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Call an External API

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Call an External API
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Call an External API

Julie Plummer
Julie Plummer
November 26, 2020
Created by
Julie Plummer
September 13, 2018
Beginner
30 min.
SAP BTP, ABAP environment, SAP Business Technology Platform, Beginner, Cloud, Tutorial, ABAP Development
Point to an external API and display its output in the console.

You will learn

  • How to create a new destination in SAP Cloud Cockpit
  • How to call an external API from inside an ABAP class by pointing to this destination
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Prerequisites

You will create a new destination service instance, 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.
This enables you to avoid hard-coding the URL of the external API in your ABAP class.

Throughout this tutorial, objects name include the suffix XXX. Always replace this with your group number or initials.

Step 1: Create destination service

You will now create a destination in the ABAP Environment. This must be created at subaccount (not Space) level.

  1. In the SAP Cloud Platform Cockpit of your Cloud Foundry subaccount, navigate to your subaccount.

step1a-subaccount

  1. Choose Destinations, then choose New Destinations.

    step1a-cf-cockpit-new-destination

  2. Enter the following values and choose Save:

    Field Name Value
    Name e.g. Z_STREETMAP_XXX as here
    Type HTTP
    Description Can be anything, here Streetmap
    URL https://www.openstreetmap.org/#map=18/49.29271/8.64401 (In your browser, this would display Walldorf, Germany)
    Proxy Type Internet
    Authentication NoAuthentication
    step2b-destination-streetmap

  3. Choose Check Connection. You should get the following response.

step1c-check-connection-200

Done
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Step 2: Create new package

  1. In ABAP Development Tools (ADT), select the ABAP Cloud Project and choose New > ABAP Package.

  2. Enter the following and choose Next:

    • Name = Z_EXTERNAL_API_XXX
    • Description = Call external API
    • Package type = Development
    Image depicting step1a-create-package

  3. Choose Create new transport request, enter a description, such as “External API”, then choose Finish.

    step1c-new-transport-request
Done
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Step 3: Create 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
Done
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Step 4: Add INTERFACES statement
View Full Instructions

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.

Done
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Step 5: Copy code
View Full Instructions

To be able to access the external service, you must:
- maintain a cloud destination for the remote system
- create an HTTP client
- send an HTTP request
- output the response in the ABAP console
- wrap the code in an exception

Copy the following code. Replace the xxx of i_name with your group number:

METHOD if_oo_adt_classrun~main.
    TRY.
        DATA(lo_destination) = cl_http_destination_provider=>create_by_cloud_destination(
          i_name                  = 'Z_STREETMAP_XXX'
          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.
Done
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Step 6: Check, save, and activate
  1. Check your syntax (Ctrl+F2).
  2. Save (Ctrl+S) and activate (Ctrl+F3) your class.
Done
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Step 7: Run class in ABAP Console

Run your class in the console (F9).

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

Done
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Step 8: Test yourself
Which of the following is code snippets is correct? Choose all that apply.
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