hardware query layer

   Date: Tue, 22 Apr 2003 03:26:31 -0400
   From: Havoc Pennington <[email protected]>

   C. Device abstraction library
   ===

   Linked to by individual user applications; automatically listens to
   systemwide dbus events, loads the device database information, or
   whatever else is required to build and maintain a list of devices on
   the system.

This sounds suspiciously like part of the networking support that
Colin and I are designing: a "state daemon" that watches for a variety
of events on the D-BUS, and uses these events to track the implied
state of the networking environment.  An application can subsequently
query this daemon about the environment, using a language that
supports structured queries (perhaps boolean combinations).

The advantage of this approach is that it relieves applications of the
need to track events and deduce state.  All they need do is ask
questions and receive answers.  And the knowledge of how to do the
deductions, and how to efficiently store the state, will be
concentrated in one place.

This state daemon can be designed in a modular way so that it can be
extended to handle different kinds of state.  One module understands
network state and another understands devices.  Later there is bound
to be other state that needs tracking.

I will make sure that what we build is designed this way.  When you
get around to needing it, ping us.

Chris