1. PHP to Python:
No Regrets
The Grass Is Always Greener
Alex Ezell
Emma
July 31, 2011

2. the on e on th e left.
Hi, I’m

3. The bloodiest wars in history
have been religious wars.
-Richard M. Nixon

4. Why did we change?
How did we change?
Would I do it all again?
What did we learn?

5. Why did we change?

6. Change Is What We Do

7. Big, Hairy Ass Goals
Rewrite the platform incrementally
Provide a world-class customer API
Reexamine every tool
Quadruple the tech team
Lead instead of follow

8. Opportunity
Major push from the business for new features more
often and the freedom to make that happen
Team growth
Stability and agreement in other areas: infrastructure,
strategic planning, etc.
Developer desire - we simply wanted more.
Necessity with regards to current codebase

9. Code Unity / Management
Lots of background, server processes managing parts
of our application. Desire for code in background
processes to more closely resemble application code
Threading, decoupling, and queueing.
Third-party mailer integration.
Several small teams working on a single project.

10. Modernizing Our Toolset
Homegrown PHP Web Framework -> Django
PEAR_DB -> SQLAlchemy
Apache -> WSGI
No Testing/Docs -> nose and Sphinx
CVS Update -> Fabric Deploys of Git Repo

11. Why Python?
Maturity and capability
Ease of use / Powerful / Low learning curve
Rapid development
Future of the technology
Ecosystem of tools

12. How did we change?

13. Revolution or Evolution?
Stop for a full rewrite and not have something
compelling when you reboot
No new features while the rewrite occurs
Inability to really beta test new stuff
Fairly entrenched customer base
Competition is innovating quickly

14. Service API
Scalability, Speed, Fault-tolerant, Easy Deployment
Collection of Python WSGI Apps
Delayed processes, log readers, and queue consumers
New structure for all business logic
Smaller, tighter codebase - Easier to build on
Public API is just a wrapper
Heavy use of Redis

15. Module Fiesta
accounts
tantuclient tantu
audience
queueworkers jumper
dbsession
logparser graffiti

16. Learn the Python Ecosystem
Fabric==1.1.2 meld3==0.6.7
Jinja2==2.5.5 nose==1.0.0
Pygments==1.4 paramiko==1.7.7.1
SQLAlchemy==0.7.0 psycopg2==2.4.1
Sphinx==1.0.7 pycrypto==2.3
Tempita==0.5.1 redis==2.0.0
WebOb==1.0 requests==0.5.0
WebTest==1.2.2 setproctitle==1.1
coverage==3.4 supervisor==3.0a10
decorator==3.3.1 wsgiref==0.1.2
distribute==0.6.16 yoyo-migrations==4.1.0
docutils==0.7

17. Testing! Testing! Testing!
nose, WebOb, WebTest
Rapid iteration
Distributed team
No testing of the Django app piece

18. Session Handling
Let PHP continue to handle session authentication
Teach Python how to read/write PHP serialization using
Scott Hurring’s code: http://hurring.com/scott/code/
python/serialize/
Django has built-in memcache support, so we make
PHP save sessions in memcache

19. Gotta Get That Data
PEAR_DB handled all queries and the database
connection with hand-written SQL
Moving to multi-database, sharded model - handle
connections seamlessly
Handle different types of encoding seamlessly
Rewrite all queries in SQLAlchemy from straight SQL

22. The Campaign Edit Example
2600 lines of code to 700
Exact same functionality including some additional stuff
Number of database queries stayed close to the same
Very Javascript heavy, so changes might not be as
extensive as other sections

25. What did we learn?

26. What We Learned
We don’t really need a web framework
Django is awesome, so is Flask, so is WSGI
git is invaluable for distributed teams on big projects
Easy deployment is vital
Data encoding sucks and is hard
Timezone handling sucks and is hard

27. What We Learned
PHP frameworks (CakePHP and Symfony) have come
a long way and are on par with Django
The shift to sqlalchemy has provided lots of challenges
Django template parsing can be slow in certain
situations
Hiring Python developers can be tough, especially in
Nashville
Juggling multiple systems is fraught with danger

28. What We Learned
Incremental rewrites are technically more difficult
Starting from scratch would have left us lost in the
marketplace
Many of our problems had nothing to do with language
choice or tools or frameworks

29. Learning a New Language
Porting is bad
Bad habits are easy to break in Python, though not
unavoidable
Python’s interactive interpreter makes tinkering easy
Every developer learns in unique ways and at different
rates
Reading great code

30. Would I do it all again?

31. www.wordle.net

32. Positives
Codebase is becoming more standardized
Developer energy is high
Features we have implemented have turned out well
and been easy to add functionality to
Python’s standard library offers powerful, quality add-
on modules for free
Developers we have hired have been able to contribute
quickly and be impactful

33. Many of us crucify ourselves
between two thieves - regret for
the past and fear of the future.
- Fulton Oursler

34. We’re Launching It Sept.
1

35. Contact Me
Email: alex@myemma.com
Twitter: @aezellisdead or @emmaemailtech

36. We Are Hiring at Emma
Happy Hour Tonight at Eddie
George’s Grill from 6-8pm
http://myemma.com/tech-jobs/
Email: alex@myemma.com
Twitter: @aezellisdead or
@emmaemailtech

37. Photo Credits
Nixon - BusinessWeek: http://images.businessweek.com/ss/07/04/0426_dow/
source/5.htm
Change - http://www.flickr.com/photos/spursfan_ace/2328879637/
Kofi Annan - http://www.gambianow.com/news/Open-Forum/Have-Your-Say/
Many_Give_Annan_High_Marks_as_UN_Chief_Despite_Flaws.html
Butterflies - http://21stcenturylearning.typepad.com/blog/2009/01/why-
change.html
Sad boy - http://www.psychologytoday.com/blog/ulterior-motives/200806/will-i-
regret-it-in-the-morning-how-about-when-im-64