OffiServ presentation on tech.3camp.pl barcamp event in Gdynia Pomeranian Science and Technology Park.

1. 1
Google App Engine
Alek Kowalczyk
1.10.2013
www.offiserv.com

2. 2
LAMP vs GAELAMP vs GAE

3. 3
LAMP vs GAELAMP vs GAE
Components:
✔Linux
✔Apache
✔MySQL
✔PHP, Python, Ruby, Perl
Components:
✔Python
Tasks:
✔ Keep secure
✔ Maintain updates
✔ Design and keep scalable
✔ Maintain load balancing
Tasks:
Pay monthly bills

4. 4
GAE Dev EnvGAE Dev Env
Python libs:
Services:
Task Queues
Users & OAuth
XMPP
Memcache
Logs
Mail
Development server
Languages:

5. 5
MissingMissing
Preview

6. 6
HRD – High Replication DatastoreHRD – High Replication Datastore
Schema-less

Dynamic properties

Watch out missing
or type-varying columns!
Database Access:

ORM:

DB API older

NDB newer – advanced caching

GQL

Low level API

7. 7
Forget about what you know on SQL...Forget about what you know on SQL...
No planned downtimes
(I haven't noticed unplanned ones too)
Scalability
100 records query performs the same when
searching in 100 records
as in 1 000 000 000 records
Query limitations

>, <, != conditions:
one field only
(who cares...)

No LIKE, GROUP BY,
COUNT or SUM (again, who cares...)
No JOIN queries
What? 

8. 8
Eventual ConsistencyEventual Consistency
GAE
High Replication
Datastore
Nope...
?
SELECT *
WHERE
name='Alex'
GAE
High Replication
Datastore
__key__=5
name='Alex'
GAE
High Replication
Datastore
id=5
name='Alex'
SELECT *
WHERE
name='Alex'
?

9. 9
How can I live with that?How can I live with that?
>>> ses = Session(cookie=cookie, user=user)
>>> ses.put()
# next request:
>>> ses = GqlQuery(“SELECT * FROM Session WHERE cookie=:1”, cookie).get()
None # or <Session object> if lucky...
>>> ses = Session.all().filter('cookie', cookie).get()
None # or <Session object> if lucky...
>>> ses = Session(key_name=COOKIE, user=userid, …)
>>> ses.put()
# next request:
>>> ses = Session.get_by_key_name(cookie)
<Session object> # for sure
Most likely won't hurt
If hurts:

Entity groups/ancestor queries

Primary key queries
Some code?
Google BigTable is used by:
Google Search, Google Maps,
Gmail, YouTube, Orkut,
Google Earth,...

10. 10
BillingBilling
Google App Engine charges for:
Outgoing Bandwidth
Frontend & Backend Instances
Stored Data (Datastore, Logs Data, Task Queue)
Memcache
Recipients Emailed
SNI SSL certificates
PageSpeed bandwidth
DB Write Operation
DB Read Operation
(and more...)
Free quotas for each app

11. 11
Good and badGood and bad
✔New apps
✔Big data – small result sets
✔Google integration
✗Legacy apps
✗Binary code
✗CPU-intensive / background apps
¿Big data - big result sets – runtime analytics
•
Integrate with Google BigQuery
•
MapReduce

12. 12
Q&A
Mobile developers needed
https://www.offiserv.com/career

13. 13
Application Versions supportApplication Versions support
V1 V2
V2 – 70%V1 – 30%
Versioning
A/B Testing

14. 14
Backup: Development setupBackup: Development setup
I. Create a free app on your google account:
https://appengine.google.com/
II. Download SDK:
http://goo.gl/hoK5tk
III. Create WSGI python app
IV. Create app.yaml configuration file
V. Run app at http://localhost:8000:
dev_appserver.py ­­port=8000 <app­name>
VI. Upload app google credentials
appcfg.py update app-name
VII. http://app-name.appspot.com

15. 15
Backup: The SandboxBackup: The Sandbox
An application cannot:
 Open a socket
 Access another host - except URL Fetch Service
 Respond slowly – 60 secs
 Write to the filesystem - reading is OK
 Run other programs
 Run binary (C) extensions – pure Python only