Call a Remote Function Module From ABAP Environment

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Call a Remote Function Module From ABAP Environment

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Call a Remote Function Module From ABAP Environment

Requires Customer/Partner License

Julie Plummer

2019-11-07

Advanced

1 hr.

Call a remote function module located in an on-Premise system, such as an S/4HANA System, from the ABAP Environment

You will learn

How to open a secure tunnel connection between your SAP Cloud Platform ABAP Environment and an on-premise SAP System, e.g. SAP S/4HANA
How to create a destination service instance with HTTP and RFC connections
How to create a communication arrangement to integrate this destination service
How to create a communication arrangement to integrate SAP Cloud Connector
How to test the connection using an ABAP handler class

For more information on setup, see:

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

Throughout this tutorial, replace XXX with your initials or group number.

If you have bought an entitled to SAP

The problem:

There are two problems when setting up connectivity between the Cloud Platform ABAP Environment and an on-premise:

The ABAP Environment “lives” in the Internet, but customer on-premise systems are behind a firewall.
RFC is not internet-enabled.

The solution:

Set up a connection from the on-premise system to the SAP Neo Environment using SAP Cloud Connector.
Set up a connection from the SAP Neo to SAP Cloud Foundry Environment.

Specifically:

Fetch the destination, i.e. from Cloud Foundry to on-premise (using a Cloud Foundry destination service)
Send request to open a tunnel, from Cloud Foundry (i.e. ABAP) to Neo
Send request to open a tunnel, from Neo to the on-premise system
Open a secure tunnel for HTTP and RFC
Communicate through the tunnel via HTTP or RFC

Step 1: Configure SAP Cloud Connector

First, you need to connect your ABAP on-premise system to a Neo subaccount by means of SAP Cloud Connector.

Log on to SAP Cloud Connector:
- Address = e.g. https://localhost:<port> (Default = 8443)
- User = Administrator
- Initial password = Manage (You will change this when you first log in)
Choose Add Subaccount:

Region = Your region. You can find this in SAP Cloud Cockpit (see screenshot below). Note that your Neo and Cloud Foundry accounts need to run in the same region (e.g. here, Europe Rot)
Subaccount = “Neo Technical Name”. You can find this by choosing your SAP Cloud Platform, NEO, subaccount in SAP Cloud Cockpit and choosing the information (i) icon. (see screenshot below)
Display Name = (Neo Subaccount) Display Name. You can find this in by choosing your SAP Cloud Platform, NEO, subaccount in SAP Cloud Cockpit (see screenshot below)
Subaccount User = for the Neo Subaccount
Password
Location ID = Optional here. However, it is mandatory if you want to connect several Cloud Connectors to your subaccount. This can be any text, e.g. your initials

Image depicting step1g-create-subacc
Image depicting step1f-choose-subacc
Image depicting step1b-neo-tech-name

Your configuration should now look like this:

Image depicting step1-check-scc

Done

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Step 2: Add your on-Premise System

In your sub-account, Display Name, choose Cloud to On-Premise > Access Control.

Image depicting step2e-add-onP-system

In the Mapping Virtual… pane, choose Add (+).

Image depicting step2f-add-2

Enter the following values, and choose Save.
- Backend Type = ABAP
- Protocol = RFC
- Without load balancing…
- Internal Host and port (see below)
- Virtual Host = e.g. es5host. Here, es5host represents an external hostname, so that you can hide the internal hostname from the outside world. You will need this external hostname and port later.
- Virtual Port = usually, enter the internal Port
- Principal Type = None
- Check Internal Host = Ticked
To find the port, in your on-premise system, choose the transaction SMICM > Goto > Services, then choose an active HTTP port.

The mapping should now look something like this. Check that the status = Reachable. If not, check that you chose the correct port, or whether an internal firewall is preventing communication:

Image depicting step1a-scc-resources-sid

Done

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Step 3: Specify the remote function modules and BAPIs

Now, still in the Cloud to On-Premise > Access Control tab, enter the resource you need, RFC_SYSTEM_INFO.

Add the resource RFC_SYSTEM_INFO by choosing the Protocol = RFC, then choosing +.
Enter the name of the RFC, e.g. RFC_SYSTEM_INFO. Alternatively, add RFC as a Prefix. Then choose Save
Add BAPIs to the list of resources by choosing + again. (You will need this BAPI in a later tutorial.)
Enter the name BAPI_EPM as a Prefix, then choose Save.
The list of resources should now look like this:

Done

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Step 4: Open the destination service instance

You will now create two destinations in the ABAP Environment. These must be created at Space level, e.g. Dev, not subaccount level.

In SAP Cloud Cockpit, open your ABAP Environment > your space, such as Dev, then choose Service Instances.
Open the destination service you created in Create a Communication Arrangement for Outbound Communication
Create a new destination for the destination service instance

Done

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Step 5: Create a new RFC destination for the destination service instance

Again, choose New Destination and enter the following values:
- Name, e.g. : ES5_RFC_XXX
- Type: RFC
- Description, e.g. Test ES5
- Location ID: same as in step 1, e.g. your initials
- User: Your user for the on-premise system
- Password: Your password
Add the following additional properties and values, by choosing New Property:
- jco.client.ashost = <myHost> - again, the external hostname of your on-premise ABAP System in lower-case
- jco.client.client = <Your ABAP System client, e.g. 002
- jco.client.sysnr = <Your ABAP System number>, e.g. 11

You have now created a destination service instance destination for your communication arrangement. Take note of the name, here ES5_RFC_XXX, since you will need it later.

Done

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Step 6: Create a Communication System for SAP Cloud Connector

(When you created the Communication System for outbound communication, you created the Arrangement first, then the System. This time, it is easiest to create the System first, then the Arrangement.)

Go back to your space Dev and choose Service Instances, then choose your abap service instance, e.g. T02.
Open the Dashboard.
In the Dashboard, choose Communication Systems > New.
Enter the credentials for the SAP Cloud Connector administration user for your SAP CP Neo account (i.e. the same user as in step 1 above):
- Hostname
- User and Password

Done

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Step 7: Create a Communication Arrangement for SAP Cloud Connector

Go back to the Dashboard Home, choose Communication Arrangements again, then choose New.
Enter the following values and choose Create.
- Scenario: SAP_COM_0200 (SAP Cloud Connector Integration)
- Name: SAP_COM_0200_XXX
Enter the Communication System you have just created.
In the details screen, enter the Account Name: <NEO Technical Name>

Done

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Step 8: Create an ABAP class for the RFC connection

Create a new ABAP class: Choose File > New > Other… > ABAP Class.
Enter a name and description. The name should be in the form ZCL_...RFC_XXX. Replace XXX with your group number or initials.
Create or assign a transport request.

Done

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Step 9: Add the interfaces statement; implement the main method

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

interfaces if_oo_adt_classrun.

This allows you to test your class by displaying the output in the ABAP Console.
In the implementation section, add the METHOD and ENDMETHOD statements:

METHOD IF_OO_ADT_CLASSRUN~MAIN.
ENDMETHOD.

Done

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Step 10: Create variables

View Full Instructions

Create the data types that specify your remote connection information:

DATA(lo_destination) = cl_rfc_destination_provider=>CREATE_BY_CLOUD_DESTINATION(
                        i_name                  = 'ES5_RFC_XXX'
                        i_service_instance_name = 'OutboundComm_for_RFCDemo_XXX'
                       ).

DATA(lv_destination) = lo_destination->get_destination_name( ).

DATA lv_result type c length 200.

Replace the i_service_instance_name with your service instance name, specified in the Communication Arrangement (which you created in Create a Communication Arrangement for Outbound Communication).
Replace the i_name with your the name of the specific RFC destination (which you created in SAP Cloud Cockpit in the tutorial Create a Communication Arrangement for Outbound Communication).

Done

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Step 11: Call the remote function from the on-premise system

View Full Instructions

CALL function 'RFC_SYSTEM_INFO'
destination lv_destination
  IMPORTING
    RFCSI_EXPORT      = lv_result.

Done

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Step 12: Output the result

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Output the result of the RFC to the ABAP Console

out->write( lv_result ).

Done

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Step 13: Wrap the method in an exception

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Wrap the whole method in an exception using TRY…CATCH.

catch cx_root into data(lx_root).
  out->write( lx_root->get_text( ) ).
endtry.

Done

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Step 14: Check your code

View Full Instructions

You code should look roughly like this:

class ZCL_A4C_RFC_XXX definition
  public
  final
  create public .

public section.
  interfaces if_oo_adt_classrun.
protected section.
private section.
ENDCLASS.



CLASS ZCL_A4C_RFC_XXX IMPLEMENTATION.
  METHOD IF_OO_ADT_CLASSRUN~MAIN.
    TRY.
      DATA(lo_destination) = cl_rfc_destination_provider=>CREATE_BY_CLOUD_DESTINATION(
                              i_name                  = 'ES5_RFC_XXX'
                              i_service_instance_name = 'OutboundComm_for_RFCDemo_XXX'
                             ).

      DATA(lv_destination) = lo_destination->get_destination_name( ).

      DATA lv_result type c length 200.

      CALL function 'RFC_SYSTEM_INFO'
      destination lv_destination
        IMPORTING
          RFCSI_EXPORT      = lv_result.

        out->write( lv_result ).
    catch cx_root into data(lx_root).
      out->write( lx_root->get_text( ) ).
    endtry.
  ENDMETHOD.

ENDCLASS.

Done

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Step 15: Test the class

Save and activate the class, using Ctrl+S, Ctrl+F3.
Run the class by choosing F9. Some system information, such as the hostname, the System ID ( <SID> ), and the IP address should be displayed.

Done

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Step 16: Test yourself

In the ABAP class, what entity does the i_service_instance_name point to? Choose only one answer. Communication arrangement name Communication scenario name Communication system name Destination service instance name

Step 17: Add error handling to the class for the RFC connection

View Full Instructions

Go back to your RFC class. Remove the period (.) after the IMPORTING parameter and add the following exception parameters to the function call RFC_SYSTEM_INFO:
```
EXCEPTIONS
  system_failure        = 1 MESSAGE msg
  communication_failure = 2 MESSAGE msg
  OTHERS                = 3.
```

Now evaluate sy-subrc by adding the following CASE…ENDCASE statement:


CASE sy-subrc.
   WHEN 0.
     out->write( lv_result ).
   WHEN 1.
     out->write( |EXCEPTION SYSTEM_FAILURE | && msg ).
   WHEN 2.
     out->write( |EXCEPTION COMMUNICATION_FAILURE | && msg ).
   WHEN 3.
     out->write( |EXCEPTION OTHERS| ).
 ENDCASE.