuration. Select your current project and name the configuration using the default name.
    

    

16. Bind the configuration to your HDI container, My_HANA_HDI_Container, by clicking the bind icon and selecting the HDI container.

    

17. Then, run the configuration by clicking the bind icon.

    

18. You will be prompted to open a service in a new tab. Click Open in a New Tab.

    

19. Select Fiori preview for the BOOK_REVIEWS table.

    

20. Click the gear icon to open the table settings.

    

    Ensure all the columns are selected.

    

21. You are now able to view the data in the BOOK_REVIEWS table.

    

Congratulations! You have now created a CAP application that connects to and queries an SAP HANA-managed, SAP data lake, Relational Engine database.