An Automation Overview

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Automation is a means by which a program written in Microsoft Visual Basic for Applications (VBA), Microsoft Visual Basic, C/C++, or another programming language that supports Automation can incorporate the functionality of Microsoft Visio simply by using its objects.

The way that objects in an application are related to each other, along with each object's properties (data), methods (behavior), and events, is called the program's object hierarchy or object model. In the Visio object model, most objects correspond to items that you can see and select in the Visio user interface. For example, a Shape object represents a shape in a drawing.

In Automation, the application that provides the objects (such as Visio, sometimes called the Automation server) makes the objects accessible to other applications and provides the properties and methods that control them. This is called exposing the objects.

The application that uses the objects (such as your program, sometimes called the Automation client) creates instances of the objects and then sets their properties or invokes their methods to make the objects serve the application.

The Automation server and Automation client interact using COM (Component Object Model) services, which are installed when any version of the Microsoft Windows operating system later than Windows 95 is installed.

Visio (versions 4.5 and later) includes VBA, so you don't need to use a separate development environment to write your programs. However, you can write programs that control Visio in any language that supports Automation clients. The examples in this guide are written in VBA, but the principles apply to any programming language.