Since I spend so much time railing about applets, I also tend to look at applets to see what they do (after all, the first step in knowing how to defeat the enemy is to understand the enemy).
In general, applets seem to fall into several rough categories:
- Notification Area Handlers
- Helper applications
- Services (I did say that I lump services into the same category as applets).
Let me take them in turn...
Updaters: I LIKE updaters. Updaters are awesome. IMHO, I trust applications that include updates more than those that don't (because an updater implies a commitment to further development and bug fixes). However way too many vendors build programs that run all the time and do absolutely nothing other than wait to check for updates every week (or every month). One other problem with updaters is that sometimes the authors of the updater use the updater to push unrelated software (at the moment, I'm particularly annoyed at the iTunes updater - if you install just Quicktime, the updater tries to get you to install Quicktime+iTunes, and there seems to be no way of shutting it up).
Notification Area Handlers: Every application seems to want to put its own icon in the notification area. To me, the functionality that is offered by many of these is of limited value. For example, my display driver includes an applet that allows the user to quickly switch between screen resolutions, but I almost never change my screen resolution - so why provide a easy shortcut for that functionality? I'm not sure why, but personally I believe it's because of branding (since you get to put an icon with your notification area handler, it makes it obvious to the user that you've installed the software). Some pieces of notification area functionality are quite useful (the "big 4" (Sound, Network, Battery, Clock) in Windows are good examples, as are things like RSSBandits' status indicator), but many of them make me wonder (which is why I suspect that branding is the real reason behind many of the notification area icons).
Helper applications: These are things like "FlashUtil9d.exe" (running on my machine right now) and other support processes. Users often don't see these (since they don't bring up UI), but they live there nonetheless. I have an HP 7400 printer at home, and the printer driver for that runs 2 separate processes for each user (one of which hangs during shutdown every time a user logs off).
Services: A special class of helper application, services have some significant advantages over helper applications (and some drawbacks). Services can be centrally managed, and expose a common startup/shutdown interface. They also can be automatically started at system boot, have strict dependencies, and can run in arbitrary user contexts (including elevated contexts). On the other hand, it's difficult (and in many ways effectively impossible) to have services run in the context of the currently logged on user. I'm a huge fan of services, but it's possible to totally overdo it. In Windows Vista, there were a slew of new services introduced, and more and more applications are creating services, since the currently logged in user is no longer an administrator. An example of a helper service is the WHSConnector service that comes with Windows Home Server (another of my current favorite products), and there are a bazillion others.
I'm sure that there are other categories of applets, but these 4 appear to be the biggies.
Tomorrow: So why are applets bad?