[xmonad] Question about desktop notifications

I've recently started running xmonad on Arch Linux, with no desktop environment, and can't seem to figure out how the desktop notifications are being generated. - Here's a link to a snapshot, to show what my notifications currently look like: https://imgur.com/a/dLMbj3w - Running `notify-send 'Hello world!' 'This is an example notification.'` yields the error `GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.Notifications was not provided by any .service files`. Can anyone shed some light on this mystery? Thank you, Adam Cooper