SAP BTP, ABAP environment, SAP Business Application Studio, OData

Connecting Multiple Databases and OData Services to SAP BTP using BAS

David Miller

Introduction

In this post, I will explain how to connect multiple databases and OData services to SAP BTP using BAS . This guide covers configuring UI5 applications to consume multiple OData services from both SAP S/4HANA (on-premise) and SAP BTP ABAP environment, ensuring seamless data integration.

Context

I aim to integrate three different OData services from different database sources :

  1. On-Premise S/4HANA OData V2 Services
    • ZPR_EMP_DETAILS_SRV : Fetches employee details.
    • ZFI_TEST_ODATA_SRV : Fetches financial data.
  2. SAP BTP ABAP Environment OData V4 Service
    • ZUI_TAB_TRAVDAT_O4_AKS_001: Fetches travel-related data using the RAP Model.

Steps to Connect Multiple OData Services

Step 1: Add Data Sources in UI5 Application

  1. Create a UI5 application in VS Code.
  2. While creating the application, provide the service URL to configure an OData service automatically.
  3. Navigate to webapp/manifest.json.
  4. Modify the dataSources section to include multiple OData services as follows:
"dataSources": {
  "mainService": {
    "uri": "/sap/opu/odata/sap/ZPR_EMP_DETAILS_SRV/",
    "type": "OData",
    "settings": {
      "odataVersion": "2.0"
    }
  },
  "subService": {
    "uri": "/sap/opu/odata/sap/ZFI_TEST_ODATA_SRV/",
    "type": "OData",
    "settings": {
      "odataVersion": "2.0"
    }
  },
  "rapService": {
    "uri": "/sap/opu/odata4/sap/zui_tab_travdat_o4_aks_001/",
    "type": "OData",
    "settings": {
      "odataVersion": "4.0"
    }
  }
}

Step 2: Configure Models in manifest.json

Each model corresponds to an OData service:

"models": {
  "": {
    "dataSource": "mainService",
    "preload": true,
    "settings": {}
  },
  "subModel": {
    "dataSource": "subService",
    "preload": true,
    "settings": {}
  },
  "rapModel": {
    "dataSource": "rapService",
    "preload": true,
    "settings": {
      "operationMode": "Server",
      "autoExpandSelect": true,
      "earlyRequests": true
    }
  }
}

Step 3: Configure ui5.yaml for Backend Connections

In ui5.yaml, configure the destinations for OData services:

server:
  customMiddleware:
    - name: ui5-middleware-simpleproxy
      afterMiddleware: compression
      configuration:
      ui5:
          path:
            - /resources
            - /test-resources
          url: https://ui5.sap.com
        backend:
# On-premise SAP System Destination 1 - Replace with your URL
        - scp: true
        path: /sap/opu/odata/sap/ZPR_EMP_DETAILS_SRV/
        url: https://your-onpremise-system-hostname:port/
        destination: SAHANA_CONN
        client: 'your client ID'
        authenticationType: BasicAuthentication

  # On-premise SAP System Destination 2 - Replace with your URL  
        - scp: true
        path: /sap/opu/odata/sap/ZFI_TEST_ODATA_SRV
        url: https://your-onpremise-system-hostname:port/
        destination: SAHANA_CONN
        client: 'your client ID'
        authenticationType: BasicAuthentication

  # SAP BTP ABAP Environment Destination - Replace with your instance URL
        - scp: true
        path: /sap/opu/odata/sap/zui_tab_travdat_o4_aks_001/
        url: https://your-abap-instance-guid.abap.region.hana.ondemand.com
        destination: abap-cloud-default_abap-trial-9a87acc7trial-dev
        client: 'your client ID'
        authenticationType: OAuth2UserTokenExchange

Destination:

S4HANA_CONN is used for two OData V2 services hosted in the on-premise S/4HANA system as shown in below screenshot.

abap-cloud-default_abap-trial-9a87ace7trial-dev is for the RAP-based OData V4 service hosted on SAP BTP as shown in below screenshot.

Authentication Types:

  • On-premise S/4HANA services use BasicAuthentication, which is simpler but less secure for cloud-based scenarios.
  • The SAP BTP service uses OAuth2UserTokenExchange, enabling secure token-based communication.

All the Connected OData will be Listed in Service Manager as shown in below screenshot.

Important Note on OData Connection Methods:

Avoid connecting directly to OData services via the Service Manager, as it can lead to data inconsistency issues (e.g., all requests may unintentionally retrieve only the last edited destination). Instead, I prefer using the Destination Service (as shown in the configuration above) for:

  • Stable & secure connections
  • Proper authentication handling (Basic/OAuth2)
  • Consistent data retrieval (prevents mixing/overwriting datasets).

Conclusion

By following these steps, you can successfully integrate multiple OData services in a SAP BTP-based Fiori application. This setup allows seamless data flow between on-premise S/4HANA and cloud-based SAP BTP ABAP environment, ensuring a modern, scalable architecture.

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