WebSocket RFC to Cloud

First, you have to create a communication scenario based on a remote-enabled function module (RFM) in the provider cloud system. You can also use your own communication scenario and RFM, or use one of the SAP-delivered communication scenarios, for example SAP_COM_0636. For this tutorial, we will create a simple RFM that can receive a string, adds another string to it and returns the result to the sender.

1. Launch ABAP development tools (ADT) in the provider cloud system.
2. Select the relevant package, open the context menu and choose New > Other ABAP Repository Object > ABAP Function Group
   • Name: Z_Function_Group_XXX
   • Description: Function Group for RFM
3. Save and activate the function group.
4. Select the newly created function group, open the context menu and choose New > ABAP Function Module.
   • Name: Z_RFM_XXX
   • Description: RFM for WebSocket RFC
5. Paste the following code.
   ABAP

   Copy

       FUNCTION Z_RFM_XXX
   
         IMPORTING
           VALUE(input) TYPE string
         EXPORTING
           VALUE(output) TYPE string.
   
         output = input && ' How are you?'.
   
       ENDFUNCTION.
   
   

6. Save and activate the function module.

1. In the project explorer, select the RFM.
2. Choose File > Properties > Specific.
   • Processing Type: RFC
   • RFC Scope: From any system
   • RFC Interface Contract: Any
   
3. Save and activate the RFM.

1. In the relevant package, open the context menu and choose New > Other ABAP Repository Object > Communication Scenario.
   • Name: Z_WS_RFC_XXX
   • Description: Communication Scenario for WebSocket RFC
2. Go to tab Inbound.
3. In the section Inbound Services, choose Add.
4. In the field Inbound Service ID, enter the name of your RFM: Z_RFM_XXX_RFC. The _RFC is automatically added.
5. Make sure that in the field Service Type, the value RFC is specified.
6. Choose Finish.
7. Save the communication scenario.
8. Choose Publish Locally.

1. In the provider system, log on to SAP Fiori launchpad.
2. Go to Communication Management and choose Communication Arrangements.
3. Choose New.
   • Scenario: Z_WS_RFC_XXX
   • Arrangement Name: Z_WS_RFC_ARRANGEMENT_XXX
4. Choose Create.
5. In the section Common Data in field Communication System, choose New.
   • System ID: Z_WS_RFC_SYSTEM_XXX
   • System Name: Z_WS_RFC_SYSTEM_XXX
6. Choose Create.
7. In the section Technical Data, activate Inbound Only.
8. Under Users for Inbound Communication, choose Add.
9. In the New Inbound Communication User, choose New User.
   • User Name: IB_RFC_XXX
   • Description: User for inbound WebSocket RFC
   • Password: Inbound_WebSocket_RFC_XXX
10. Choose Create.
11. In the New Inbound Communication User window, choose OK.
12. Choose Save. You are redirected back to the communication arrangements screen.
13. Under Inbound Communication, make sure the new inbound communication user IB_RFC_XXX is entered.
14. Choose Save.
15. Copy the API-URL.
    

Now that you have set up the provider cloud system, you have to create a destination in the consumer on-premise system. This destination allows you to connect to the provider system.

1. Log on to the consumer system in SAP Logon and run transaction SM59.
2. Choose Create.
   • Destination: Z_WSRFCDEST_XXX
   • Connection Type: W RFC connection to other ABAP system using WebSockets
3. On the tab Technical Settings, enter the following properties:
   • Host: The API URL you have copied in step 5.15. without the https:// prefix.
   • Port: 443
   
   Including the https:// prefix leads to an error when you test the connection.

4. On the tab Logon & Security, enter the following properties. Use the data of the inbound communication user from your communication system:

   • Explicit Client: by Hostname
   • by User/Password: activate Alias User
   • Alias User: IB_RFC_XXX
   • Password: Inbound_WebSocket_RFC_XXX
     
5. Choose Save.
6. Choose Connection Test.

The connection test returns a ping result.

1. Open ADT in the consumer on-premise system.
2. Select the relevant package, open the context menu and choose New ABAP Class.
   • Name: Z_WS_RFC_CALL_XXX
   • Description: WebSocket RFC Call
3. Paste the following code.
   ABAP

   Copy

   
     CLASS z_ws_rfc_call_xxx DEFINITION
       PUBLIC
       FINAL
       CREATE PUBLIC .
   
       PUBLIC SECTION.
   
         INTERFACES if_oo_adt_classrun .
       PROTECTED SECTION.
       PRIVATE SECTION.
     ENDCLASS.
   
     CLASS z_ws_rfc_call_xxx IMPLEMENTATION.
   
       METHOD if_oo_adt_classrun~main.
   
         DATA lv_output TYPE string.
         DATA lv_input TYPE string VALUE 'Hello world!'.
   
         CALL FUNCTION 'Z_RFM_XXX' DESTINATION 'Z_WSRFCDEST_XXX'
           EXPORTING
             input  = lv_input
           IMPORTING
             output = lv_output.
   
   
         out->write( lv_output ).
   
       ENDMETHOD.
     ENDCLASS.
   
   

4. Save and activate the class.

5. Choose Run > Run AS > ABAP Application (Console).

You can use also a service consumption model for the RFC call. See Generating Proxies for Remote Function Call (RFC) and Enable RFC Communication in Your ABAP Code. You can download the required service metadata file from the communication arrangement in SAP Fiori launchpad.

You have sent a test string (Hello world!) to the RFM in the provider system. The string is returned as Hello world! How are you? to the consumer system.