NAME
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;
[...]
mapi_object_init(&obj_store);
retval = OpenMsgStore(&obj_store);
if (retval != MAPI_E_SUCCESS) {
mapi_errstr(’OpenMsgStore’, GetLastError());
exit (1);
}
mapi_object_release(&obj_store);
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.