ABAP and Swagger/OpenAPI

[larshp]

Swagger

Swagger is a set of tools for creating, generating, documenting, and testing RESTful services.
It is centered around a specification file(https://swagger.io/specification/), which contains the description of the REST services, much like a SOAP WSDL or OData metadata file.

There are many powerful tools in the Swagger family, which all are open source:

• Editor


• UI


• Inspector

These tools are free and works in the browser. SAP also use Swagger as part of API management.

 

ABAP

A while ago I started building a tool for integrating ABAP and Swagger using an inside-out approach.

Lets jump right into it and see how it works, suppose I want to expose the methods of the following class as REST services:

CLASS zcl_todo DEFINITION PUBLIC CREATE PUBLIC.



  PUBLIC SECTION.

    METHODS create

      IMPORTING

        is_data      TYPE ztodo_data

      RETURNING

        VALUE(rs_key) TYPE ztodo_key .

    METHODS delete

      IMPORTING

        is_key TYPE ztodo_key .

    METHODS list

      RETURNING

        VALUE(rt_list) TYPE ztodo_tt .

    METHODS update

      IMPORTING

        iv_guid TYPE ztodo_key-guid

        is_data TYPE ztodo_data .



ENDCLASS.



CLASS ZCL_TODO IMPLEMENTATION.



  METHOD create.



    DATA: ls_todo TYPE ztodo.





    TRY.

        rs_key-guid = cl_system_uuid=>if_system_uuid_static~create_uuid_c22( ).

      CATCH cx_uuid_error.

        ASSERT 0 = 1.

    ENDTRY.



    MOVE-CORRESPONDING rs_key TO ls_todo.

    MOVE-CORRESPONDING is_data TO ls_todo.



    INSERT ztodo FROM ls_todo.

    ASSERT sy-subrc = 0.



  ENDMETHOD.



  METHOD delete.



    DELETE FROM ztodo WHERE guid = is_key-guid.

    ASSERT sy-subrc = 0.



  ENDMETHOD.



  METHOD list.



    SELECT * FROM ztodo INTO TABLE rt_list.             "#EC CI_NOWHERE



  ENDMETHOD.



  METHOD update.



    DATA: ls_todo TYPE ztodo.





    ls_todo-guid = iv_guid.

    MOVE-CORRESPONDING is_data TO ls_todo.



    UPDATE ztodo FROM ls_todo.

    ASSERT sy-subrc = 0.



  ENDMETHOD.

ENDCLASS.

Interface ZIF_SWAG_HANDLER must be implemented, and metadata added for the methods to be exposed,

  METHOD zif_swag_handler~meta.



    FIELD-SYMBOLS: <ls_meta> LIKE LINE OF rt_meta.





    APPEND INITIAL LINE TO rt_meta ASSIGNING <ls_meta>.

    <ls_meta>-summary   = 'List'(001).

    <ls_meta>-url-regex = '/list$'.

    <ls_meta>-method    = zcl_swag=>c_method-get.

    <ls_meta>-handler   = 'LIST'.



    APPEND INITIAL LINE TO rt_meta ASSIGNING <ls_meta>.

    <ls_meta>-summary   = 'Create'(002).

    <ls_meta>-url-regex = '/create$'.

    <ls_meta>-method    = zcl_swag=>c_method-post.

    <ls_meta>-handler   = 'CREATE'.



    APPEND INITIAL LINE TO rt_meta ASSIGNING <ls_meta>.

    <ls_meta>-summary   = 'Delete'(003).

    <ls_meta>-url-regex = '/delete$'.

    <ls_meta>-method    = zcl_swag=>c_method-post.

    <ls_meta>-handler   = 'DELETE'.



    APPEND INITIAL LINE TO rt_meta ASSIGNING <ls_meta>.

    <ls_meta>-summary   = 'Update'(004).

    <ls_meta>-url-regex = '/update/(w+)$'.

    APPEND 'IV_GUID' TO <ls_meta>-url-group_names.

    <ls_meta>-method    = zcl_swag=>c_method-post.

    <ls_meta>-handler   = 'UPDATE'.



  ENDMETHOD.

Add the handler to a custom SICF node, and thats about it! ABAP-Swagger will automatically generate a spec from the method definitions, and it is possible to use the Swagger UI to test the services. ABAP-Swagger is open source and works from 702 and up.



The full example can be found at https://github.com/larshp/todo_logic

 

Find more Open Source ABAP projects on dotabap.org

 

ABAP is like the sun, it will keep shining for a million years