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Call an External API

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Call an External API
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Call an External API

01/14/2019

Point to an external API and display its output in the console.

You will learn

  • How to call an external API from inside an ABAP system


Predefined communication scenarios allow you to, for example, exchange data between a SAP Cloud Platform system and an external system.
A communication arrangement specifies the metadata for a communication scenario. (For more information, see Maintain a Communication Arrangement for an Exposed Service.)

You will create a new destination for an existing communication arrangement, specifying the URL for an external API, user/password, and authentication.
You will then create a class that calls the API and displays the output from it in the console.

Step 1: Navigate to the communication arrangement instance

First, navigate to the communication arrangement instance OutboundCommunication.

  1. In your space in the SAP Cloud Platform Cockpit, open Service Marketplace and choose Destination:

    Image depicting step-1a-destination
  2. Choose Instances > OutboundCommunication:

    Image depicting step-1b-outboundcomm
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Step 2: Create a new destination
  1. Choose New Destination:

    Image depicting step-2a-new-destination
  2. Then enter the following (replacing xxx with your group number). Then choose Save:

    • Name = Z_CHUCKNORRIS_xxx
    • URL = http://api.icndb.com/jokes/random?limitTo=[nerdy]
    • Proxy type = Internet
    • Authentication = NoAuthentication
    Image depicting step-2b-config-dest
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Step 3: Check the connection

Check the connection:

Image depicting step-3-test-connection
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Step 4: Create an ABAP class

Now, you will create an ABAP class that will call your destination, and which you can run in the console.

  1. In the ABAP Development Tools (ADT), in the Package Explorer, select your package and choose New > ABAP Class from the context menu:

    Image depicting step-4a-create-class
  2. Enter a name and description for your class and choose Next. Remember to change XXX to your group number:

    Image depicting step-4b-name-class
  3. Choose or create a transport request, then choose Finish:

    Image depicting step-4c-class-transport-request

The class is displayed in a new editor:

Image depicting step-4d-class-editor
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Step 5: Add an interface statement

Now you will implement the class.
Add the following interfaces statement to the public section:

PUBLIC SECTION.
  INTERFACES if_oo_adt_classrun.
PRIVATE SECTION.

This enables you to run the class in the console.

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Step 6: Implement the method
  1. Add the method implementation below and wrap it in an exception.
  2. Then replace the xxx of i_name with your group number. Leave the service instance name ZSAP_COM_0276 as it is.
METHOD if_oo_adt_classrun~main.
    TRY.
        DATA(lo_destination) = cl_http_destination_provider=>create_by_cloud_destination(
          i_name                  = 'Z_CHUCKNORRIS_xxx'
          i_service_instance_name = 'ZSAP_COM_0276'
          i_authn_mode = if_a4c_cp_service=>service_specific ).

        DATA(lo_http_client) = cl_web_http_client_manager=>create_by_http_destination( i_destination = lo_destination ).
        DATA(lo_request) = lo_http_client->get_http_request( ).
        DATA(lo_response) = lo_http_client->execute( i_method = if_web_http_client=>get ).
          out->write( lo_response->get_text( ) ).

      CATCH cx_root INTO DATA(lx_exception).
        out->write( lx_exception->get_text( ) ).
    ENDTRY.
  ENDMETHOD.

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Step 7: Check, save, and activate
  1. Check your syntax (Ctrl+F2).
  2. Save (Ctrl+S) and activate (Ctrl+F3) your class.
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Step 8: Run the class in the console

Run your class in the console (F9).

The output should look something like this:
Image depicting step-9-console

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Step 9: Test yourself

Create the variable lo_request using the DATA statement and the get_http_request method of the lo_http_client object. Enter the correct text below:

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