What is OLE and DDE?

Hello!

What is OLE and DDE? Anyone please explain me the difference?

At the Windows operating system level, both OLE and dynamic data exchange (DDE) are protocols for exchanging data and sending commands between applications. For Windows versions 3.0 and 3.1, neither the OLE libraries nor the Dynamic Data Exchange Management Library (DDEML) depend on special interprocess communications (IPC) mechanisms provided by the operating system. Rather, both OLE and DDE depend on the Windows messaging facility.

At the Windows operating system level, the OLE protocol is built on top of the DDE protocol. More specifically, the OLE protocol is largely a set of DDE Execute command strings that follow a conventional syntax.

At the application level, a function-based application program interface (API) is available for both OLE and DDE. For OLE, this API is provided to clients by the OLECLI.DLL file and to servers by the OLESVR.DLL file. For DDE, this API is provided by the DDEML.DLL file.

Despite the fact that OLE uses DDE as its transport mechanism, the present implementation of OLE is independent of the DDEML. This does not signify any functional or performance deficiencies of DDEML. Because the OLE libraries and DDEML were implemented in parallel, the schedule did not allow for this version of the OLE libraries to use DDEML.

It is quite likely that future versions of the OLE libraries will use DDEML rather than directly coding DDE messages.

Object Linking and Embedding (OLE) is a distributed object system and protocol developed by Microsoft.OLE allows an editor to "farm out" part of a document to another editor and then reimport it. For example, a desktop publishing system might send some text to a word processor or a picture to a bitmap editor using OLE. The main benefit of using OLE, next to reduced file size, is the ability to create a master file. References to data in this file can be made and the master file can then have changed data which will then take effect in the referenced document.DDE stands for Dynamic Data Exchange. That's exactly what it does, and nothing more. It sends data between applications using Windows messages according to a documented protocol. Saying that DDE is old-fashioned and is being replaced by COM is something you see repeated parrot fashion over and over again. DDE and COM do not work in the same way and they solve different problems.

OLE (Object Linking and Embedding) is designed to link to files created by other applications and allow you to edit the object using its native program (such as Calc), without leaving the host program (such as Writer). The word "link" in this case really just means a one-time pointer to the file address. Read on to see what I mean by that.

To insert an OLE object:

In the menu bar, choose Insert> Object> OLE object.

This opens a dialog in which you can either choose to create a new blank object (that's the default) or create the object from an existing file. The "new" list shows only OOo modules, but there is an item at the bottom of the list, "Further objects." This expands the list to show all the kinds of OLE objects that OOo can use.

DDE (Dynamic Data Exchange) creates an active---in other words, dynamic---link to the object. The content in Writer will update when the original file is updated.

To create a DDE link to a Calc spreadsheet:

Open the spreadsheet.

Select the data range that you want displayed in Writer. (If you have named data ranges, you can select it that way; or you can simply drag a selection area.)

In the Writer document, choose Edit> Paste Special, and click DDE link in the list of available formats.

The pasted DDE content will paste as a plain-looking table. It does not carry formatting from the spreadsheet. You can use Writer's table tools or AutoFormat features (or create your own AutoFormat) to make the table appear the way you wish.

If you're creating an OLE object from an existing file, please understand that this inserts a copy of the original. It is in no way linked to the existing file.

After you insert the object, you can double-click to edit it in its native program without leaving the Writer window. Again, this is a copy, so you are not editing the original file nor creating a new separate file.