What is this? How this works?


Originally designed for home automation, this is a daemon which is
written in Perl, using POE (an event-driven, non-blocking,
multitasking framework). Daemon can be run in different modes on
different devices. Daemons communicate over TCP/IP using TCP
transport with SSL (AES256, DHE, 2048bit keys). IPv6 support is
designed in as one of the first features, with possibility to run
on IPv6-only network (not yet tested in reality, currently running
with dual-stack setup). Authentication is done using certificates
only. Every device has own certificate and certificate's CN is
used to address devices internally. I've got round-trip delays
like 6.454 milliseconds on Ethernet network, which is pretty fast.
One-way trip time 3.227 milliseconds should avoid any "press
button, wait for light to come on" cases. It's currently designed
to be run with one server, although failover operation is planned
(both master / slave and multi-master). Master / slave failover
can be implemented using CARP. Example of system layout can be
like this: You have one daemon in server mode, running on somewhat
higher powered hardware (like i386 / amd64) which handles all the
data processing tasks (which might involve large SQL database) and
several clients that handle physical I/O which can use low power
embedded hardware (since they only forward data). I chose to use
FreeBSD as OS and BeagleBone Black as first client device
hardware, since it has lots of I/O already integrated to SoC and
price is low compared with what you get. Next considerations
include Carambola2 and devices based on same SoC. FreeBSD ARM
support for that specific TI SoC is good enough for stable
operation of this system. I'll try my best to work out any kinks
there. The main requirement, digital 0/1 I/O works best. As of
2014-05-22, 4 PWM outputs also work (of 6 (8?) total), 7 ADC
inputs work (one is internal, look at schematics), I2C bus'es
work (all 3). GPIO interrupts basically work (2015-01-15, needs
some polishing) (ability to reliably watch, for example, pulse
outputs of power meters). Client in BBB and it's child processes
are currently run with maximum realtime priority, to avoid normal
system processes interfering with I/O that must be operate as fast
as possible. POE allows nonblocking multitasking but not all my
code is like that, so I forked off several child processes to cope
with this. Those could later be implemented directly in POE.


Children include:

gpio {poll,change,ws2801}   Perl code
sysctl {get,set}            Perl code
ntpdc -ni                   from base, compiled C code
dnschild                    Shell
bbb-i2csysutil              C code
ownet                       Perl code
owserver                    Shell wrapper for owserver
watchdog                    Perl code
gpio-irq-event              C code
...


On FreeBSD, you need to install following ports / packages:

security/p5-POE-Filter-SSL
devel/p5-Time-Duration
sysutils/p5-BSD-Sysctl
comms/p5-Device-SerialPort (optional)
comms/owfs (optional)
net/rsync (optional, only needed for remote upgrades)

(they install lot of dependencies)

Additionally I use Perl modules from MisterHouse & OWFS
+ POE::Component::AIO from CPAN (needs devel/p5-IO-AIO)

I also use some local patches for POE & POE::Filter::SSL
I'm working to include those bug fixes in upstream.

And POE::Component::AIO should be added to ports.


Yes, I'm bad when it comes to text longer than one sentence...


-- 2014  Sulev-Madis Silber <ketas@si.pri.ee>