Google App Engine is a development platform that allows users to build and host web applications on the same infrastructure as Google. It provides four runtime environments - PHP, Python, Java, and Go. Code runs in a secure sandbox that distributes requests across servers and scales automatically. Data storage options include the App Engine datastore, Cloud SQL, and Cloud Storage. The platform charges users based on usage rather than a fixed cost, allowing applications to scale as needed.

1. Google App engine
Senthilkumar M
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2. What is Google App Engine?
• Google App Engine is a complete development
stack that uses familiar technologies to build
and host applications on the
same infrastructure used at Google.
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3. Four runtime environments
PHP
Python
Java
GO
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4. Your code runs in a sandbox
• Secure environment that provides limited
access to the underlying operating system.
• The sandbox allows App Engine to
• distribute web requests across multiple servers
• start and stop servers to meet traffic demands
• isolate apps in a secure, reliable environment
• abstract hardware, operating system and
physical location of the web server
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5. Sandbox limitations
• outbound connections: only through the provided URL
fetch and email services or the experimental Socket API.
• inbound connections: only HTTP(s) on ports 80/443.
• File system access: writing files is not allowed. An
application can read only files uploaded with the
application code.
• no native code: libraries that depend on native code
are generally not available.
• time limits: app code must terminate within given time
limits. (60s for web requests, 10m for tasks but
unlimited time for backend jobs)
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6. Storing data
• Three options for data storage
App Engine Data store
NoSQL schemeless data
storage built in GAE
Google Cloud SQL
relational SQL database
service based on MySQL
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Google Cloud Storage
file based storage
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7. What special in host on GAE
• No fixed cost pay only on what you use
• FREE!!!!
• Your APP running on the platform which
powers Google service.
• App can be scalable to any extend.
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8. Lets Run your First App
• Download the SDK
• Go
to https://developers.google.com/appengine/
downloads and grab the Python installer.
• Download Python 2.7 installer.
• Go to
http://www.python.org/download/releases/2.7/
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9. Startup the Launcher
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10. Create a Sample Application
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11. Lets write your first code
• App.yaml => It is configuration file for your application
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12. Main.py
#!/usr/bin/env python
import webapp2
class MainHandler(webapp2.RequestHandler):
def get(self):
self.response.write('Hello world!')
app = webapp2.WSGIApplication([
('/', MainHandler)], debug=True)
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13. Datastore(s)
• There are two implementations of datastore
• The original one is implemented
in google.appengine.ext.db
• The new one is called NDB and it is
implemented in google.appengine.ext.ndb
• They are very similar but not identical
• We will cover NDB
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14. Creating Data store Entity
from google.appengine.ext import ndb
class Contact(ndb.Model):
name = ndb.StringProperty()
email = ndb.StringProperty()
birth_date = ndb.DateProperty()
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15. Querying the Data store
from google.appengine.ext import ndb
def StoresByCity(city, limit):
query = Store.query(Store.city == city).order(Store.name)
return query.fetch(limit, projection=[Store.name, Store.address])
•
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•
•
The Data store API is Object Oriented.
Queries are objects
Filters and projections are specified by calling methods
Make sure you know the limits!
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16. Querying the Data store with GQL
from google.appengine.ext import ndb
def query_info():
qry = ndb.gql("SELECT * FROM Account WHERE balance < :1", 100)
return qry
• You can write queries with GQL, a SQL-like language.
• GQL is translated to NDB's native query API. (This is the
opposite of what traditional ORM libraries do!)
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17. View templates
<html>
<body>
{% for contact in contacts %}
{% if contact.name %}
<b>{{ contact.name }}</b>
{% else %}
Unnamed contact
{% endif %}
<{{ contact.email }}>
{% endfor %}
<a href="{{ url }}">{{ url_linktext }}</a>
</body>
</html>
If you use webapp2, Django Templates are supported
by default.
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18. Dispatch to view templates
Here is how to render a template in with webapp2
def render_template(self, view_filename, params=None)
if not params:
params = {}
path = os.path.join(os.path.dirname(__file__), 'views', view_filename)
self.response.out.write(template.render(path, params)):
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19. Memcache
• Memcache is a high-performance, distributed
memory object caching system.
• Can be used to minimize hits to the Datastore
or to save transient state information.
from google.appengine.api import memcache
def get_data():
data = memcache.get('key')
if data is not None:
return data
else:
data = self.query_for_data()
memcache.add('key', data, 60)
return data
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20. My sample host apps
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•
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Check out this links
http://senonscreen.appspot.com/
http://me2mentor.appspot.com/
http://sentengo.appspot.com/
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21. Questions?
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