Create Object History in SAP Blockchain

Preface – This post is part of the Blockchain on SAP Cloud Platform and ABAP Programs series.

In this article, we will learn how to create a block in Blockchain on the SAP Cloud Platform.

 METHOD create_object_history.
    DATA: lo_http_client TYPE REF TO if_http_client.
    DATA: response TYPE string,
          lv_url   TYPE string,
          lv_auth  TYPE string.
    CONSTANTS : lv_initial_url TYPE string VALUE '<Your_Service>'.
    IF iv_object_id IS NOT INITIAL.
*** Getting Token
      TYPES:
        BEGIN OF t_entry,
          access_token TYPE string,
          token_type   TYPE string,
          expires_in   TYPE n LENGTH 8,
          scope        TYPE string,
          jti          TYPE string,
        END OF t_entry .
      TYPES:
        t_entry_map TYPE SORTED TABLE OF t_entry WITH UNIQUE KEY access_token.
      DATA: m_entries TYPE t_entry.
      DATA: lr_instance  TYPE REF TO  /ui5/cl_json_parser.
      CREATE OBJECT lr_instance.
      CALL METHOD me->get_token.
      IF gv_token IS NOT INITIAL.
        /ui2/cl_json=>deserialize(
        EXPORTING json = gv_token pretty_name = /ui2/cl_json=>pretty_mode-camel_case CHANGING data = m_entries ).
        DATA lv_auth2 TYPE string.
        lv_auth2 = m_entries-access_token.
*        gv_token = gv_token+17.
        CONCATENATE 'Bearer' lv_auth2 INTO lv_auth SEPARATED BY space.
      ENDIF.
      DATA lv_object_id TYPE string.
      lv_object_id = iv_object_id.
      TRANSLATE lv_object_id TO LOWER CASE.
      CONCATENATE lv_initial_url lv_object_id INTO lv_url. "Appending Fix URL and the Object ID to get the Request URL
      "create HTTP client by url
      CALL METHOD cl_http_client=>create_by_url
        EXPORTING
          url                = lv_url
        IMPORTING
          client             = lo_http_client
        EXCEPTIONS
          argument_not_found = 1
          plugin_not_active  = 2
          internal_error     = 3
          OTHERS             = 4.
      "Available API Endpoints
      "https://blockchain-service.cfapps.sap.hana.ondemand.com/blockchain/proofOfHistory/api/v1
      "https://blockchain-service.cfapps.eu10.hana.ondemand.com/blockchain/proofOfHistory/api/v1
      "https://blockchain-service.cfapps.us10.hana.ondemand.com/blockchain/proofOfHistory/api/v1
      IF sy-subrc <> 0.
        "error handling
      ENDIF.
      "setting request method
      lo_http_client->request->set_method('POST').
      "adding headers
      lo_http_client->request->set_header_field( name = 'Content-Type' value = 'application/x-www-form-urlencoded' ).
      lo_http_client->request->set_header_field( name = 'Accept' value = 'application/json' ).
      lo_http_client->request->set_header_field( name = 'Authorization' value = lv_auth ).
      "Available Security Schemes for productive API Endpoints
      "OAuth 2.0
      CALL METHOD lo_http_client->send
        EXCEPTIONS
          http_communication_failure = 1
          http_invalid_state         = 2
          http_processing_failed     = 3
          http_invalid_timeout       = 4
          OTHERS                     = 5.
      IF sy-subrc = 0.
        CALL METHOD lo_http_client->receive
          EXCEPTIONS
            http_communication_failure = 1
            http_invalid_state         = 2
            http_processing_failed     = 3
            OTHERS                     = 5.
      ENDIF.
      IF sy-subrc <> 0.
        "error handling
        response = lo_http_client->response->get_cdata( ).
        ev_response = response.
      ELSE.
        response = lo_http_client->response->get_cdata( ).
        IF response IS NOT INITIAL.
          ev_response = response.
        ELSE.
          ev_response = 'Block created successfully'.
        ENDIF.
      ENDIF.
    ENDIF.
  ENDMETHOD.