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Get Data from a Remote System Using a Custom Entity

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Get Data from a Remote System Using a Custom Entity
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Get Data from a Remote System Using a Custom Entity

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Julie Plummer

06/12/2019

Advanced
45 min.
SAP Cloud Platform, ABAP environment, Tutorial, SAP Cloud Platform, Advanced, ABAP Development, Cloud
Get data from an on-Premise System Using RFC, by Implementing a Custom Entity in ABAP Environment

You will learn

  • How to create a suitable custom entity to get data from a remote system
  • How to implement a query provider class to get the data, using a BAPI (Business Application Programming Interface)
  • How to expose the custom entity as a business service
  • How to display the data in a Fiori Elements Preview, using the service binding

A BAPI is a standard interface to a business object model, implemented as a function module. For more information, see: BAPI

Custom entities are used for data models whose runtime is implemented manually. There is no SELECT statement on the data source. Rather, you define the elements and their types in the custom entity. Then you implement the data retrieval logic in an ABAP class, which is referenced in an entity annotation.
Custom entities allow you to get data using an OData service or, as here, using RFC.

For more information on CDS custom entities, see SAP Help Portal: Using a CDS Custom Entity to Define the Data Model for an OData Service

To see this tutorial group as a blog series by Andre Fischer, see: How to call a remote function module in your on-premise SAP system from SAP Cloud Platform – ABAP Environment

This includes a longer class code sample, which implements filtering.

Step 1: Create a class

First, you create the class that implements the data retrieval logic.

  1. In ADT, open your ABAP package and choose New > Class.

    Image depicting step1-new-class

  2. Enter a name and description:

    • zcl_product_via_rfc_xxx
    • Read product data via RFC

  3. Choose the transport request, then choose Finish.

Done
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Step 2: Add the interfaces statement

The signature of the method IF_A4C_RAP_QUERY_PROVIDER~SELECT contains the import parameter io_request. This parameter represents the OData query options that are delegated from the UI and used as input for the SELECT method. Whenever the OData client requests data, the query implementation class must return the data that matches the request, or throw an exception if the request cannot be fulfilled.

  1. Implement the interface by adding this statement to the public section:

    interfaces if_a4c_rap_query_provider.

  2. Choose Quick Fix (Ctrl+1), then choose Implement the SELECT method….

Later in this tutorial, you will implement the SELECT method of the interface.

Done
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Step 3: Create a custom entity (CDS View)

  1. Now choose New > Other… > Core Data Services > Data Definition.

  2. Enter a name and description:

    • z_product_via_rfc_xxx
    • Read product data via RFC from On-Premise

  3. Choose the transport request, then choose Next. Do not choose Finish, yet!

  4. Choose Define Custom Entity with Parameters, then choose Finish.

    Image depicting step1b-custom-entity
Done
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Step 4: Specify the class in the CDS view
View Full Instructions

Add the following annotation to the view:


@QueryImplementedBy: 'zcl_product_via_rfc_xxx'
Done
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Step 5: Define the CDS view
View Full Instructions

Add the following to the view, after the @QueryImplementedBy annotation:


@UI: {
  headerInfo: {
  typeName: 'Product',
  typeNamePlural: 'Products'
  }
}

define root custom entity ZJP_PRODUCT_VIA_RFC_5
{

      @UI.facet     : [
        {
          id        :       'Product',
          purpose   :  #STANDARD,
          type      :     #IDENTIFICATION_REFERENCE,
          label     :    'Product',
          position  : 10 }
      ]
      // DDL source code for custom entity for BAPI_EPM_PRODUCT_HEADER
      // generated on: 20190214 at:142338
      @UI           : {
      lineItem      : [{position: 10, importance: #HIGH}],
      identification: [{position: 10}],
      selectionField: [{position: 10}]
      }
  key ProductId     : abap.char( 10 );
      TypeCode      : abap.char( 2 );
      @UI           : {
      lineItem      : [{position: 20, importance: #HIGH}],
      identification: [{position: 20}],
      selectionField: [{position: 20}]
      }
      Category      : abap.char( 40 );
      @UI           : {
      lineItem      : [{position: 30, importance: #HIGH}],
      identification: [{position: 30}]
      }
      Name          : abap.char( 255 );
      @UI           : {
      identification: [{position: 40}]
      }
      Description   : abap.char( 255 );
      SupplierId    : abap.char( 10 );
      SupplierName  : abap.char( 80 );
      TaxTarifCode  : abap.int1;
      @Semantics.unitOfMeasure: true
      MeasureUnit   : abap.unit( 3 );
      @Semantics.quantity.unitOfMeasure: 'WeightUnit'
      WeightMeasure : abap.quan( 13, 3 );
      @Semantics.unitOfMeasure: true
      WeightUnit    : abap.unit( 3 );
      @UI           : {
      lineItem      : [{position: 50, importance: #HIGH}],
      identification: [{position: 50}]
      }
      Price         : abap.dec( 23, 4 );
      @Semantics.currencyCode: true
      CurrencyCode  : abap.cuky( 5 );
      @Semantics.quantity.unitOfMeasure: 'DimUnit'
      Width         : abap.quan( 13, 3 );
      @Semantics.quantity.unitOfMeasure: 'DimUnit'
      Depth         : abap.quan( 13, 3 );
      @Semantics.quantity.unitOfMeasure: 'DimUnit'
      Height        : abap.quan( 13, 3 );
      @Semantics.unitOfMeasure: true
      DimUnit       : abap.unit( 3 );
      ProductPicUrl : abap.char( 255 );

}

You will now implement the data retrieval logic in the class

Done
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Step 6: Define some variables in the class
View Full Instructions

Go back to the class. You will start by defining an local internal table and structure, which you will fill by retrieving the data from the back end.

DATA lt_product TYPE STANDARD TABLE OF zjp_product_via_rfc_5.
DATA ls_product TYPE zjp_product_via_rfc_5 .
Done
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Step 7: Define the connection
View Full Instructions

  1. Define the connection as follows, replacing XXX in both i_name and i_service_instance_name.


    DATA(lo_rfc_dest) = cl_rfc_destination_provider=>create_by_cloud_destination(
                           i_name = |S4TEST_RFC_XXX|
                           i_service_instance_name = |OutboundComm_for_RFCDemo_XXX| ).

DATA(lv_rfc_dest_name) = lo_rfc_dest->get_destination_name( ).

  2. Wrap this block in a TRY…CATCH…ENDTRY block.


    TRY.
...

  CATCH cx_rfc_dest_provider_error INTO DATA(lx_dest).

ENDTRY.
Done
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Step 8: Call the remote BAPI
View Full Instructions

  1. Check whether data is being requested.


    IF io_request->is_data_requested( ).

ENDIF.

  2. If so, call the BAPI.


    DATA lv_maxrows TYPE int4.
DATA(ls_paging)      = io_request->get_paging( ).
lv_maxrows = ls_paging-maximum_rows + ls_paging-start_row .

CALL FUNCTION 'BAPI_EPM_PRODUCT_GET_LIST'
  DESTINATION lv_rfc_dest_name
  EXPORTING
     max_rows   = lv_maxrows

  TABLES
    headerdata = lt_product.
Done
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Step 9: Set the total number of records
View Full Instructions

Set the total number of records requested.


IF io_request->is_total_rec_number_requested( ).
io_response->set_total_number_of_records( lines( lt_product ) ).
ENDIF.
Done
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Step 10: Return the data
View Full Instructions

  1. Return the data in the internal table.


    io_response->set_data( lt_product ).

  2. Again, wrap the BAPI call in a TRY…CATCH block:


    CATCH cx_a4c_rap_query_provider INTO DATA(lx_exc).
    Image depicting step9-try-catch
Done
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Step 11: Check the code for your class
View Full Instructions

CLASS zcl_product_via_rfc_xxx DEFINITION
  PUBLIC
  FINAL
  CREATE PUBLIC .

  PUBLIC SECTION.
    INTERFACES if_a4c_rap_query_provider.
  PROTECTED SECTION.
  PRIVATE SECTION.
ENDCLASS.



CLASS zcl_jp_product_via_rfc_6 IMPLEMENTATION.
  METHOD if_a4c_rap_query_provider~select.

    "variables needed to call BAPIs - z_product_via_rfc_xxx = the CDS View
    DATA lt_product TYPE STANDARD TABLE OF z_product_via_rfc_xxx.
    DATA ls_product TYPE z_product_via_rfc_xxx .

    TRY.
        DATA(lo_rfc_dest) = cl_rfc_destination_provider=>create_by_cloud_destination(
                                   i_name = |S4TEST_RFC_XXX|
                                   "
                                   i_service_instance_name = |OutboundComm_for_RFCDemo_XXX| ).

        DATA(lv_rfc_dest_name) = lo_rfc_dest->get_destination_name( ).

      CATCH cx_rfc_dest_provider_error INTO DATA(lx_dest).

    ENDTRY.

    TRY.

        IF io_request->is_data_requested( ).

          DATA lv_maxrows TYPE int4.
          DATA(ls_paging)      = io_request->get_paging( ).
          lv_maxrows = ls_paging-maximum_rows + ls_paging-start_row .

          CALL FUNCTION 'BAPI_EPM_PRODUCT_GET_LIST'
            DESTINATION lv_rfc_dest_name
            EXPORTING
             max_rows   = lv_maxrows
    *              max_rows   = 10
            TABLES
              headerdata = lt_product.
        ENDIF.

        IF io_request->is_total_rec_number_requested( ).
          io_response->set_total_number_of_records( lines( lt_product ) ).
        ENDIF.

        io_response->set_data( lt_product ).

    "error handling
    CATCH cx_a4c_rap_query_provider INTO DATA(lx_exc).


    ENDTRY.
  ENDMETHOD.
ENDCLASS.
Done
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Step 12: Create a service definition

Now that you have defined your view, you can expose it as a service. A service consists of a definition and a binding. This allows you to provide several bindings for the same definition, e.g. to expose the service to a UI, and to an A2X provider. Start with the definition:

  1. From your package, choose New > Other… > Service Definition from the context menu, then choose Next.

    Image depicting step10-service-def

  2. Choose a name and description:

    • ZSD_A4C_RFC_XXX
    • Read product data via RFC

  3. Choose the transport request; choose Next.

  4. Use the selected template; choose Finish.

Done
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Step 13: Specify the view name
View Full Instructions

In the editor that appears, replace entity_name with the name of your custom entity.


@EndUserText.label: 'Read product data'
define service ZSD_A4C_RFC_XXX {
  expose zcl_product_via_rfc_xxx;

}
Image depicting step11-expose-view
Done
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Step 14: Create the service binding

  1. From your package, choose New > Other… > Service Binding from the context menu, then choose Next.

  2. Choose:

    • Name = ZSB_A4C_RFC_XXX
    • Description = Read product data via RFC
    • Binding Type = ODATA V2 (UI…)
    • Service Definition = ZSD_A4C_RFC_XXX
    Image depicting step12-choose-binding-type

  3. Choose the transport request; choose Next.

  4. Use the selected template; choose Finish.

Done
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Step 15: Activate the service binding;

  1. In the editor that appears, choose Activate.

    Image depicting step13-activate-service-endpoint

  2. You can now see the Service URL and Entity Set.

    Image depicting step13b-service-details
Done
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Step 16: Display the Fiori Elements Preview

  1. Select the entity set and choose Preview.

    Image depicting step14-preview

  2. Log in using your ABAP Environment user and password; the Fiori Elements Preview appears.

  3. Display the data by choosing Go.

    Image depicting step14b-preview-with-data
Done
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Step 17: Test yourself
In which entity do you specify that your service is to be consumed by a SAPUI5 application? Choose one answer only:
×
Step 18: Troubleshooting: Test data retrieval using the ABAP Console
View Full Instructions

If the data does not display, check that the BAPI is retrieving the data, as follows:

  1. Open the class you created in Test the Connection to the Remote System.

  2. Replace the type ty_bapi_epm_product_header:


    DATA lt_product TYPE STANDARD TABLE OF  ty_bapi_epm_product_header.
DATA ls_product TYPE ty_bapi_epm_product_header.

with the type of your custom entity:

```ABAP

DATA lt_product TYPE STANDARD TABLE OF z_product_via_rfc_xxx.
DATA ls_product TYPE z_product_via_rfc_xxx.

```

The console output should look like this:

Image depicting test-output-in-console
Done
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