Groovy Update, Groovy Ecosystem, and Gaelyk -- Devoxx 2010 -- Guillaume Laforge

Groovy Update, Groovy Ecosystem, and Gaelyk -- Devoxx 2010 -- Guillaume Laforge
Groovy University Groovy update, Groovy ecosystem, and Gaelyk Guillaume Laforge Groovy 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 lundi 15 novembre 2010
Bug killer... real insects with legs! • Thanks to Groovy, with one hand left for coding, I’m still more productive than with Java! 3 lundi 15 novembre 2010
Bug killer... real insects with legs! • Thanks to Groovy, with one hand left for coding, I’m still more productive than with Java! 3 lundi 15 novembre 2010
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 lundi 15 novembre 2010
Groovy Update Past, Present, Future Major features, and what’s cooking lundi 15 novembre 2010
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 lundi 15 novembre 2010
looking into the Past lundi 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 lundi 15 novembre 2010
Multiple assignement // multiple assignment def (a, b) = [1, 2] assert a == 1 && b == 2 // with typed variables def (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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
@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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
JMX Builder • A DSL for handling JMX –in addition of Groovy MBean // Create a connector server def jmx = new JmxBuilder() jmx.connectorServer(port:9000).start() // Create a connector client jmx.connectorClient(port:9000).connect() //Export a bean jmx.export { bean new MyService() } // Defining a timer jmx.timer(name: "jmx.builder:type=Timer", event: "heartbeat", period: "1s").start() // JMX listener jmx.listener(event: "someEvent", from: "bean", call: { evt ‐> /* do something */ }) 17 lundi 15 novembre 2010
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 lundi 15 novembre 2010
AIC and NC • Anonymous Inner Classes and Nested Classes 20 lundi 15 novembre 2010
AIC and NC • Anonymous Inner Classes and Nested Classes For Java copy’n paste compatibility sake :-) 20 lundi 15 novembre 2010
Annonymous Inner Classes boolean called = false Timer timer = new Timer() timer.schedule(new TimerTask() { void run() { called = true } }, 0) sleep 100 assert called 21 lundi 15 novembre 2010
Annonymous Inner Classes boolean called = false Timer timer = new Timer() timer.schedule(new TimerTask() { void run() { called = true } }, 0) sleep 100 assert called { called = true } as TimerTask 21 lundi 15 novembre 2010
Nested Classes class Environment { static class Production extends Environment {} static class Development extends Environment {} } new Environment.Production() 22 lundi 15 novembre 2010
Anotations anywhere • You can now put annotations –on imports –on packages –on variable declarations • Examples with @Grab following... 23 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
Grape improvements (3/4) • Groovy 1.7 introduced Grab resolver –For when you need to specify a specific repository for 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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
Power Asserts (1/2) • Much better assert statement! –Invented and developed in the Spock framework • Given this script... def energy = 7200 * 10**15 + 1 def mass = 80 def celerity = 300000000 assert energy == mass * celerity ** 2 28 lundi 15 novembre 2010
Power Asserts (2/2) • You’ll get a more comprehensible output 29 lundi 15 novembre 2010
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 lundi 15 novembre 2010
AST Viewer 31 lundi 15 novembre 2010
AST Builder // Ability to build AST parts // ‐‐> from a String new AstBuilder().buildFromString(''' "Hello" ''') // ‐‐> from code new AstBuilder().buildFromCode { "Hello" } // ‐‐> from a specification List<ASTNode> nodes = new AstBuilder().buildFromSpec { block { returnStatement { constant "Hello" } } } 32 lundi 15 novembre 2010
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 lundi 15 novembre 2010
SQL support refinements // batch statements sql.withBatch { stmt ‐> ["Paul", "Jochen", "Guillaume"].each { name ‐> stmt.addBatch "insert into PERSON (name) values ($name)" } } // transaction support def persons = sql.dataSet("person") sql.withTransaction { persons.add name: "Paul" persons.add name: "Jochen" persons.add name: "Guillaume" persons.add name: "Roshan" } 34 lundi 15 novembre 2010
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 lundi 15 novembre 2010
Map improvements // map auto‐vification def m = [:].withDefault { key ‐> "Default" } assert m['z'] == "Default" assert m['a'] == "Default" // default sort m.sort() // sort with a comparator m.sort({ a, b ‐> a <=> b } as Comparator) 36 lundi 15 novembre 2010
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.book def builder = new StreamingMarkupBuilder() assert builder.bindNode(someNode).toString() == "<book isbn='12345'>Groovy in Action</book>" 37 lundi 15 novembre 2010
Currying improvements // right currying def divide = { a, b ‐> a / b } def halver = divide.rcurry(2) assert halver(8) == 4 // currying n‐th parameter def joinWithSeparator = { one, sep, two ‐> one + sep + two } def joinWithComma = joinWithSeparator.ncurry(1, ', ') assert joinWithComma('a', 'b') == 'a, b' 38 lundi 15 novembre 2010
New String methods println """ 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 '1234567t8t '.expand() == '1234567 8 ' assert ' x '.unexpand() == ' xt ' 39 lundi 15 novembre 2010
...and beyond! lundi 15 novembre 2010
Groovy 1.8 & beyond • Still subject to discussion • Always evolving roadmap • Things may change! 41 lundi 15 novembre 2010
What’s cooking? lundi 15 novembre 2010
What we’re working on • More runtime performance improvements • Closures –annotation parameters composition, 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 lundi 15 novembre 2010
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 runtime 44 lundi 15 novembre 2010
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 lundi 15 novembre 2010
Closure composition • Functional flavor! 46 def plus2 = { it + 2 } def times3 = { it * 3 } def composed1 = plus2 << times3 assert composed1(3) == 11 assert composed1(4) == plus2(times3(4)) def composed2 = times3 << plus2 assert composed2(3) == 15 assert composed2(5) == times3(plus2(5)) // reverse composition assert composed1(3) == (times3 >> plus2)(3) lundi 15 novembre 2010
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 cached def cAtMost = { ... }.memoizeAtMost(10) // between 10 and 20 invocations cached def cAtLeast = { ... }.memoizeBetween(10, 20) lundi 15 novembre 2010
Closure trampoline • No more infamous StackOvervlow errors for deeply recursive algorithms –if you use closure trampolines explicitely 48 def fact fact = { 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... lundi 15 novembre 2010
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 lundi 15 novembre 2010
lundi 15 novembre 2010
More adhoc build More modular Groovy lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
Groovy Update Summary lundi 15 novembre 2010
Summary • No need to wait for Java 7, 8, 9... –closures, properties, interpolated strings, extended annotations, metaprogramming, [YOU NAME IT]... 57 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
Q&A lundi 15 novembre 2010
Groovy Ecosystem A very rich & lively ecosystem For concurrency, for testing, for building applications... lundi 15 novembre 2010
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 interaction 60 lundi 15 novembre 2010
Grails –Don’t miss Graeme’s session on Grails! –And Christian on Eclipse tooling for Groovy and Grails 61 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 } lundi 15 novembre 2010
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 } } } } lundi 15 novembre 2010
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.scriptResult } } } } lundi 15 novembre 2010
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.scriptResult } } } } lundi 15 novembre 2010
GPars (1/6) • Actors, dataflow, concurrency, and more –for harnessing our multicore platforms • GPars web site: –http://gpars.codehaus.org 66 lundi 15 novembre 2010
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() } lundi 15 novembre 2010
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 tasks // to calculate and store own result return count + childrenResults.sum(0) } } lundi 15 novembre 2010
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!' } } } } lundi 15 novembre 2010
GPars (5/6) • DataFlow concurrency 70 new DataFlows().with { task { z = x + y println "Result: ${z.val}" } task { x = 10 } task { y = 5 } } lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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" lundi 15 novembre 2010
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 } lundi 15 novembre 2010
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 } } lundi 15 novembre 2010
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 } } lundi 15 novembre 2010
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 lundi 15 novembre 2010
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"] } lundi 15 novembre 2010
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 lundi 15 novembre 2010
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() } lundi 15 novembre 2010
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) } lundi 15 novembre 2010
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 Ant.' otherStuff() } target(otherStuff: 'A target to do some other stuff') { println 'OtherStuff' echo message: 'Another message from Ant.' clean() } setDefaultTarget stuff lundi 15 novembre 2010
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 lundi 15 novembre 2010
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.+’ } lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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}" } } } lundi 15 novembre 2010
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.statusLine}" assert resp.statusLine.statusCode == 200 } lundi 15 novembre 2010
HTTPBuilder (3/3) • Posting XML content to a URL 89 http.request(POST, XML) { body = { auth { user 'Bob' password 'pass' } } } lundi 15 novembre 2010
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" lundi 15 novembre 2010
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() lundi 15 novembre 2010
Ecosystem Summary lundi 15 novembre 2010
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 lundi 15 novembre 2010
Gaelyk A lightweight Groovy toolkit For developing web applications on Google App Engine lundi 15 novembre 2010
Cloud Computing lundi 15 novembre 2010
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 IaaS 97 lundi 15 novembre 2010
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 supported 98 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
Quotas 102 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 Outdated ﬁgures lundi 15 novembre 2010
The Datastore lundi 15 novembre 2010
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 lundi 15 novembre 2010
...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 transaction 107 lundi 15 novembre 2010
Nice dashboard lundi 15 novembre 2010
F http://gaelyk.appspot.com lundi 15 novembre 2010
F http://gaelyk.appspot.com lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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/ lundi 15 novembre 2010
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 lundi 15 novembre 2010
MVC: Groovlets and templates Groovlets (controllers) Templates (views) En55es (domain) lundi 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 lundi 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 Auto‐reloading lundi 15 novembre 2010
A template <html> <body> <% def message = "Hello World!" print message %> <%= message %> ${message} <ul> <% 3.times { %> <li>${message}</li> <% } %> </ul> </body> </html> 117 lundi 15 novembre 2010
A template <html> <body> <% def message = "Hello World!" print message %> <%= message %> ${message} <ul> <% 3.times { %> <li>${message}</li> <% } %> </ul> </body> </html> 117 Auto‐reloading lundi 15 novembre 2010
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 lundi 15 novembre 2010
DEMO lundi 15 novembre 2010
Groovy sugar! lundi 15 novembre 2010
Sending emails with Gaelyk mail.send to: 'foobar@gmail.com', from: 'other@gmail.com', subject: 'Hello World', htmlBody: '<bold>Hello</bold>' 121 lundi 15 novembre 2010
...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("admin@example.com", "Admin")); msg.addRecipient(Message.RecipientType.TO, new InternetAddress("user@example.com", "Mr. User")); msg.setSubject("Your Example.com account has been activated"); msg.setText(msgBody); Transport.send(msg); } catch (AddressException e) {} } catch (MessagingException e) {} 122 lundi 15 novembre 2010
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 notation entity.age = 32 entity.save() entity.delete() datastore.withTransaction { // do stuff with your entities // within the transaction } 123 lundi 15 novembre 2010
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 datastore def query = new Query("savedscript") // sort results by descending order of the creation date query.addSort("dateCreated", Query.SortDirection.DESCENDING) // filters the entities so as to return only scripts by a certain author query.addFilter("author", Query.FilterOperator.EQUAL, params.author) PreparedQuery preparedQuery = datastore.prepare(query) // return only the first 10 results def entities = preparedQuery.asList( withLimit(10) ) 124 lundi 15 novembre 2010
...into something groovier? def entities = datastore.query { select all from savedscript sort desc by dateCreated where author == params.author limit 10 } as List 125 lundi 15 novembre 2010
...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 Implemented! 125 lundi 15 novembre 2010
Task queue API // access a configured queue using the subscript notation queues['dailyEmailQueue'] // or using the property access notation queues.dailyEmailQueue // you can also access the default queue with: queues.default defaultQueue // add a task to the queue queue << [ countdownMillis: 1000, url: "/task/dailyEmail", taskName: "sendDailyEmailNewsletter", method: 'PUT', params: [date: '20090914'], payload: content ] 126 lundi 15 novembre 2010
Jabber / XMPP support (1/3) • Sending instant messages String recipient = "someone@gmail.com" // check if the user is online if (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 lundi 15 novembre 2010
Jabber / XMPP support (2/3) • Sending instant messages with an XML payload String recipient = "service@gmail.com" // check if the service is online if (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 lundi 15 novembre 2010
Jabber / XMPP support (2/3) • Sending instant messages with an XML payload String recipient = "service@gmail.com" // check if the service is online if (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 lundi 15 novembre 2010
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 message message.body // get the sender Jabber ID message.from // get the list of recipients Jabber IDs message.recipients // if the message is an XML document instead of a raw string message if (message.isXml()) { // get the raw XML message.stanza // get a document parsed with XmlSlurper message.xml } 129 lundi 15 novembre 2010
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 cache if ('FR' in memcache) { // use the subscript notation to get an entry from the cache using a key def countryFromCache = memcache['FR'] } 130 lundi 15 novembre 2010
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 call def totalPics = countEntityes('photos') // second call, hitting the cache totalPics = countEntityes('photos') lundi 15 novembre 2010
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 response blob.serve response // read the content of the blob blob.withReader { Reader r -> ... } blob.withStream { InputStream is -> ... } // delete the blob blob.delete() lundi 15 novembre 2010
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) lundi 15 novembre 2010
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 } lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 lundi 15 novembre 2010
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 } lundi 15 novembre 2010
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 lundi 15 novembre 2010
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.groovy 139 lundi 15 novembre 2010
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 binding binding { 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 lundi 15 novembre 2010
Gaelyk Summary lundi 15 novembre 2010
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 capabilities 142 lundi 15 novembre 2010
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 lundi 15 novembre 2010
Thanks for your attention! Guillaume Laforge Head of Groovy Development Email: glaforge@gmail.com TwiEer: @glaforge • References: • http://gaelyk.appspot.com/ • http://groovy.codehaus.org/ • http://code.google.com/appengine/ 145 lundi 15 novembre 2010
Images used in this presentation Three fingers http://markyoungtrainingsystems.com/wp-content/uploads/2009/10/three-fingers.jpg Bandage http://image.made-in-china.com/2f0j00fIGaTPEYDQnB/Elastic-Crepe-Bandage-Gauze-.jpg RIP http://gipsydan.files.wordpress.com/2009/11/rip.jpg House / 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=263521 Light bulb: https://newsline.llnl.gov/retooling/mar/03.28.08_images/lightBulb.png Speed limit : http://www.morguefile.com/archive/display/18492 Warehouse : http://www.morguefile.com/archive/display/85628 Check mark: http://www.lnl.infn.it/~epics/WikiDumps/localhost/600px-symbol_ok.svg.png Puzzle: http://www.everystockphoto.com/photo.php?imageId=263521 Light bulb: https://newsline.llnl.gov/retooling/mar/03.28.08_images/lightBulb.png Clouds http://www.morguefile.com/archive/display/627059 http://www.morguefile.com/archive/display/625552 http://www.morguefile.com/archive/display/629785 Duke ok GAE http://weblogs.java.net/blog/felipegaucho/archive/ae_gwt_java.png Python logo : http://python.org/images/python-logo.gif Gaelyc cross with clouds : http://www.morguefile.com/archive/display/37889 Speed limit : http://www.morguefile.com/archive/display/18492 Warehouse : http://www.morguefile.com/archive/display/85628 Snow 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.jpg Green 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.jpg Butt kick: http://www.brentcsutoras.com/wp-content/uploads/2009/12/kick-ass-1.jpg Griffon: http://aldaria02.a.l.pic.centerblog.net/lz2levrz.jpg Soap: http://www.flickr.com/photos/geishaboy500/104137788/ 146 lundi 15 novembre 2010

Groovy Update, Groovy Ecosystem, and Gaelyk -- Devoxx 2010 -- Guillaume Laforge

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