How to implement a session control system scalable and reliable with an open source stack.

1. Simultaneous
Access
Control
with a full open source stack
Walter Traspadini
@uollter

2. non conventional architecture (?)
why redis ?
why flask ?

3. Redis.io
Salvatore Sanfilippo
@antirez
Sponsored by
Open Source
key-value store
no-sql ?((made in italy)

4. Who is using Redis

5. Redis.io
keys can expire
master-slave
in memory dataset
persistence
Data Structure
- String
- Integer (mainly for counting)
- List
- Set
- Ordered set
- Hash stored list

6. Don't do this !!
rs = redis.Redis()
rs.keys('*')
- time complexity O(n)
- 10^6 keys database in 40 msec.
- IT MAY RUIN PERFORMANCES

7. Best practices
SADD SERVICES [QOL, S24, PROF]
HSET SERVICE:QOL expire 60
HSET SERVICE:QOL max_count 1
HSET SERVICE:QOL:bob max_count 3
ZADD ACTIVITY:QOL:bob:20121010 '14:50 Login' 1450
ZADD ACTIVITY:QOL:bob:20121010 '15:15 Logout' 1515
ZRANGE ACTIVITY:QOL:bob:20121010 1200, 1600 O(log(N) + M)
(N: # of elements in the sorted set. M: # of element returned)
list
objects
scores

8. Flask
> micro-framework for python
> builtin server
> RESTful request dispatching
> WSGI compliant
> integrated support for unit testing

9. ...... easy .....
code example
@app.route('/logout/<username>/<service>/<label>' , methods=['GET'])
@jsonp.jsonp
def logout(username, service, label, device_type=None):
user.sessions = g.r_server.get('USER:%s:%s:%s' %(username, service, label)))
if user.sessions and int(user.sessions) > 0:
g.r_server.delete(user.key())
return jsonify({'user': user.to_json(), 'error': messages.OK_NO_ERROR})
return jsonify({'error': messages.NOT_LOGGEDIN_ERROR, 'user': user.to_json()})

10. ..... siac .... api .....
/chack_access/EntroBol04/QOL/<fingerprint>
MMMD5 ( browser capabilities
+
browser plugins )
cf4ceeb4398b80132eeceadea0a2f9ee
/logout/EntroBol04/QOL/<fingerprint>

11. headache
> does redis scale ?
> which is the failover policy ?
> what about clustering ?

12. my early prototype .......
SIAC
REDIS
MASTER
REDIS
SLAVE

13. spreecast http://www.spreecast.com/

14. Apache ZooKeeper
Centralized service for maintaining:
configuration information,
naming,
distributed synchronization

15. .. the final solution .. <3 production
Redis
Redis Redis
SIAC SIAC
ZooKeeper
Cluster Monitor
Monitor
Redis Redis

16. redis_failover ... for python ...
https://github.com/uolter/redis_failover

17. ....share the code Luke ....

18. continuous integration as a service

19. want to learn more ....
> Redis: http://redis.io
> Video redis: http://vimeo.com/21539227
> Flask: http://flask.pocoo.org
> Spreecast & Redis Failover: http:
//engineering.speecast.com/spreecast-redis-
failover
> ZooKeeper: http://zookeeper.apache.org

20. Walter Traspadini
http://bit.ly/uolter
@uollter