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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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09/30/2019

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.

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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_rap_query_provider.

  2. Choose Quick Fix (Ctrl+1), then choose Add implementation for SELECT….

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

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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:

    • zce_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. Ignore the errors for now.

    Image depicting step1b-custom-entity
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Step 4: Specify the class in the custom entity

Add the following annotation to the view, pointing to the class you have just created:


@ObjectModel.query.implementedBy: 'ABAP:zcl_product_via_rfc_xxx'
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Step 5: Define the CDS view
  1. Remove the following lines from the view:



    define root custom entity zce_product_via_rfc_xxx with parameters parameter_name : parameter_type { key key_element_name : key_element_type; element_name : element_type; }
  2. Add the following to the view, after the @QueryImplementedBy annotation:


    @UI: { headerInfo: { typeName: 'Product', typeNamePlural: 'Products' } } define root custom entity zce_product_via_rfc_xxx { @UI.facet : [ { id : 'Product', purpose : #STANDARD, type : #IDENTIFICATION_REFERENCE, label : 'Product', position : 10 } ] // DDL source code for custom entity for BAPI_EPM_PRODUCT_HEADER @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.

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Step 6: Define some variables in the class

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. The type of the local variables is the CDS View that you just created. Add the following code to the if_rap_query_provider~select method.


DATA lt_product TYPE STANDARD TABLE OF zce_product_via_rfc_xxx. DATA ls_product TYPE zce_product_via_rfc_xxx.
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Step 7: Define the connection to the on-premise system

Define the connection as follows, replacing XXX in both i_name and i_service_instance_name to your initials or group number. Ignore the warning for now.

```ABAP

DATA(lo_rfc_dest) = cl_rfc_destination_provider=>create_by_cloud_destination(
                            i_name                  = 'ES5_RFC_XXX'
                            i_service_instance_name = 'OutboundComm_for_RFCDemo_XXX'
   ).

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

```
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Step 8: Call the remote BAPI
  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(lv_skip) = io_request->get_paging( )->get_offset( ). DATA(lv_top) = io_request->get_paging( )->get_page_size( ). lv_maxrows = lv_skip + lv_top. CALL FUNCTION 'BAPI_EPM_PRODUCT_GET_LIST' DESTINATION lv_rfc_dest_name EXPORTING max_rows = lv_maxrows TABLES headerdata = lt_product.
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Step 9: Set the total number of records and return the data
  1. Set the total number of records requested.


    IF io_request->is_total_numb_of_rec_requested( ). io_response->set_total_number_of_records( lines( lt_product ) ). ENDIF.
  2. Return the data in the internal table.


    io_response->set_data( lt_product ).
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Step 10: Catch the exception if raised

Wrap the whole BAPI call in a TRY...CATCH block. Add the TRY. statement immediately after the DATA declarations. Add the CATCH. ... ENDTRY. statements just before ENDMETHOD..

```ABAP

TRY.
...
  CATCH cx_rfc_dest_provider_error INTO DATA(lx_dest).
ENDTRY.

```

![Image depicting step10-try-catch](step10-try-catch.png)
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Step 11: Check the code for your class

CLASS zcl_product_via_rfc_xxx DEFINITION PUBLIC FINAL CREATE PUBLIC . PUBLIC SECTION. INTERFACES if_rap_query_provider. PROTECTED SECTION. PRIVATE SECTION. ENDCLASS. CLASS zcl_product_via_rfc_xxx IMPLEMENTATION. METHOD if_rap_query_provider~select. "variables needed to call BAPIs - zce_product_via_rfc_xxx = the CDS View DATA lt_product TYPE STANDARD TABLE OF zce_product_via_rfc_xxx. DATA ls_product TYPE zce_product_via_rfc_xxx. TRY. DATA(lo_rfc_dest) = cl_rfc_destination_provider=>create_by_cloud_destination( i_name = 'ES5_RFC_XXX' i_service_instance_name = 'OutboundComm_for_RFCDemo_XXX' ). DATA(lv_rfc_dest_name) = lo_rfc_dest->get_destination_name( ). IF io_request->is_data_requested( ). DATA lv_maxrows TYPE int4. DATA(lv_skip) = io_request->get_paging( )->get_offset( ). DATA(lv_top) = io_request->get_paging( )->get_page_size( ). lv_maxrows = lv_skip + lv_top. * Retrieve data by calling BAPI CALL FUNCTION 'BAPI_EPM_PRODUCT_GET_LIST' DESTINATION lv_rfc_dest_name EXPORTING max_rows = lv_maxrows TABLES headerdata = lt_product. * Set total no. of records IF io_request->is_total_numb_of_rec_requested( ). io_response->set_total_number_of_records( lines( lt_product ) ). ENDIF. * Output the data io_response->set_data( lt_product ). ENDIF. CATCH cx_a4c_rap_query_provider INTO DATA(lx_exc). ENDTRY. ENDMETHOD. ENDCLASS.
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Step 12: Create a service definition

Now that you have defined your view, and retrieved the data using the class, you can expose the view 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, select your custom entity, zce_product_via_rfc_xxx, then choose New > Service Definition from the context menu, then choose Next.

    Image depicting step12-choose-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. The name of your custom entity is inserted automatically.

    Image depicting step11-expose-view
  5. Save and activate ( Ctrl+S, Ctrl+F3 ) the service definition.

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Step 13: Create the service binding
  1. Select your service definition, then choose 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.

The service binding automatically references the service definition and thus the exposed custom entity.

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Step 14: 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-binding-details
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Step 15: 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
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Step 16: Test yourself
In which entity do you specify that your service is to be consumed by a SAPUI5 application? Choose one answer only:
×
Step 17: Troubleshooting: Test data retrieval using the ABAP Console

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 zce_product_via_rfc_xxx.
DATA ls_product TYPE zce_product_via_rfc_xxx.

```

The console output should look like this:

Image depicting test-output-in-console
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Next Steps

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