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GGUP ParisGroovy Grails User Group
Session inaugurale10 Juin 2010
Introduction à Groovy et son écosystème
par Guillaume Laforge
Luis AriasBalsamiq
Guillaume LaforgeSpringSource
VMWare
Stéphane Maldinidoc4web
Heeuu, mais qu’est-ce qu’on fait ici ?
Au choix !
des présentations...
des débats...
un bon restau...
coding dojos...
Let’s start!
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Groovy intro and ecosystem
by Guillaume LaforgeGroovy Project Manager
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Guillaume Laforge
• Groovy Project Manager• JSR-241 Spec Lead• Head of Groovy Development
at SpringSource / VMWare• Initiator of the Grails framework• Castcodeurs! (French Java podcast)• Co-author of Groovy in Action
• Speaker: JavaOne, QCon, JavaZone, Sun TechDays, Devoxx, The Spring Experience, SpringOne, JAX, Dynamic Language World, IJTC, and more...
13
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Contact information
• Email–[email protected]
• Twitter–@glaforge
• Blog–http://glaforge.free.fr/blog/groovy
• Groovy mailing-lists–http://old.nabble.com/codehaus---Groovy-f11866.html
14
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
A little story
15
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Agenda• Introduction to Groovy
–syntax basics–useful APIs
• Rich ecosystem
16
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Agenda• Introduction to Groovy
17
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
• Groovy is a dynamic language for the JVM–with a Meta Object Protocol–compiles directly to bytecode–provides seamless Java interoperability
• Groovy was created in 2003, is hosted at Codehaus, and is under the Apache license
• Relaxed grammar deriving from Java 5–annotations, generics, static imports, enums, varargs...–borrowed good ideas from Ruby, Python, Smalltalk–flat learning curve for Java developers
18
Groovy in a few words
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Features at a glance
• Fully Object-Oriented: same as Java• Closures: reusable/assignable code blocks• Properties: no more boring getters/setters• Optional typing: your choice!• Various shortcut notations: native syntax for lists,
maps, ranges, regex...• Handy wrapper APIs: XML, JDBC, template
engine, Swing UIs, collection methods...• Strong ability for authoring DSLs• A rich and lively ecosystem of additional modules
19
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Mandatory Hello World
• Java style...
20
public class HelloWorld { private String name;
public String getName() { return name; } public void setName(String name) {
this.name = name; } public String greet() { return "Hello " + name;
} public static void main(String[] args) {
HelloWorld helloWorld = new HelloWorld();
helloWorld.setName("Groovy");
System.out.println(helloWorld.greet());
}}
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Mandatory Hello World
• Groovy style...
21
public class HelloWorld { private String name;
public String getName() { return name; } public void setName(String name) {
this.name = name; } public String greet() { return "Hello " + name;
} public static void main(String[] args) {
HelloWorld helloWorld = new HelloWorld();
helloWorld.setName("Groovy");
System.out.println(helloWorld.greet());
}}
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Mandatory Hello World
• Groovy style...
22
class HelloWorld { String name String greet() { "Hello $name" }
}
def helloWorld = new HelloWorld(name: "Groovy")
println helloWorld.greet()
Take 2!
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Syntax basics
• Grammar deriving from Java 5–annotations, enums, static imports, generics...
• Usual Java keywords, control structures...• Same APIs
–strings, collections, regex, security, threading...• Same Object Orientation
–No impedance mismatch!–Flat learning curve for Java developers!
• But offers additional native syntax constructs
23
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
On Java interoperability
• Groovy is the alternative JVM language providing the best integration with Java
• Mix and match Groovy and Java–even with a cyclic language dependency
• Groovy comes with a «joint compiler»–compiling Groovy as Java stubs–calling the Javac compiler–compiling the Groovy classes
• Excellent IDE support (Eclipse/IntelliJ/NetBeans)24
JInterface
<<implements>>
GClass
JClass
GInterface
JClass
GClass
<<implements>>
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Native syntax constructs
• Listsdef someNumbers = [1, 2, 3, 5, 7, 11]
• Rangesdef range = 1..18
• Mapsdef states = [CA: ‘California’, TX: ‘Texas’]
• Regular expressions~/fo*/‘foo’ =~ /fo*/‘foo’ ==~ /fo*/
25
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
GStrings
• Sexiest feature of the language!
• Ability to embed variablesinside strings
26
def firstname = "Guillaume"def lastname = "${firstname} Laforge"
assert lastname == "Guillaume Laforge"
def date = "Today is: ${new Date()}"
def multiline = """Hello,How are you?"""
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Closures
• A reusable / assignable code block–⚠ CS 101 for a proper definition
27
def helloPrinter = { println "hello" }
helloPrinter()
def twice = { it * 2 }assert twice(3) == 6assert twice('foo') == 'foofoo'
def mult = { int a, int b -> a * b }
def multBy5 = mult.curry(5)assert multBy5(4) == 20
def apply(closure) { closure() }
apply { /* do something */ }
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Time savers
• The «Groovy Truth»
• Safe graph navigation
• Elvis operator
28
def blank = ""; assert !blank
def empty = []; assert !empty
def order = nullassert order?.customer?.address == null
def name = customer.name ?: "Unknown"
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
GDK: Groovy Development Kit
• Thanks to Groovy’s dynamic nature, we «decorate» existing JDK classes to add new handy methods–we can’t extend java.io.File or java.lang.String, can we?
• Add your own extensions!
29
new File("apache.log").eachLine { println it }
(1..100).findAll { it % 2 == 1 }
speakers.groupBy { it.lastname }
"123".padLeft(5, '0')"ls -la".execute()"R3Jvb3Z5IHJvY2tzIQ==".decodeBase64()
Thread.start { /* code to execute */ }
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Now onto APIs!
• After this language crash course, let’s have a look at the APIs Groovy provides:
–Markup builders and slurpers–Swing builder–Template engine–JDBC facilities–JMX builder–Ant scripting
30
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Markup builder
• Producing markup content
• Will yield
31
new MarkupBuilder().languages {
language(name: "Groovy") { feature(coolness: "low", "SQL")
feature(coolness: "high", "Template")
} language(name: "Perl")}
<languages> <language name = "Groovy"> <feature coolness="low">SQL</feature
>
<feature coolness="high">Template</feature>
</language> <language name: "Perl"/></languages>
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XML slurper
• Easily parsing and consumming XML content• Navigating through the nodes as an object graph
32
def xml = """\<languages> <language name="Groovy">
<feature coolness="low">SQL</feature>
<feature coolness="high">Template</feature>
</language> <language name="Perl"/></languages>"""
def root = new XmlSlurper().parseText(xml)
println root.language.feature[1].text()
root.language.feature.findAll{ it['@coolness'] == "low" }
.each{ println it.text() }
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Swing builder
• Creating Swing UI with a programmatic descriptive Domain-Specific Language
33
import groovy.swing.SwingBuilder
import java.awt.BorderLayout as BL
def count = 0new SwingBuilder().edt { frame(title: 'Frame', size: [300,300], s
how: true) {
borderLayout() textlabel = label(text: "Click the b
utton!",
constraints: BL.NORTH)
button(text: 'Click Me',
actionPerformed: { count++ textlabel.text = "Clicked ${
count} time(s)."
println "clicked"},
constraints:BL.SOUTH)
}}
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Template engine
• Templating capabilities, with embedded GStrings, and scriptlet notation
• A template servlet also exists
35
import groovy.text.SimpleTemplateEngine
def text = '''\Dear <%= firstname %>So nice to meet you in <% print city %>.
${signed}'''
def binding = [firstname: "Guillaume", city: "The Hague",
signed: "MrG"]
def engine = new SimpleTemplateEngine()
template = engine.createTemplate(text).make(binding)
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
JDBC facilities
• Transparent resource handling thanks to closures
• A poorman’s dataset notion
36
def sql = Sql.newInstance(url, usr, pwd, driver)
sql.execute("insert into table values ($foo, $bar)")
sql.execute("insert into table values(?,?)", [a, b])
sql.eachRow("select * from USER") { print it.name }
def list = sql.rows("select * from USER")
def set = sql.dataSet("USER")set.add(name: "Johnny", age: 33)set.each { user -> println user.name }
set.findAll { it.age > 22 && it.age < 42 }
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
JMX Builder
• Expose, configure JMX beans, export operations, create timers, event handling with closures, and more...
• You could easily monitor your Spring application’s exposed JMX beans through some Groovy script!
37
def jmx = new JmxBuilder()
def beans = jmx.export { bean(new CpuLoadMonitor())
bean(new DiskOccupationMonitor())
}
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Ant builder
• Script and reuse any Ant task–FTP, SSH, Javac, file handling, etc.
• Used in Gant and Gradle
38
new AntBuilder().sequential {
def buildClasses = "build/classes"
// create classes directory
mkdir dir: buildClasses // compile sources javac srcdir: "src", destdir: buildClass
es
// jar everything jar destfile: "my.jar", basedir: buildCl
asses
}
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Grape: a great way for sharing Groovy scripts
• Grape: Groovy Advanced Packagning Engine
• You can «grab» dependencies in your scripts–first run will download the dependencies–next runs, the dependencies will be found in the ivy
cache on your system
39
@Grab("net.sf.json-lib:json-lib:2.3:jdk15")
import net.sf.json.groovy.*
assert new JsonSlurper().parseText(
new JsonGroovyBuilder().json {
book(title: "Groovy in Action", author: "Guillaume")
}.toString()).book.title == "Groovy in Action"
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Benefits of the Groovy APIs
• Easily share scripts thanks to Grape–no need to package JARs–automate all repetitive tasks with Ant builder
• Simple to create reports or generate code with markup builders or template engines
• You can migrate / inject / modify data with the SQL facilities accessing your database through JDBC
• Create simple Swing UIs to interact with backends
• You can monitor server farms through JMX builder
40
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Spring integration (1/2)
•Groovy integrated in Spring since 2.0–ability to define beans in Groovy–to monitor changes of Groovy beans on the filesystem–to modify the behaviour of Groovy scripts and beans–to inline Groovy scripts with <lang:inline-script>
41
<lang:groovy id="messenger"
refresh-check-delay="5000"
script-source="classpath:Messenger.groovy">
<lang:property name="message" value="Hi" />
</lang:groovy>
<bean id="bookingService" class="x.y.DefaultBookingService">
<property name="messenger" ref="messenger" />
</bean>
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Spring integration (2/2)
• Grails provides a Spring bean builder–for programmatically define Spring configurations–more flexible than pure XML declarative descriptions
42
def bb = new grails.spring.BeanBuilder()
bb.beans { adder(AdderImpl) calcBean(CalcImpl)}
def ctx == bb.createApplicationContext()
def calc = ctx.getBean(‘calcBean’)
println calc.doAdd(3, 4)
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Agenda• The Groovy Ecosystem
43
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The Groovy Ecosystem
• Many projects based on Groovy
• Serve various purposes:–build applications (ie. frameworks)
•Grails (web apps), Gaelyk (Google App Engine),Griffon (Swing apps)
–enhanced testing•Easyb (BDD), Spock, Gmock (mocking), SoapUI (WS)
–help building projects•Gant (ant sugar), Gradle (adhoc build system)
–web services interaction•HTTPBuilder (REST), GroovyWS (SOAP)
44
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•Groovy on Google App Engine–Lightweight Groovy tooking for writing
applications in Groovy on GAE/J–Leverages Groovlets and
Groovy’s template engine–http://gaelyk.appspot.com
• Groovy Web Console–http://groovyconsole.appspot.com
45
Gaelyk
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GPars
• Actors, dataflow, concurrency, and more–for harnessing our
multicore platforms
• GPars web site:–http://gpars.codehaus.org
46
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Easyb (1/4)
• From the website:–« Easyb is a behavior driven development (BDD)
framework for the Java platform. By using a specification based Domain-Specific Language, Easyb aims to enable executable, yet readable documentation »
• Write specifications in Groovy• Run them from CLI, Maven, or Ant
–provides various report formats
• BDD == given/when/then paradigm
47
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Easyb (2/4)
• First, let’s write a story
48
given "an invalid zip code"
and "given the zipcodevalidator is initialized"
when "validate is invoked with the invalid zip code"
then "the validator instance should return false"
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Easyb (3/4)
• Let’s write the test itself
• Afterwards, write the code that make the test pass
49
given "an invalid zip code", { invalidzipcode = "221o1"}
and "given the zipcodevalidator is initialized", {
zipvalidate = new ZipCodeValidator()
}
when "validate is invoked with the invalid zip code", {
value = zipvalidate.validate(invalidzipcode)
}
then "the validator instance should return false", {
value.shouldBe false}
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Easyb (4/4)
• There’s also the specification format
50
before "initialize zipcodevalidator instance", {
zipvalidate = new ZipCodeValidator();
}
it "should deny invalid zip codes", {
["221o1", "2210", "22010-121o"].each { zip ->
zipvalidate.validate(zip).is false
}}
it "should accept valid zip codes", {
["22101", "22100", "22010-1210"].each { zip ->
zipvalidate.validate(zip).shouldBe true
}}
Spock testing framework
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Spock (1/3)
• From the horse’s mouth:–« Spock is a testing and specification framework for Java
and Groovy applications. What makes it stand out from the crowd is its beautiful and highly expressive specification language. »
52
class HelloSpock extends spock.lang.Specification {
def "can you figure out what I'm up to?"() {
expect: name.size() == size
where: name | size
"Kirk" | 4 "Spock" | 5 "Scotty" | 6 }}
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Spock (2/3)
• Extensible (but transparent) use of AST transformations to «pervert» the Groovy language–reuse of labels for the BDD actions
• Spock brought Groovy 1.7’s enhanced asserts
53
Condition not satisfied:
max(a, b) == c| | | | |3 1 3 | 2 false
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Spock (3/3)
• Another example of the expressive language
54
def "subscribers receive published events at least once"() {
when: publisher.send(event)
then: (1.._) * subscriber.receive(event)
where: event << ["started", "paused", "stopped"]
}
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
GMock (1/3)
• GMock is a mocking framework for Groovy
• Mocking capabilities
55
File mockFile = mock(File, constructor("/a/path/file.txt"))
mockFile.getName().returns("file.txt")
play { def file = new File("/a/path/file.txt")
assertEquals "file.txt", file.getName()
}
–method calls–property access–static calls–partial mocks
–constructor calls–time matching–order matching–regex method matching
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
GMock (2/3)
• Mocking method calls
• Mock static calls
56
def loader = mock()loader.put("fruit").returns("apple")
play { assertEquals "apple", loader.put("fruit")
}
def mockMath = mock(Math)mockMath.static.random().returns(0.5)
play { assertEquals 0.5, Math.random()
}
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
GMock (3/3)
57
• Expecting exceptions
• Time matching–never, once, atLeastOnce, atMostOnce, stub, times,
atLeast, atMost
loader.put("throw exception").raises(RuntimeException, "an exception")
mockLoader.load(2).returns(3).atLeastOnce()
play { assertEquals 3, mockLoader.load(2)
assertEquals 3, mockLoader.load(2)
}
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Gant
• Gant is a tool for scripting Ant tasks using Groovy instead of XML to specify the logic
58
includeTargets << gant.targets.Clean
cleanPattern << ['**/*~', '**/*.bak']
cleanDirectory << 'build'
target(stuff: 'A target to do some stuff.') {
println 'Stuff' depends clean echo message: 'A default message from A
nt.'
otherStuff()}
target(otherStuff: 'A target to do some other stuff') {
println 'OtherStuff'
echo message: 'Another message from Ant.'
clean()}
setDefaultTarget stuff
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
Gradle (1/2)
• From the website:
« Gradle is an enterprise-grade build system providing:–A very flexible general purpose build tool like Ant–Switchable, build-by-convention frameworks à la Maven,
for Java, Groovy and Scala projects–Groovy build scripts–Powerful support for multi-project builds–Dependency management based on Ivy–Full support for existing Maven or Ivy repository infra–Support for transitive dependency management–Ant tasks and builds as first class citizens. »
59
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Gradle (2/2)
• For example, for a classical Java project
60
usePlugin ‘java’
repositories { mavenCentral()}
dependencies { compile group: ‘commons-collection’,
module: ‘commons-collection’, version: ‘3.2’
testCompile group: ‘junit’,
module: ‘junit’, version: ‘4.+’
}
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Other build and quality tools
• You can use Ant, Gant, Maven (GMaven plugin) or Gradle to build your projects–fits nicely in an existing build and continuous
integration infrastructure
• A few Groovy-friendly tools provide handy metrics–CodeNarc: provides various rules for static analysis of
your Groovy codebase (style, size, braces, naming...)–Simian: detects duplication in your Groovy code base–Cobertura, Clover: gives code coverage metrics
61
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HTTPBuilder (1/3)
• HTTPBuilder provides a convenient builder API for complex HTTP requests
62
def http = new HTTPBuilder( 'http://ajax.googleapis.com' )
http.request(GET, JSON) {
uri.path = '/ajax/services/search/web'
uri.query = [v: '1.0', q: 'Calvin and Hobbes']
headers.'User-Agent' = 'Mozilla/5.0 Ubuntu/8.10 Firefox/3.0.4'
response.success = { resp, json ->
println resp.statusLine
json.responseData.results.each {
println " ${it.titleNoFormatting} : ${it.visibleUrl}"
} }}
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HTTPBuilder (2/3)
• Posting to a URL
63
import groovyx.net.http.HTTPBuilderimport static groovyx.net.http.ContentType.URLENC def http = new HTTPBuilder( 'http://twitter.com/statuses/' )def postBody = [status: 'update!', source: 'httpbuilder']
http.post( path: 'update.xml', body: postBody, requestContentType: URLENC ) { resp -> println "Tweet response status: ${resp.statusLine}" assert resp.statusLine.statusCode == 200}
Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.
HTTPBuilder (3/3)
• Posting XML content to a URL
64
http.request(POST, XML) { body = { auth { user 'Bob' password 'pass' } }}
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GroovyWS (1/2)
• Publishing and consuming WS-I compliant SOAP web services
• Can also deal with complex objects
65
import groovyx.net.ws.WSClient
def proxy = new WSClient(
"http://www.w3schools.com/webservices/tempconvert.asmx?WSDL",
this.class.classLoader)
proxy.initialize()
def result = proxy.CelsiusToFahrenheit(0)
println "You are probably freezing at ${result} degrees Farhenheit"
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GroovyWS (2/2)
• Publishing a service–considering a service
–publishing the service
66
class MathService {
double add(double arg0, double arg1) { arg0 + arg1 }
double square(double arg0) { arg0 * arg0 }
}
import groovyx.net.ws.WSServer
def server = new WSServer()
server.setNode("MathService", "http://localhost:6980/MathService")
server.start()
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Agenda• Summary
• Q & A
67
Make your life easier
Great fit for Domain-Specific
Languages
Rich and active ecosystem
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Question & Answers
71
What’s next?
GrailsGriffonGradleSpockGParsEasyb
...
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Picture credits
• http://www.flickr.com/photos/featheredtar/2305070061/
• http://www.thedailygreen.com/cm/thedailygreen/images/WT/christmas-tree-with-gifts-flipbook.jpg
• http://www.flickr.com/photos/chicoer2001/188468490/
• http://www.flickr.com/photos/olibac/4054644737/
• http://www.flickr.com/photos/epsos/3384297473/
• http://media.techeblog.com/images/clapboard.jpg (clap)
• http://www.flickr.com/photos/diegocupolo/3614879332/ (flower power)
• http://www.flickr.com/photos/oskay/237442629/sizes/m/ (danger)
• http://www.partybox.co.uk/data/partyimages/250x250/6ftcutoutaustinpowers.jpg (austin powers)
• http://www.flickr.com/photos/27663074@N07/3413698337/ (jeepers creepers)
• http://www.flickr.com/photos/wheatfields/420088151/sizes/l/
• http://www.flickr.com/photos/therefromhere/518053737/sizes/l/
• http://www.flickr.com/photos/romainguy/230416692/sizes/l/
• http://www.flickr.com/photos/addictive_picasso/2874279971/sizes/l/
• http://www.flickr.com/photos/huangjiahui/3127634297/sizes/l/
• http://www.flickr.com/photos/25831000@N08/3064515804/sizes/o/
• http://www.flickr.com/photos/lanier67/3147696168/sizes/l/
• http://www.flickr.com/photos/ktb/4916063/sizes/o/
• http://www.flickr.com/photos/nathonline/918128338/sizes/l/
• http://www.flickr.com/photos/kevinsteele/39300193/sizes/l/
• http://commons.wikimedia.org/wiki/File:Brueghel-tower-of-babel.jpg
• http://commons.wikimedia.org/wiki/File:Platypus.jpg
• http://www.flickr.com/photos/joaomoura/2317171808/sizes/l/
• http://www.flickr.com/photos/wiccked/132687067/
• http://www.flickr.com/photos/timsamoff/252370986/sizes/l/
• http://www.flickr.com/photos/29738009@N08/2975466425/sizes/l/
• http://www.flickr.com/photos/howie_berlin/180121635/sizes/o/
• http://www.flickr.com/photos/yogi/1281980605/sizes/l/
• http://www.flickr.com/photos/dorseygraphics/1336468896/sizes/l/
• http://www.flickr.com/photos/xcbiker/386876546/sizes/l/
• http://www.flickr.com/photos/pietel/152403711/sizes/o/
• http://www.flickr.com/photos/forezt/192554677/sizes/o/
• http://keremkosaner.files.wordpress.com/2008/04/softwaredevelopment.gif
• http://www.jouy.inra.fr
• http://www.flickr.com/photos/ejpphoto/408101818/sizes/o/
• http://www.flickr.com/photos/solaro/2127576608/sizes/l/
• http://www.flickr.com/photos/biggreymare/2846899405/sizes/l/
• http://www.flickr.com/photos/wwworks/2222523978/ (earth)
• http://static-p3.fotolia.com/jpg/00/01/64/30/400_F_1643044_YrBQoPnt0SC5gHAueG0bhx20yCSL42.jpg (trafic light)
• http://aldaria02.a.l.pic.centerblog.net/lz2levrz.jpg (griffon)
• http://www.flickr.com/photos/geishaboy500/104137788/ (soap)
• Matriochka http://lang.russe.free.fr/images/matriochka.jpg
•
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