Control Hubs: Bringing It All Together - Smart Home Automation with Linux and Raspberry Pi - page 225

Echo
Output only.
This is the simplest to understand because it merely reflects all the input parameters to the current console. It is
used primarily for debugging the conduits and address book.
Email
Input/output.
Like most of the conduits that support input and output methods, the two are separated by a large expanse of
code. For the input side of the conduit, procmail is triggered automatically from the mail server after parsing the
incoming mail to determine whether it's originated from someone who is able to send messages. This is covered fully
in Chapter 5.
The output conduit uses the standard mail program directly.
Infrared Remote Control
Output only.
This calls the irsend code to determine the device and protocol necessary.
Logging
Output only.
This writes all messages into /var/log/minerva/msglog and is also used primarily for debugging.
SMS
Input/output.
The output conduit works through mxsms , which is symlinked to one of three possible driver scripts,
mxsms-gnokii , mxsms-intelli , or mxsms-txtlocal , depending on who is providing the current output service.
If adopting the ideas of Chapter 5, you can make mxsms a script in its own right to consider the priority of the
transmitting user and determine which service to use.
For input, you will have Apache triggering the code when a specific web page is downloaded from a remote
SMS-PC gateway or from a custom script checking message through Gnokii (courtesy of crontab).
Twitter
Output only.
This uses the tweet command to update their Twitter status, thereby using the configuration information from
the given user, with their credentials being stored in $MINBASE/etc/users/[user]/external/twitter .
The Voice Conduit
Input/output.
In its current state, all voice recognition input is taken from an HTTP request on a separate page that triggers the
msgrcv script with the given command. The output conduit has a direct connection to the Festival speech synthesis
suite, which has already been abstracted through Bearskin with say and announce . Vocal output is also a very good
debugging conduit, since the output is immediately accessible.