While developing this testing assignment I tried to keep everything as simple and light as possible. Result was tested with Python 2.7 only.

###Back-end

Following technologies are used:

• Tornado is used to implement a websockets server. It's asynchronious and supports an event-loop inside.
• Redis is used as a publish-subscribe bus. To make it compatible with Tornado coroutines gredis is used as Python driver (which is a small async extension of standart redis package).

###API

API for usage from Python code consist of one function: notify. Usage:

from nserv import notify

# level can be {success|info|warning|danger}
notify('A message', 'warning')

###Command-line tool

(env)utyf@utyf-ThinkPad-T420:~/work/viasto$ ./nserv_notify.py --help
usage: nserv_notify.py [-h] -m MESSAGE -l LEVEL

Post a notification.

optional arguments:
-h, --help            show this help message and exit
-m MESSAGE, --message MESSAGE
-l LEVEL, --level LEVEL

###Front-end

As front-end is not part of evaluation, I made a small experiment there, writing it in some kind of "functional" style. State is strictly separated from logic, every state transition is a pure function.

Following technologies are used:

• React.js as library for visual components
• Bootstrap as CSS framework

###Install and start

git clone https://github.com/utyf/nserv
cd nserv

# assuming, that python 2.7 is there
virtualenv env
. env/bin/activate
pip install -r requirements.txt
python nserv.py

# in other console (add host and port if needed):
redis-server

# open http://localhost:8080/