------
```
- parallel +----------+ +----------+ +----------+
- stateless | sensor_1 | | sensor_2 | ... | sensor_n |
- collectors +----------+ +----------+ +----------+
- | | |
- data data data
- | | |
- V V V
- serial +-----------------------------------------+
- stateful | controller |
- observer +-----------------------------------------+
- |
- decisions
- |
- V
- serial +-----------------------------------------+
- stateless | actuator |
- executor +-----------------------------------------+
- |
- system commands
- |
- V
- ~~~~~~
- ~ OS ~
- ~~~~~~
+parallel +----------+ +----------+ +----------+
+stateless | sensor_1 | | sensor_2 | ... | sensor_n |
+collectors +----------+ +----------+ +----------+
+ | | | |
+ data data data data
+ | | | |
+ V V V V
+serial +----------------------------------------------+
+stateful | controller |
+observer +----------------------------------------------+
+ |
+ decision messages
+decision |
+messages |
+copied to |
+any number |
+of interested |
+filter/actuator |
+combinations |
+ |
+ V
+ +-------------+-+---------+---------+
+ | | | |
+ V V V V
+parallel +------------+ +------------+ +------------+
+stateless | filter_1 | | filter_2 | ... | filter_n |
+filters +------------+ +------------+ +------------+
+ | | | |
+ V V V V
+parallel +------------+ +------------+ +------------+
+stateless | actuator_1 | | actuator_2 | ... | actuator_n |
+executors +------------+ +------------+ +------------+
+ | | | |
+ commands commands commands commands
+ | | | |
+ V V V V
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ ~~~~~~~~~~~~~ operating system ~~~~~~~~~~~~~~~~~
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```
### Actuator
-By default, actuator is left disconnected from the controller's output, so if
+Actuator is anything that takes action upon controller messages. A few generic
+ones are included:
+
+- `khatus_actuate_alert_to_notify_send`
+- `khatus_actuate_status_bar_to_xsetroot_name`
+
+and, by default, are left disconnected from the controller's output, so if
desired - it needs to be manually attached when starting `khatus`. For example,
in my `.xinitrc` I have:
```sh
$BIN/khatus \
-2> >($BIN/twrap.sh >> $HOME/var/log/khatus.log) \
-| $BIN/khatus_actuator \
- -v pid="$$" \
- -v display=":0" \
-2> >($BIN/twrap.sh >> $HOME/var/log/khatus-actuator.log) \
+2> >($BIN/twrap >> $HOME/var/log/khatus.log) \
+| tee \
+ >($BIN/khatus_actuate_status_bar_to_xsetroot_name) \
+ >(grep -v MpdNowPlaying | $BIN/khatus_actuate_alert_to_notify_send) \
+2> >($BIN/twrap >> $HOME/var/log/khatus-actuators.log) \
&
```
+(where `twrap` is a simple script which prefixes a timestamp to each line)
-(`twrap.sh` is a simple script which prefixes a timestamp to each line)
-
-The idea is to later have multiple, (some more-general and some more-specific)
-actuators which can be selected as needed, say for example:
+The idea is to give maximum flexibility for what to do with the controller
+output, say, for instance:
```sh
$BIN/khatus \
| tee \
->(awk '/^STATUS_BAR/ {sub("^" $1 " *", ""); system("xsetroot -name \" " $0 " \"")}') \
+... \
>(grep '^REPORT' | actuate_report_to_email) \
>(grep '^ALERT' | grep mpd | actuate_alert_to_email) \
>(grep '^ALERT' | grep IntrusionAttempt | actuate_intruder_to_iptables_drop) \
>(grep '^ALERT' | grep NewDevice | actuate_alert_to_notify_send)
>(grep '^ALERT' | grep DiskError | actuate_call_mom)
+...
```
-
-... and/or any other such fun you might imagine.
+... and so on, for any other such fun you might imagine.
### Errors
Any errors encountered by any sensor are propagated as alerts by the
controller, which are in turn actualized as desktop notifications by the
-actuator:
+`khatus_actuate_alert_to_notify_send` actuator:
![screenshot-self-error-propagation](screenshot-self-error-propagation.jpg)
+
+TODO
+----
+
+- retry/cache for sensors fetching flaky remote resources (such as weather)
+- throttling of broken sensors (constantly returns errors)
+- alert specification language
+ - trigger threshold
+ - above/bellow/equal to threshold value
+ - priority
+ - snooze time (if already alerted, when to re-alert?)
+ - text: subject/body