groovy update, groovy ecosystem, and gaelyk -- devoxx 2010 -- guillaume laforge

Groovy UniversityGroovy update, Groovy ecosystem, and Gaelyk

Guillaume LaforgeGroovy Project Manager

SpringSource, a divison of VMWare

lundi 15 novembre 2010

Guillaume Laforge• Groovy Project Manager• JSR-241 Spec Lead• Head of Groovy Development

at SpringSource• Initiator of the Grails framework• Founder of the Gaelyk toolkit• Co-author of Groovy in Action

• Speaker: JavaOne, QCon, JavaZone, Sun TechDays, Devoxx, The Spring Experience, SpringOne2GX, JAX, Dynamic Language World, IJTC, and more... 2


Bug killer... real insects with legs!• Thanks to Groovy, with one hand left for coding,

I’m still more productive than with Java!

3


Agenda: 3 big parts!

• Groovy Update– past / present / future

• Groovy’s Ecosystem– a rich and lively ecosystem

• Gaelyk, Groovy into the Cloud– a lightweight Groovy toolkit

for Google App Engine

4


Groovy Update

Past, Present, FutureMajor features, and what’s cooking


Agenda

• Past–Groovy 1.6 flashback

• Present–Groovy 1.7 novelties–A few Groovy 1.7.x refinements

• Future–What’s cooking for 1.8 and beyond

6


looking into the Pastlundi 15 novembre 2010

Big highlights of Groovy 1.6• Greater compile-time and runtime performance• Multiple assignments• Optional return for if/else and try/catch/finally• Java 5 annotation definition• AST Transformations• The Grape module and dependency system• Various Swing related improvements• JMX Builder• Metaprogramming additions• JSR-223 scripting engine built-in• Out-of-the-box OSGi support 8


Multiple assignement

// multiple assignmentdef (a, b) = [1, 2]assert a == 1 && b == 2

// with typed variablesdef (int c, String d) = [3, "Hi"]assert c == 3 && d == "Hi"

def geocode(String place) { [48.8, 2.3] }def lat, lng// assignment to existing variables(lat, lng) = geocode('Paris')

// classical variable swaping example(a, b) = [b, a]

9


More optional return// optional return for if statements

def m1() { if (true) 1 else 0}assert m1() == 1

// optional return for try/catch/finally

def m2(bool) { try { if (bool) throw new Exception()

1 } catch (any) { 2 } finally { 3 }}assert m2(true) == 2 && m2(false) == 1

10


AST Transformation (1/2)• Groovy 1.6 introduced AST Transformations

–AST: Abstract Syntax Tree• Ability to change what’s being compiled by the

Groovy compiler... at compile time–No runtime impact!–Change the semantics of your programs! Even hijack

the Groovy syntax!–Implementing recurring patterns in your code base–Remove boiler-plate code

• Two kinds: global and local–triggered by annotations

11


AST Transformations (2/2)• Transformations introduced in 1.6

–@Singleton–@Immutable, @Lazy, @Delegate–@Newify–@Category, @Mixin–@PackageScope–Swing’s @Bindable and @Vetoable–Grape’s own @Grab

12


@Immutable• To properly implement immutable classes

–No mutations — state musn’t change–Private final fields–Defensive copying of mutable components–Proper equals() / hashCode() / toString()

for comparisons or as keys in maps

@Immutable class Coordinates { Double lat, lng}def c1 = new Coordinates(lat: 48.8, lng: 2.5)

def c2 = new Coordinates(48.8, 2.5)assert c1 == c2

13


Grab a grape!• Simple distribution and sharing of Groovy scripts• Dependencies stored locally

–Can even use your own local repositories

@Grab(group = 'org.mortbay.jetty',

module = 'jetty‐embedded',

version = '6.1.0')

def startServer() { def srv = new Server(8080)

def ctx = new Context(srv , "/", SESSIONS)

ctx.resourceBase = "."

ctx.addServlet(GroovyServlet, "*.groovy")

srv.start()}

14


Metaprogramming additions (1/2)• ExpandoMetaClass DSL

–factoring EMC changes

Number.metaClass { multiply { Amount amount ‐> amount.times(delegate) } div { Amount amount ‐> amount.inverse().times(delegate)

}}

15


Metaprogramming additions (2/2)• Runtime mixins

class FlyingAbility { def fly() { "I'm ${name} and I fly!" }

}

class JamesBondVehicle { String getName() { "James Bond's vehicle" }

}

JamesBondVehicle.mixin FlyingAbility

assert new JamesBondVehicle().fly() ==

"I'm James Bond's vehicle and I fly!"

16


JMX Builder• A DSL for handling JMX

–in addition of Groovy MBean

// Create a connector serverdef jmx = new JmxBuilder()jmx.connectorServer(port:9000).start()

// Create a connector clientjmx.connectorClient(port:9000).connect()

//Export a beanjmx.export { bean new MyService() }

// Defining a timerjmx.timer(name: "jmx.builder:type=Timer",

event: "heartbeat", period: "1s").start()

// JMX listenerjmx.listener(event: "someEvent", from: "bean",

call: { evt ‐> /* do something */ }) 17


into the Present...lundi 15 novembre 2010

Big highlights of Groovy 1.7• Anonymous Inner Classes and Nested Classes• Annotations anywhere• Grape improvements• Power Asserts• AST Viewer• AST Builder• Customize the Groovy Truth!• Rewrite of the GroovyScriptEngine• Groovy Console improvements• SQL support refinements

19


AIC and NC• Anonymous Inner Classes and Nested Classes

20


AIC and NC• Anonymous Inner Classes and Nested Classes

For Java

copy’n paste

compatibility

sake :-)

20


Annonymous Inner Classes

boolean called = false

Timer timer = new Timer()

timer.schedule(new TimerTask() {

void run() {

called = true

}}, 0)

sleep 100assert called

21


Annonymous Inner Classes

boolean called = false

Timer timer = new Timer()

timer.schedule(new TimerTask() {

void run() {

called = true

}}, 0)

sleep 100assert called

{ called = true } as TimerTask

21


Nested Classes

class Environment { static class Production extends Environment {}

static class Development extends Environment {}

}

new Environment.Production()

22


Anotations anywhere

• You can now put annotations–on imports–on packages–on variable declarations

• Examples with @Grab following...

23


Grape improvements (1/4)• @Grab on import

@Grab(group = 'net.sf.json‐lib',

module = 'json‐lib', version = '2.3', classifier = 'jdk15')import net.sf.json.groovy.*

assert new JsonSlurper().parseText(

new JsonGroovyBuilder().json {

book(title: "Groovy in Action",

author: "Dierk König et al")

}.toString()).book.title == "Groovy in Action"

24


Grape improvements (2/4)• Shorter module / artifact / version parameter

–Example of an annotation on a variable declaration

@Grab('net.sf.json‐lib:json‐lib:2.3:jdk15')

def builder = new net.sf.json.groovy.JsonGroovyBuilder()

def books = builder.books { book(title: "Groovy in Action", author: "Dierk Koenig")

}assert books.toString() == '{"books":{"book":{"title":"Groovy in Action",' +

'"author":"Dierk Koenig"}}}'

25


Grape improvements (3/4)• Groovy 1.7 introduced Grab resolver

–For when you need to specify a specific repositoryfor a given dependency

@GrabResolver( name = 'restlet.org', root = 'http://maven.restlet.org')

@Grab('org.restlet:org.restlet:1.1.6')

import org.restlet.Restlet

26


http://maven.restlet.org/











Grape improvements (4/4)• Groovy 1.7.5 even further shrinks the grab

resolver definition:

27

@GrabResolver('http://maven.restlet.org')

@Grab('org.restlet:org.restlet:1.1.6')

import org.restlet.Restlet













Power Asserts (1/2)• Much better assert statement!

–Invented and developed in the Spock framework

• Given this script...

def energy = 7200 * 10**15 + 1def mass = 80def celerity = 300000000

assert energy == mass * celerity ** 2

28


Power Asserts (2/2)• You’ll get a more comprehensible output

29


Easier AST Transformations• AST Transformations are a very powerful feature• But are still rather hard to develop

–Need to know the AST API closely

• To help with authoring your own transformations, we’ve introduced–the AST Viewer in the Groovy Console–the AST Builder

30


AST Viewer

31


AST Builder

// Ability to build AST parts

// ‐‐> from a Stringnew AstBuilder().buildFromString(''' "Hello" '''

)

// ‐‐> from codenew AstBuilder().buildFromCode { "Hello" }

// ‐‐> from a specification

List<ASTNode> nodes = new AstBuilder().buildFromSpec {

block { returnStatement {

constant "Hello"

} }}

32

Customize the Groovy Truth!• Ability to customize the truth by implementing a boolean asBoolean() method

class Predicate { boolean value boolean asBoolean() { value }

}

def truePred = new Predicate(value: true)

def falsePred = new Predicate(value: false)

assert truePred && !falsePred

33


SQL support refinements

// batch statementssql.withBatch { stmt ‐>

["Paul", "Jochen", "Guillaume"].each { name ‐>

stmt.addBatch "insert into PERSON (name) values ($name)"

}}

// transaction supportdef persons = sql.dataSet("person")

sql.withTransaction { persons.add name: "Paul" persons.add name: "Jochen"

persons.add name: "Guillaume"

persons.add name: "Roshan"

}

34


Groovy 1.7.x changes

• Since Groovy 1.7.0...Groovy 1.7.1, 1.7.2, 1.7.3, 1.7.4 and 1.7.5 have been released already!

• Here’s what’s new!

35


Map improvements

// map auto‐vificationdef m = [:].withDefault { key ‐> "Default" }

assert m['z'] == "Default"

assert m['a'] == "Default"

// default sortm.sort()

// sort with a comparatorm.sort({ a, b ‐> a <=> b } as Comparator)

36

XML back to String• Ability to retrieve the XML string from a node

from an XmlSlurper GPathResult

def xml = """<books> <book isbn="12345">Groovy in Action</book>

</books>"""def root = new XmlSlurper().parseText(xml)

def someNode = root.bookdef builder = new StreamingMarkupBuilder()

assert builder.bindNode(someNode).toString() ==

"<book isbn='12345'>Groovy in Action</book>"

37

Currying improvements

// right curryingdef divide = { a, b ‐> a / b }

def halver = divide.rcurry(2)

assert halver(8) == 4 // currying n‐th parameterdef joinWithSeparator = { one, sep, two ‐>

one + sep + two}def joinWithComma = joinWithSeparator.ncurry(1, ', ')

assert joinWithComma('a', 'b') == 'a, b'

38


New String methodsprintln """ def method() { return 'bar' }""".stripIndent()

println """ |def method() { | return 'bar' |}""".stripMargin('|')

// string "translation" (UNIX tr)

assert 'hello'.tr('z‐a', 'Z‐A') == 'HELLO'

assert 'Hello World!'.tr('a‐z', 'A') == 'HAAAA WAAAA!'

assert 'Hello World!'.tr('lloo', '1234') == 'He224 W4r2d!'

// capitalize the first letter

assert 'h'.capitalize() == 'H'

assert 'hello'.capitalize() == 'Hello'

assert 'hello world'.capitalize() == 'Hello world'

// tab/space (un)expansion (UNIX expand command)

assert '1234567\t8\t '.expand() == '1234567 8 '

assert ' x '.unexpand() == ' x\t '

39


...and beyond!lundi 15 novembre 2010

Groovy 1.8 & beyond

• Still subject to discussion• Always evolving roadmap• Things may change!

41


What’s cooking?lundi 15 novembre 2010

What we’re working on• More runtime performance improvements• Closures

–annotation parameterscomposition, memoization, and trampoline

• Native JSON support–builder and parser

• New AST transformations• Gradle build• Modularizing Groovy• Align with JDK 7 / Java 7 / Project Coin• Enhanced DSL support 43


Closure annotation parameters• Groovy 1.5 brought Java 5 annotations

• What if... we could go beyond what Java offered?–In 1.7, we can put annotations on packages, imports

and variable declarations–But annotations are still limited in terms of parameters

they allow

• Here comes closure annotation parameters!–Groovy 1.8 will give us the ability to access annotation

with closure parameters at runtime44


GContracts• Closures are already allowed in the Groovy 1.7

Antlr grammar–André Steingreß created GContracts,

a «design by contract» module

// a class invariant@Invariant({ name.size() > 0 && age > ageLimit() })

class Person { String name; int age }

// a method pre‐condition@Requires({ message != null })void greet(String message) { ... }

// a method post‐condition@Ensures({ returnResult % 2 == 0 })

int evenResult() { ... }45


Closure composition• Functional flavor!

46

def plus2 = { it + 2 }def times3 = { it * 3 } def composed1 = plus2 << times3assert composed1(3) == 11assert composed1(4) == plus2(times3(4))

def composed2 = times3 << plus2assert composed2(3) == 15assert composed2(5) == times3(plus2(5))

// reverse compositionassert composed1(3) == (times3 >> plus2)(3)

Closure memoization• Memoization: remember the outcome of previous

(ideally side-effect free) invocations

47

def c = { a, b ‐> sleep 1000; a + b }.memoize()

assert c(1, 2) == 3 // after 1000ms

assert c(1, 2) == 3 // return immediately

// other forms:// at least 10 invocations cached

def cAtLeast = { ... }.memoizeAtLeast(10)

// at most 10 invocations cacheddef cAtMost = { ... }.memoizeAtMost(10)

// between 10 and 20 invocations cached

def cAtLeast = { ... }.memoizeBetween(10, 20)


Closure trampoline• No more infamous StackOvervlow errors for

deeply recursive algorithms–if you use closure trampolines explicitely

48

def factfact = { int n, BigInteger accu ‐>

n > 1 ? fact.curry(n ‐ 1, n * accu) : accu

}

def factorial = { int n ‐> fact(n, 1) }

assert factorial.trampoline(1) == 1

assert factorial.trampoline(3) == 6

assert factorial.trampoline(1000) == 402387260077...


New AST Transformations• Many new transformations coming up for removing even

more boiler plate code

49

@Log inject a logger in your classes@Field creates a field in your scripts@PackageScope improvements (methods & fields)@Synchronized providing safer synchronization semantics@InheritConstructor ex. when extending Exception@IndexedProperties JavaBeans indexed property support@AutoClone automatic cloning of your beans@AutoExternalizable automatic externalization of your beans@Canonical adding equals, hashCode, toString@EqualsAndHashCode only adding equals and hashCode@ToString only adding toString@TupleConstructor for adding a tuple constructor


More adhoc build

More modular Groovy


More modular build• «Not everybody needs everything!» ™

• A lighter Groovy-core–what’s in groovy-all?

• Modules–test, jmx, swing, xml, sql, web, template–integration (bsf, jsr-223)–tools (groovydoc, groovyc, shell, console, java2groovy)

51


Java 7 / 8 / Project Coin• JSR-292 InvokeDynamic

• Simple Closures (8)

• Proposals from Project Coin–Strings in switch (7)–Automatic Resource Management (7)–Improved generics type inference (diamond <>) (7)–Simplified varargs method invocation (7)–Better integral literals (7)–Language support for collections (8?)

52

Improved DSL support

• GEP-3: an extended command expression DSL–Groovy Extension Proposal #3

• Command expressions–basically top-level statements without parens–combine named and non-named arguments in the mix

• for nicer Domain-Specific Languages–(methodName arguments)*

53


Before GEP-3• The idea: extend command-expressions, beyond

top-level statements, for chained method calls• Before

send("Hello").to("Graeme")

check(that: margherita).tastes(good)

sell(100.shares).of(MSFT)

take(2.pills).of(chloroquinine).after(6.hours)

wait(10.minutes).and(execute { })

blend(red, green).of(acrylic)

54


With GEP-3• The idea: extend command-expressions, beyond

top-level statements, for chained method calls• After

send "Hello" to "Graeme"

check that: margherita tastes good

sell 100.shares of MSFT

take 2.pills of chloroquinine after 6.hours

wait 10.minutes and execute { }

blend red, green of acrylic

55


With GEP-3• The idea: extend command-expressions, beyond

top-level statements, for chained method calls• After

send "Hello" to "Graeme"

check that: margherita tastes good

sell 100.shares of MSFT

take 2.pills of chloroquinine after 6.hours

wait 10.minutes and execute { }

blend red, green of acrylic

Less parens& commas

55


Groovy UpdateSummary


Summary

• No need to wait for Java 7, 8, 9...–closures, properties, interpolated strings, extended

annotations, metaprogramming, [YOU NAME IT]...

57


Summary

• No need to wait for Java 7, 8, 9...–closures, properties, interpolated strings, extended

annotations, metaprogramming, [YOU NAME IT]...

Groovy’s still

innovative

since 2003!

57


Q&A


Groovy Ecosystem

A very rich & lively ecosystemFor concurrency, for testing,

for building applications...


The Groovy Ecosystem• Many projects based on Groovy• Serve various purposes:

–build applications (ie. frameworks)• Grails (web apps), Griffon (Swing apps),Gaelyk (Google App Engine)

–tame new concurrency paradigms• GPars (actors, agents, fork/join, map/filter/reduce...)

–enhanced testing• Easyb (BDD), Spock, Gmock (mocking), SoapUI (WS)

–help building projects• Gant (ant sugar), Gradle (adhoc build system)

–web services interaction60


Grails

–Don’t miss Graeme’s session on Grails!–And Christian on Eclipse tooling for Groovy and Grails

61


Griffon (1/4)• Griffon is a Grails-like application framework for

developing rich desktop applications

–MVC, DRY, CoC patterns

–Easy threading,data binding and observing

–Support in IDEs

62


Griffon (2/4)• Let’s create a simple demo console

for executing Groovy scripts

• A data model

63

import groovy.beans.Bindable

class DemoConsoleModel {

String scriptSource

@Bindable def scriptResult

@Bindable boolean enabled = true

}


Griffon (3/4)• A controller

64

class DemoConsoleController {

GroovyShell shell = new GroovyShell()

// automatically injected by Griffon

def model, view

def executeScript(ActionEvent evt = null) {

model.enabled = false

doOutside {

def result = shell.evaluate(model.scriptSource)

edt { model.enabled = true

model.scriptResult = result

} } }}


Griffon (4/4)• And a view

65

application(title: 'DemoConsole', pack: true, locationByPlatform: true) {

panel(border: emptyBorder(6)) {

borderLayout()

scrollPane(constraints: CENTER) {

textArea(text: bind(target: model, targetProperty: 'scriptSource'),

enabled: bind { model.enabled },

columns: 40, rows: 10)

}

hbox(constraints: SOUTH) {

button("Execute", actionPerformed: controller.&executeScript,

enabled: bind { model.enabled })

hstrut 5 label "Result:"

hstrut 5 label text: bind { model.scriptResu

lt }

} }}


GPars (1/6)

• Actors, dataflow, concurrency, and more–for harnessing our

multicore platforms

• GPars web site:–http://gpars.codehaus.org

66


http://gpars.codehaus.org

http://gpars.codehaus.org

GPars (2/6)• Improving over JSR-166y’s ParallelArray

• Asynchronous closures returning Futures

67

GParsPool.withPool { // using fork/join

// a map-reduce functional style

def smallestSelfPortrait =

images.parallel.filter { it.contains me }

.map { it.resize() }

.min { it.sizeInMB }

}

GParsExecutorsPool.withPool { // using JDK executors

// adds callAsync() to closures

assert 6 == { it * 2 }.callAsync(3).get()

}


GPars (3/6)• Improving over JSR-166y’s Fork / Join

68

withPool(2) { pool ->

println "Number of files: " +

runForkJoin(new File("./src")) { File file ->

long count = 0

file.eachFile {

if (it.isDirectory()) {

println "Forking a child task for $it"

// fork a child task

forkOffChild(it)

} else {

count++

} } // use results of children task

s

// to calculate and store own result

return count + childrenResults.sum(0)

}}


GPars (4/6)• Actors

–(see also dynamic dispatch actors, and more) 69

loop { println 'Waiting for a gift'

react { gift -> if (myWife.likes(gift)) {

reply 'Thank you!'

} else { reply 'Try again, please'

react { anotherGift ->

if (myChildren.like(anotherGift))

reply 'Thank you!'

} } }}


GPars (5/6)• DataFlow concurrency

70

new DataFlows().with {

task { z = x + y println "Result: ${z.val}"

}

task { x = 10 } task { y = 5 }}


GPars (6/6)• Agents

71

class Conference extends Agent<Integer> {

def Conference() { super(0) }

private register(long num) { data += num }

private unregister(long num) { data -= num }

}

final Agent conference = new Conference()

// send commands in parallel threads

final Thread t1 = Thread.start {

conference << { register 10 }

}final Thread t2 = Thread.start {

conference << { register 5 }

}final Thread t3 = Thread.start {

conference << { unregister 3 }

}

[t1, t2, t3]*.join()assert 12 == conference.val

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

72


Easyb (2/4)• First, let’s write a story

73

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"


Easyb (3/4)• Let’s write the test itself

74

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}


Easyb (4/4)• There’s also the specification format

75

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 (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. »

76

class HelloSpock extends Specification {

def "can you figure out what I'm up to?"() {

expect: name.size() == size

where: name | size

"Kirk" | 4 "Spock" | 5 "Scotty" | 6 }}


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

77

Condition not satisfied:

max(a, b) == c| | | | |3 1 3 | 2 false


Spock (3/3)• Another example of the expressive language

–with powerful mocking capabilities

78

def "subscribers receive published events at least once"() {

when: publisher.send(event)

then: (1.._) * subscriber.receive(event)

where: event << ["started", "paused", "stopped"]

}

GMock (1/3)• GMock is a mocking framework for Groovy

• Mocking capabilities

79

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


GMock (2/3)• Mocking method calls

• Mock static calls

80

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()

}


GMock (3/3)

81

• 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)

}


Gant• Gant is a tool for scripting Ant tasks using Groovy

instead of XML to specify the logic

82

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

Gradle (1/3)• Gradle is an enterprise-grade build system

–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

83


Gradle (2/3)• For example, for a classical Java project

84

apply plugin: ‘java’

repositories { mavenCentral()}

dependencies { compile group: ‘commons-collection’,

module: ‘commons-collection’, version: ‘3.2’

testCompile group: ‘junit’,

module: ‘junit’, version: ‘4.+’

}


Gradle (3/3)• Major projects migrate to Gradle

–Hibernate–Various SpringSource projects–Groovy -based projects: Grails, Groovy, GPars, Gaelyk–Customers with 200+ multi-projects

85


Other build and quality tools• You can use Ant, Gant, Maven (GMaven plugin)

or Gradle to build your projects–fits nicely in any 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: give code coverage metrics

86


HTTPBuilder (1/3)• HTTPBuilder provides a convenient builder API

for complex HTTP requests

87

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}"

} }}


http://ajax.googleapis.com







HTTPBuilder (2/3)• Posting to a URL

88

import groovyx.net.http.HTTPBuilder

import 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.stat

usLine}"

assert resp.statusLine.statusCode == 200

}


http://twitter.com/statuses/







HTTPBuilder (3/3)• Posting XML content to a URL

89

http.request(POST, XML) { body = { auth { user 'Bob' password 'pass'

} }}


GroovyWS (1/2)• Publishing and consuming WS-I

compliant SOAP web services

• Can also deal with complex objects

90

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"


http://www.w3schools.com/webservices/tempconvert.asmx?WSDL








GroovyWS (2/2)• Publishing a service

–considering a service

–publishing the service

91

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()


http://localhost:6980/MathService








EcosystemSummary


Summary• «Groovy» is way more than just a language!

• It’s also a very rich and active ecosystem!–Grails, Griffon, Gradle, GPars, Spock, Gaelyk...

93


Q&A


Gaelyk

A lightweight Groovy toolkitFor developing web applications

on Google App Engine


CloudComputing


IaaS, PaaS, SaaS

• Software as a Service–Gmail, SalesForce.com

• Platform as a Service–Google App Engine

• Infrastructure as a Service–Amazon EC2

SaaS

PaaS

IaaS97


Google App Engine• Google’s PaaS solution• Run your app on Google’s infrastructure

• Initially just Python supported

• 1+ year ago, Java supported added too–Sandboxed JVM–Jetty servlet container

• Several JVM-compatible language supported98


Key aspects• You can use most of your usual web frameworks for

developping apps on App Engine Java–A WAR file, basically!–Uploading to the cloud by sending deltas of changes

• No OS image, or software to install–Unlike with Amazon EC2

• All the scaling aspects are handled for you–Database / session replication, load balancing...

• There are quotas, but you need a high traffic application to start being charged–Free to get started 99


Available services• Memcache

–JCache implementation–Save on CPU and DB

• URL Fetch–Access remote resources–HttpUrlConnection

• Mail–Support both incoming

and outgoing emails

• Images–Resize, crop, rotate...

• XMPP

–Send / receive Jabber messages (GTalk)

• User–Use Google’s user/

authentication system–OAuth support

• Cron & Task queues–Schedule tasks at regular

intervals–Queue units of work

• Blobstore–For storing large content

• And much more...100


Limitations• Not our usual relational database

–key / value datastore

• 30 seconds request duration limit• Forbidden to

–write on the file system–create threads–use raw sockets–issue system calls–use IO / Swing / etc. directly

• There’s a whitelist of classes allowed

• Number of files and their size are limited 101


Quotas

102


Quotas (1/2)• Bandwidth

–1,3M requests/day–1GB/day in/out–6.5 CPU hours/day

• Datastore–10M calls–1GB/day–12GB in / 115GB out–60 CPU hours/day

• Mail–7K calls/day–2K recepients/day–5K emails/day–2K attachments–100MB of attachments

• URL Fetch–657K calls/day–4GB in/out /day

103


Quotas (2/2)• XMPP

–657K calls/day–4GB data sent/day–657K recepients/day–1MB invitations/day

• Image manipulation–864 calls/day–1GB in / 5GB out–2.5M transforms

• Memcache–8.6M calls/day–10GB in–50GB out

• Task queues–100K calls

104


Quotas (2/2)• XMPP

–657K calls/day–4GB data sent/day–657K recepients/day–1MB invitations/day

• Image manipulation–864 calls/day–1GB in / 5GB out–2.5M transforms

• Memcache–8.6M calls/day–10GB in–50GB out

• Task queues–100K calls

104

Outdate

d figures


The Datastore


The datastore...• It’s not your father’s relational database! «NoSQL»

• Distributed key / value store–Based on Google’s «BigTable»–Schema-less approach

• Supporting–Transactions and partitioning–Hierarchies through entity groups

• Data access APIs–JPA and JDO

• but adds a big request load time factor–Direct low-level APIs

106


...and its «limitations»• You’re not using SQL

–No joins–No database constraints–No aggregation functions (count, avg...)

• In a query, you can only filter on one column for inequality

• Transactions only available in entity groups

• You can only update an entity once in a transaction107


Nice dashboard


F

http://gaelyk.appspot.com




Gaelyk• Gaelyk is a lightweight Groovy toolkit on top of

the Google App Engine Java SDK

• Gaelyk builds on Groovy’s servlet support–Groovlets: Groovy scripts instead of raw servlets!–Groovy templates: JSP-like template engine–Both allow for a clean separation of views and logic

• Gaelyk provides several enhancements around the GAE Java SDK to make life easier, thanks to Groovy’s dynamic nature

110


Why Groovy?• Groovy is a dynamic language for the JVM

–very flexible, malleable, expressive and concise syntax–easy to learn for Java developers

• deriving from the Java 5 grammar–provides powerful APIs to simplify the life of developers

• possibility to dynamically enrich existing APIs–support for Groovlets and its own template engine

• The truth: We worked with the Google App Engine Java team before the official launch of the platform, to ensure Groovy would run well on this new environment, and Gaelyk emerged from our test-bed project, and people asked me to Open-Source it!111


First steps...

• Go to http://gaelyk.appspot.com

• Download the template project

• Put your first Groovlet in /WEB-INF/groovy

• And your templates in /WEB-INF/pages

• And you’re ready to go!

• Launch dev_appserver.sh

• Go to http://localhost:8080/




http://localhost:8080

http://localhost:8080

The web.xml

<web-app xmlns="http://java.sun.com/xml/ns/javaee" version="2.5">

<servlet> <servlet-name>GroovletServlet</servlet-name>

<servlet-class>groovyx.gaelyk.GaelykServlet</servlet-class>

</servlet> <servlet> <servlet-name>TemplateServlet</servlet-name>

<servlet-class>groovyx.gaelyk.GaelykTemplateServlet</servlet-class>

</servlet>

<servlet-mapping> <servlet-name>GroovletServlet</servlet-name>

<url-pattern>*.groovy</url-pattern>

</servlet-mapping> <servlet-mapping> <servlet-name>TemplateServlet</servlet-name>

<url-pattern>*.gtpl</url-pattern>

</servlet-mapping>

<welcome-file-list> <welcome-file>index.gtpl</welcome-file>

</welcome-file-list></web-app>

114


http://web.xml

http://web.xml

http://java.sun.com/xml/ns/javaee

MVC: Groovlets and templates

Groovlets(controllers)

Templates(views)

En55es(domain)

115lundi 15 novembre 2010

A groovlet• Instead of writing full-blown servlets, just write

Groovy scripts (aka Groovlets)

def numbers = [1, 2, 3, 4]def now = new Date()

html.html { body { numbers.each { number -> p number } p now }}

116


A groovlet• Instead of writing full-blown servlets, just write

Groovy scripts (aka Groovlets)

def numbers = [1, 2, 3, 4]def now = new Date()

html.html { body { numbers.each { number -> p number } p now }}

116

Auto‐re

loading


A template

<html> <body> <% def message = "Hello World!" print message %> <%= message %> ${message} <ul> <% 3.times { %> <li>${message}</li> <% } %> </ul> </body></html>

117

A template

<html> <body> <% def message = "Hello World!" print message %> <%= message %> ${message} <ul> <% 3.times { %> <li>${message}</li> <% } %> </ul> </body></html>

117

Auto‐re

loading

Shortcuts• Google services

– datastore– blobstore– memcache– capabilities– images– urlFetch– mail– userService / user– defaultQueue / queues– xmpp– namespace

• Variables available– request / response– context / application– sessions– params / headers– out / sout / html– localMode / app.*

• Methods available– include / forward / redirect– println / print

118


DEMO


Groovy sugar!


Sending emails with Gaelyk

mail.send to: '[email protected]', from: '[email protected]', subject: 'Hello World', htmlBody: '<bold>Hello</bold>'

121


mailto:[email protected]

...compared to Java

Properties props = new Properties();

Session session = Session.getDefaultInstance(props, null);

String msgBody = "...";

try { Message msg = new MimeMessage(session);

msg.setFrom(new InternetAddress("[email protected]", "Admin"));

msg.addRecipient(Message.RecipientType.TO,

new InternetAddress("[email protected]", "Mr. User"));

msg.setSubject("Your Example.com account has been activated");

msg.setText(msgBody);

Transport.send(msg);} catch (AddressException e) {}

} catch (MessagingException e) {}

122


Accessing the datastore• Direct interaction with the low-level datastore API

import com.google.appengine.api.datastore.Entity

Entity entity = new Entity("person") // subscript notation, like when accessing a map

entity['name'] = "Guillaume Laforge" // normal property access notationentity.age = 32

entity.save()entity.delete()

datastore.withTransaction { // do stuff with your entities // within the transaction}

123


Querying to be improved...

import com.google.appengine.api.datastore.*import static com.google.appengine.api.datastore.FetchOptions.Builder.* // query the scripts stored in the datastoredef query = new Query("savedscript") // sort results by descending order of the creation datequery.addSort("dateCreated", Query.SortDirection.DESCENDING) // filters the entities so as to return only scripts by a certain authorquery.addFilter("author", Query.FilterOperator.EQUAL, params.author)

PreparedQuery preparedQuery = datastore.prepare(query) // return only the first 10 resultsdef entities = preparedQuery.asList( withLimit(10) )

124


...into something groovier?

def entities = datastore.query { select all from savedscript sort desc by dateCreated where author == params.author limit 10} as List

125


...into something groovier?

def entities = datastore.query { select all from savedscript sort desc by dateCreated where author == params.author limit 10} as List

Not Yet

Implem

ented!

125


Task queue API// access a configured queue using the subscript notationqueues['dailyEmailQueue'] // or using the property access notationqueues.dailyEmailQueue // you can also access the default queue with:queues.defaultdefaultQueue

// add a task to the queuequeue << [ countdownMillis: 1000, url: "/task/dailyEmail", taskName: "sendDailyEmailNewsletter", method: 'PUT', params: [date: '20090914'], payload: content]

126

Jabber / XMPP support (1/3)• Sending instant messages

String recipient = "[email protected]" // check if the user is onlineif (xmpp.getPresence(recipient).isAvailable()) { // send the message def status = xmpp.send(to: recipient, body: "Hello, how are you?") // checks the message was successfully // delivered to all the recipients assert status.isSuccessful()}

127


Jabber / XMPP support (2/3)• Sending instant messages with an XML payload

String recipient = "[email protected]" // check if the service is onlineif (xmpp.getPresence(recipient).isAvailable()) { // send the message def status = xmpp.send(to: recipient, xml: { customers { customer(id: 1) { name 'Google' } } }) // checks the message was successfully delivered to the service assert status.isSuccessful()}

128








Jabber / XMPP support (2/3)• Sending instant messages with an XML payload

String recipient = "[email protected]" // check if the service is onlineif (xmpp.getPresence(recipient).isAvailable()) { // send the message def status = xmpp.send(to: recipient, xml: { customers { customer(id: 1) { name 'Google' } } }) // checks the message was successfully delivered to the service assert status.isSuccessful()}

<customers> <customer id=’1’> <name>Google</name>

</customer></customers>

128

Jabber / XMPP support (3/3)• Receving incoming instant messages

–Configure the XmppServlet in web.xml–Add the inbound message service in appengine-

web.xml

// get the body of the messagemessage.body// get the sender Jabber IDmessage.from// get the list of recipients Jabber IDsmessage.recipients // if the message is an XML document instead of a raw string messageif (message.isXml()) { // get the raw XML message.stanza // get a document parsed with XmlSlurper message.xml}

129


http://web.xml

http://web.xml

Memcache service• Map notation access to the cache

class Country implements Serialzable { String name } def countryFr = new Country(name: 'France') // use the subscript notation to put a country object in the cache

// (you can also use non-string keys)memcache['FR'] = countryFr // check that a key is present in the cacheif ('FR' in memcache) { // use the subscript notation to get an entry from the cache using a key

def countryFromCache = memcache['FR']}

130


Closure memoization• Cache the return values for each dinstinct

invocation (for a given arguments set)

131

def countEntities = memcache.memoize { String kind -> datastore.prepare( new Query(kind) ) .countEntities()}

// first calldef totalPics = countEntityes('photos')

// second call, hitting the cachetotalPics = countEntityes('photos')


Blobstore enhancements• The blobstore allows to store some large content

–images, videos, etc.

132

def blob = ...print blob.filename // contentType, creation, size

// output the content of the blob to the responseblob.serve response

// read the content of the blobblob.withReader { Reader r -> ... }blob.withStream { InputStream is -> ... }

// delete the blobblob.delete()


Images service• Readable DSL for manipulating images

133

def blobKey = ...

def image = blobKey.image.transform { resize 1600, 1200 crop 0.1, 0.1, 0.9, 0.9 horizontal flip // vertical flip too rotate 90 feeling lucky // image corrections}

def thumbnail = image.resize(100, 100)


Capabilities• Google App Engine allows you to know the status

and availability of the various services–DATASTORE, DATESTORE_WRITE, MEMCACHE...–ENABLED, DISABLED, UNKNOWN,

SCHEDULED_MAINTENANCE–is() and not() methods

134

if (capabilities[DATASTORE_WRITE].is(ENABLED)) { // write some content in the datastore} else { // otherwise, redirect to some maintenance page}


URL Routing system (1/3)• You can have friendly URL mappings with the

URL routing system

–You’ll have to configure the RouteFilter in web.xml

all "/blog/@year/@month/@day/@title", forward: "/blog.groovy?year=@year&month=@month@day=@day@title=@title"

get "/blog/@year/@month/@day", forward: "/blog.groovy?year=@year&month=@month@day=@day"

all "/aboutus", redirect: "/blog/2008/10/20/about-us"

get "/book/isbn/@isbn", forward: "/book.groovy?isbn=@isbn", validate: { isbn ==~ /\d{9}(\d|X)/ }

135


URL Routing system (2/3)• You can also define caching times

–Nice for GAE’s infamous «loading requests»

get "/aboutus", cache: 24.hours, forward: "/aboutus.gtpl"

get "/breaking-news", cache: 1.minute, forward: "/news.groovy?last=10"

136


URL Routing system (3/3)• Namespace awareness: nice for multitenancy• Capability awareness: for graceful degradation

137

// @cust customer variable could be « acme »post "/@cust/update", forward: "/update.groovy", namespace: { "ns-$cust" }

// different destinations depending on the GAE services status

get "/speakers", forward { to "/speakers.groovy" // default destination // when the datastore is not available to "/unavailable.gtpl" on DATASTORE not ENABLED // show some maintenance is upcoming to "/speakers.groovy?maintenance=true" on DATASTORE \ is SCHEDULED_MAINTENANCE}


Simple plugin system (1/3)• Gaelyk features a simple plugin system for

extending your apps and share commonalities

• A plugin lets you–provide additional groovlets and templates–contribute new URL routes–add new categories–define variables in the binding–provide any static content–add new libraries–do any initialization

138


Simple plugin system (2/3)

• A plugin is actually just a zip file!–Basically, just a Gaelyk application, minus...

• the Groovy / Gaelyk / GAE JARs• the web.xml and appengine-web.xml descriptors

–But with a /WEB-INF/plugins/myplugin.groovy descriptor

• A plugin must be referenced in /WEB-INF/plugins.groovy with–install myplugin

• shortcut to /WEB-INF/plugins/myplugin.groovy139


http://web.xml

http://web.xml

Simple plugin system (3/3)

• An example plugin descriptor–/WEB-INF/plugins/jsonPlugin.groovy

import net.sf.json.*import net.sf.json.groovy.* // add new variables in the bindingbinding {

jsonLibVersion = "2.3" // a simple string variable

json = new JsonGroovyBuilder() // an instance of a class of a 3rd‐party JAR

} // add new routes with the usual routing system format

routes {get "/json", forward: "/json.groovy"

} // install a category you've developped

categories jsonlib.JsonlibCategory // any other initialization code you'd need

140


GaelykSummary


Summary

• Easy access to a cloud solution–Deploying Java apps, as easily as you would with PHP

• Familiar to Java folks–Your good old Servlet centric webapps style

• Pretty cheap–You need a high-trafficed website to reach the quotas

• Gaelyk provides a simplified approach to creating Servlet centric webapps in a productive manner–Leveraging Groovy’s servlet / template support and

dynamic capabilities142


What’s coming next?• Gaelyk 0.5.6 released couple weeks ago with

additional URL routing support –capabilities, namespace support

• Expect more sugar around the Datastore–An SQL-like query DSL–Easier relationship management (builder)

• Perhaps pre-compiled groovlets and templates• Testing facilities specific to Gaelyk• More generally...

–Anything that’ll come up in upcoming GAE SDK versions

143


Q&A


Thanks for your attention!

Guillaume Laforg

e

Head of Groovy

Development

Email: [email protected]

TwiEer: @glaforge

• References:• http://gaelyk.appspot.com/• http://groovy.codehaus.org/• http://code.google.com/appengine/

145


















http://groovy.codehaus.org

http://groovy.codehaus.org

http://code.google.com/appengine/

http://code.google.com/appengine/

Images used in this presentationThree fingers http://markyoungtrainingsystems.com/wp-content/uploads/2009/10/three-fingers.jpgBandage http://image.made-in-china.com/2f0j00fIGaTPEYDQnB/Elastic-Crepe-Bandage-Gauze-.jpgRIP http://gipsydan.files.wordpress.com/2009/11/rip.jpgHouse / past: http://www.flickr.com/photos/jasonepowell/3680030831/sizes/o/Present clock: http://www.flickr.com/photos/38629278@N04/3784344944/sizes/o/Future: http://www.flickr.com/photos/befuddledsenses/2904000882/sizes/l/Cooking: http://www.flickr.com/photos/eole/449958332/sizes/l/Puzzle: http://www.everystockphoto.com/photo.php?imageId=263521Light bulb: https://newsline.llnl.gov/retooling/mar/03.28.08_images/lightBulb.pngSpeed limit : http://www.morguefile.com/archive/display/18492Warehouse : http://www.morguefile.com/archive/display/85628Check mark: http://www.lnl.infn.it/~epics/WikiDumps/localhost/600px-symbol_ok.svg.pngPuzzle: http://www.everystockphoto.com/photo.php?imageId=263521Light bulb: https://newsline.llnl.gov/retooling/mar/03.28.08_images/lightBulb.pngClouds http://www.morguefile.com/archive/display/627059http://www.morguefile.com/archive/display/625552http://www.morguefile.com/archive/display/629785Duke ok GAE http://weblogs.java.net/blog/felipegaucho/archive/ae_gwt_java.pngPython logo : http://python.org/images/python-logo.gifGaelyc cross with clouds : http://www.morguefile.com/archive/display/37889Speed limit : http://www.morguefile.com/archive/display/18492Warehouse : http://www.morguefile.com/archive/display/85628Snow foot steps : http://www.flickr.com/photos/robinvanmourik/2875929243/Sugar : http://www.flickr.com/photos/ayelie/441101223/sizes/l/Press release: http://www.napleswebdesign.net/wp-content/uploads/2009/06/press_release_11.jpgGreen leaf: http://www.flickr.com/photos/epsos/3384297473/Jeepers creepers: http://www.flickr.com/photos/27663074@N07/3413698337/Earth: http://www.flickr.com/photos/wwworks/2222523978/Trafic light: http://rihancompany.com/var/243/35581-Traffic%20light%20drawing.jpgButt kick: http://www.brentcsutoras.com/wp-content/uploads/2009/12/kick-ass-1.jpgGriffon: http://aldaria02.a.l.pic.centerblog.net/lz2levrz.jpgSoap: http://www.flickr.com/photos/geishaboy500/104137788/

146


http://markyoungtrainingsystems.com/wp-content/uploads/2009/10/three-fingers.jpg

http://markyoungtrainingsystems.com/wp-content/uploads/2009/10/three-fingers.jpg

http://image.made-in-china.com/2f0j00fIGaTPEYDQnB/Elastic-Crepe-Bandage-Gauze-.jpg

http://image.made-in-china.com/2f0j00fIGaTPEYDQnB/Elastic-Crepe-Bandage-Gauze-.jpg

http://gipsydan.files.wordpress.com/2009/11/rip.jpg

http://gipsydan.files.wordpress.com/2009/11/rip.jpg

http://www.flickr.com/photos/jasonepowell/3680030831/sizes/o/

http://www.flickr.com/photos/jasonepowell/3680030831/sizes/o/

http://www.flickr.com/photos/38629278@N04/3784344944/sizes/o/

http://www.flickr.com/photos/38629278@N04/3784344944/sizes/o/

http://www.flickr.com/photos/befuddledsenses/2904000882/sizes/l/

http://www.flickr.com/photos/befuddledsenses/2904000882/sizes/l/

http://www.flickr.com/photos/eole/449958332/sizes/l/

http://www.flickr.com/photos/eole/449958332/sizes/l/

http://www.everystockphoto.com/photo.php?imageId=263521


https://newsline.llnl.gov/retooling/mar/03.28.08_images/lightBulb.png


http://www.morguefile.com/archive/display/18492




http://www.lnl.infn.it/~epics/WikiDumps/localhost/600px-symbol_ok.svg.png

http://www.lnl.infn.it/~epics/WikiDumps/localhost/600px-symbol_ok.svg.png











http://weblogs.java.net/blog/felipegaucho/archive/ae_gwt_java.png

http://weblogs.java.net/blog/felipegaucho/archive/ae_gwt_java.png

http://python.org/images/python-logo.gif

http://python.org/images/python-logo.gif







http://www.flickr.com/photos/robinvanmourik/2875929243/

http://www.flickr.com/photos/robinvanmourik/2875929243/

http://www.flickr.com/photos/ayelie/441101223/sizes/l/

http://www.flickr.com/photos/ayelie/441101223/sizes/l/

http://www.napleswebdesign.net/wp-content/uploads/2009/06/press_release_11.jpg

http://www.napleswebdesign.net/wp-content/uploads/2009/06/press_release_11.jpg

http://www.flickr.com/photos/epsos/3384297473/

http://www.flickr.com/photos/epsos/3384297473/

http://www.flickr.com/photos/27663074@N07/3413698337/

http://www.flickr.com/photos/27663074@N07/3413698337/

http://www.flickr.com/photos/wwworks/2222523978/

http://www.flickr.com/photos/wwworks/2222523978/

http://rihancompany.com/var/243/35581-Traffic%20light%20drawing.jpg

http://rihancompany.com/var/243/35581-Traffic%20light%20drawing.jpg

http://www.brentcsutoras.com/wp-content/uploads/2009/12/kick-ass-1.jpg

http://www.brentcsutoras.com/wp-content/uploads/2009/12/kick-ass-1.jpg

http://aldaria02.a.l.pic.centerblog.net/lz2levrz.jpg

http://aldaria02.a.l.pic.centerblog.net/lz2levrz.jpg

http://www.flickr.com/photos/geishaboy500/104137788/

http://www.flickr.com/photos/geishaboy500/104137788/

groovy update, groovy ecosystem, and gaelyk -- devoxx 2010 -- guillaume laforge

Technology