groovy update, groovy ecosystem, and gaelyk -- devoxx 2010 -- guillaume laforge
DESCRIPTION
University (3 hours) presentation given at Devoxx 2010.TRANSCRIPT
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
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
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Groovy Update
Past, Present, FutureMajor 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 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
lundi 15 novembre 2010
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
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
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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
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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
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@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
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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 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
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
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AIC and NC• Anonymous Inner Classes and Nested Classes
20
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AIC and NC• Anonymous Inner Classes and Nested Classes
For Java
copy’n paste
compatibility
sake :-)
20
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Annonymous Inner Classes
boolean called = false
Timer timer = new Timer()
timer.schedule(new TimerTask() {
void run() {
called = true
}}, 0)
sleep 100assert called
21
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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
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Nested Classes
class Environment { static class Production extends Environment {}
static class Development extends Environment {}
}
new Environment.Production()
22
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Anotations anywhere
• You can now put annotations–on imports–on packages–on variable declarations
• Examples with @Grab following...
23
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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
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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
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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
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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 + 1def mass = 80def celerity = 300000000
assert energy == mass * celerity ** 2
28
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Power Asserts (2/2)• You’ll get a more comprehensible output
29
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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
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AST Viewer
31
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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
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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 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
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
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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
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.bookdef builder = new StreamingMarkupBuilder()
assert builder.bindNode(someNode).toString() ==
"<book isbn='12345'>Groovy in Action</book>"
37
lundi 15 novembre 2010
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
lundi 15 novembre 2010
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
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...and beyond!lundi 15 novembre 2010
Groovy 1.8 & beyond
• Still subject to discussion• Always evolving roadmap• Things may change!
41
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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
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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
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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
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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)
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 cacheddef cAtMost = { ... }.memoizeAtMost(10)
// between 10 and 20 invocations cached
def cAtLeast = { ... }.memoizeBetween(10, 20)
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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...
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
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More adhoc build
More modular Groovy
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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
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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
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
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
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
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
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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
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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
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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
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Groovy UpdateSummary
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
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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
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Q&A
lundi 15 novembre 2010
Groovy Ecosystem
A very rich & lively ecosystemFor 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 interaction60
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Grails
–Don’t miss Graeme’s session on Grails!–And Christian on Eclipse tooling for Groovy and Grails
61
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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
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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
}
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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
} } }}
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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 }
} }}
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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 }
} }}
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GPars (1/6)
• Actors, dataflow, concurrency, and more–for harnessing our
multicore platforms
• GPars web site:–http://gpars.codehaus.org
66
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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()
}
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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)
}}
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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!'
} } }}
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GPars (5/6)• DataFlow concurrency
70
new DataFlows().with {
task { z = x + y println "Result: ${z.val}"
}
task { x = 10 } task { y = 5 }}
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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
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Easyb (1/4)• From the website:
–«Easyb is a behavior driven development (BDD) framework for the Java platform. By using a specification based Domain-Specific Language, Easyb aims to enable executable, yet readable documentation»
• Write specifications in Groovy• Run them from CLI, Maven, or Ant
–provides various report formats• BDD == given / when / then paradigm
72
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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"
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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}
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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
}}
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Spock (1/3)• From the horse’s mouth:
–« Spock is a testing and specification framework for Java and Groovy applications. What makes it stand out from the crowd is its beautiful and highly expressive specification language. »
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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 }}
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Spock (2/3)• Extensible (but transparent) use of AST
transformations to «pervert» the Groovy language–reuse of labels for the BDD actions
• Spock brought Groovy 1.7’s enhanced asserts
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Condition not satisfied:
max(a, b) == c| | | | |3 1 3 | 2 false
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Spock (3/3)• Another example of the expressive language
–with powerful mocking capabilities
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def "subscribers receive published events at least once"() {
when: publisher.send(event)
then: (1.._) * subscriber.receive(event)
where: event << ["started", "paused", "stopped"]
}
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GMock (1/3)• GMock is a mocking framework for Groovy
• Mocking capabilities
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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
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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()
}
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GMock (3/3)
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• 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)
}
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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
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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
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Gradle (2/3)• For example, for a classical Java project
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apply plugin: ‘java’
repositories { mavenCentral()}
dependencies { compile group: ‘commons-collection’,
module: ‘commons-collection’, version: ‘3.2’
testCompile group: ‘junit’,
module: ‘junit’, version: ‘4.+’
}
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Gradle (3/3)• Major projects migrate to Gradle
–Hibernate–Various SpringSource projects–Groovy -based projects: Grails, Groovy, GPars, Gaelyk–Customers with 200+ multi-projects
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Other build and quality tools• You can use Ant, Gant, Maven (GMaven plugin)
or Gradle to build your projects–fits nicely in 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
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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}"
} }}
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HTTPBuilder (2/3)• Posting to a URL
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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
}
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HTTPBuilder (3/3)• Posting XML content to a URL
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http.request(POST, XML) { body = { auth { user 'Bob' password 'pass'
} }}
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GroovyWS (1/2)• Publishing and consuming WS-I
compliant SOAP web services
• Can also deal with complex objects
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"
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GroovyWS (2/2)• Publishing a service
–considering a service
–publishing the service
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class MathService {
double add(double arg0, double arg1) { arg0 + arg1 }
double square(double arg0) { arg0 * arg0 }
}
import groovyx.net.ws.WSServer
def server = new WSServer()
server.setNode("MathService", "http://localhost:6980/MathService")
server.start()
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EcosystemSummary
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Summary• «Groovy» is way more than just a language!
• It’s also a very rich and active ecosystem!–Grails, Griffon, Gradle, GPars, Spock, Gaelyk...
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Q&A
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Gaelyk
A lightweight Groovy toolkitFor developing web applications
on Google App Engine
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CloudComputing
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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
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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
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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
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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
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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
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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
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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
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Quotas
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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
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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
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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
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Outdate
d figures
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The Datastore
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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
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...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
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Nice dashboard
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F
http://gaelyk.appspot.com
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F
http://gaelyk.appspot.com
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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
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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
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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/
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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>
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MVC: Groovlets and templates
Groovlets(controllers)
Templates(views)
En55es(domain)
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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 }}
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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 }}
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Auto‐re
loading
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A template
<html> <body> <p><% def message = "Hello World!" print message %> </p> <p><%= message %></p> <p>${message}</p> <ul> <% 3.times { %> <li>${message}</li> <% } %> </ul> </body></html>
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A template
<html> <body> <p><% def message = "Hello World!" print message %> </p> <p><%= message %></p> <p>${message}</p> <ul> <% 3.times { %> <li>${message}</li> <% } %> </ul> </body></html>
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Auto‐re
loading
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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
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DEMO
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Groovy sugar!
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Sending emails with Gaelyk
mail.send to: '[email protected]', from: '[email protected]', subject: 'Hello World', htmlBody: '<bold>Hello</bold>'
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...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) {}
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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}
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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) )
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...into something groovier?
def entities = datastore.query { select all from savedscript sort desc by dateCreated where author == params.author limit 10} as List
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...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!
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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]
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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()}
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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()}
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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>
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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}
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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']}
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Closure memoization• Cache the return values for each dinstinct
invocation (for a given arguments set)
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def countEntities = memcache.memoize { String kind -> datastore.prepare( new Query(kind) ) .countEntities()}
// first calldef totalPics = countEntityes('photos')
// second call, hitting the cachetotalPics = countEntityes('photos')
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Blobstore enhancements• The blobstore allows to store some large content
–images, videos, etc.
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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()
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Images service• Readable DSL for manipulating images
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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)
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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
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if (capabilities[DATASTORE_WRITE].is(ENABLED)) { // write some content in the datastore} else { // otherwise, redirect to some maintenance page}
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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)/ }
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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"
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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}
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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
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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
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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
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GaelykSummary
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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
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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
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Q&A
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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/
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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/
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