How to Expose a CDS View as an OData Service for SAP BTP Applications

Exposing a CDS (Core Data Services) view as an OData service for SAP Business Technology Platform (BTP) applications can streamline data access and integration. Here’s a step-by-step guide to achieving this setup, including all essential concepts and procedures.

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1. Understand the Core Concepts

Before diving into the process, familiarize yourself with the fundamental components involved in exposing CDS views through OData:

  • Core Data Services (CDS): CDS views are virtual data models created on top of database tables, simplifying data access and making them ideal for use in applications.
  • OData Services: These RESTful APIs allow seamless data consumption in applications, especially those on SAP BTP, which natively supports OData.
  • SAP Gateway: The SAP Gateway is a crucial component for exposing and managing OData services in on-premise SAP systems.

2. Create the CDS View

Define a CDS view with necessary fields and join conditions. Here’s an example joining LFA1 (Vendor Master) and LFB1 (Company Code Data) tables:

@AbapCatalog.sqlViewName: 'ZVENDOR_CDS'
@AbapCatalog.compiler.compareFilter: true
@AccessControl.authorizationCheck: #NOT_REQUIRED
@EndUserText.label: 'CDS View for Vendor Data from LFA1 and LFB1'
@OData.publish: true

define view Z_VENDOR_DATA as select from lfa1
    inner join lfb1 on lfa1.lifnr = lfb1.lifnr
{
    key lfa1.lifnr        as Vendor,       // Vendor Number
    lfa1.name1            as VendorName,   // Vendor Name
    lfa1.ort01            as City,         // City
    lfb1.bukrs            as CompanyCode,  // Company Code
    lfb1.zuawa            as PaymentMethod // Payment Method
}

Key annotations in this example:

  • @OData.publish: true: Automatically generates an OData service for the CDS view.
  • key: Designates fields as key fields, crucial for data binding.

3. Activate the CDS View

Once your CDS view is defined, activate it. The @OData.publish: true annotation generates a corresponding OData service in the system, typically named with the CDS view name followed by _CDS.

4. Register the OData Service in SAP Gateway

To make this OData service accessible from external applications, register it in the SAP Gateway.

  • Go to SAP Gateway Service Builder (/IWFND/MAINT_SERVICE).
  • Select Add Service.
  • Choose your system alias and find the generated OData service (Z_VENDOR_DATA_CDS).
  • Select Add Selected Services, provide a package or save locally.

This registration makes the service available for testing and access.

5. Test the OData Service

After registration, it’s important to test your OData service:

  • Use SAP Gateway Client (/IWFND/GW_CLIENT) or an external tool like Postman.
  • Access the service URL:rubyCopy codehttps://<your_sap_system>/sap/opu/odata/sap/Z_VENDOR_DATA_CDS/
  • Test basic GET requests to ensure data is fetched as expected.

6. Connect the OData Service to SAP BTP

In SAP BTP, set up a connection to your SAP backend system to consume the OData service.

  • Create a Destination: In SAP BTP, configure a destination pointing to your SAP system. This setup involves:
    • URL: The OData service URL.
    • Authentication: Choose an appropriate authentication method.
    • Proxy Type: Select OnPremise if connecting through SAP Cloud Connector.
  • SAP Cloud Connector: If your OData service is hosted on-premise, configure the SAP Cloud Connector to securely link SAP BTP to your on-premise SAP system.

7. Consume the OData Service in SAP BTP Application

With your destination configured, use the OData service in SAP BTP applications:

  • SAP Fiori or SAP UI5 Applications: Bind data models in your app to the OData service using the destination you created.
  • API Calls: For applications that use custom logic, make API calls to the OData service URL to fetch data.

8. Manage Authorizations and Security

  • Authorization Checks: In CDS views, use @AccessControl.authorizationCheck to control data access as per roles assigned.
  • Roles and Permissions: Ensure users in both SAP Gateway and SAP BTP have appropriate roles to access the OData service.
  • Data Security: Consider encryption, secure authentication, and data masking techniques where necessary.

Key Concepts to Remember

  1. CDS Views: Ensure the CDS view is designed with all required fields, relationships, and filters.
  2. OData Protocol: Understand how RESTful API operations work with OData services.
  3. SAP Gateway: Essential for exposing and managing OData services on SAP systems.
  4. SAP BTP Destinations and Connectivity: Crucial for linking on-premise OData services with SAP BTP applications.
  5. Security and Authorization: Manage data access, ensure secure connections, and apply role-based access controls.

By following these steps, you can expose a CDS view as an OData service, register it in SAP Gateway, and securely consume it within an SAP BTP application. This integration empowers users to leverage SAP BTP’s cloud capabilities while accessing SAP data in real time.

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