Real life experience from AppEngine & Django
Real life experience from AppEngine & Django
Udi h Bauman
Google Developers Day Israel 08
About me
SW architect and developer
Expertise in BI and Semantic Web
Using Python, Django, AppEngine & EC2 for daily work
Could elaborate about following but it will probably defocus
from PPT goal:
Perform complex logic & analytics (e.g., Semantic Web
services, complex content manipulations)
Work against Flash GUI or XUL-based Desktop application
Successfully use the Google API's available for AppEngine
applications
About my company
We develop and automate Value Creation Processes and by that
enable enterprises to maximize their profits.
Our solution is Django
based & considered one
of the largest & most
complex enterprise products developed in Django.
Our CEO is Orr Mendelson, a top expert in Value Creation
We are in Beta stage in several enterprises
My experience in web applications
[Been doing Enterprise Web Applications since 1994It was always
a pain, even with the best possible architectures &
technologiesDecided 2 years ago to try a technology, which changed
all this]
(Orr: I hope the effect works for you)
Great Web Technologies Pain!
CGI
ASP
ColdFusion
Servlets
JSP
EJB
.Net
Open-Source Java frameworks
AJAX frameworks
PHP
Ruby
Rails
Lesson #1
is the best Web technology today.
Django Example
Web site for Visualizing time differences around Daylight Saving
Time events
http://daylight-savings-time.info
[Some Start-up asked me to build a site for] visualizing time
differences around Daylight Saving Time events
[They previously asked some Web shop to develop it, using a more
common technology (PHP)Although seemingly simple, the other shop
gave up after a few months, due to the logic complexity]
Using Django
Data model takes minutes to define
Django builds the DB based on the data model
Django generates the back-office administration screens
Django provided the I18N layer
The logic written in Python is OO, simple & succinct, so
both dev & maintenance are extra fast
I could focus only on the logic
I kept it simple
Start with: [Django enabled me to easily develop the site]
End with: [that even my client (non-programmer) understood
everything without explanation]
Is it mature enough? Does it scale?
Dev technology is really tested when the project passes a
certain level of size & complexity
Some technologies, optimized for rapid development, don't scale
beyond that point: they don't allow the flexibility & power to
grow in complexity & scale, without compromising features &
simplicity
After working for 2 years, building a very large & complex
enterprise product, I can truly say Django is mature enough &
scales extremely well
Still have to take care of:
Deployment
Configuring Apache, DB, Virtual hosting, Prod & Staging
environments, &c
Specific application requirements:
Traffic peaks
DB clustering & extreme scalability
Start with: [there are still 2 problems one faces today, not
handled by Django]
2. Besides that I had to meet 2 challenging requirements:
Very affordable hosting
Must handle extreme peaks of traffic (most of the year traffic
is low, but around DST events, traffic can be >1M hits per
day)
Using AppEngine
AppEngine is based on Django, & solves the 1 pain left when
using it - it just takes from you all the worries & boring work
on:
deployment
hosting
scalability
DB management
Ends with: [You really should have seen my face when Google
announced AppEngine]
Lesson #2
is awesome!
AppEngine Demo
Alex Arshavski & me made a small Demo of using AppEngine for
a previous developers event at Google
It took us 2 cafe meetings
Try application at:
http://ppl-search.appspot.com
Download source code:
http://code.google.com/p/ppl-search
How come we could build it so fast?
Because AppEngine (& Django) let's you focus just on the
business logic, & do it simply
Because we used of components & Web-Services, that we just
needed to mash-up
Because the documentation is extremely good, & you can get
an answer to any problem you encounter
What's the catch?
Experienced people always think long-term & manage risks
So their main concern is vendor locking being tied to Google for
ever with their application
It turns out Google had to make some modifications to Django, so
writing for AppEngine, isn't like writing pure Django (which can
run anywhere)
Tip
Always use the AppEngine Django Helper
Using the Django helper
Let's you write regular Django application, and adapts them to
AppEngine
Abstracts some of the Google API's
Allows you to take your site to other cloud/hosting services
with only minor changes
To use it:
Create an app using the AppEngine SDK
Replace the content of the folder created with the content of
the helper
Rename the app in the app.yaml file
Is AppEngine production ready?
Make sure to be familiar with the quota of the service
Requests are limited to 10s
Throughput is limited
Note that its not yet production ready, mainly in the aspects of
uptime SLA & support.
Subscribe to the outage announecement Google group to get
notifications on Up-Time
There's also a great monitoring dashboard of cloud services:
http://cloudstatus.com
BTW, about Amazon EC2
The main difference is that EC2 just provides the cloud
infrastructure, but not the application stack, so you still have
the headaches of deployment, configuration &c
The good thing is that it's completely flexible, & can run
any technology / legacy application
Say in the end: [You may end up having a cloud hybrid some
back-end services on EC2 & the front-end on AppEngine]
Criticism on Django
Why I hate Django - hilarious keynote from DjangoCon, by Cal
Henderson (Flickr's Architect):
http://tinyurl.com/hatedjango
Extremely funny..
Thank you !
Udi h Bauman
http://twitter.com/dibau_naum_h
[email protected]
