If you have used a PC then OBJECT-ACTION should be familiar

If you use Start -> Search -> For Files and Folders on your Windows desktop then you end-up with a MS-Windows form that looks like something like this:

Here you also have a:


Where you specify what documents you would like to search for.

Business Object Instance List

The list of documents MS-Word and MS-PowerPoint documents (say) that match your filter's search criteria. These documents are your business objects.      

Business Object Commands

Shown on the pop-up menu when you right click (e.g.: Open, Print, Delete, Properties, etc.).  Sometimes you may execute a command by clicking on an icon on the tool bar.   

Command Handlers

The programs that execute when you execute a command. In this example MS-Word handles the "Open" command, a message box confirms that you really want to "Delete" and the document's "Properties" are shown as multiple tabs in a separate form.  



In this example the OBJECT-ACTION approach is being used at a high level.

The OBJECT-ACTION design works right down to a very low level as well.

Think about how you change the head of an arrow in MS-PowerPoint: 

You select the OBJECT (the arrow) then choose the ACTION (Format AutoShape).