System 7 is the newest Macintosh operating system. Like MS-DOS on the PC, it controls the central processor and coordinates your keyboard and monitor. It also creates the mouse interface or "desktop" screen you see when you turn on the Mac, and helps you create and delete files, store files on disk, and find them again when you need them. Publish-and-Subscribe System 7 is much more, however. One of System 7's magic tricks is the way it integrates simple applications using what Apple calls Inter- Application Communication, or "Publish-and-Subscribe." Simply put, Publish-and-Subscribe links applications and lets them "talk" to each other. By sharing information, individual applications dedicated to a single function, like drafting or number-crunching, can combine to form hybrid applications that perform more
