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       mapiconcepts - MAPI Concepts

   MAPI objects
       Almost any MAPI data you access, read or edit is associated with an
       object. No matter whether you intend to browse mailbox hierarchy, open
       folders, create tables or access items (messages, appointments,
       contacts, tasks, notes), you will have to initialize and use MAPI
       objects: object understanding and manipulation is fundamental.

       · When developing MAPI clients with Microsoft framework, instantiated
         objects inherit from parent classes. As a matter of fact, developers
         know which methods they can apply to objects and we suppose it makes
         their life easier.

       · In OpenChange, objects are opaque. They are generic data structures
         which content is set and accessed through MAPI public functions.
         Therefore, Linux MAPI developers must know what they are doing.

       An example of MAPI object manipulation is shown below:

               mapi_object     obj_store;


               retval = OpenMsgStore(&obj_store);
               if (retval != MAPI_E_SUCCESS) {
                       mapi_errstr(’OpenMsgStore’, GetLastError());
                       exit (1);

   MAPI Handles
       Beyond memory management considerations, understanding MAPI handles
       role in object manipulation provides a better understanding why
       mapi_object_release() matters.

       Handles are temporary identifiers returned by Exchange when you access
       or create objects on the server. They are used to make reference to a
       particular object all along its session lifetime. They are stored in
       unsigned integers, are unique for each object but temporary along MAPI
       session. Handles are the only links between objects accessed on the
       client side and efficiently stored on the server side.

       Although OpenChange MAPI makes handles manipulation transparent for
       developers, mapi_object_release() frees both the allocated memory for
       the object on client side, but also releases the object on the server.