1. Google App Engine
Ikai Lan
Kuala Lumpur, GTUG Hackathon
Twitter: @ikai
June 18, 2011
Saturday, June 18, 2011
2. About the speaker
• Developer Relations at Google based out
of San Francisco, CA
• Primarily work in Java and Python
nowadays; lots of experience with Ruby,
JavaScript, PHP <5.3
• Focus: Cloud products
• Twitter: @ikai
Saturday, June 18, 2011
3. Agenda
• What is Google App Engine?
• Various features of GAE
• How to get started
• Introduction to Go
• Important tools + some tips
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4. Software
Platform
Infrastructure
Source: Gartner AADI Summit Dec 2009
Saturday, June 18, 2011
5. Software
Platform
Infrastructure
Source: Gartner AADI Summit Dec 2009
Saturday, June 18, 2011
6. Software
Platform
Infrastructure
Source: Gartner AADI Summit Dec 2009
Saturday, June 18, 2011
7. Software
Platform
Infrastructure
Source: Gartner AADI Summit Dec 2009
Saturday, June 18, 2011
8. • Easy to build
• Easy to manage
• Easy to scale
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9. “We wear pagers so
you don’t have to”
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12. SDK & “The Cloud”
Hardware
Networking
Operating system
Application runtime
Java, Python, Go
Static file serving
20
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13. Development Cycle
• Write code locally
• Test, push to Google Servers
• Administer via a web interface - http://
appengine.google.com
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17. Core APIs
Memcache Datastore URL Fetch
Mail XMPP Task Queue
Images Blobstore User Service
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18. High Replication
• Strongly consistent, multi-datastore, multi-
data center serving solution
• Write once, have your data be available in a
highly consistent manner
• No data loss, no datastore outages
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19. Other APIs
• High performance image serving
• App Engine Map Reduce
• Prospective Search API
• Pipeline API
• OAuth provider
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20. Prospective Search
• Matches a high rate of incoming documents
• 100,000 matches a second
• Think: How might we build something like
Google Alerts?
• http://code.google.com/appengine/docs/
python/prospectivesearch/
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21. A basic Python app
• 2 files: app.yaml and main.py
• Easier to use when Python SDK is in your
system path
• Start server with dev_appserver.py
• Deploy via appcfg.py
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24. Getting started with
Java
• Servlets API
• Google Plugin for Eclipse will generate a
skeleton project: http://code.google.com/
eclipse/beta/docs/download.html
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25. Go: why I like it
• “The next version of C, brought to you by
the guys who didn’t bring you C++”
• Modern, type safe compiled language (stdlib
includes: json parsing, web server)
• Functions as first class objects
• Concurrency baked in via goroutines and
channels
• Very fast compilation times
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26. Flexible interfaces
// This is an interface declaration
type myInterface interface {
set(i int)
}
// This is a Type declaration. Note that it is a type, not a class
type myType struct {
i int
}
// This is how we define a function where myType is a receiver
// With an instance of myType we can call myType.set(123)
func (p *myType) set(i int) {
p.i = i
}
// Because myType defines a function with the signature set(int i) method,
// we can use it anywhere myInterface is accepted!
func setToThousand(x myInterface) {
myInterface.set(1000)
}
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27. First class functions
package main
import "fmt"
// Make a function that returns a new function
func makeAdd(increment int) (counter func(int) int) {
return func(v int) int {
return v + increment;
}
}
func main() {
fmt.Printf("value of makeAdd(100)(1) is %vn", makeAdd(100)(1));
fmt.Printf("value of makeAdd(200)(2) is %vn", makeAdd(200)(2));
}
// Outputs:
// value of makeAdd(100)(1) is 101
// value of makeAdd(200)(2) is 202
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28. Goroutines and
package main
Channels
import (
"fmt"
"time"
)
func doLotsOfWork(until int, ch chan int) {
c := 0
for i := 0; i < until; i++ {
c += i
time.Sleep(1000)
}
ch <- c
}
func main() {
ch := make(chan int)
// First the work off into the background
go doLotsOfWork(5, ch)
// Do more work here while we wait for this process to complete
// Block until doLotsOfWork sends data back on this channel
i := <- ch
fmt.Printf("Final value: %vn", i)
}
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29. It runs on App Engine!
• Currently requires whitelisting
• Experimental status
• Goroutines allow for concurrency within
request; concurrent requests coming
• Demo app: http://moustach-io.appspot.com/
• Source: https://code.google.com/p/
appengine-go/source/browse/example/
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31. General tips
• The datastore is built on top of BigTable. It
is non-relational!
• Be aware of limits: 30 second requests, 10
minute tasks queues/cron jobs, whitelisted
classes
• Python 2.5 compatible (but can use 2.6 or
2.7 locally)
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33. Java tips
• Use low-level datastore API or third party
API: http://code.google.com/p/objectify-
appengine/
• Start with servlets API - will have to do
some work to make your favorite
framework work. Slim3 is a good GAE
specific framework
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34. Summary
• Hopefully people here are interested in
hacking on App Engine
• Java, Python and Go
• Ask me if you have general questions, I will
be around all weekend
Saturday, June 18, 2011
