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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

August 2, 2020
Created by
June 12, 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 service definition
  • How to display the data in a Fiori Elements Preview, using a service binding

Prerequisites

Note that, if you are using the trial version, currently you cannot access an on-premise system using RFC. In that case, you will test the class using mock data.

A BAPI is a standard interface to a business object model, implemented as a function module.

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.


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_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_xxx
    • Read product data via RFC
  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 (immediately after the ‘@EndUserText.label’ annotation), pointing to the class you have just created - NOTE: Use upper case!


@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_xxx with parameters parameter_name : parameter_type { key key_element_name : key_element_type; element_name : element_type; }
  2. Add the header information to the view, after the @QueryImplementedBy annotation.
    For more information on the UI Annotations used here, see
    SAP Help Portal: SAP Cloud Platform: ABAP RESTful PM: Defining UI Annotations


    @UI: { headerInfo: { typeName: 'Product', typeNamePlural: 'Products' } }
  3. Add the fields and their associations.


    define root custom entity zce_product_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.

  1. You will start by defining an local internal table, which you will fill by retrieving the data from the back end. The type of the local variable 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_xxx.
  2. Create a variable, lv_abap_trial. If you are using the full version of SAP Cloud Platform, ABAP Environment, set it to false, otherwise true.


    DATA(lv_abap_trial) = abap_false.
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Step 7: Define the connection to the on-premise system

If your are working in the full version of ABAP Environment: 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. Wrap this in a TRY. ...CATCH... ENDTRY.

```ABAP

IF lv_abap_trial = abap_false.

  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( ).

  CATCH cx_rfc_dest_provider_error INTO DATA(lx_dest).
  ENDTRY.

ENDIF.

```

If you are working in the trial version, omit this step.

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Step 8: Call the remote BAPI or insert the mock data
  1. Check whether data is being requested.


    IF io_request->is_data_requested( ). ENDIF.
  2. Now add an IF... ELSE. ... ENDIF. block.

  3. If you are using the trial version, fill the internal table lt_product with the mock data. If not, 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. IF lv_abap_trial = abap_true. lt_product = VALUE #( ( productid = 'HT-1000' name = 'Notebook' ) ( productid = 'HT-1001' name = 'Notebook' ) ( productid = 'HT-1002' name = 'Notebook' ) ( productid = 'HT-1003' name = 'Notebook' ) ( productid = 'HT-1004' name = 'Notebook' ) ( productid = 'HT-1005' name = 'Notebook' ) ). ELSE. CALL FUNCTION 'BAPI_EPM_PRODUCT_GET_LIST' DESTINATION lv_rfc_dest_name EXPORTING max_rows = lv_maxrows TABLES headerdata = lt_product. ENDIF.
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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. Output 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 data retrieval logic call in a second TRY. ..CATCH...ENDTRY block.

```ABAP

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

```
Image depicting step10-try-catch
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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. DATA lt_product TYPE STANDARD TABLE OF ZCE_PRODUCT_XXX . "In the trial version we cannot call RFC function module in backend systems DATA(lv_abap_trial) = abap_true. "Set RFC destination 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( ). "Check if data is requested 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. IF lv_abap_trial = abap_true. lt_product = VALUE #( ( productid = 'HT-1000' name = 'Notebook' ) ( productid = 'HT-1001' name = 'Notebook' ) ( productid = 'HT-1002' name = 'Notebook' ) ( productid = 'HT-1003' name = 'Notebook' ) ( productid = 'HT-1004' name = 'Notebook' ) ( productid = 'HT-1005' name = 'Notebook' ) ). ELSE. "Call BAPI CALL FUNCTION 'BAPI_EPM_PRODUCT_GET_LIST' DESTINATION lv_rfc_dest_name EXPORTING max_rows = lv_maxrows TABLES headerdata = lt_product . ENDIF. "Set total no. of records io_response->set_total_number_of_records( lines( lt_product ) ). "Output data io_response->set_data( lt_product ). ENDIF. CATCH cx_rfc_dest_provider_error INTO DATA(lx_dest). 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 Business Service. A Business Service consists of a Service Definition and a Service Binding.

You use a Service Definition to define which data is to be exposed (with the required granularity) as a Business Service.

You then use the Service Binding to bind a service definition to a client-server communication protocol such as OData. 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.

For more information, see:

  • Business Service Definition in ADT Help.

  • Business Service Binding in ADT Help.

Start with the Service Definition:

  1. From your package, select your custom entity, zce_product_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:

    • Z_EXPOSE_PRODUCTS_XXX
    • Expose 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 = Z_BIND_PRODUCTS_XXX
    • Description = Bind product data via RFC
    • Binding Type = ODATA V2 (UI…)
    • Service Definition = ZSD_PRODUCT_XXX
    Image depicting step12-choose-binding-type
  3. Choose the transport request; choose Finish.

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

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Step 14: Activate 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
  3. You can open the Service Document (XML) in your browser, by choosing Service URL.

    step14c-service-url-in-browser
  4. In the browser, you can also see the Metadata Document of the Business Service by adding $metadata to the URL: sap/opu/odata/sap/Z_BIND_PRODUCT_TEST_001/$metadata.

    step14d-service-metadata-in-browser
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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 (and you are using the licensed version), 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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