Implementing failover of the Home Automation Rule Enforcer (HARE) in a federated environment.

[Marc F Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

In a typical PC-centric Home Automation (HA) system, only one instance of
the HA program (Homeseer, Premise Systems, CQS, MisterHouse ) is running at
any given time. However one legacy HA program (Savoy's CyberHouse) has
intrinsically provided for mutual cooperation of more than one server since
at least 1998.

The principal function of HA programs is to provide for the development and
execution of rules that cause specific outputs and outcomes based on a
variety of inputs: hence the moniker introduced here of Home Automation
Rules Enforcer and its acronym HARE.

Because of the mission-critical, central importance of the HARE, it is
useful to consider ways to provide redundancy. One way to accomplish this is
to provide mirrored HAREs with a thoroughly validated method for failover
http://en.wikipedia.org/wiki/Failover of one HARE to another.

XP provides for execution of scheduled tasks through individual files with
.job extensions in the windows\tasks directory. So a network administrator
can control the behavior of PC's from any device capable of copying .job
files over a network to the windows\tasks directory on target PC's. One can
use a remote PCs or Personal Digital Assistants (PDAs), or another HARE to
cause a remote PC to run most any program that can be started from the
command line.

One way to effect a failover under XP and Server 2003 would be through the
use power settings for sleep, hibernation, monitor, cpu and hard disk etc
using the powerconfig.exe command. ( See Start-->Run-->Cmd-->powercfg /? for
descriptions of the numerous options.)  Among other things, powercfg
provides for creation, import and export of .pow files. There are some
potentially very useful options including text and audio notification of low
UPS battery, wake on modem ring, as well as the various power management
features that most folks are familiar with.

I am exploring use of these capabilities for two or more PC's to serve as
mutual/reciprocal  watchdogs, and to provide for  failover of the active
HARE to an other PC that may be asleep (to conserve energy) or already have
another function in the network (e.g. file server). It might also consist in
reversion to a better-tested, older rule, or simpler rule set for the same
HA program or to a different HA program (in my case, Homeseer or CQS to
CyberHouse).

The ability of two or more PC's to provide for structured failover would be
particularly useful in a 'federated' HA environment with multiple subsystems
(security panel, thermostats, audio server, video over IP etc).

Ideally the granularity of these subsystems and the functions that they
provide  should be fine enough that all essential HA Input/Output (I/O) --
including audio and video and control of devices that communicate using
TCP/IP, and RS-xxx -- can be accessed/accomplished by more than one PC. This
makes possible redundancy of the most important element of an HARE-based
environment, namely the PC running the Primary Rule Set (PRS). How to
dependably replicate and maintain the PRS is one of the challenges.

Seems to me that this work is sufficiently generic, (i.e. independent of the
actual HARE program used) that we could share our ideas.

I'll post my own solutions for my Windows XP and Server 2003 environment as
they are developed and to the extent I don't judge doing so to be a security
risk.

HTH ... Marc
Marc_F_Hult
www.ECOntrol.org