SAP CRM One Order header extension的缓存机制设计原理

In one of my previous blog A small tip to analyze code by code and export to markdown format it is introduced that the following header extension are supported in One order read function module CRM_ORDER_READ.

When the given header extension is read via CRM_ORDER_READ, take OPPORT_H for example:

DATA: lt_header_guid TYPE  crmt_object_guid_tab,
      lv_guid        TYPE crmt_object_guid,
      lv_object_id   TYPE CRMT_OBJECT_ID_DB value '21',
      lt_oppt        TYPE CRMT_OPPORT_H_WRKT,
      lt_partner     TYPE crmt_partner_external_wrkt.

START-OF-SELECTION.
CALL FUNCTION 'CONVERSION_EXIT_ALPHA_INPUT'
   EXPORTING
      input = lv_object_id
   IMPORTING
      output = lv_object_id.

  SELECT SINGLE guid INTO lv_guid FROM crmd_orderadm_h
      WHERE object_id = lv_object_id AND process_type = 'CXOP'.

  CHECK sy-subrc = 0.

  APPEND lv_guid TO lt_header_guid.

  CALL FUNCTION 'CRM_ORDER_READ'
    EXPORTING
      it_header_guid = lt_header_guid
    IMPORTING
*      et_partner     = lt_partner
      et_opport_h   = lt_oppt.

The calling hierarchy could be found from below:

Every header extension has one corresponding read function module acting as entry point for read which will be called by CRM_ORDER_READ_OW with naming convention CRM_