Google App Engine

David PageThe OTOBAS Group Pty Ltd

19 April 2008BarCamp Canberra

OverviewWhat is the Google App Engine?FeaturesLimitationsWhere is it going?

What is Google App Engine?Trial beta announced on April 7Web application development environmentBased on Python scripting languageIncludes a data store (non-relational)Google hosts the application

Can use default domain or use your ownBasic is free, Fee based structure yet to be

announcedhttp://code.google.com/appengine/

FeaturesDynamic web serving, with full support for

common web technologiesPersistent storage with queries, sorting and

transactionsAutomatic scaling and load balancingAPIs for authenticating users and sending

email using Google AccountsA fully featured local development

environment that simulates Google App Engine on your computer

The Data StoreDistributed data storage serviceFeatures a query engine and supports

transactions including optimistic locking and rollback

The distributed datas tore grows with the dataThe data store is not like a traditional relational

database:Data objects, or "entities," have a kind and a set

of properties. Queries can retrieve entities of a given kind

filtered and sorted by the values of the properties.

Other FeaturesAccount administration done via Google

accountsAPIs can access other web resourcesEnvironment is sandboxed, but scaling is

automaticThe SDK provides a complete runtime

environment

LimitationsAn application can only access other

computers on the Internet through the provided URL fetch and email services and APIs.

Other computers can only connect to the application by making HTTP (or HTTPS) requests on the standard ports.

An application cannot write to the file system. An app can read files, but only files uploaded

with the application code. The app must use the App Engine data store

for all data that persists between requests.

LimitationsApplication code only runs in response to a web

request Must return response data within a few seconds. A request handler cannot spawn a sub-process

or execute code after the response has been sent.

A query can only return 1,000 resultsFree environment limits:

500mb data store5 million page views per month

Where is it Going?Google is stalking on-line computing:

Search engineGoogle mailTabbed home page with widgetsGoogle office applicationsGoogle Apps

Web pages Collaboration (document sharing, intranet, chat etc) Calendar Documents

Google App Engine

Where is it Going?Implications:

Explosion of small on-line web applications = more users

Modularised approach = mash-upsOpportunity to move small business from PC to webGreatly reduced cost of deploymentCheaper to move to online tradingAffordable scaling of application

Where next?Move to cheap web enabled devices/mobile devicesBroaden base and apply search ability to everythingMore eyeballs = more advertising revenue