Integrate the SAP BTP Application with SAP Business One

In this section, you enhance Poetry Slam Manager, your SAP BTP solution, to make sure that it supports SAP Business One as the back end.

Front-end integration:

Navigate from Poetry Slams to related SAP Business One purchase orders.

Back-channel integration:

Create SAP Business One purchase orders from Poetry Slams and display purchase order information on the object page of a poetry slam using OData APIs with principal propagation.

Enhance the Core Application for ERP Integration

In this section, you learn how to import the SAP Business One OData service as a "remote service" into your SAP Cloud Application Programming Model (CAP) project and how to use the OData service to create SAP Business One purchase orders to allow the procurement of anything required for the organization or staging of your poetry slams.

You keep the core of your multi-tenant application, which you developed in the previous tutorials, and add changes for the ERP integration.

Note: Your solution is now in a good state to save a version of your implementation in your version control system, which enables you to go back to the multi-tenant application without ERP integration at any time.

Import SAP Business One OData Service

The SAP Business One OData service is consumed by using a destination. SAP Cloud Application Programming Model uses a one-to-one binding of remote services and destinations. To propagate the logged-in business user to SAP Business One, an OAuth 2.0 SAML Bearer authentication is used. This way, the SAP Business One OData service for purchase orders considers the user authorizations.

Run the $metadata URL of the SAP Business One OData service in a browser window: https://<service-layer server>/b1s/v2/$metadata
Save the service response payload with the metadata with file extension .edmx:
- File b1_sbs_v2.edmx for user propagation
Note: Ensure a unique file name without special characters except "_".

Note: The response contains many entities, which you don't require for this integration scenario. It's sufficient to use a self-contained excerpt of the complete $metadata file. For the example described here, you can use the file b1_sbs_v2.edmx.
In SAP Business Application Studio, to import the SAP Business One OData service into the SAP Cloud Application Programming Model (CAP) project, create a folder with the name external_resources in the root folder of the application.
Open the context menu of the ./external_resources folder and upload the .edmx file with the OData service.
Open a terminal and ensure that you're in the root folder of the application. Import the .edmx file using the command cds import ./external_resources/b1_sbs_v2.edmx --as cds.

Note: Don't use the CDS import command parameter --keep-namespace because it would result in the CDS service name cust, which would lead to service name clashes if you import multiple SAP Business One custom OData services.

After the command is executed, the file app/poetryslams/package.json is updated with a CDS configuration referring to the remote OData service, and a folder with path ./srv/external is created. The folder contains the configuration files for the remote services.

Note: Typically, remote services don't require any persistency. Make sure the entities in the corresponding CDS files in the folder ./srv/external are annotated with @cds.persistence.skip : true. You may encounter errors during the deployment with the db-deployer service if the persistency-skip-annotation is missing.

Enhance the Entity Model to Store Key Purchase Order Information

In SAP Business Application Studio, enhance the SAP Cloud Application Programming Model entity models in the file /db/poetrySlamManagerModel.cds with elements to store purchase order key information, which makes it possible to associate poetry slams to purchase orders in the remote ERP systems.

Enhance the entity PoetrySlams with the following elements:

purchaseOrderID       : String;
purchaseOrderObjectID : String;
purchaseOrderURL      : String;
purchaseOrderSystem   : String;

Enhance the annotations of entity PoetrySlams with the following elements:

purchaseOrderID       @title: '{i18n>purchaseOrderID}';
purchaseOrderObjectID @title: '{i18n>purchaseOrderObjectID}' @readonly;
purchaseOrderURL      @title: '{i18n>purchaseOrderURL}'      @readonly;
purchaseOrderSystem   @title: '{i18n>purchaseOrderSystem}'   @readonly;

Enhance the labels of the entity PoetrySlams in the file /db/i18n/i18n.properties with the labels:
```
purchaseOrderID       = Purchase Order
purchaseOrderObjectID = Purchase Order Internal ID
purchaseOrderURL      = Purchase Order URL
purchaseOrderSystem   = Purchase Order System Type
```
In the reference example, the /db/i18n/i18n_de.properties file with the German texts is available, too. You can take them over accordingly.

Enhance the Service Model With the Remote Service

To extend the SAP Cloud Application Programming Model service model by remote entities, open the file /srv/poetryslam/poetrySlamService.cds with the service models.

Expose SAP Business One purchase order data throughout the SAP Cloud Application Programming Model service model for principal propagation:

// -------------------------------------------------------------------------------
// Extend service PoetrySlamService by SAP Business One Purchase Orders

using {b1_sbs_v2 as RemoteB1} from '../external/b1_sbs_v2';

extend service PoetrySlamService with {
entity B1PurchaseOrder                as
    projection on RemoteB1.PurchaseOrders {
    key DocEntry     as docEntry,
        DocNum       as docNum,
        DocType      as docType,
        DocDate      as docDate,
        DocDueDate   as docDueDate,
        CreationDate as creationDate,
        CardCode     as cardCode,
        CardName     as cardName,
        DocTotal     as docTotal,
        DocCurrency  as docCurrency
    }
}

Enhance the service model of the service PoetrySlamService with virtual elements to pass on the name of the ERP system from the destination to the UI, and the visualization of actions:

// Poetry Slams (draft enabled)
@odata.draft.enabled
@Common.SemanticObject: 'poetryslams'
@Common.SemanticKey   : [ID]
entity PoetrySlams                    as
    select from poetrySlamManagerModel.PoetrySlams
    into {
        // Selects all fields of the PoetrySlams domain model,
        *,
        maxVisitorsNumber - freeVisitorSeats as bookedSeats                  : Integer @title     : '{i18n>bookedSeats}',
        // Relevant for coloring of status in UI to show criticality
        virtual null                         as statusCriticality            : Integer @title     : '{i18n>statusCriticality}',
        // SAP Business One purchase order: visibility of button "Create Purchase Order in SAP Business One"
        virtual null                         as createB1PurchaseOrderEnabled : Boolean @odata.Type: 'Edm.Boolean',
        virtual null                         as purchaseOrderSystemName      : String  @title     : '{i18n>purchaseOrderSystemName}'  @odata.Type: 'Edm.String',
        virtual null                         as isB1                         : Boolean @odata.Type: 'Edm.Boolean',
        toB1PurchaseOrder
    }

Enhance the service model of the service *PoetrySlamService * with an association to the remote purchase order in SAP Business One:

// Poetry Slams (draft enabled)
@odata.draft.enabled
@Common.SemanticObject: 'poetryslams'
@Common.SemanticKey   : [ID]
entity PoetrySlams as select from poetrySlamManagerModel.PoetrySlams
    mixin {
        // SAP Business One purchase orders: Mix-in of SAP Business One Purchase Order Data
        toB1PurchaseOrder : Association to RemoteB1.PurchaseOrders
                                on toB1PurchaseOrder.DocNum = $projection.purchaseOrderID;
    }

Enhance the service model of the service PoetrySlamService with an action to create remote purchase orders:

// SAP Business One purchase order: action to create a purchase order in SAP Business One
@(
    Common.SideEffects             : {TargetEntities: [
        '_poetryslam',
        '_poetryslam/toB1PurchaseOrder'
    ]},
    cds.odata.bindingparameter.name: '_poetryslam'
)
action createB1PurchaseOrder() returns PoetrySlams;

Note: The side effect annotation refreshes the purchase order data right after executing the action.

Enhance the Authentication Model to Cover Remote Purchase Orders

To extend the authorization annotation of the SAP Cloud Application Programming Model service model by restrictions referring to the remote services, open the file /srv/poetryslam/poetrySlamServiceAuthorizations.cds with the authorization annotations.

Enhance the authorization model for the service entity B1PurchaseOrder.

// SAP Business One purchase orders: Managers can read and create remote purchase orders
annotate PoetrySlamService.B1PurchaseOrder with @(restrict: [{
    grant: ['*'],
    to   : 'PoetrySlamFull',
}]);

Create Files with Reuse Functions for the ERP System Integration

You can define reuse functions that handle the connection for the different Enterprise Resource Planning (ERP) systems in separate files.

Create a file to check and get the destinations in path /srv/poetryslam/util/destination.js.
Add the functions readDestination, getDestinationURL, and getDestinationDescription from the file /srv/poetryslam/util/destination.js.

Note: The reuse functions readDestination, getDestinationURL, and getDestinationDescription are designed to work for single-tenant and for multi-tenant deployments. For single-tenant deployments, they read the destination from the SAP BTP subaccount that hosts the app, and for multi-tenant deployments, they read the destination from the subscriber subaccount. This system behavior is achieved by passing the JSON Web Token of the logged-in user to the function to get the destination. The JSON Web Token contains the tenant information.

Note: The reuse function getDestinationDescription returns the destination description from the SAP BTP consumer subaccount.
Since the npm module @sap-cloud-sdk/connectivity is used in the file destination.js, add the corresponding npm modules to your project. To do so, open a terminal and run the commands:
1. npm add @sap-cloud-sdk/connectivity
2. npm add @sap-cloud-sdk/http-client
The dependencies are added to the dependencies section in the package.json file.
Create a file with the path /srv/poetryslam/connector/connector.js. This file is reused for different ERP integrations.
Copy the ERP connection reuse functions in the file /srv/poetryslam/connector/connector.js into your project. It delegates the OData requests and holds the destinations.

Create a File with Functions for SAP Business One

Reuse functions specific to SAP Business One are defined in a separate file.

Create a file with the path /srv/poetryslam/connector/connectorB1.js.
Copy the SAP Business One-related functions in the file /srv/poetryslam/connector/connectorB1.js into your project. The file contains functions to delegate OData requests to SAP Business One, to read SAP Business One purchase order data, and to assemble an OData payload to create SAP Business One purchase orders.

Note: This file contains sample data, which can vary depending on the system. Check the data set and maintain it accordingly to ensure consistency between the Partner Reference App and SAP Business One. The sample data is marked with a block comment Purchase order data for SAP Business One; needs to be adopted according to SAP Business One configuration of the customer system.

Enhance the Business Logic to Operate on SAP Business One Data

Enhance the implementation of the SAP Cloud Application Programming Model services to create and read SAP Business One purchase order data using the remote SAP Business One OData service.

Delegate requests to the remote OData service.

Create a new file srv/poetryslam/poetrySlamServiceERPImplementation.js in your project.

Copy the following code snippet into the newly created file. As a reference you can have a look at the file poetrySlamServiceERPImplementation.js in the reference application.

'strict';

// Add connector for project management systems
const ConnectorB1 = require('./connector/connectorB1');

module.exports = async (srv) => {
    // ----------------------------------------------------------------------------
    // Implementation of remote OData services (back-channel integration with SAP Business One)
    // ----------------------------------------------------------------------------

    // Delegate OData requests to SAP Business One remote purchase order entities
    srv.on(
        ['READ', 'CREATE', 'UPDATE', 'DELETE'],
        'B1PurchaseOrder',
        async (req) => {
        const connector = await ConnectorB1.createConnectorInstance(req);
        return await connector.delegateODataRequests(
            req,
            ConnectorB1.PURCHASE_ORDER_SERVICE
        );
        }
    );
}

Note: Without delegation, the remote entities return the error code 500 with the message: SQLITE_ERROR: no such table (local testing).

Enhance the /srv/poetryslam/poetrySlamServiceImplementation.js to call the ERP implementation.
1. Import the ERP forward handler.
```
const erpForwardHandler = require('./poetrySlamServiceERPImplementation');
```
1. Call the ERP forward handler.
```
erpForwardHandler(srv); // Forward handler to the ERP systems
```

In the file /srv/poetryslam/poetrySlamServicePoetrySlamsImplementation.js, the poetry slams entity is enriched with SAP Business One-specific data.

Determine the connected back-end systems and read the purchase order data from the remote system. Set the virtual element createB1PurchaseOrderEnabled to control the visualization of the action to create purchase orders dynamically and pass on the purchase order system name.

// Expand poetry slams
srv.on('READ', ['PoetrySlams.drafts', 'PoetrySlams'], async (req, next) => {
    // Read the PoetrySlams instances
    let poetrySlams = await next();

    // In case none of these enriched fields are requested, we do not need to read from the external services
    // So we first check if the requested columns contain any of the enriched columns and return if not
    const requestedColumns = req.query.SELECT.columns?.map((item) =>
    Array.isArray(item.ref) ? item.ref[0] : item.as
    );

    const enrichedFields = [
        'purchaseOrderSystemName',
        'createB1PurchaseOrderEnabled',
        'isB1',
        'toB1PurchaseOrder'
    ];

    if (
        requestedColumns &&
        !enrichedFields.some((item) => requestedColumns?.includes(item))
    ) {
        return poetrySlams;
    }

    // The requested columns include some of the enriched fields, so we do add the corresponding data

    // SAP Business One
    // Check and read SAP Business One purchase order data
    const connectorB1 = await ConnectorB1.createConnectorInstance(req);
    if (connectorB1?.isConnected()) {
        poetrySlams = await connectorB1.readPurchaseOrder(poetrySlams);
    }

    for (const poetrySlam of convertToArray(poetrySlams)) {
        [
            'purchaseOrderSystemName'
        ].forEach((item) => {
            poetrySlam[item] = poetrySlam[item] || '';
        });

        // Update PO system name and visibility of the "Create Purchase Order"-button
        if (poetrySlam.purchaseOrderID) {
            poetrySlam.createB1PurchaseOrderEnabled = false;
            poetrySlam.purchaseOrderSystemName = connectorB1.getSystemName();
        } else {
            poetrySlam.createB1PurchaseOrderEnabled = connectorB1.isConnected();
        }

        // Update the backend system connected indicator used in the UI for controlling the visibility of UI elements
        poetrySlam.isB1 = connectorB1.isConnected();
    }

    // Return remote data
    return poetrySlams;
});

Note: The connector creates destinations called b1 and b1-url, which connect to the ERP system. You create the destinations later on in the consumer subaccount in SAP BTP.

Add the implementation of the action createB1PurchaseOrder:

Copy the method createB1PurchaseOrder into the implementation.

//---------------------------------------------------------------------------
// Implementation of entity events (entity PoetrySlams)
// with impact on remote services of SAP Business One
//---------------------------------------------------------------------------

// Entity action: Create SAP Business One Purchase Order
srv.on('createB1PurchaseOrder', async (req) => {
    await createPurchaseOrder(
    req,
    srv,
    ConnectorB1,
    'ACTION_CREATE_PURCHASE_ORDER_NO_B1_SYSTEM'
    );
});

Add the import of the connector at the beginning of the file:
```
const ConnectorB1 = require('./connector/connectorB1');
```

Import the createPurchaseOrder function from the entityCalculations.

const {
    calculatePoetrySlamData,
    updatePoetrySlam,
    convertToArray,
    createPurchaseOrder
} = require('./util/entityCalculations');

Extend the on-update event of the PoetrySlams entity with an implementation to clear all purchase order data if the purchaseOrderID is deleted:

srv.on('UPDATE', ['PoetrySlams.drafts', 'PoetrySlams'], async (req, next) => {
    ...

    // Remove all purchase order data if the purchase order id is cleared
    if (req.data.purchaseOrderID === '') {
        req.data.purchaseOrderID = null;
        req.data.purchaseOrderObjectID = null;
        req.data.purchaseOrderURL = null;
        req.data.purchaseOrderSystem = null;
        req.data.purchaseOrderSystemName = null;
    }

    ...
});

Copy the function createPurchaseOrder from the file /srv/poetryslam/util/entityCalculations.js into the implementation and export the function at the end of the file.

Add the system messages to the file /srv/i18n/messages.properties.

In the reference example, the /srv/i18n/messages_de.properties file with the German texts is available too. You can take them over accordingly.

ACTION_CREATE_PURCHASE_ORDER_DRAFT                      = Purchase orders cannot be created for draft Poetry Slams.
ACTION_CREATE_PURCHASE_ORDER_NO_B1_SYSTEM               = No SAP Business One system connected. Purchase order cannot be created.
ACTION_CREATE_PURCHASE_ORDER_FAILED                     = Purchase order creation failed. Poetry Slam {0} was not updated.
ACTION_READ_PURCHASE_ORDER_CONNECTION                   = Purchase order cannot be retrieved.

Enhance the Web App to Display SAP Business One Data

Adopt the SAP Fiori elements annotations of the web app in the file /app/poetryslams/annotations.cds.

Add purchase order annotations to the PoetrySlams entity:

purchaseOrderObjectID        @UI.Hidden;
createB1PurchaseOrderEnabled @UI.Hidden;
isB1                         @UI.Hidden;

Add a facet Purchase Order Data to display information from the remote service by following the toB1PurchaseOrder association:

Add facet:

{
    $Type        : 'UI.ReferenceFacet',
    Label        : '{i18n>purchaseOrderData}',
    ID           : 'PurchaseOrderData',
    Target       : '@UI.FieldGroup#PurchaseOrderData',
    ![@UI.Hidden]: {$edmJson: {$Not: {$Path: 'isB1'}}} // Display PurchaseOrderData only in case a SAP Business One system is connected
}

Add a field group #PurchaseOrderData:

FieldGroup #PurchaseOrderData : {Data: [
    // SAP Business One specific fields
    {
        $Type: 'UI.DataFieldWithUrl',
        Label: '{i18n>purchaseOrderID}',
        Value: purchaseOrderID,
        Url  : purchaseOrderURL
    },
    {
        $Type: 'UI.DataField',
        Label: '{i18n>purchaseOrderSystemName}',
        Value: purchaseOrderSystem
    },
    {
        $Type                  : 'UI.DataField',
        Label                  : '{i18n>deliveryDate}',
        Value                  : toB1PurchaseOrder.docDueDate,
        ![@Common.FieldControl]: #ReadOnly
    },
    {
        $Type                  : 'UI.DataField',
        Label                  : '{i18n>creationDate}',
        Value                  : toB1PurchaseOrder.creationDate,
        ![@Common.FieldControl]: #ReadOnly
    },
    {
        $Type                  : 'UI.DataField',
        Label                  : '{i18n>purchaseOrderValue}',
        Value                  : toB1PurchaseOrder.docTotal,
        ![@Common.FieldControl]: #ReadOnly
    },
    {
        $Type                  : 'UI.DataField',
        Label                  : '{i18n>purchaseOrderCurrency}',
        Value                  : toB1PurchaseOrder.docCurrency,
        ![@Common.FieldControl]: #ReadOnly
    },
]}

Extend the list page with a link to the purchase order:

// Definition of fields shown on the list page / table
LineItem                      : [
    ...,
    {
        $Type: 'UI.DataFieldWithUrl',
        Value: purchaseOrderID,
        Url  : purchaseOrderURL
    }
]

Add a button to the identification area:

// Create a purchase order in the connected SAP Business One system
{
    $Type        : 'UI.DataFieldForAction',
    Label        : '{i18n>createB1PurchaseOrder}',
    Action       : 'PoetrySlamService.createB1PurchaseOrder',
    ![@UI.Hidden]: {$edmJson: {$Not: {$And: [
        {$Path: 'createB1PurchaseOrderEnabled'},
        {$Path: 'IsActiveEntity'}
    ]}}}
}

Note: The visibility of the Create Purchase Order in SAP Business One button is dynamically controlled based on the value of the transient field createB1PurchaseOrderEnabled, which is calculated in the after read-event of the entity PoetrySlam.

In the srv folder, edit language-dependent labels in the file i18n.properties. Add labels for purchase order fields and the button to create purchase orders:

# -------------------------------------------------------------------------------------
# Transient Service Elements

purchaseOrderSystemName = Purchase Order System

# -------------------------------------------------------------------------------------
# Service Actions

createB1PurchaseOrder   = Create Purchase Order in SAP Business One

In the reference example, the /srv/i18n/i18n_de.properties file with the German texts is available too. You can take them over accordingly.

Edit the language-dependent labels of the poetryslams app in the file app/poetryslams/i18n.properties. Add a label for the facet and the added fields:
```
purchaseOrderData       = Purchase Order Data

deliveryDate            = Delivery Date
creationDate            = Creation Date
purchaseOrderValue      = Value
purchaseOrderCurrency   = Currency
```
In the reference example, the app/poetryslams/i18n/i18n_de.properties file with the German texts is available too. You can take them over accordingly.

Enhance the Configuration of the SAP Cloud Application Programming Model Project

Enhance the file package.json with development configurations for local testing and productive configurations. Ensure that the flag csrf and csrfInBatch is set in the file package.json to enable the management of cross-site request forgery tokens (required for POST requests at runtime) using destinations of the type:

"b1_sbs_v2": {
    "kind": "odata",
    "model": "srv/external/b1_sbs_v2",
    "csrf": true,
    "csrfInBatch": true,
    "[development]": {
        "credentials": {
            "url": "https://{{b1-hostname}}/b1s/v2",
            "authentication": "BasicAuthentication",
            "username": "{{test-user}}",
            "password": "{{test-password}}"
        }
    },
    "[production]": {
        "credentials": {
            "destination": "b1",
            "path": "/b1s/v2"
        }
    }
}

Note: The package.json refers to the destinations b1 that needs to be created in the consumer SAP BTP subaccount. The destination b1 refers to business users with principal propagation.

Note: For local testing, replace {{b1-hostname}}, {{test-user}}, and {{test-password}} with a system, user, and password from SAP Business One. The test-user is an object with company and username, e.g. User name = {"UserName": "{{user}}", "CompanyDB": "{{company}}"}. Don't push this information to your GitHub repository.

Test Locally

Open a terminal and start the app with the development profile using the run command cds watch --profile development.
Use the test users as listed in the file .cdsrc.json.

Note: If you would like to test with different users, clear the browser cache first.
Test the critical connection points to SAP Business One:
1. Test the Service Endpoint for B1PurchaseOrder: The system returns the respective data of SAP Business One (without filtering).
2. The Create Purchase Order in SAP Business One button is dependent on the setup of the destinations. Once the destinations are correctly configured and the application is deployed to SAP BTP Cloud Foundry runtime, the Create Purchase Order in SAP Business One button will be active. To test this button locally, in connectorB1.js, method createConnectorInstance, change the value of connector.isConnectedIndicator to true after the connector instance is created:
```
const connector = new ConnectorB1(data);
connector.isConnectedIndicator = true;
```
  Note: This change is required as the isConnectedIndicator value is dependent on the setup of destinations. Destinations only work on a deployed application and cannot be tested locally.
Open the /poetryslams/webapp/index.html web application and open one of the poetry slams.
Choose Create Purchase Order in SAP Business One. The system creates a purchase order in SAP Business One and displays the details in the Purchase Order Data section.

Note: The link to the purchase order won't work in a local application. To test the full integration including navigation to the SAP Business One system, you will have to test with the deployed application.

Deploy the Application

Update your application in the provider subaccount. For detailed instructions, refer to the section Deploy the Multi-Tenant Application to a Provider Subaccount.

Note: Make sure any local changes have been reverted before deployment.

You have now successfully deployed the application to the provider subaccount and you're ready to provision tenants of the multi-tenant application to customers and connect with SAP Business One.

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33a-B1-Integration.md

33a-B1-Integration.md

Integrate the SAP BTP Application with SAP Business One

Enhance the Core Application for ERP Integration

Import SAP Business One OData Service

Enhance the Entity Model to Store Key Purchase Order Information

Enhance the Service Model With the Remote Service

Enhance the Authentication Model to Cover Remote Purchase Orders

Create Files with Reuse Functions for the ERP System Integration

Create a File with Functions for SAP Business One

Enhance the Business Logic to Operate on SAP Business One Data

Enhance the Web App to Display SAP Business One Data

Enhance the Configuration of the SAP Cloud Application Programming Model Project

Test Locally

Deploy the Application

Files

33a-B1-Integration.md

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33a-B1-Integration.md

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Integrate the SAP BTP Application with SAP Business One

Enhance the Core Application for ERP Integration

Import SAP Business One OData Service

Enhance the Entity Model to Store Key Purchase Order Information

Enhance the Service Model With the Remote Service

Enhance the Authentication Model to Cover Remote Purchase Orders

Create Files with Reuse Functions for the ERP System Integration

Create a File with Functions for SAP Business One

Enhance the Business Logic to Operate on SAP Business One Data

Enhance the Web App to Display SAP Business One Data

Enhance the Configuration of the SAP Cloud Application Programming Model Project

Test Locally

Deploy the Application