This document provides an overview of the GAEO web framework for Google App Engine. It discusses what GAEO is, how it works, and how to use it. Key points include that GAEO is a Model-View-Controller based framework inspired by Rails and Zend Framework. It uses URL routing, action controllers, models and templates. The document also outlines GAEO's architecture, code layout, URL routing conventions, action controllers and models. It provides instructions on installing and using GAEO utilities to generate projects.

1. An Introduction
to GAEO web
framework
ericsk
OSDC.tw 2009

2. Agenda
Google App Engine
Why GAEO?
How to use GAEO
Roadmap
Live Demo

3. Google App Engine
Host your web application and data (w/
quota limits)
You don't need to maintain the server,
focus on your application
Pay for what you use. (no setup fee)
Scalable servers and storages
Google's infrastructure
Cron service (NEW )
Both Python and Java (NEW ) are
supported

4. Google App Engine (cont.)
Dashboard

5. Why GAEO?
I need a web framework.
webapp is too simple; django is too complicated.
GAEO: Google App Engine Oil
Convension over configuration.
More easily development on GAE to Rails/Zend
Framework developers.

6. What is GAEO?
Model-Template-Controller -based web framework.
based on webapp
inspired from Rails/Zend Framework
Implemented in *pure* Python
More libraries for request/response processing.
easy and powerful URL routing convention
session support
easy and quick for different output types
easy object-relation-model
controller and model's hook

7. GAEO's Architecture
action
action
dispatcher
client
.
request
dispatch .
.
action
response

8. Code Layout (GAEO-0.3)
$APP_BASE/
application/
controllers/
models/
templates/
assets/
css/
img/
js/
gaeo/
libs/
plugins/
app.yaml
favicon.ico
main.py

9. GAEO URL Routing
Default:
http://example.com/foo/bar/1234
controller: foo (FooController class)action: bar (bar method in FooController)id: 1234
Configurable & Parameterize:
route.connect('/signin', controller='account',
action='signin')
route.connect('/user/:name', controller='user', action='show')
route.connect('/foo/:action/:x/:y/:z', controller='foo')

10. GAEO Action Controller
Each request is distributed to an action
In GAEO, an action is a method of an action controller
Create a controller class that extends gaeo.controller.
BaseController
Implement the action
class FooController(BaseController):
def bar(self):
quot;quot;quot;
TODO: do things for /foo/bar request
quot;quot;quot;
pass

11. GAEO Action Controller (cont.)
Use render method to output different response data. (helps set
the Content-Type header)
Use redirect method to redirect to another action (or URL)
Hook action in before_action and after_action function
Mobile device detection. (_is_mobile, _is_iphone,
_is_android)
Session object.

12. GAEO Action Controller (cont.)
Sample controller:
from gaeo.controller import BaseController
class FooController(BaseController):
def bar(self):
name = self.params.get('name', 'anonymous')
self.render(html='<h1>Hello, %s' % name)
def update(self):
if self._request_method == 'post':
// update some model
self.redirect('/foo/edit')
else:
self.render(text=quot;Invalid Requestquot;)

13. GAEO Model
Extends GAE's Model class.
Add one-to-many and many-to-many helper
Update properties within single method -- update_attributes
Add before_put and after_put hook.

14. GAEO Model (cont.)
model sample:
from gaeo.model import BaseModel
class User(BaseModel):
name = db.StringProperty()
email = db.EmailProperty()
created = db.DateTimeProperty(auto_now_add=True)
def before_put(self):
// TODO: check property values
if failed:
return False

15. How to Use GAEO

16. Installation
Download the release archive, and unpack it.
Install it through easy_install
Setup the $PATH for using GAEO's utilities.

17. GAEO Utilities
gaeo.py - Create a GAEO project.
gaeogen.py - Generate a GAEO a controller, model, or
plugin.

18. Live Demo

19. GAEO's Roadmap
XML-RPC support
Caching
i18n support
RESTful
Extend the Template engine
CMS
...

20. GAEO Resources
Project home:
http://code.google.com/p/google-app-engine-oil/
Document site:
http://doc.gaeo.org/, http://doc-zhtw.gaeo.org/, http://doc-fr.
gaeo.org/, http://doc-ja.gaeo.org/
Groups:
http://groups.google.com/group/google-app-engine-oil
IRC:
#gaeo on irc.freenode.net

21. Q&A
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