Groovy Power Features

2006-2

Dr Paul King

paulk@asert.com.au

@paulk_asert

ASERT, Australia

Groovy Power Features!

Topics

Groovy Intro

• Leveraging the language

• Use and abuse of Design Patterns

• Web Services

• Writing DSLs

• Groovy Testing

• Polyglot Groovy

• Parallel Processing

• Enterprise Groovy

• More Info

QCON 2010 - 2

2006-2

QCON 2010 - 3

2006-2

What is Groovy?

• “Groovy is like a super version

of Java. It can leverage Java's

enterprise capabilities but also

has cool productivity features like closures,

DSL support, builders and dynamic typing.”

Groovy = Java – boiler plate code+ mostly dynamic typing+ closures+ domain specific languages+ builders+ metaprogramming+ GDK library

QCON 2010 - 4

2006-2

Groovy Goodies Overview• Fully object oriented

• Closures: reusable

and assignable

pieces of code

• Operators can be

overloaded

• Multimethods

• Literal declaration for

lists (arrays), maps,

ranges and regular

expressions

• GPath: efficient

object navigation

• GroovyBeans

• grep and switch

• Templates, builder,

swing, Ant, markup,

XML, SQL, XML-RPC,

Scriptom, Grails,

tests, Mocks

Growing Acceptance …

A slow and steady start but now gaining in

momentum, maturity and mindshare

Now free

… Growing Acceptance …

2006-2

QCON 2010 - 6

2006-2

QCON 2010 - 7

Groovy and Grails downloads:

70-90K per month and growing

2006-2

QCON 2010 - 8

Source: http://www.grailspodcast.com/

Source: http://www.micropoll.com/akira/mpresult/501697-116746

2006-2

QCON 2010 - 9

http://www.java.net

http://www.jroller.com/scolebourne/entry/devoxx_2008_whiteboard_votes

2006-2

QCON 2010 - 10http://www.leonardoborges.com/writings

What alternative JVM language are you using or intending to use

2006-2

QCON 2010 - 11

http://it-republik.de/jaxenter/quickvote/results/1/poll/44 (translated using http://babelfish.yahoo.com)

2006-2

QCON 2010 - 12

http://pollpigeon.com/jsf-grails-wicket/r/25665/

… Growing Acceptance

QCON 2010 - 13

2006-2

QCON 2010 - 14

2006-2

The Landscape of JVM Languages

Java bytecode calls

for static types

Dynamic features call

for dynamic types

mostly

dynamic

typing

The terms “Java Virtual Machine” and “JVM” mean a Virtual Machine for the Java™ platform.

QCON 2010 - 15

2006-2

Groovy StarterSystem.out.println("Hello, World!"); // optional semicolon,println 'Hello, World!' // System.out, brackets,

// main() method, class defn

def name = 'Guillaume' // dynamic typingprintln "$name, I'll get the car." // GString

String longer = """${name}, the caris in the next row.""" // multi-line string

// with static typing

assert 0.5 == 1/2 // BigDecimal equals()

def printSize(obj) { // optional duck typingprint obj?.size() // safe dereferencing

def pets = ['ant', 'bee', 'cat'] // native list syntaxpets.each { pet -> // closure support

assert pet < 'dog' // overloading '<' on String} // or: for (pet in pets)...

A Better Java...

QCON 2010 - 16

2006-2

import java.util.List;import java.util.ArrayList;

class Erase {private List removeLongerThan(List strings, int length) {

List result = new ArrayList();for (int i = 0; i < strings.size(); i++) {

String s = (String) strings.get(i);if (s.length() <= length) {

result.add(s);}

}return result;

}public static void main(String[] args) {

List names = new ArrayList();names.add("Ted"); names.add("Fred");names.add("Jed"); names.add("Ned");System.out.println(names);Erase e = new Erase();List shortNames = e.removeLongerThan(names, 3);System.out.println(shortNames.size());for (int i = 0; i < shortNames.size(); i++) {

String s = (String) shortNames.get(i);System.out.println(s);

This code

is valid

Java and

valid Groovy

Based on an

example by

Jim Weirich

& Ted Leung

...A Better Java...

QCON 2010 - 17

2006-2

import java.util.List;import java.util.ArrayList;

List result = new ArrayList();for (int i = 0; i < strings.size(); i++) {

String s = (String) strings.get(i);if (s.length() <= length) {

result.add(s);}

}return result;

}public static void main(String[] args) {

List names = new ArrayList();names.add("Ted"); names.add("Fred");names.add("Jed"); names.add("Ned");System.out.println(names);Erase e = new Erase();List shortNames = e.removeLongerThan(names, 3);System.out.println(shortNames.size());for (int i = 0; i < shortNames.size(); i++) {

String s = (String) shortNames.get(i);System.out.println(s);

Do the

semicolons

add anything?

And shouldn‟t

we us more

modern list

notation?

Why not

import common

libraries?

...A Better Java...

QCON 2010 - 18

2006-2

List result = new ArrayList()for (String s in strings) {

if (s.length() <= length) {result.add(s)

}}return result

public static void main(String[] args) {List names = new ArrayList()names.add("Ted"); names.add("Fred")names.add("Jed"); names.add("Ned")System.out.println(names)Erase e = new Erase()List shortNames = e.removeLongerThan(names, 3)System.out.println(shortNames.size())for (String s in shortNames) {

System.out.println(s)}

...A Better Java...

QCON 2010 - 19

2006-2

List result = new ArrayList()for (String s in strings) {

if (s.length() <= length) {result.add(s)

}}return result

public static void main(String[] args) {List names = new ArrayList()names.add("Ted"); names.add("Fred")names.add("Jed"); names.add("Ned")System.out.println(names)Erase e = new Erase()List shortNames = e.removeLongerThan(names, 3)System.out.println(shortNames.size())for (String s in shortNames) {

Do we need

the static types?

Must we always

have a main

method and

class definition?

How about

improved

consistency?

...A Better Java...

QCON 2010 - 20

2006-2

def removeLongerThan(strings, length) {def result = new ArrayList()for (s in strings) {

if (s.size() <= length) {result.add(s)

}}return result

names = new ArrayList()names.add("Ted")names.add("Fred")names.add("Jed")names.add("Ned")System.out.println(names)shortNames = removeLongerThan(names, 3)System.out.println(shortNames.size())for (s in shortNames) {

...A Better Java...

QCON 2010 - 21

2006-2

def removeLongerThan(strings, length) {def result = new ArrayList()for (s in strings) {

if (s.size() <= length) {result.add(s)

}}return result

names = new ArrayList()names.add("Ted")names.add("Fred")names.add("Jed")names.add("Ned")System.out.println(names)shortNames = removeLongerThan(names, 3)System.out.println(shortNames.size())for (s in shortNames) {

Shouldn‟t we

have special

notation for lists?

And special

facilities for

list processing?

Is „return‟

needed at end?

...A Better Java...

QCON 2010 - 22

2006-2

def removeLongerThan(strings, length) {strings.findAll{ it.size() <= length }

names = ["Ted", "Fred", "Jed", "Ned"]System.out.println(names)shortNames = removeLongerThan(names, 3)System.out.println(shortNames.size())shortNames.each{ System.out.println(s) }

...A Better Java...

QCON 2010 - 23

2006-2

def removeLongerThan(strings, length) {strings.findAll{ it.size() <= length }

names = ["Ted", "Fred", "Jed", "Ned"]System.out.println(names)shortNames = removeLongerThan(names, 3)System.out.println(shortNames.size())shortNames.each{ System.out.println(s) }

Is the method

now needed?

Easier ways to

use common

methods?

Are brackets

required here?

...A Better Java...

QCON 2010 - 24

2006-2

names = ["Ted", "Fred", "Jed", "Ned"]println namesshortNames = names.findAll{ it.size() <= 3 }println shortNames.size()shortNames.each{ println it }

...A Better Java

QCON 2010 - 25

2006-2

names = ["Ted", "Fred", "Jed", "Ned"]println namesshortNames = names.findAll{ it.size() <= 3 }println shortNames.size()shortNames.each{ println it }

[Ted, Fred, Jed, Ned]3TedJedNed

Topics

• Groovy Intro

Leveraging the language

• Web Services

• Writing DSLs

• Groovy Testing

• Polyglot Groovy

• More Info

QCON 2010 - 26

2006-2

Better Control Structures: Switch

• Extensible– Implement your own isCase() method

QCON 2010 - 27

2006-2

switch (10) {case 0 : assert false ; breakcase 0..9 : assert false ; breakcase [8,9,11] : assert false ; breakcase Float : assert false ; breakcase {it%3 == 0} : assert false ; breakcase ~/../ : assert true ; breakdefault : assert false ; break

QCON 2010 - 28

2006-2

Better Control Structures: Switch – Custom isCase

enum Color {

yellow, orange, purple

def isCase(thing) { thing.color == this }

import static Color.*

class Banana { def color = yellow }

class Orange { def color = orange }

class Grape { def color = purple }

fruits = [new Banana(), new Orange(), new Grape()]

fruits.each { println inspectFruit(it) }

def inspectFruit(f) {

switch (f) {

case yellow: return 'Found something yellow'

case orange: return 'Found something orange'

default: return 'Unknown color'

}Found something yellowFound something orangeUnknown color

WARNING:

Advanced

Topic!

QCON 2010 - 29

2006-2

enum Color { yellow, orange, purple }

import static Color.*

class Banana { def color = yellow }

class Orange { def color = orange }

class Grape { def color = purple }

fruits = [new Banana(), new Orange(), new Grape()]

fruits.each { println inspectFruit(it) }

def inspectFruit(f) {

switch (f.color) {

case [yellow, orange]:

return "Found something $f.color"

default: return 'Unknown color'

Found something yellowFound something orangeUnknown color

QCON 2010 - 30

2006-2

enum Color {yellow, orange, purpledef isCase(thing) {

thing?.hasProperty('color') && thing.color == this }}

enum State {peeled, unpeeleddef isCase(thing) {

try {return thing.color == this

} catch (MissingPropertyException) {return false

import static Color.*import static State.*

class Banana { def color = yellow; def state = peeled }class Orange { def color = orange }class Grape { def state = peeled }...

WARNING:

Advanced Topic!

QCON 2010 - 31

2006-2

...fruits = [new Banana(), new Orange(), new Grape()]fruits.each { println inspectFruit(it) }

def inspectFruit(f) {def yellowAndPeeled = { yellow.isCase(it) &&

peeled.isCase(it) }switch (f) {

case yellowAndPeeled:return 'Possibly found a banana split'

case yellow:return 'Found something yellow'

case peeled:return 'Found something peeled'

default:return 'No comment'

WARNING:

Advanced Topic!

Possibly found a banana splitNo commentFound something peeled

QCON 2010 - 32

2006-2

Better Control Structures: Switch Poker…

suits = 'SHDC'ranks = '23456789TJQKA'suit = { String card -> suits.indexOf(card[1]) }rank = { String card -> ranks.indexOf(card[0]) }rankSizes = { List cards ->

cards.groupBy(rank).collect{ k, v -> v.size() }.sort() }rankValues = { List cards ->

cards.collect{ rank(it) }.sort() }// ...

8C TS KC 9H 4S 7D 2S 5D 3S AC

hand1 hand2

println rankSizes(["7S", "7H", "2H", "7D", "AH"])// => [1, 1, 3]

QCON 2010 - 33

2006-2

…Better Control Structures: Switch Poker…

// ...flush = { List cards -> cards.groupBy(suit).size() == 1 }straight = { def v = rankValues(it); v == v[0]..v[0]+4 }straightFlush = { List cards -> straight(cards) && flush(cards) }fourOfAKind = { List cards -> rankSizes(cards) == [1, 4] }fullHouse = { List cards -> rankSizes(cards) == [2, 3] }threeOfAKind = { List cards -> rankSizes(cards) == [1, 1, 3] }twoPair = { List cards -> rankSizes(cards) == [1, 2, 2] }pair = { List cards -> rankSizes(cards) == [1, 1, 1, 2] }// ...

QCON 2010 - 34

2006-2

… Better Control Structures: Switch Poker

// ...def rankHand(List cards) {

switch (cards) {case straightFlush : return 9case fourOfAKind : return 8case fullHouse : return 7case flush : return 6case straight : return 5case threeOfAKind : return 4case twoPair : return 3case pair : return 2default : return 1

}}// ...

Topics

• Groovy Intro

Use and abuse of Design Patterns

• Web Services

• Writing DSLs

• Groovy Testing

• Polyglot Groovy

• More Info

QCON 2010 - 35

2006-2

Grapes / Grab

QCON 2010 - 36

2006-2

// Google Collections exampleimport com.google.common.collect.HashBiMap

@Grab(group='com.google.collections',module='google-collections',version='1.0-rc2')

def getFruit() {[ grape:'purple',

lemon:'yellow',orange:'orange' ] as HashBiMap

assert fruit.lemon == 'yellow'assert fruit.inverse().yellow == 'lemon'

Better Design Patterns: Immutable...

• Java Immutable Class– As per Joshua Bloch

Effective Java

QCON 2010 - 37

2006-2

public final class Punter {private final String first;private final String last;

public String getFirst() {return first;

public String getLast() {return last;

@Overridepublic int hashCode() {

final int prime = 31;int result = 1;result = prime * result + ((first == null)

? 0 : first.hashCode());result = prime * result + ((last == null)

? 0 : last.hashCode());return result;

public Punter(String first, String last) {this.first = first;this.last = last;

}// ...

// ...@Overridepublic boolean equals(Object obj) {

if (this == obj)return true;

if (obj == null)return false;

if (getClass() != obj.getClass())return false;

Punter other = (Punter) obj;if (first == null) {

if (other.first != null)return false;

} else if (!first.equals(other.first))return false;

if (last == null) {if (other.last != null)

return false;} else if (!last.equals(other.last))

return false;return true;

@Overridepublic String toString() {

return "Punter(first:" + first+ ", last:" + last + ")";

...Better Design Patterns: Immutable...

QCON 2010 - 38

2006-2

public final class Punter {private final String first;private final String last;

public String getFirst() {return first;

public String getLast() {return last;

@Overridepublic int hashCode() {

final int prime = 31;int result = 1;result = prime * result + ((first == null)

? 0 : first.hashCode());result = prime * result + ((last == null)

? 0 : last.hashCode());return result;

public Punter(String first, String last) {this.first = first;this.last = last;

}// ...

// ...@Overridepublic boolean equals(Object obj) {

if (this == obj)return true;

if (obj == null)return false;

if (getClass() != obj.getClass())return false;

Punter other = (Punter) obj;if (first == null) {

if (other.first != null)return false;

} else if (!first.equals(other.first))return false;

if (last == null) {if (other.last != null)

return false;} else if (!last.equals(other.last))

return false;return true;

@Overridepublic String toString() {

return "Punter(first:" + first+ ", last:" + last + ")";

• Java Immutable Class– As per Joshua Bloch

Effective Java

boilerplate

...Better Design Patterns: Immutable

QCON 2010 - 39

2006-2

@Immutable class Punter {String first, last

QCON 2010 - 40

2006-2

Better Design Patterns: Singleton

class Calculator {def total = 0def add(a, b) { total++; a + b }

def INSTANCE = new Calculator()Calculator.metaClass.constructor = { -> INSTANCE }

def c1 = new Calculator()def c2 = new Calculator()

assert c1.add(1, 2) == 3assert c2.add(3, 4) == 7

assert c1.is(c2)assert [c1, c2].total == [2, 2]

@Singleton(lazy=true)class X {

def getHello () {"Hello, World!"

println X.instance.hello

QCON 2010 - 41

2006-2

Better Design Patterns: Delegate…

import java.util.Date;

public class Event {private String title;private String url;private Date when;

public String getUrl() {return url;

public void setUrl(String url) {this.url = url;

public String getTitle() {return title;

public void setTitle(String title) {this.title = title;

}// ...

public Date getWhen() {return when;

public void setWhen(Date when) {this.when = when;

public boolean before(Date other) {return when.before(other);

public void setTime(long time) {when.setTime(time);

public long getTime() {return when.getTime();

public boolean after(Date other) {return when.after(other);

}// ...

QCON 2010 - 42

2006-2

…Better Design Patterns: Delegate…

import java.util.Date;

public class Event {private String title;private String url;private Date when;

public String getUrl() {return url;

public void setUrl(String url) {this.url = url;

public String getTitle() {return title;

public void setTitle(String title) {this.title = title;

}// ...

public Date getWhen() {return when;

public void setWhen(Date when) {this.when = when;

public boolean before(Date other) {return when.before(other);

public void setTime(long time) {when.setTime(time);

public long getTime() {return when.getTime();

public boolean after(Date other) {return when.after(other);

}// ...

boilerplate

QCON 2010 - 43

2006-2

…Better Design Patterns: Delegate

class Event {String title, url@Delegate Date when

def gr8conf = new Event(title: "GR8 Conference",url: "http://www.gr8conf.org",when: Date.parse("yyyy/MM/dd", "2009/05/18"))

def javaOne = new Event(title: "JavaOne",url: "http://java.sun.com/javaone/",when: Date.parse("yyyy/MM/dd", "2009/06/02"))

assert gr8conf.before(javaOne.when)

Topics

• Groovy Intro

Web Services

• Writing DSLs

• Groovy Testing

• Polyglot Groovy

• More Info

QCON 2010 - 44

2006-2

SOAP Client and Server

QCON 2010 - 45

2006-2

class MathService {double add(double a, double b) {

a + b}double square(double c) {

c * c}

import groovy.net.soap.SoapServer

def server = new SoapServer('localhost', 6789)server.setNode('MathService')server.start()

import groovy.net.soap.SoapClient

def math = new SoapClient('http://localhost:6789/MathServiceInterface?wsdl')

assert math.add(1.0, 2.0) == 3.0

assert math.square(3.0) == 9.0

Better Testing: SoapUI

• Tool for testing Web Services has a built-

in Groovy editor for custom steps

QCON 2010 - 46

2006-2

Topics

• Groovy Intro

• Web Services

Writing DSLs

• Groovy Testing

• Polyglot Groovy

• More Info

QCON 2010 - 47

2006-2

Groovy DSL Features

• Literal Syntax Conventions

• Scripts as well as Classes & Optional Syntax

• Optional Typing & Named Arguments

• Type Transformations

• Using With

• Operator Overloading

• Closures

• Runtime Metaprogramming

• Compile-time Metaprogramming (AST Macros)

• Builders

QCON 2010 - 48

2006-2

Literal Syntax Conventions

• Lists– Special syntax for list literals

– Additional common methods (operator overloading)

• Maps– Special syntax for map literals

– Additional common methods

• Ranges– Special syntax for various kinds of ranges

QCON 2010 - 49

2006-2

def list = [3, new Date(), 'Jan']assert list + list == list * 2

def map = [a: 1, b: 2]assert map['a'] == 1 && map.b == 2

def letters = 'a'..'z'def numbers = 0..<10

Scripts as well as Classes & Optional Syntax

• Java

• Groovy

QCON 2010 - 50

2006-2

public class HelloJava {public static void main(String[] args) {

System.out.println("Hello World");}

System.out.println('Hello World');

println 'Hello World'

class HelloGroovy {static main(String[] args) {

System.out.println("Hello World");}

Optional Typing & Named Params

• Java

• Groovy

QCON 2010 - 51

2006-2

import java.util.Date;import java.util.HashMap;import java.util.Map;

public class OptionalSyntax {public static void printDetails(Map<String, String> args) {

System.out.println("Details as at: " + new Date());String first = args.get("first");System.out.println("First name: " + (first != null ? first : "unknown"));String last = args.get("last");System.out.println("Last name: " + (last != null ? last : "unknown"));

public static void main(String[] args) {Map<String, String> details = new HashMap<String, String>();details.put("first", "John");details.put("last", "Smith");printDetails(details);

}} def printDetails(args) {

println """Details as at: ${new Date()}First name: $args.firstLast name: $args.last"""}printDetails first:'John', last:'Smith'

Closures

• Traditional mainstream languages– Data can be stored in variables, passed around,

combined in structured ways to form more complex

data; code stays put where it is defined

• Languages supporting closures– Data and code can be stored in variables, passed

around, combined in structured ways to form more

complex algorithms and data

QCON 2010 - 52

2006-2

doubleNum = { num -> num * 2 }println doubleNum(3) // => 6

processThenPrint = { num, closure ->num = closure(num); println "num is $num"

}processThenPrint(3, doubleNum) // => num is 6processThenPrint(10) { it / 2 } // => num is 5

Static Imports

QCON 2010 - 53

2006-2

import groovy.swing.SwingXBuilderimport static java.awt.Color.*import static java.lang.Math.*

def swing = new SwingXBuilder()def frame = swing.frame(size: [300, 300]) {

graph(plots: [[GREEN, {value -> sin(value)}],[BLUE, {value -> cos(value)}],[RED, {value -> tan(value)}]

])}.show()

Using '.with' Example

QCON 2010 - 54

2006-2

letters = ['a', 'b', 'c']

range = 'b'..'d'

letters.with {

add 'd'

remove 'a'

assert letters == range

map = [a:10, b:4, c:7]

map.with {

assert (a + b) / c == 2

Coin example...

QCON 2010 - 55

2006-2

enum Coin {

penny(1), nickel(5), dime(10), quarter(25)

Coin(int value) { this.value = value }

int value

import static Coin.*

assert 2 * quarter.value +

1 * nickel.value +

2 * penny.value == 57

...Coin example...

QCON 2010 - 56

2006-2

class CoinMath {

static multiply(Integer self, Coin c) {

self * c.value

use (CoinMath) {

assert 2 * quarter +

1 * nickel +

2 * penny == 57

// EMC equivalent

Integer.metaClass.multiply = {

Coin c -> delegate * c.value

assert 2 * quarter + 1 * nickel + 2 * penny == 57

...Coin example

QCON 2010 - 57

2006-2

class CoinValues {

static get(Integer self, String name) {

self * Coin."${singular(name)}".value

static singular(String val) {

val.endsWith('ies') ? val[0..-4] + 'y' : val.endsWith('s') ? val[0..-2] : val

use (CoinValues) {

assert 2.quarters + 1.nickel + 2.pennies == 57

// EMC equivalent

Integer.metaClass.getProperty = { String name ->

def mp = Integer.metaClass.getMetaProperty(name)

if (mp) return mp.getProperty(delegate)

def singular = name.endsWith('ies') ? name[0..-4] + 'y' :

name.endsWith('s') ? name[0..-2] : name

delegate * Coin."$singular".value

assert 2.quarters + 1.nickel + 2.pennies == 57

Game example...

QCON 2010 - 58

2006-2

// Trying out the game DSL idea by Sten Anderson from:

// http://blogs.citytechinc.com/sanderson/?p=92

class GameUtils {

static VOWELS = ['a', 'e', 'i', 'o', 'u']

static listItems(things) {

def result = ''

things.eachWithIndex{ thing, index ->

if (index > 0) {

if (index == things.size() - 1) result += ' and '

else if (index < things.size() - 1) result += ', '

result += "${thing.toLowerCase()[0] in VOWELS ? 'an' : 'a'} $thing"

result ?: 'nothing'

import static GameUtils.*

...Game example...

QCON 2010 - 59

2006-2

class Room {

def description

def contents = []

...Game example...

QCON 2010 - 60

2006-2

class Player {

def currentRoom

def inventory = []

void look() {

println "You are in ${currentRoom?.description?:'the void'} which contains ${listItems(currentRoom?.contents)}"

void inv() {

println "You are holding ${listItems(inventory)}"

void take(item) {

if (currentRoom?.contents?.remove(item)) {

inventory << item

println "You took the $item"

} else {

println "I see no $item here"

...Game example...

QCON 2010 - 61

2006-2

void drop(item) {

if (inventory?.remove(item)) {

currentRoom?.contents << item

println "You dropped the $item"

} else {

println "You don't have the $item"

def propertyMissing(String name) {

if (metaClass.respondsTo(this, name)) {

this."$name"()

...Game example...

QCON 2010 - 62

2006-2

Room plainRoom = new Room(description:'a plain white room',

contents:['dagger', 'emerald', 'key'])

Player player = new Player(currentRoom:plainRoom)

player.with{

take dagger

take emerald

take key

drop emerald

assert player.inventory == ['dagger', 'key']

...Game example

QCON 2010 - 63

2006-2

// now try some error conditions

plainRoom.description = null

player.with {

drop gold

take gold

drop emerald

take emerald

Grails Criteria

QCON 2010 - 64

2006-2

// Account is a POJO in our domain/model

def c = Account.createCriteria()

def results = c {

like("holderFirstName", "Fred%")

between("balance", 500, 1000)

eq("branch", "London")

maxResults(10)

order("holderLastName", "desc")

}// source: Grails doco: 5. Object Relational Mapping (GORM): 5.4.2 Criteria

Grails Criteria Example

QCON 2010 - 65

2006-2

// Book is a POJO in our domain/model

def book = Book.findByTitle("The Stand")

book = Book.findByTitleLike("Harry Pot%")

book = Book.findByReleaseDateBetween( firstDate, secondDate )

book = Book.findByReleaseDateGreaterThan( someDate )

book = Book.findByTitleLikeOrReleaseDateLessThan(

"%Something%", someDate )

books = Book.findAllByTitleLikeAndReleaseDateGreaterThan(

"%Java%", new Date()-30)

// source: Grails doco: 5. Object Relational Mapping (GORM): 5.4.1 Dynamic Finders

Grails Bean Builder Example

QCON 2010 - 66

2006-2

bb.beans {

marge(Person) {

name = "marge"

husband = { Person p ->

name = "homer"

age = 45

props = [overweight:true, height:"1.8m"]

children = [bart, lisa]

bart(Person) {

name = "Bart"

age = 11

lisa(Person) {

name = "Lisa"

age = 9

// source: 14. Grails and Spring: 14.3 Runtime Spring with the Beans DSL

Groovy Lab Example

QCON 2010 - 67

2006-2

// require GroovyLab

import static org.math.array.Matrix.*

import static org.math.plot.Plot.*

def A = rand(10,3) // random Matrix of 10 rows and 3 columns

def B = fill(10,3,1.0) // one Matrix of 10 rows and 3 columns

def C = A + B // support for matrix addition with "+" or "-"

def D = A - 2.0 // support for number addition with "+" or "-"

def E = A * B // support for matrix multiplication or division

def F = rand(3,3)

def G = F**(-1) // support for matrix power (with integers only)

println A // display Matrix content

plot("A",A,"SCATTER") // plot Matrix values as ScatterPlot

def M = rand(5,5) + id(5) //Eigenvalues decomposition

println "M=\n" + M

println "V=\n" + V(M)

println "D=\n" + D(M)

println "M~\n" + (V(M) * D(M) * V(M)**(-1))

Operator Overloading Example

QCON 2010 - 68

2006-2

BigDecimal a = new BigDecimal(3.5d);

BigDecimal b = new BigDecimal(4.0d);

assert a.multiply(b).compareTo(new BigDecimal(14.0d)) == 0;

assert a.multiply(b).equals(new BigDecimal(14.0d).setScale(1));

def c = 3.5, d = 4.0

assert c * d == 14.0

Type Transformation Example

QCON 2010 - 69

2006-2

class InventoryItem {

def weight, name

InventoryItem(Map m) {

this.weight = m.weight; this.name = m.name

InventoryItem(weight, name) {

this.weight = weight; this.name = name

InventoryItem(String s) {

s.find(/weight=(\d*)/) { all, w -> this.weight = w }

s.find(/name=(.*)/) { all, n -> this.name = n }

def room = [:]

def gold = [weight:50, name:'Gold'] as InventoryItem

def emerald = [10, 'Emerald'] as InventoryItem

def dagger = ['weight=5, name=Dagger'] as InventoryItem

room.contents = [gold, emerald, dagger]

room.contents.each{ println it.dump() }

AST Builder

• Numerous approaches, still evolving.

“From code” approach:

• Produces:

def result = new AstBuilder().buildFromCode {println "Hello World"

BlockStatement-> ReturnStatement

-> MethodCallExpression-> VariableExpression("this")-> ConstantExpression("println")-> ArgumentListExpression

-> ConstantExpression("Hello World")

Topics

• Groovy Intro

• Web Services

• Writing DSLs

Groovy Testing

• Polyglot Groovy

• More Info

QCON 2010 - 71

2006-2

Types of Testing

QCON 2010 - 72

2006-2

Unit Testing

Mock/interaction testing

State-based testing

Integration Testing

Acceptance Testing

Web drivers

Non-web drivers

Test runners

Techniques

Testing DSLs

ATDD/BDD

Data-driven

Logic-driven

Model-driven

Performance

testing

All-pairs &

combinations

Groovy's Value Add for Testing

• Unit testing– Built-in asserts, support for JUnit 3&4 and TestNG,

GroovyTestCase with shouldFail and other methods

– Built-in mocking and compatible with Java mocking

• Integration testing– Metaprogramming allows various kinds of IOC like

intercepting and hooking up of components

– Wealth of GDK methods for Ant, Processes, Files,

Threads, etc. make the automating part much simpler

• Acceptance Testing and Generally– Allows creation of English-like testing DSLs using

Closures, builders, metaprogramming

– Simpler syntax great for non hard-core testers

– Grapes make tests easier to share QCON 2010 - 73

2006-2

Groovy and Testing Tool Spectrum*

QCON 2010 - 74

2006-2

Database

Drivers

DbUnit

DataSets

SqlUnit

groovy.sql

BigTable

SOAP /

Drivers

GroovyWS

XML-RPC

JAX-WS

JAX-RS

Utilities

AllPairs, Combinations

Polyglot languages

Logic programming

Threads, Parallel /

Concurrency libraries

Data-driven libraries

Networking libraries

XML Processing

Read/write files /

Excel / Word / CSV

Reporting, Logging

Drivers

AntUnit

Telnet

ExecTools

iTest2, SoapUI, Twist,

IDEs, JMeter, Text

editors, Recorders,

Sahi, Build Tools, CI

Drivers

WebTest

WebDriver

JWebUnit

Tellurium

Selenium

HtmlUnit

HttpBuilder

Cyberneko

Runners

Native Groovy, JUnit, TestNG, Spock, EasyB,

JBehave, Cucumber, Robot Framework

* Tools/libraries/frameworks don't always neatly fall into one category – still useful conceptually

HtmlUnit• 100% Java-based headless browser emulator

– Can test any Web site: Java, .Net, PHP, Rails, ...

• Open Source– Apache 2 license

– Hosted at SourceForge

– 7 committers (3 very active)

– Very mature

• Useful for:– Integration and acceptance testing

– Screen scraping, deployment automation, ...

• Used by other drivers:– Canoo WebTest , JWebUnit , WebDriver , JSFUnit , Celerity

• Special features:– Easy ajax mode, emulation of multiple browsers

QCON 2010 - 75

2006-2

HtmlUnit: Testing New Blog Post...

QCON 2010 - 76

2006-2

@Grab('net.sourceforge.htmlunit:htmlunit:2.6')import com.gargoylesoftware.htmlunit.WebClient

def client = new WebClient()def page = client.getPage('http://localhost:8080/postForm')// check page titleassert 'Welcome to SimpBlog' == page.titleText

// fill in blog entry and post itdef form = page.getFormByName('post')form.getInputByName('title').

setValueAttribute('Bart was here (and so was HtmlUnit)')form.getSelectByName('category').getOptions().find{

it.text == 'Home' }.setSelected(true)form.getTextAreaByName('content').setText('Cowabunga Dude!')def result = form.getInputByName('btnPost').click()

...HtmlUnit: Testing New Blog Post

QCON 2010 - 77

2006-2

// check blog post detailsassert result.getElementsByTagName('h1').item(0).

textContent.matches('Post.*: Bart was here.*')def h3headings = result.getElementsByTagName('h3')assert h3headings.item(1).textContent == 'Category: Home'assert h3headings.item(2).textContent == 'Author: Bart'

// expecting:// <table><tr><td><p>Cowabunga Dude!</p></td></tr></table>def cell = result.getByXPath('//TABLE//TR/TD')[0]def para = cell.getFirstChild()assert para.textContent == 'Cowabunga Dude!'

QCON 2010 - 78

2006-2

WebTest testing Web Sitesdef ant = new AntBuilder()

def webtest_home = System.properties.'webtest.home'

ant.taskdef(resource:'webtest.taskdef') {

classpath {

pathelement(location:"$webtest_home/lib")

fileset(dir:"$webtest_home/lib", includes:"**/*.jar")

def config_map = [:]

['protocol','host','port','basepath','resultfile',

'resultpath', 'summary', 'saveresponse','defaultpropertytype'].each {

config_map[it] = System.properties['webtest.'+it]

ant.testSpec(name:'groovy: Test Groovy Scripting at creation time') {

config(config_map)

steps {

invoke(url:'linkpage.html')

for (i in 1..10) {

verifyText(description:"verify number ${i} is on pages", text:"${i}")

WebTest testing Emails

QCON 2010 - 79

2006-2

def ant = new AntBuilder()

def webtest_home = System.properties.'webtest.home'

ant.taskdef(resource:'webtest.taskdef'){

classpath(){

pathelement(location:"$webtest_home/lib")

fileset(dir:"$webtest_home/lib", includes:"**/*.jar")

ant.testSpec(name:'Email Test'){

steps {

emailSetConfig(server:'localhost', password:'password',

username:'devteam@mycompany.org', type:'pop3')

emailStoreMessageId(subject:'/Build notification/',

property:'msg')

emailStoreHeader(property:'subject',

messageId:'#{msg}', headerName:'Subject')

groovy('''def subject = step.webtestProperties.subject

assert subject.startsWith('Build notification')''')

emailMessageContentFilter(messageId:'#{msg}')

verifyText(text:'Failed build')

Spock Testing Framework...

QCON 2010 - 80

2006-2

...Spock Testing Framework

QCON 2010 - 81

2006-2

• Testing framework for Java and Groovy

• Highly expressive specification language– No assertion API

– No record &

replay

mocking API

– No

superfluous

annotations

– Meaningful

assert error

messages

– Extensible

– Compatible

with JUnit

reportingwise

@Speck@RunWith(Sputnik)class PublisherSubscriberSpeck {def "events are received by all subscribers"() {def pub = new Publisher()def sub1 = Mock(Subscriber)def sub2 = Mock(Subscriber)pub.subscribers << sub1 << sub2

when:pub.send("event")

then:1 * sub1.receive("event")1 * sub2.receive("event")

Spock Example...

QCON 2010 - 82

2006-2

import com.gargoylesoftware.htmlunit.WebClientimport spock.lang.*import org.junit.runner.RunWith

@Speck ()@RunWith (Sputnik)class TestSimpBlogSpock {def page, subheadings, para, form, result

@Unroll("When #author posts a #category blog with content '#content' it should succeed"def "when creating a new blog entry"() {given:page = new WebClient().getPage('http://localhost:8080/postForm')form = page.getFormByName('post')

when:form.getInputByName('title').setValueAttribute("$author was here (and so was Spock)"form.getSelectByName('category').getOptions().find { it.text == category }.form.getSelectByName('author').getOptions().find { it.text == author }.setSelectedform.getTextAreaByName('content').setText(content)result = form.getInputByName('btnPost').click()subheadings = result.getElementsByTagName('h3')para = result.getByXPath('//TABLE//TR/TD/P')[0]

...Spock Example

QCON 2010 - 83

2006-2

...then:page.titleText == 'Welcome to SimpBlog'result.getElementsByTagName('h1').item(0).textContent.matches("Post.*: $author was here.*"subheadings.item(1).textContent == "Category: $category"subheadings.item(2).textContent == "Author: $author"

and:para.textContent == content

where:author << ['Bart', 'Homer', 'Lisa']category << ['Home', 'Work', 'Food']content << ['foo', 'bar', 'baz']

// Optional use of 'and:'

QCON 2010 - 84

2006-2

• Description: BDD, Rspec-like testing librarynarrative 'segment flown', {

as_a 'frequent flyer'i_want 'to accrue rewards points for every segment I fly'so_that 'I can receive free flights for my dedication to the airline'

scenario 'segment flown', {given 'a frequent flyer with a rewards balance of 1500 points'when 'that flyer completes a segment worth 500 points'then 'that flyer has a new rewards balance of 2000 points'

scenario 'segment flown', {given 'a frequent flyer with a rewards balance of 1500 points', {

flyer = new FrequentFlyer(1500)}when 'that flyer completes a segment worth 500 points', {

flyer.fly(new Segment(500))}then 'that flyer has a new rewards balance of 2000 points', {

flyer.pointsBalance.shouldBe 2000}

EasyB Example ...

• When run will be marked as pending– perfect for ATDD

QCON 2010 - 85

2006-2

scenario "Bart posts a new blog entry", {given "we are on the create blog entry page"when "I have entered 'Bart was here' as the title"and "I have entered 'Cowabunga Dude!' into the content"and "I have selected 'Home' as the category"and "I have selected 'Bart' as the author"and "I click the 'Create Post' button"then "I expect the entry to be posted"

...EasyB Example...

QCON 2010 - 86

2006-2

description "Post Blog Entry Feature"

narrative "for feature", {as_a "Blogger"i_want "to be able to post a blog"so_that "I can keep others informed"

before "posting blog", {given "we are on the create blog entry page", {

webClient = new com.gargoylesoftware.htmlunit.WebClient()page = webClient.getPage('http://localhost:8080/postForm')

scenario "Bart was here blog", {

when "I have entered 'Bart was here' as the title", {form = page.getFormByName('post')form.getInputByName('title').setValueAttribute(

'Bart was here (and so was EasyB)')}

...EasyB Example...

QCON 2010 - 87

2006-2

...and "I have entered 'Cowabunga Dude!' into the content", {

form.getTextAreaByName('content').setText('Cowabunga Dude!')}

and "I have selected 'Home' as the category", {form.getSelectByName('category').getOptions().find { it.text == 'Home' }.setSelected(true

and "I click the 'Create Post' button", {result = form.getInputByName('btnPost').click()

then "I expect the entry to be posted", {// check blog post detailsassert result.getElementsByTagName('h1').item(0).textContent.matches('Post.*: Bart was here.*'def h3headings = result.getElementsByTagName('h3')assert h3headings.item(1).textContent == 'Category: Home' // traditional styleh3headings.item(2).textContent.shouldBe 'Author: Bart' // BDD style

// expecting: <table><tr><td><p>Cowabunga Dude!</p></td></tr></table>def cell = result.getByXPath('//TABLE//TR/TD')[0]def para = cell.firstChildassert para.textContent == 'Cowabunga Dude!'// para.shouldHave textContent: 'Cowabunga Dude!'

...EasyB Example...

QCON 2010 - 88

2006-2

...EasyB Example

QCON 2010 - 89

2006-2

2 scenarios (including 1 pending) executed successfully.

Story: simp blog initial

scenario Bart posts a new blog entry [PENDING]

given we are on the create blog entry page

when I have entered 'Bart was here' as the title

when I have entered 'Cowabunga Dude!' into the content [PENDING]

when I have selected 'Home' as the category [PENDING]

when I have selected 'Bart' as the author [PENDING]

when I click the 'Create Post' button [PENDING]

then I expect the entry to be posted [PENDING]

Story: simp blog

Post Blog Entry Feature

for feature

As a Blogger

I want to be able to post a blog

So that I can keep others informed

given we are on the create blog entry page

scenario Bart was here blog

when I have entered 'Bart was here' as the title

when I have entered 'Cowabunga Dude!' into the content

when I have selected 'Home' as the category

when I click the 'Create Post' button

then I expect the entry to be posted

easyb is preparing to process 2 file(s)

Running simp blog initial story (SimpBlogInitialStory.groovy)

Scenarios run: 1, Failures: 0, Pending: 1, Time elapsed: 1.049 sec

Running simp blog story (SimpBlogStory.groovy)

Scenarios run: 1, Failures: 0, Pending: 0, Time elapsed: 1.356 sec

2 total behaviors ran (including 1 pending behavior) with no failures

easyb execution passed

Cucumber• Description

– Loose coupling

between text spec

and step defns

QCON 2010 - 90

2006-2

# language: enFeature: AdditionIn order to avoid silly mistakesAs a math idiot I want to be told the sum of two numbers

Scenario Outline: Add two numbersGiven I have entered <input_1> into the calculatorAnd I have entered <input_2> into the calculatorWhen I press <button>Then the stored result should be <output>

Examples:| input_1 | input_2 | button | output || 20 | 30 | add | 50 || 2 | 5 | add | 7 || 0 | 40 | add | 40 |

# language: enFeature: DivisionIn order to avoid silly mistakesCashiers must be able to calculate a fraction

Scenario: Regular numbersGiven I have entered 3 into the calculatorAnd I have entered 2 into the calculatorWhen I press divideThen the stored result should be 1.5

Cucumber Example...

QCON 2010 - 91

2006-2

# language: en

@newpost

Feature: New Blog Post

In order to create a new blog entry

Bloggers should be able to select their name and category and enter text

Scenario: New Posting

Given we are on the create blog entry page

When I have entered "Bart was here" as the title

And I have entered "Cowabunga Dude!" as the content

And I have selected "Home" from the "category" dropdown

And I have selected "Bart" from the "author" dropdown

And I click the 'Create Post' button

Then I should see a heading message matching "Post.*: Bart was here.*"

...Cucumber Example...

QCON 2010 - 92

2006-2

...Cucumber Example

QCON 2010 - 93

2006-2

import com.gargoylesoftware.htmlunit.WebClientthis.metaClass.mixin(cuke4duke.GroovyDsl)

Given ~/we are on the create blog entry page/, { ->page = new WebClient().getPage('http://localhost:8080/postForm')

When(~/I have entered "(.*)" as the title/) {String title ->form = page.getFormByName('post')form.getInputByName('title').setValueAttribute(title + ' (and so was Cucumber)')

When(~'I have entered "(.*)" as the content') {String content ->form.getTextAreaByName('content').setText(content)

When(~'I have selected "(.*)" from the "(.*)" dropdown') {String option, String name ->form.getSelectByName(name).getOptions().find {

it.text == option }.setSelected(true)}

When(~"I click the 'Create Post' button") { ->result = form.getInputByName('btnPost').click()

Then(~'I should see a heading message matching "(.*)"') {String pattern ->// ensureThat result.getElementsByTagName('h1').item(0).textContent.matches(pattern)

assert result.getElementsByTagName('h1').item(0).textContent.matches(pattern)}

Cucumber Data Driven Example...

QCON 2010 - 94

2006-2

# language: en@newpostFeature: New Blog PostIn order to create a new blog entryBloggers should be able to select their name and category and enter text

Scenario Outline: New PostingGiven we are on the create blog entry pageWhen I have entered "<title>" as the titleAnd I have entered "<content>" as the contentAnd I have selected "<category>" from the "category" dropdownAnd I have selected "<author>" from the "author" dropdownAnd I click the 'Create Post' buttonThen I should see a heading message matching "Post.*: <title>.*"

Examples:| title | content | category | author || Title 1 | Content 1 | Home | Bart || Title 2 | Content 2 | Work | Homer || Title 3 | Content 3 | Food | Marge |

...Cucumber Data Driven Example

QCON 2010 - 95

2006-2

JBehave

• Description– Behaviour-driven development in Java

• Also works out of the box for Groovy

– Behavior scenarios written in text

• Use the words Given, When, Then and And.

– Mapped using regular expressions and annotations

to step methods

– Web Runner available for non-technical users to

easily run tests

– Hooks to Selenium available in JBehave Web

• Other Java libraries (e.g. HtmlUnit) easy to use too

– Supports parameter converters

• Getting 'String' parameters into appropriate Object values

– Supports a 'StepDoc' function

• For listing available scenario clausesQCON 2010 - 96

2006-2

JBehave Example...

QCON 2010 - 97

2006-2

Given we are on the create blog entry pageWhen I have entered "Bart was here" as the titleAnd I have entered "Cowabunga Dude!" as the contentAnd I have selected "Home" from the "category" dropdownAnd I have selected "Bart" from the "author" dropdownAnd I click the 'Create Post' buttonThen I should see a heading message matching "Post.*: Bart was here.*"

import org.jbehave.scenario.Scenarioimport org.jbehave.scenario.steps.Steps

class NewPostScenario extends Scenario {NewPostScenario() {

super([new CreateBlogSteps()] as Steps[])}

}Scenario:

Given we are on the create blog entry page

When I have entered "Bart was here" as the title

And I have entered "Cowabunga Dude!" as the content

And I have selected "Home" from the "category" dropdown

And I have selected "Bart" from the "author" dropdown

And I click the 'Create Post' button

Then I should see a heading message matching "Post.*: Bart was here.*"

...JBehave Example

QCON 2010 - 98

2006-2

import org.jbehave.scenario.steps.Stepsimport org.jbehave.scenario.annotations.*import com.gargoylesoftware.htmlunit.WebClient

class CreateBlogSteps extends Steps {def page, form, result

@Given("we are on the create blog entry page")void gotoEntryPage() {

page = new WebClient().getPage('http://localhost:8080/postForm')}

@When('I have entered "$title" as the title')void enterTitle(String title) {

form = page.getFormByName('post')form.getInputByName('title').

setValueAttribute(title + ' (and so was JBehave)')}

@When('I have entered "$content" as the content')void enterContent(String content) {

form.getTextAreaByName('content').setText(content)}

Example uses HtmlUnit which must be added to CLASSPATH

Topics

• Groovy Intro

• Web Services

• Writing DSLs

• Groovy Testing

Polyglot GroovyOther languages, other styles

• More InfoQCON 2010 - 99

2006-2

Polyglot Programming...

QCON 2010 - 100

2006-2

@Grab('org.clojure:clojure:1.0.0')import clojure.lang.Compilerimport clojure.lang.RT

def src = new File('temp.clj')src.text = '''(ns groovy)(defn factorial [n]

(if (< n 2)1(* n (factorial (- n 1))))

src.withReader { reader ->Compiler.load reader

def fac = RT.var('groovy', 'factorial')println fac.invoke(4)

...def jy = getEngine("jython")jy?.eval('''def factorial(n):

i=fact=1while i <= n:

fact=fact*ii=i+1

return fact

result = factorial(4)''')println jy?.result

...Polyglot Programming

• But so what?– I can use Groovy for Scripting my

environment and or leveraging its runners

and other testing capabilities

– I can call out to other languages when needed

• Cucumber via JRuby for more native control

• Watir instead of Watij

• ScalaCheck for test data generation

• Jython for Robot Framework for more native

control

• Rhino for JavaScript testing

• Rules engine integration

QCON 2010 - 101

2006-2

Functional Programming in Groovy

• Java functional programming goodness– Normal OO methods

– Ability to have immutable types

– Some concurrency building blocks

• Closures for greater flexibility– Enabler for concurrency

• Lazy evaluation with Closures– Built in to some libraries, e.g. data access

• Metaprogramming to enhance existing

libraries

• Third party Java libraries– Functional Java, FunctionalJ, Commons Functor, Scala

QCON 2010 - 102

2006-2

QCON 2010 - 103

2006-2

Functional Programming…

def fac(n) { n == 0 ? 1 : n * fac(n - 1) }assert 24 == fac(4)

// define and use infinite streamsdef integers(n) { cons(n, { integers(n+1) }) }def naturalnumbers = integers(1)assert '1 2 3 4 5 6 7 8 9 10' ==

naturalnumbers.take(10).join(' ')def evennumbers =

naturalnumbers.filter{ it % 2 == 0 }assert '2 4 6 8 10 12 14 16 18 20' ==

evennumbers.take(10).join(' ')

QCON 2010 - 104

2006-2

…Functional Programming…

import fj.data.Stream

//some metaprogramming to make fj mesh well with GroovyStream.metaClass.filter = { Closure c ->

delegate.filter(c as fj.F) }Stream.metaClass.getAt = { n ->

delegate.index(n) }Stream.metaClass.getAt = { Range r ->

r.collect{ delegate.index(it)}}Stream.metaClass.asList = { ->

delegate.toCollection().asList() }

def evens = Stream.range(0).filter{ it % 2 == 0 }assert evens.take(5).asList() == [0, 2, 4, 6, 8]assert (8..12).collect{ evens[it] } == [16, 18, 20, 22, 24]assert evens[3..6] == [6, 8, 10, 12]

QCON 2010 - 105

2006-2

…Functional Programming

import fj.data.Streamimport static fj.data.Stream.cons

// some metaprogramming to make Closures mesh well with// fj functions and productsStream.metaClass.filterTail = { Closure c ->

delegate.tail()._1().filter(c as fj.F) }Stream.metaClass.static.cons = { h, Closure c ->

delegate.cons(h, ['_1':c] as fj.P1) }

def sieve(nums) {cons nums.head(), {

sieve nums.filterTail{ n -> n % nums.head() != 0 }}

println sieve(Stream.range(2)).index(100) // => 547

Enabling a functional style …

• Consider the Maximum Segment Sum

(MSS) problem– Take a list of integers; the MSS is the maximum of the sums of

any number of adjacent integers

• Imperative solution:

QCON 2010 - 106

2006-2

def numbers = [31,-41,59,26,-53,58,97,-93,-23,84]

def size = numbers.size()def max = null(0..<size).each { from ->(from..<size).each { to ->def sum = numbers[from..to].sum()if (max == null || sum > max) max = sum

println "Maximum Segment Sum of $numbers is $max"

... Enabling a functional style …

• A first attempt at a more functional style:

QCON 2010 - 107

2006-2

def numbers = [31,-41,59,26,-53,58,97,-93,-23,84]

def size = numbers.size()def max = [0..<size, 0..<size].combinations().collect{numbers[it[0]..it[1]].sum()

}.max()

println "Maximum Segment Sum of $numbers is $max"

• An even more functional style– A known solution using functional composition:

mss = max º sum* º (flatten º tails* º inits)

– Where inits and tails are defined as follows:

QCON 2010 - 108

2006-2

assert letters.inits() == [['a'],['a', 'b'],['a', 'b', 'c'],['a', 'b', 'c', 'd']

letters = ['a', 'b', 'c', 'd']

assert letters.tails() == [['d'],

['c', 'd'],['b', 'c', 'd'],

['a', 'b', 'c', 'd']]

• An even more functional stylemss = max º sum* º (flatten º tails* º inits)

Notes:

– sum() is one-level flatten in Groovy, flatten() is recursive

– Metaprogramming allowed us to enhance all Lists

QCON 2010 - 109

2006-2

List.metaClass {inits{ (0..<delegate.size()).collect{ delegate[0..it] } }tails{ delegate.reverse().inits() }

def segs = { it.inits()*.tails().sum() }

def solve = { segs(it)*.sum().max() }

def numbers = [31,-41,59,26,-53,58,97,-93,-23,84]

println "Maximum Segment Sum of $numbers is ${solve numbers}"

Source: http://hamletdarcy.blogspot.com/2008/07/groovy-vs-f-showdown-side-by-side.html

...Constraint/Logic Programming...

QCON 2010 - 110

2006-2

Source: http://xkcd.com/287/

...Constraint/Logic Programming...

QCON 2010 - 111

2006-2

// requires choco 2.1.0-basic.jar from http://choco.emn.fr/import static choco.Choco.*import choco.kernel.model.variables.integer.IntegerVariable

def m = new choco.cp.model.CPModel()def s = new choco.cp.solver.CPSolver()

def menu = ['Mixed fruit' : 215,'French fries' : 275,'Side salad' : 335,'Hot wings' : 355,'Mozzarella sticks' : 420,'Sampler plate' : 580

]def numOrdered = new IntegerVariable[menu.size()]def priceEach = new int[menu.size()]def sum = 1505...

Found a solution:7 * Mixed fruit

Found a solution:1 * Mixed fruit2 * Hot wings1 * Sampler plate

...Constraint/Logic Programming

QCON 2010 - 112

2006-2

...menu.eachWithIndex { name, price, i ->

// number ordered >= 0// number ordered * price <= sumnumOrdered[i] = makeIntVar(name, 0, sum.intdiv(price))priceEach[i] = price

}m.addConstraint(eq(scalar(numOrdered, priceEach), sum))s.read(m)

def more = s.solve()while (more) {

println "Found a solution:"numOrdered.each {

def v = s.getVar(it)if (v.val) println " $v.val * $v.name"

}more = s.nextSolution()

ModelJUnit...

QCON 2010 - 113

2006-2

// require modeljunit.jarimport nz.ac.waikato.modeljunit.coverage.*import nz.ac.waikato.modeljunit.*

class VendingMachineModel implements FsmModel {def state = 0 // 0,25,50,75,100void reset(boolean testing) {state = 0}

boolean vendGuard() {state == 100}@Action void vend() {state = 0}

boolean coin25Guard() {state <= 75}@Action void coin25() {state += 25}

boolean coin50Guard() {state <= 50}@Action void coin50() {state += 50}

def tester = new RandomTester(new VendingMachineModel())tester.buildGraph()def metrics = [new ActionCoverage(), new StateCoverage(),

new TransitionCoverage(), new TransitionPairCoverage()]metrics.each { tester.addCoverageMetric it }

tester.addListener "verbose"tester.generate 20

println '\nMetrics Summary:'tester.printCoverage()

...ModelJUnit...

QCON 2010 - 114

2006-2

done (0, coin50, 50)done (50, coin25, 75)done (75, coin25, 100)done Random reset(true)done (0, coin50, 50)done (50, coin25, 75)done (75, coin25, 100)done (100, vend, 0)done (0, coin50, 50)done (50, coin50, 100)done (100, vend, 0)done (0, coin25, 25)done (25, coin25, 50)done Random reset(true)done (0, coin50, 50)done (50, coin25, 75)done (75, coin25, 100)done (100, vend, 0)done (0, coin50, 50)done (50, coin25, 75)...

Metrics Summary:action coverage: 3/3state coverage: 5/5transition coverage: 7/8transition-pair coverage: 8/12...

...ModelJUnit: SimpBlog Case Study

QCON 2010 - 115

2006-2

ScalaCheck

• Description– Tool for testing Scala, Java and Groovy programs

– Based on property specifications and automatic

random test data generation

QCON 2010 - 116

2006-2

> scala -classpath ScalaCheck-1.5.jarWelcome to Scala version 2.7.6.final

scala> import org.scalacheck.Prop.forAll

scala> val propConcatLists = forAll { (l1: List[Int], l2: List[Int]) =>| l1.size + l2.size == (l1 ::: l2).size }

propConcatLists: org.scalacheck.Prop = Prop

scala> propConcatLists.check+ OK, passed 100 tests.

scala> val propSqrt = forAll { (n: Int) => scala.Math.sqrt(n*n) == n }propSqrt: org.scalacheck.Prop = Prop

scala> propSqrt.check! Falsified after 2 passed tests.> ARG_0: "-1" (1 shrinks, original arg: "-2")

ScalaCheck: SimpBlog Case Study...

QCON 2010 - 117

2006-2

class SimpBlogChecker {static postAndCheck = nullstatic clean(s) { s.replace('\\', '\\\\').replace('\n', '\\n') }static ResultHolder postAndReturn(String title, String content,

String author, String category) {if (!postAndCheck) postAndCheck = new GroovyShell().parse('''@Grab('net.sourceforge.htmlunit:htmlunit:2.5')import com.gargoylesoftware.htmlunit.WebClientdef page = new WebClient().getPage('http://localhost:8080/postForm')def form = page.getFormByName('post')form.getInputByName('title').setValueAttribute(title)form.getSelectByName('category').getOptions().find {

it.text == category }.setSelected(true)form.getSelectByName('author').getOptions().find {

it.text == author }.setSelected(true)form.getTextAreaByName('content').setText(content)def result = form.getInputByName('btnPost').click()def titleResult = result.getElementsByTagName('h1').item(0).textContentdef h3headings = result.getElementsByTagName('h3')def categoryResult = h3headings.item(1).textContentdef authorResult = h3headings.item(2).textContentdef para = result.getByXPath('//TABLE//TR/TD/P')[0]def contentResult = para.textContentreturn new ResultHolder(titleResult, contentResult, authorResult, categoryResult)''')...

...ScalaCheck: SimpBlog Case Study...

QCON 2010 - 118

2006-2

...def binding = new Binding()binding.setVariable('title', title)binding.setVariable('content', clean(content))binding.setVariable('author', author)binding.setVariable('category', category)postAndCheck.binding = bindingpostAndCheck.run()

class ResultHolder {String title, content, author, categoryResultHolder(String title, String content,

String author, String category) {this.title = titlethis.content = contentthis.author = authorthis.category = category

> groovyc SimpBlogChecker.groovy

QCON 2010 - 119

2006-2

//CheckSimpBlog.scala

import org.scalacheck.Prop._import org.scalacheck.ConsoleReporter.testStatsEximport org.scalacheck.Test.checkimport org.scalacheck.Arbitrary._import org.scalacheck.Gen._

object CheckSimpBlog {

val fieldsGen = for {title <- elements("Title 1", "Title 2")content <- arbitrary[String]author <- elements("Bart", "Homer", "Lisa", "Marge", "Maggie")category <- elements("Home", "Work", "Food", "Travel")

} yield (title, content, author, category)...

> scalac -classpath .;../lib/ScalaCheck-1.5.jar;../../groovy-1.7-beta-2-SNAPSHOT/embeddable/groovy-all-1.7-beta-2-SNAPSHOT.jar CheckSimpBlog.scala

QCON 2010 - 120

2006-2

...val enterFieldsAcceptedAndEchoedProperty = forAll(fieldsGen)(

fields =>{

val (title, content, author, category) = fieldsval result = SimpBlogChecker.postAndReturn(title, content, author, category)result.getTitle contains titleresult.getContent contains contentresult.getAuthor contains authorresult.getCategory contains category

val tests = scala.List(("enterFieldsAcceptedAndEchoedProperty",

enterFieldsAcceptedAndEchoedProperty))

def main(args: scala.Array[String]) =tests foreach { case (name, p) => testStatsEx(name, check(p)) }

> scala -classpath .;../lib/ScalaCheck-1.5.jar;../../groovy-1.7-beta-2-SNAPSHOT/embeddable/groovy-all-1.7-beta-2-SNAPSHOT.jar;../../groovy-1.7-beta-2-SNAPSHOT/lib/ivy-2.1.0-rc2.jar CheckSimpBlog+ OK, passed 100 tests.

...ScalaCheck: SimpBlog Case Study

QCON 2010 - 121

2006-2

Topics

• Groovy Intro

• Web Services

• Writing DSLs

• Groovy Testing

• Polyglot Groovy

Parallel Processing

• More Info

QCON 2010 - 122

2006-2

Concurrent Programming in Groovy• Java concurrent programming goodness

– Normal OO methods

– Ability to have immutable types

– Some concurrency building blocks

• Process Enhancements– AntBuilder and GDK methods

• Closures for greater flexibility– Enabler for concurrency

– Closure is Runnable and Callable

• Third party Java libraries– Functional Java (Actors)

– Cascading.groovy subproject for Hadoop clusters

– Jetlang

– GridGain

– Groovy actorsQCON 2010 - 123

2006-2

QCON 2010 - 124

2006-2

Fibonacci…

START = 8END = 16fib = {n -> n < 2 ? n : fib(n - 1) + fib(n - 2) }(START..END).each {num ->

println "n:$num => ${fib(num)}"}

QCON 2010 - 125

2006-2

…Fibonacci…

import java.util.concurrent.*

CUTOFF = 12 // not worth parallelizing for small nTHREADS = 100

println "Calculating Fibonacci sequence in parallel..."serialFib = {n -> (n < 2) ? n : serialFib(n - 1) + serialFib(n - 2) }pool = Executors.newFixedThreadPool(THREADS)defer = {c -> pool.submit(c as Callable) }fib = {n ->

if (n < CUTOFF) return serialFib(n)def left = defer { fib(n - 1) }def right = defer { fib(n - 2) }left.get() + right.get()

(8..16).each {n -> println "n=$n => ${fib(n)}" }pool.shutdown()

gpars (formerly GParallelizer)• http://gpars.codehaus.org/

• Library classes and DSL sugar providing intuitive ways

for Groovy developers to handle tasks concurrently.

Logical parts:

– Actors provide a Groovy implementation of Scala-like

actors including "remote" actors on other machines

– Dataflow Concurrency supports natural shared-memory

concurrency model, using single-assignment variables

– Asynchronizer extends the Java 1.5 built-in support for

executor services to enable multi-threaded collection and

closure processing

– Parallelizer uses JSR-166y Parallel Arrays to enable

multi-threaded collection processing

– Safe a non-blocking mt-safe reference to mutable state

that is inspired by "agents" in ClojureQCON 2010 - 126

2006-2

gpars/GParallelizer...

QCON 2010 - 127

2006-2

// run multiple closures in parallelAsynchronizer.withAsynchronizer {

assert [10, 20] == AsyncInvokerUtil.doInParallel({calculateA()},{calculateB()}

// multiply numbers asynchronouslyParallelizer.withParallelizer(5) {

def result = [1, 2, 3, 4, 5].collectAsync {it * 2}assert result == [2, 4, 6, 8, 10]

...gpars/GParallelizer...

QCON 2010 - 128

2006-2

// support for dataflow to avoid doing synchronisationimport static org.gparallelizer.dataflow.DataFlow.thread

final def x = new DataFlowVariable()final def y = new DataFlowVariable()final def z = new DataFlowVariable()

thread {z << x.val + y.valprintln "Result: ${z.val}"

thread { x << 10 }

thread { y << 5 }

...gpars/GParallelizer...

QCON 2010 - 129

2006-2

// actor supportimport static org.gparallelizer.actors.pooledActors.PooledActors.*

def me = actor {friend.send('Hi')react(10.seconds) {

// continue conversation}

}me.metaClass.onTimeout = {->friend.send('I see, busy as usual. Never mind.')}me.start()

// safe supportimport org.gparallelizer.actors.pooledActors.SafeVariable

def jugMembers = new SafeVariable<List>(['Me']) //add Me

jugMembers.send {it.add 'James'} //add James

final Thread t1 = Thread.start {

jugMembers.send {it.add 'Joe'} //add Joe

final Thread t2 = Thread.start {

jugMembers << {it.add 'Dave'} //add Dave

jugMembers << {it.add 'Alice'} //add Alice

[t1, t2]*.join()

println jugMembers.val

jugMembers.valAsync {println "Current members: $it"}

System.in.read()

jugMembers.stop()

...gpars/GParallelizer

QCON 2010 - 130

2006-2

gpars for testing

QCON 2010 - 131

2006-2

@Grab('net.sourceforge.htmlunit:htmlunit:2.6')import com.gargoylesoftware.htmlunit.WebClient@Grab('org.gparallelizer:GParallelizer:0.8.3')import static org.gparallelizer.Parallelizer.*

def testCases = [['Home', 'Bart', 'Content 1'],['Work', 'Homer', 'Content 2'],['Travel', 'Marge', 'Content 3'],['Food', 'Lisa', 'Content 4']

withParallelizer(3) {testCases.eachAsync{ category, author, content ->

postAndCheck category, author, content}

private postAndCheck(category, author, content) {...

Topics

• Groovy Intro

• Web Services

• Writing DSLs

• Groovy Testing

• Polyglot Groovy

Enterprise Groovy

• More Info

QCON 2010 - 132

2006-2

Integration with Spring...

QCON 2010 - 133

2006-2

// traditional approach using a beans xml file

import org.springframework.context.support.ClassPathXmlApplicationContext

def ctx = new ClassPathXmlApplicationContext('calcbeans.xml')

def calc = ctx.getBean('calcBean')

println calc.doAdd(3, 4) // => 7

// using BeanBuilder

def bb = new grails.spring.BeanBuilder()

bb.beans {

adder(AdderImpl)

calcBean(CalcImpl2) { adder = adder }

def ctx = bb.createApplicationContext()

def calc = ctx.getBean('calcBean')

...Integration with Spring

QCON 2010 - 134

2006-2

// using annotations

import org.springframework.stereotype.Component

@Component class AdderImpl {

def add(x, y) { x + y }

import org.springframework.beans.factory.annotation.Autowired

import org.springframework.stereotype.Component

@Component class CalcImpl3 {

@Autowired private AdderImpl adder

def doAdd(x, y) { adder.add(x, y) }

import org.springframework.context.support.GenericApplicationContext

import org.springframework.context.annotation.ClassPathBeanDefinitionScanner

def ctx = new GenericApplicationContext()

new ClassPathBeanDefinitionScanner(ctx).scan('') // scan root package for components

ctx.refresh()

def calc = ctx.getBean('calcImpl3')

Dependency Injection: Guice

QCON 2010 - 135

2006-2

import com.google.inject.*

@ImplementedBy(CalculatorImpl)interface Calculator {

def add(a, b)}

@Singletonclass CalculatorImpl implements Calculator {

private total = 0def add(a, b) { total++; a + b }def getTotalCalculations() { 'Total Calculations: ' + total }String toString() { 'Calc: ' + hashCode()}

class Client {@Inject Calculator calc// ...

def injector = Guice.createInjector()// ...

Topics

• Groovy Intro

• Web Services

• Writing DSLs

• Groovy Testing

• Polyglot Groovy

More Info

QCON 2010 - 136

2006-2

More Information: on the web

• Web sites– http://groovy.codehaus.org

– http://grails.codehaus.org

– http://pleac.sourceforge.net/pleac_groovy (many examples)

– http://www.asert.com.au/training/java/GV110.htm (workshop)

• Mailing list for users– user@groovy.codehaus.org

• Information portals– http://www.aboutgroovy.org

– http://www.groovyblogs.org

• Documentation (1000+ pages)– Getting Started Guide, User Guide, Developer Guide, Testing

Guide, Cookbook Examples, Advanced Usage Guide

• Books– Several to choose from ...

QCON 2010 - 137

2006-2

...More Information

2006-2

Groovy Power Features

Technology

Adventures in Groovy – Part 20: Groovy On-Premise vs

Real Groovy Power Point Presentation - Kimberley Nelson

tictactoe groovy

Make your testing Groovy - events.static.linuxfound.org · What is Groovy? “Groovy is like a super version of Java. It leverages Java features but adds productivity features and

Groovy scripts with Groovy

Programming Groovy 2media.pragprog.com/titles/vslg2/toc.pdf10.3 Using Groovy Classes from Groovy ? 10.4 Intermixing Groovy and Java with Joint Compilation ? 10.5 Creating and Passing

Groovy - The features you wish Java had

What makes Groovy Groovy - Guillaume Laforge (Pivotal)

Groovy Shapes

Groovy - Nobel Biocaredownload.nobelbiocare.com/webcontent/NobelGuide/GS... · The NOBELDIRECT® Groovy implant features a revolutionary new one-piece design that is user-friendly,

Groovy 2.5 features & Groovy 3+ Roadmap · Groovy Roadmap Groovy 2.5 2.5.4 released, 2.5.5 soon Macros, AST transformation improvements, various misc. features JDK 7 minimum, runs

Groovy 2.5 features & Groovy 3+ Roadmap...What is Groovy? Groovy = Java –boiler plate code + extensible dynamic and static natures + better functional programming + better OO programming

Groovy, to Infinity and Beyond - Groovy/Grails eXchange 2009

Programming Groovy 2 - 3.droppdf.com3.droppdf.com/files/uHbLI/programming-groovy-2.pdf · 10.1 The Melting Pot of Java and Groovy 159 10.2 Running Groovy 160 10.3 Using Groovy Classes

Groovy And Grails - Chariot Solutionschariotsolutions.com/.../archive/449/groovy-grails-keynote.pdf · Groovy And Grails An Overview. Groovy. What Is Groovy?

Groovy base

Groovy Scripting - Apache Software Foundationpeople.apache.org/.../presentations/jsug-2016/groovy-scripting.pdf · • Groovy is easy for Java developers • Groovy is nice for non-trivial

Siegfried Goeschl Groovy Scripting - home.apache.orgpeople.apache.org/.../2016/linuxwochen/groovy-scripting.pdf · • Groovy is easy for Java developers • Groovy is nice for non-trivial

Groovy Primer - chrisdail.com€¦ · Groovy Primer (March 2010) Groovy … Groovy Java •Is a superset of Java –Makes interop easy •Uses Java’s Type system •Everything is

Smas061 Real Groovy Power Point Presentation