Comparing the OLE Libraries to DDEML

• Microsoft OLE version 1.0

SUMMARY

Unlike the Dynamic Data Exchange Management Library (DDEML), the OLE libraries directly support the functions listed in this article.

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Extensibility to Future Enhancements

The OLE libraries may be updated in future releases to support new data formats, link tracking, in situ editing, and other enhancements that will not be immediately available to applications that use the DDEML.

Persistent Embedding and Linking of Objects

The OLE libraries assume most of the burden of activating objects (by reestablishing the conversation between a client and server) when an embedded document is reopened. In contrast, the burden of establishing a DDE link (DDE advise loop) falls on the user (if the link is not persistent), or falls on the application (if the link is persistent).

Rendering Common Data Formats

The OLE libraries assume the burden of rendering common data formats, such as bitmaps, device-independent bitmaps (DIBs), and metafiles. In contrast, DDE applications must do this work themselves.

Server Rendering of Specialized Data Formats

The OLE libraries facilitate the rendering of specialized data formats in the client's display context. The server application or object handler actually performs the rendering, since only it has knowledge of the format. The client application has to do very little work to render the embedded or linked data in its display context. Such rendering of embedded or linked data is beyond the scope of DDE itself.

Activating Embedded and Linked Objects

The OLE libraries support activating a server to edit a linked or embedded object, as well as activating the object to render data. Activating servers for data rendering and editing is beyond the scope of the DDEML.

Creating Objects and Links from the Clipboard

The OLE libraries assume most of the burden for copying and pasting links to and from the Clipboard. The OLE libraries assume most of the burden for exchanging objects using the Clipboard. In contrast, DDE applications must call the Windows Clipboard functions directly to perform such operations.

Creating Objects and Links from Files

The OLE libraries provide direct support for exchanging data using files. In contrast, no DDE protocol is defined to exchange data using files. It is possible to pass file references through DDE, but specific DDE clients and servers must agree upon the file format as part of their communication protocol; this is rarely done.