You can create and manipulate drawing objects from any application that serves as
an Automation controller. Thus, Automation enables macro programming across applications,
a capability that does not exist in AutoLISP.

The advantage of implementing an ActiveX interface for the program is twofold:

• Programmatic access to drawings is opened up to many more programming environments.
  Before ActiveX Automation, developers were limited to an AutoLISP or C++ interface.

• Sharing data with other Windows applications, such as Microsoft Excel and Microsoft
  Word, is made dramatically easier.

For example, you might want to prompt for input, set preferences, make a selection
set, or retrieve drawing data. You can decide on the controller to use, depending
on the type of manipulation.

The displayed objects are called Automation objects. Automation objects make methods, properties, and events available. Methods are functions that perform an action on an object. Properties are functions that set or return information about the state of an object. Events are user-initiated actions or occurrences to which a program responds.

Virtually any type of application can access the exposed Automation objects within
AutoCAD. These applications can be stand-alone executables, dynamic linked library
(DLL) files, and macros within applications such as Microsoft Word or Microsoft Excel.
The most common of these is likely to be a stand-alone executable. If you are using
applications from third-party developers, follow their instructions for installation
and use of their product.

Define an External Command to Start Your Application

You can use the acad.pgp file to define a command that runs an external command to start a stand-alone application;
similar to that of a command alias which can be used to start a command.

The following example defines the RUNAPP1 command, which executes app1.exe from the c:vbapps directory. (Add this code to the external commands section of your acad.pgp file.)

RUNAPP1, start c:vbappsapp1, 0

If your application requires command line parameters, you can use the following code:

RUNAPP2, start c:vbappsapp2, 0, *Parameters: ,

This example defines the RUNAPP2 command, which prompts you for parameters and then
passes them to your application.

You can also use the AutoLISP startapp function to start an application that makes use of Automation. Once AutoLISP starts
the external application, it has no control over its actions. You can, however, use
AutoLISP to locate and run different applications based on certain parameters.

Start an Application from the User Interface

After defining an external command to start a stand-alone application, you can use
that command as part of a command macro from a user interface element.

If you use only one or two applications, you can add them to one of the standard
ribbon panels or the Quick Access toolbar. If you have a group of applications, you
can define your own ribbon panels that are specifically dedicated to those applications.