OBJECT LINKING AND EMBEDDING(OLE)

Ø Technology developed by Microsoft that allows embedding and linking to documents and other objects.

Ø OLE allows an editing application to export part of a document to another editing application and then import it with additional content. For example, a desktop publishing system might send some text to a word processor or a picture to a bitmap editor using OLE.

Ø The main benefit of OLE is to add different kinds of data to a document from different applications, like a text editor and an image editor. This creates a compound document and a master file to which the document references.

Ø Changes to data in the master file immediately affect the document that references it. This is called "linking" (instead of "embedding").

Ø Its primary use is for managing compound documents, but it is also used for transferring data between different applications using drag and drop and clipboard operations (A window should use the clipboard when cutting, copying, or pasting data. A window places data on the clipboard for cut and copy operations and retrieves data from the clipboard for paste operations).

Ø OLE objects:

·        DataObject:When implemented, enables transfer of data, and notification of data exchange.

·        OleCache: Allow visual presentation from a data object to be cached.

·        OleCacheControl: Called by the object to allow proper Updation to the cached presentation.

·        OleDocument: Allow the OLE object to support multiple views of its data.

·        OleDocumentView: A document object implements this interface for every object for controlling the size, activation, query and to show the object.

·        OleLink:Allow the object to support linking.

·        OleObject: Most important interface for an OLE object. Used by container to initialize object from data, to open and close it, to query and set the size of the object, etc.

Ø OLE Container:

·        IOleContainer:  Allow the caller to enumerate embedded objects in a container, or to find such objects by name.

·        IOleUndoManager: Provides a centralized undo service to the container itself and the embedded object.

Ø Other:

·        IDropSource: Implemented by objects that can be dragged.

·        IDropTarget: Implemented by objects that accepts dropped objects.