Flask

running app forever - supervisorctl

cascada

port = 8087

/home/pi/mypi/cascada/server/cascada.py

cascada2

port = 8088

/home/pi/mypi/cascada/server/cascada2.py

<markdown>

sudo`supervisorctl` reads configuration from `/etc/supervisor/conf.d` and runs whatever files if finds there.

a typical `conf` ile looks like:

   [program:cascada2]
   command=/usr/bin/python /home/pi/mypi/cascada/server/cascada2.py
   directory=/home/pi/mypi/cascada/server
   autostart=true
   autorestart=true
   startretries=3
   stderr_logfile=/var/log/cascada/cascada2.err.log
   stdout_logfile=/var/log/cascada/cascada2.out.log
   user=root
   environment=SECRET_PASSPHRASE='this is secret',SECRET_TWO='another secret'

you may have to `>supervisor reload` then `ctrl c` the `sudo supervisorctl` to get a new program running forever

</markdown>

pi@raspberrypi ~ $ sudo supervisorctl
cascada                          RUNNING    pid 2273, uptime 7 days, 3:17:36

tail -f /var/log/cascada/cascada.out.log
tail -f /var/log/cascada/cascada.err.log

after changing cascada.py

pi@raspberrypi ~ $ sudo supervisorctl
cascada                          RUNNING    pid 2273, uptime 7 days, 3:17:36
supervisor> stop cascada

exit w ctrl C

sudo lsof -i :8087
sudo kill -9 21118 (kill whatever port lsof returns)

pi@raspberrypi ~ $ sudo supervisorctl
cascada                          STOPPED    Jul 16 04:34 PM
supervisor> start cascada
cascada: started
supervisor>

exit w ctrl C ??

• nohup python app.py &
• use screen
• run supervisord(link) on system startup and control all through it (pythonic way :))

nohup means: do not terminate this process even when the stty is cut off.

& at the end means: run this command as a background task.

forever with supervisord

SSE - Server Side Events

http://flask.pocoo.org/snippets/116/

https://github.com/stevenewey/ssedemo

for node

https://www.npmjs.com/package/simple-sse (has room,haven't tried)

https://tomkersten.com/articles/server-sent-events-with-node/

http://www.futureinsights.com/home/real-time-the-easy-way-with-eventsource-angularjs-and-nodejs.html

SocketIO

http://stackoverflow.com/questions/17641602/how-to-emit-to-room-in-socket-io

flask socketio

https://flask-socketio.readthedocs.org/en/latest/