Smarthome Server History


This Visual Basic program is actually the evolution of the oldest part of the system. The original
implementation started with the ability to monitor and send commands to the Lynx bi-directional
X10 interface through a serial port. From that the program evolved into a program which handled
video capture, email, email handling, and all the functions of the smarthome 1 system all in one
program with a client program that made requests of it from CGI scripts.

One feature I always wanted was the ability for multiple smarthome servers running on different
Windows boxes in the house to be able to interoperate with each other and act collectively. Before
I got interested in CORBA, my main option was to use the TCP/IP protocol I wrote for communication
between the old client and the smarthome server, but I never did anything with this.

At this stage my home system consisted of each machine running a web server and a smarthome
server. I could access each system one at a time.

CORBA, refactoring and initial distributed networking

Once I found VBOrb (the CORBA implementation for Visual Basic) I realized that if I formalized
the interfaces between functional areas of the smarthome server, then eventually I'd be able to
distribute that function across multiple machines. It also gave me a reason to review the Object
Oriented design of the system to eliminate global data in the system. After I wrote the IDL
for the components and decided how I would handle error handling and reconnection to CORBA
servers, I replaced all calls from one function to another with a call through the new CORBA
interface. After that was working I could point one smarthome server at a function provided
by a different one and they would interoperate seamlessly.


One of my ultimate goals was to make the VB code that runs on each machine as "thin" as
possible and migrate whatever I could to Linux code. Now that I was using CORBA between all
subsystems I could rewrite them one by one in Java, install it on a Linux machine, and remove
the function from the smarthome server code. I also re-implemented the CGI scripts that
made requests of the servers in Java Server Pages which made direct calls to the CORBA
interfaces. This allowed me to eliminate the need for a client program and the kludgy
protocol I invented between the client and server. Now the smarthome server is little more
than a set of CORBA servers which implement pure function. At this point I was using just
one web server which could control all the smarthome servers.