A Bit of History

A few years ago, Microsoft introduced Object Linking and Embedding, a component standard for the Windows operating system. Known by its initials, OLE, this technology provided two techniques—linking and embedding—that an application could use to work with another application’s document:

When an object—a spreadsheet or a graphic image, for instance—was linked to another application, the item would automatically be updated in the containing document when it was changed in the original application. Linked objects were very useful for complex documents that were developed with a variety of tools.
Double-clicking on an object embedded in a container document would open another application within the container application that could be used to edit the object. The embedded application could use the container application’s menus, client area, and so on, essentially taking over while the embedded object was being edited.
Later Microsoft extended the OLE definition to allow the creation of OLE controls. A control is a small, well-defined mini-application that performs a specific task; a developer could build an application by hooking together several OLE controls, even ones built in different languages. Again, this is a very object-oriented concept: the ability to define discrete parts of a program and then link them into complete applications. OLE controls, which can be built in Microsoft Visual Basic or C++ or licensed from an outside vendor, provide power and flexibility in program design. A developer can use a set of OLE controls to provide a consistent design—and share code—among applications.