Google App Engine
Day of Cloud
October 16, 2009
Monday, October 19, 2009 1

About Me
Don Schwarz
schwardo@google.com
Software Engineer
Google
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Overview
• Problems with scalable web applications
• What is Google App Engine?
• Let’s Play a Game
• How much does it cost?
• Q/A
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Challenges of Building Web Apps
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Easy to start. Easy to scale.
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It’s all included!
Hardware
Connectivity
Operating System
Web Server
Language Runtimes
Software Services
Fault-tolerance
Load balancing
SSL Support
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Key Features
• No need to install or maintain your own stack
• We do the scaling for you
• Use Google’s scalable services
• We charge only for actual usage
– Always free to get started
• Built-in application management console
• Tool integration (IDE plugins, etc.)
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Architecture
Incoming Requests
App Engine App Engine App Engine
Load Balancer Front End Front End Front End
AppServer AppServer AppServer
Other Google
AppServer Infrastructure
API Layer - Bigtable
- Google Accounts
- Memcache
App App App
- Image manipulation
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Software Services
Service Google Infrastructure
Authentication Google Accounts
Datastore Bigtable
Caching Custom memcache implementation
E-mail Gmail gateway
URLFetch Caching HTTP proxy
XMPP Google Talk infrastructure
Images Picasa Web Photo Infrastructure
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Web Hooks
• Receiving XMPP
• Receiving Email
• Scheduled Tasks (cron)
• Task Queue (offline processing)
• Google Wave Robots
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Restrictions
• No threads
• No direct network connections
• ... but URLFetch & SDC
• No direct file system writes
• ... but Datastore and Memcache
• No subprocesses or native code
• “Safe” subset of runtime environment
• 30 seconds per request, 10MB limit
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Java
• Java 6 VM (with Hotspot)
• Full Servlet 2.5 Container
• HTTP Session support
• JSP support
• Services integrate with common Java Standards
• JDO/JPA for Datastore API
• JSR 107 for Memcache API
• javax.mail for Mail API
• java.net.URLConnection for URLFetch API
• IDE integration: Eclipse, IntelliJ, NetBeans
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Python
• Python 2.5.2
• CGI environment, provided by WSGI module
• Web frameworks
• webapp - Minimal built-in framework, based on WebOb
• Django 0.96 is built-in, can deploy 1.0 or 1.1
• App Engine Launcher (Mac & Windows)
• Easy access to edit, test, and deploy applications
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Datastore
• Datastore is:
• Transactional
• Natively Partitioned
• Hierarchical
• Schema-less
• Based on Bigtable
• Datastore is not:
• A relational database
• A SQL engine
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Interesting Datastore Modeling
• Ancestor
• Multi-value properties
• Variable properties
• Heterogenous property types
Kind Person Kind Person
Entity Group /Person:Ethel Entity Group /Person:Ethel
/Person:Ethel/ Key /Person:Ethel
Key
Person:Jane Age Int64: 30
Age Double: 3.5
Hobbies String: Tennis
Key:/Turtle:Sam
Pets
Key:/Dog:Ernie 15
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Datastore Transactions
• Transactions apply to a single Entity Group
• Global transactions are feasible
• get(), put(), delete() are transactional
• Ancestor queries are transactional
/Person:Ethel
Transaction /Person:Ethel/Person:Jane
/Person:Max
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Testing Locally
• “Development AppServer”
• Emulates production environment
• Enforces many of the same restrictions
• Local implementation of software services
• Disk-based datastore
• In-memory LRU memcache implementation
• Simple URLFetch implementation
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Deploying to the Cloud
• Application is available at:
• yourapp.appspot.com, or
• a custom domain
• Command-line and IDE-based tools
• Admin Console
• Dashboards, Data Viewer
• Request and diagnostic logs
• Billing
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Code Walkthrough
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http://java-demo.appspot.com
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Quotas and Billing
Resource Provided Free Additional Cost
CPU 6.5 hours/day $0.10/hour
Bandwidth In 1GByte/day $0.10/GByte
Bandwidth Out 1GByte/day $0.12/GByte
Stored Data 1 GB $0.005/GB-day
2000/day to users $0.0001/email
Emails sent
50000/day to admins
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Quotas and Billing: Estimates
• Will always be free to get started
• ~5 million pageviews/month free
• Pay only for what you use
• 10-20 million pageviews/month for
$20-30/month
• Payment via Google Checkout
• X-AppEngine-Estimated-CPM-US-Dollars
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Questions?
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Resources
• Speaker
• Don Schwarz (schwardo@google.com)
• Google App Engine
• http://code.google.com/appengine
• Google Group
• http://groups.google.com/group/google-appengine
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Backup Slides
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Does it scale?
http://whitehouse.gov/openforquestions 26
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Secure Data Connector
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Demo - Login
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Demo - Question
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Demo - Question Result
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Demo - Scoreboard
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