Build Agile Applications with Google App Engine!

1. Google App Engine

2. Advantages

3. Advantages
• No Server!
• Free (within Quota)
• Quick Deployment
• Python!

4. Disadvantages

5. Disadvantages
• Not suitable if specific dependencies are
required (e.g. poppler library on linux servers)
• Disconcerting for Developers who are used to
traditional servers
• Rewrite all Queries/ORMs! Good luck!
• Deal with query quirks, API limitations.
• Schema Migration? Problem ☺

6. Google App Engine Frameworks?

7. Why Frameworks?

8. Why Frameworks?

9. Why Frameworks?
• Agile development
• Team development
• MVC for maintainability
• Problem Isolation and Identification
• Test Driven Development on “organised
components” - Apps
• No cowboy coding
• Framework gives consistency

10. Simple Example (AEP)

11. Execution Details?
• 30 minutes quick start
• Around 2 days to be up and running
• More time for making it look pretty
• Slight confusion at the start with Django ORMs
• Django Forms! Nice.
• 1-to-1, M2M, FK relationships are different (of
course)
• Query Object Count limitations. Need “sharding”.

14. Another Framework (Kay)

15. Execution Details?
• 30 minutes quick start
• Around 2 days to be up and running
• More time for making it look pretty (in progress)
• Steeper learning curve for Jinja2 and Werkzeug
• 1-to-1, M2M, FK relationships are different (of
course)
• Query Object Count limitations. Need “sharding”.
• Gotcha - Templatetag is more complex. Url
mapping is confusing.
• Not all bad: werkzeug debugger is awesome.

16. Agile Job Board (alpha)

17. Other Framework Solutions?
• Plenty!
• The usual non-MVC webapp
• web2py
• Bottle
• App Engine Helper
• App Engine Oil
• EngineLight
• Blablabla……..

18. Take Away
• Write code to scale. Sharding techniques:
http://code.google.com/appengine/articles/sh
arding_counters.html
• Use db.run_in_transaction(txn)
User Uploaded Images
• Use boto.zip for pushing images to Amazon S3
• Or use BlobProperty()

19. What would I recommend?
• Don’t know at this point.
• Still experimenting on Live Projects.
• Ideas and Collaboration for experiments
welcome!
Criteria?
• Useful.
• Pretty.
• 1 week.
• Open source some completed components

20. Should we use App Engine?

21. Small Team. Big Apps.