Containers: Client Items
This article explains what client items are and from what classes your application should derive its client items.
Client items are data items belonging to another application that are either contained in or referenced by an OLE container application's document. Client items whose data is contained within the document are embedded; those whose data is stored in another location referenced by the container document are linked.
The document class in an OLE application is derived from the class COleDocument rather than from CDocument. The COleDocument class inherits from CDocument all the functionality necessary for using the document/view architecture on which MFC applications are based. COleDocument also defines an interface that treats a document as a collection of CDocItem objects. Several COleDocument member functions are provided for adding, retrieving, and deleting elements of that collection.
Every container application should derive at least one class from COleClientItem. Objects of this class represent items, embedded or linked, in the OLE document. These objects exist for the life of the document containing them, unless they are deleted from the document.
CDocItem is the base class for COleClientItem and COleServerItem. Objects of classes derived from these two act as intermediaries between the OLE item and the client and server applications, respectively. Each time a new OLE item is added to the document, the MFC framework adds a new object of your client application's COleClientItem-derived class to the document's collection of CDocItem objects.