Paulking groovy

© ASERT 2006-2010

Groovy Power Features!
Dr Paul King
paulk@asert.com.au
@paulk_asert
ASERT, Australia

Topics
Groovy Intro
• Leveraging the language
• Use and abuse of Design Patterns
• Web Services
• Writing DSLs
© ASERT 2006-2010

• Groovy Testing
• Polyglot Groovy
• Parallel Processing
• Enterprise Groovy
• More Info
QCON 2010 - 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.”
© ASERT 2006-2010

Groovy = Java – boiler plate code
+ mostly dynamic typing
+ closures
+ domain specific languages
+ builders
+ metaprogramming
+ GDK library
QCON 2010 - 3

Groovy Goodies Overview
• Fully object oriented
• Closures: reusable
and assignable
pieces of code
• Operators can be • GPath: efficient
overloaded
© ASERT 2006-2010

object navigation
• Multimethods • GroovyBeans
• Literal declaration for • grep and switch
lists (arrays), maps,
ranges and regular • Templates, builder,
expressions swing, Ant, markup,
XML, SQL, XML-RPC,
Scriptom, Grails,
tests, Mocks QCON 2010 - 4

Growing Acceptance …
A slow and steady start but now gaining in
momentum, maturity and mindshare

Now free

… Growing Acceptance …
© ASERT 2006-2010

QCON 2010 - 6

© ASERT 2006-2010

Groovy and Grails downloads:
70-90K per month and growing QCON 2010 - 7

© ASERT 2006-2010

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

Source: http://www.grailspodcast.com/
QCON 2010 - 8

© ASERT 2006-2010

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

http://www.java.net
QCON 2010 - 9

What alternative JVM language are you using or intending to use
© ASERT 2006-2010

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

© ASERT 2006-2010

http://it-republik.de/jaxenter/quickvote/results/1/poll/44 (translated using http://babelfish.yahoo.com)
QCON 2010 - 11

© ASERT 2006-2010

http://pollpigeon.com/jsf-grails-wicket/r/25665/
QCON 2010 - 12

… Growing Acceptance
© ASERT 2006-2010

QCON 2010 - 13

The Landscape of JVM Languages

mostly
dynamic
typing
© ASERT 2006-2010

Dynamic features call
for dynamic types Java bytecode calls
for static types

The terms “Java Virtual Machine” and “JVM” mean a Virtual Machine for the Java™ platform.
QCON 2010 - 14

Groovy Starter
System.out.println("Hello, World!"); // optional semicolon,
println 'Hello, World!' // System.out, brackets,
// main() method, class defn

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

String longer = """${name}, the car
is in the next row.""" // multi-line string
© ASERT 2006-2010

// with static typing

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

def printSize(obj) { // optional duck typing
print obj?.size() // safe dereferencing
}

def pets = ['ant', 'bee', 'cat'] // native list syntax
pets.each { pet -> // closure support
assert pet < 'dog' // overloading '<' on String
} // or: for (pet in pets)...
QCON 2010 - 15

A Better Java...
import java.util.List;
import java.util.ArrayList;

class Erase {
private List removeLongerThan(List strings, int length) { This code
List result = new ArrayList();
for (int i = 0; i < strings.size(); i++) {
is valid
String s = (String) strings.get(i); Java and
if (s.length() <= length) {
result.add(s); valid Groovy
}
}
© ASERT 2006-2010

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);
Based on an
Erase e = new Erase(); example by
List shortNames = e.removeLongerThan(names, 3); Jim Weirich
System.out.println(shortNames.size());
for (int i = 0; i < shortNames.size(); i++) { & Ted Leung
String s = (String) shortNames.get(i);
System.out.println(s);
}
}
}
QCON 2010 - 16

...A Better Java...
import java.util.List;
import java.util.ArrayList;

class Erase {
private List removeLongerThan(List strings, int length) { Do the
List result = new ArrayList();
for (int i = 0; i < strings.size(); i++) {
semicolons
String s = (String) strings.get(i); add anything?
result.add(s); And shouldn‟t
}
} we us more
© ASERT 2006-2010

}
return result; modern list
public static void main(String[] args) { notation?
List names = new ArrayList();
names.add("Ted"); names.add("Fred"); Why not
names.add("Jed"); names.add("Ned");
System.out.println(names);
import common
Erase e = new Erase(); libraries?
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);
}
}
}
QCON 2010 - 17

...A Better Java...
class Erase {
private List removeLongerThan(List strings, int length) {
List result = new ArrayList()
for (String s in strings) {
result.add(s)
}
}
return result
}

© ASERT 2006-2010

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)
}
}
}

QCON 2010 - 18

...A Better Java...
class Erase {
private List removeLongerThan(List strings, int length) {
List result = new ArrayList()
for (String s in strings) {
result.add(s)
Do we need
} the static types?
}
return result Must we always
}
have a main
public static void main(String[] args) { method and
© ASERT 2006-2010

List names = new ArrayList()
names.add("Ted"); names.add("Fred") class definition?
names.add("Jed"); names.add("Ned")
System.out.println(names) How about
Erase e = new Erase()
List shortNames = e.removeLongerThan(names, 3)
improved
System.out.println(shortNames.size()) consistency?
for (String s in shortNames) {
}
}
}

QCON 2010 - 19

...A Better Java...
def removeLongerThan(strings, length) {
def result = new ArrayList()
for (s in strings) {
if (s.size() <= length) {
result.add(s)
}
}
return result
}
© ASERT 2006-2010

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

QCON 2010 - 20

...A Better Java...
def result = new ArrayList()
for (s in strings) {
if (s.size() <= length) {
result.add(s) Shouldn‟t we
}
} have special
return result notation for lists?
}
And special
© ASERT 2006-2010

names = new ArrayList() facilities for
names.add("Ted")
names.add("Fred") list processing?
names.add("Jed") Is „return‟
names.add("Ned")
System.out.println(names) needed at end?
for (s in shortNames) {
}

QCON 2010 - 21

...A Better Java...
strings.findAll{ it.size() <= length }
}

names = ["Ted", "Fred", "Jed", "Ned"]
shortNames.each{ System.out.println(s) }
© ASERT 2006-2010

QCON 2010 - 22

...A Better Java...
strings.findAll{ it.size() <= length }
}
Is the method
names = ["Ted", "Fred", "Jed", "Ned"] now needed?
shortNames = removeLongerThan(names, 3) Easier ways to
System.out.println(shortNames.size()) use common
shortNames.each{ System.out.println(s) }
methods?
© ASERT 2006-2010

Are brackets
required here?

QCON 2010 - 23

...A Better Java...
println names
shortNames = names.findAll{ it.size() <= 3 }
println shortNames.size()
shortNames.each{ println it }
© ASERT 2006-2010

QCON 2010 - 24

...A Better Java
println names
shortNames = names.findAll{ it.size() <= 3 }
println shortNames.size()
shortNames.each{ println it }
© ASERT 2006-2010

[Ted, Fred, Jed, Ned]
3
Ted
Jed
Ned

QCON 2010 - 25

Topics
• Groovy Intro
Leveraging the language
• Web Services
• Writing DSLs
© ASERT 2006-2010

• Groovy Testing
• Polyglot Groovy
• More Info
QCON 2010 - 26

Better Control Structures: Switch

switch (10) {
case 0 : assert false ; break
case 0..9 : assert false ; break
case [8,9,11] : assert false ; break
case Float : assert false ; break
case {it%3 == 0} : assert false ; break
case ~/../ : assert true ; break
© ASERT 2006-2010

default : assert false ; break
}

• Extensible
– Implement your own isCase() method

QCON 2010 - 27

Better Control Structures: Switch – Custom isCase
WARNING:
enum Color { Advanced
yellow, orange, purple Topic!
def isCase(thing) { thing.color == this }
}
import static Color.*
class Banana { def color = yellow }
class Orange { def color = orange }
class Grape { def color = purple }
© ASERT 2006-2010

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 yellow
Found something orange
Unknown color
QCON 2010 - 28


enum Color { yellow, orange, purple }
class Banana { def color = yellow }
class Grape { def color = purple }
© ASERT 2006-2010

switch (f.color) {
case [yellow, orange]:
return "Found something $f.color"
default: return 'Unknown color'
}
}

Found something yellow
Found something orange
Unknown color
QCON 2010 - 29

enum Color { WARNING:
yellow, orange, purple Advanced Topic!
def isCase(thing) {
thing?.hasProperty('color') && thing.color == this }
}

enum State {
peeled, unpeeled
def isCase(thing) {
try {
© ASERT 2006-2010

return thing.color == this
} catch (MissingPropertyException) {
return false
}
}

import static State.*

class Banana { def color = yellow; def state = peeled }
class Grape { def state = peeled }
...
QCON 2010 - 30

WARNING:
...
Advanced Topic!

def yellowAndPeeled = { yellow.isCase(it) &&
peeled.isCase(it) }
switch (f) {
© ASERT 2006-2010

case yellowAndPeeled:
return 'Possibly found a banana split'
case yellow:
return 'Found something yellow'
case peeled:
return 'Found something peeled'
default:
return 'No comment'
} Possibly found a banana split
} No comment
Found something peeled
QCON 2010 - 31

Better Control Structures: Switch Poker…
hand1 hand2

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

suits = 'SHDC'
ranks = '23456789TJQKA'
suit = { String card -> suits.indexOf(card[1]) }
rank = { String card -> ranks.indexOf(card[0]) }
rankSizes = { List cards ->
© ASERT 2006-2010

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

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

QCON 2010 - 32

…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) }
© ASERT 2006-2010

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 - 33

… Better Control Structures: Switch Poker

// ...
def rankHand(List cards) {
switch (cards) {
case straightFlush : return 9
case fourOfAKind : return 8
case fullHouse : return 7
case flush : return 6
© ASERT 2006-2010

case straight : return 5
case threeOfAKind : return 4
case twoPair : return 3
case pair : return 2
default : return 1
}
}
// ...

QCON 2010 - 34

Topics
• Groovy Intro
Use and abuse of Design Patterns
• Web Services
• Writing DSLs
© ASERT 2006-2010

• Groovy Testing
• Polyglot Groovy
• More Info
QCON 2010 - 35

Grapes / Grab
// Google Collections example
import com.google.common.collect.HashBiMap

@Grab(group='com.google.collections',
module='google-collections',
version='1.0-rc2')
© ASERT 2006-2010

def getFruit() {
[ grape:'purple',
lemon:'yellow',
orange:'orange' ] as HashBiMap
}

assert fruit.lemon == 'yellow'
assert fruit.inverse().yellow == 'lemon'
QCON 2010 - 36

Better Design Patterns: Immutable...
• Java Immutable Class
– As per Joshua Bloch // ...
@Override
Effective Java public boolean equals(Object obj) {
if (this == obj)
public final class Punter { return true;
private final String first; if (obj == null)
private final String last; return false;
if (getClass() != obj.getClass())
public String getFirst() { return false;
return first; Punter other = (Punter) obj;
} if (first == null) {
© ASERT 2006-2010

if (other.first != null)
public String getLast() { return false;
return last; } else if (!first.equals(other.first))
} return false;
if (last == null) {
@Override if (other.last != null)
public int hashCode() { return false;
final int prime = 31; } else if (!last.equals(other.last))
int result = 1; return false;
result = prime * result + ((first == null) return true;
? 0 : first.hashCode()); }
result = prime * result + ((last == null)
? 0 : last.hashCode()); @Override
return result; public String toString() {
} return "Punter(first:" + first
+ ", last:" + last + ")";
public Punter(String first, String last) { }
this.first = first;
this.last = last; }
}
// ...
QCON 2010 - 37

...Better Design Patterns: Immutable...
• Java Immutable Class boilerplate
– As per Joshua Bloch // ...
@Override
Effective Java public boolean equals(Object obj) {
if (this == obj)
public final class Punter { return true;
private final String first; if (obj == null)
private final String last; return false;
if (getClass() != obj.getClass())
public String getFirst() { return false;
return first; Punter other = (Punter) obj;
} if (first == null) {
© ASERT 2006-2010

if (other.first != null)
public String getLast() { return false;
return last; } else if (!first.equals(other.first))
} return false;
if (last == null) {
@Override if (other.last != null)
public int hashCode() { return false;
final int prime = 31; } else if (!last.equals(other.last))
int result = 1; return false;
result = prime * result + ((first == null) return true;
? 0 : first.hashCode()); }
result = prime * result + ((last == null)
? 0 : last.hashCode()); @Override
return result; public String toString() {
} return "Punter(first:" + first
+ ", last:" + last + ")";
public Punter(String first, String last) { }
this.first = first;
this.last = last; }
}
// ...
QCON 2010 - 38

...Better Design Patterns: Immutable

@Immutable class Punter {
String first, last
© ASERT 2006-2010

}

QCON 2010 - 39

Better Design Patterns: Singleton
class Calculator {
def total = 0
def add(a, b) { total++; a + b }
}

def INSTANCE = new Calculator()
Calculator.metaClass.constructor = { -> INSTANCE }
© ASERT 2006-2010

def c1 = new Calculator()
def c2 = new Calculator()
@Singleton(lazy=true)
assert c1.add(1, 2) == 3 class X {
assert c2.add(3, 4) == 7 def getHello () {
"Hello, World!"
assert c1.is(c2) }
assert [c1, c2].total == [2, 2] }

println X.instance.hello

QCON 2010 - 40

Better Design Patterns: Delegate…
public Date getWhen() {
import java.util.Date;
return when;
}
public class Event {
private String title;
public void setWhen(Date when) {
private String url;
this.when = when;
private Date when;
}
public String getUrl() {
public boolean before(Date other) {
return url;
return when.before(other);
}
© ASERT 2006-2010

}
public void setUrl(String url) {
public void setTime(long time) {
this.url = url;
when.setTime(time);
}
}
public String getTitle() {
public long getTime() {
return title;
return when.getTime();
}
}
public void setTitle(String title) {
public boolean after(Date other) {
this.title = title;
return when.after(other);
}
}
// ...
// ...
QCON 2010 - 41

…Better Design Patterns: Delegate…
public Date getWhen() {
return when;
boilerplate }
public class Event {
private String title;
public void setWhen(Date when) {
private String url;
this.when = when;
private Date when;
}
public String getUrl() {
public boolean before(Date other) {
return url;
return when.before(other);
}
© ASERT 2006-2010

}
public void setUrl(String url) {
public void setTime(long time) {
this.url = url;
when.setTime(time);
}
}
public String getTitle() {
public long getTime() {
return title;
return when.getTime();
}
}
public void setTitle(String title) {
public boolean after(Date other) {
this.title = title;
return when.after(other);
}
}
// ...
// ...
QCON 2010 - 42

…Better Design Patterns: Delegate

class Event {
String title, url
@Delegate Date when
}
© ASERT 2006-2010

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)

QCON 2010 - 43

Topics
• Groovy Intro
Web Services
• Writing DSLs
© ASERT 2006-2010

• Groovy Testing
• Polyglot Groovy
• More Info
QCON 2010 - 44

SOAP Client and Server
class MathService {
double add(double a, double b) {
a + b
}
double square(double c) {
c * c
}
}
© ASERT 2006-2010

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

QCON 2010 - 45

Better Testing: SoapUI
• Tool for testing Web Services has a built-
in Groovy editor for custom steps
© ASERT 2006-2010

QCON 2010 - 46

Topics
• Groovy Intro
• Web Services
Writing DSLs
© ASERT 2006-2010

• Groovy Testing
• Polyglot Groovy
• More Info
QCON 2010 - 47

Groovy DSL Features
• Literal Syntax Conventions
• Scripts as well as Classes & Optional Syntax
• Optional Typing & Named Arguments
• Type Transformations
• Using With
© ASERT 2006-2010

• Operator Overloading
• Closures
• Runtime Metaprogramming
• Compile-time Metaprogramming (AST Macros)
• Builders

QCON 2010 - 48

Literal Syntax Conventions
• Lists
– Special syntax for list literals
– Additional common methods (operator overloading)
def list = [3, new Date(), 'Jan']
assert list + list == list * 2

• Maps
© ASERT 2006-2010

– Special syntax for map literals
– Additional common methods
def map = [a: 1, b: 2]
assert map['a'] == 1 && map.b == 2

• Ranges
– Special syntax for various kinds of ranges
def letters = 'a'..'z'
def numbers = 0..<10
QCON 2010 - 49

Scripts as well as Classes & Optional Syntax
• Java
public class HelloJava {
System.out.println("Hello World");
}
}
© ASERT 2006-2010

• Groovy
class HelloGroovy {
static main(String[] args) {
System.out.println("Hello World");
}
}
System.out.println('Hello World');
println 'Hello World'
QCON 2010 - 50

Optional Typing & Named Params
• Java
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"));
© ASERT 2006-2010

String last = args.get("last");
System.out.println("Last name: " + (last != null ? last : "unknown"));
}

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.first

• Groovy
Last name: $args.last"""
}
printDetails first:'John', last:'Smith'

QCON 2010 - 51

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
© ASERT 2006-2010

around, combined in structured ways to form more
complex algorithms and data
doubleNum = { num -> num * 2 }
println doubleNum(3) // => 6

processThenPrint = { num, closure ->
num = closure(num); println "num is $num"
}
processThenPrint(3, doubleNum) // => num is 6
processThenPrint(10) { it / 2 } // => num is 5
QCON 2010 - 52

Static Imports

import groovy.swing.SwingXBuilder
© ASERT 2006-2010

import 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()
QCON 2010 - 53

Using '.with' Example
letters = ['a', 'b', 'c']
range = 'b'..'d'
letters.with {
add 'd'
remove 'a'
}
assert letters == range
© ASERT 2006-2010

map = [a:10, b:4, c:7]
map.with {
assert (a + b) / c == 2
}

QCON 2010 - 54

Coin example...

enum Coin {
penny(1), nickel(5), dime(10), quarter(25)
Coin(int value) { this.value = value }
int value
}
© ASERT 2006-2010

import static Coin.*

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

QCON 2010 - 55

...Coin example...
class CoinMath {
static multiply(Integer self, Coin c) {
self * c.value
}
}
use (CoinMath) {
© ASERT 2006-2010

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
QCON 2010 - 56

...Coin example
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) {
© ASERT 2006-2010

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 QCON 2010 - 57

Game example...
// 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) {
© ASERT 2006-2010

if (index == things.size() - 1) result += ' and '
else if (index < things.size() - 1) result += ', '
}
result += "${thing.toLowerCase()[0] in VOWELS ? 'an' : 'a'} $thin
}
result ?: 'nothing'
}
}
import static GameUtils.*
...
QCON 2010 - 58

...Game example...
...
class Room {
def description
def contents = []
}
...
© ASERT 2006-2010

QCON 2010 - 59

...Game example...
...
class Player {
def currentRoom
def inventory = []
void look() {
println "You are in ${currentRoom?.description?:'the void'} which contains ${listItems(currentRoom?.contents)}
}
void inv() {
© ASERT 2006-2010

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"
}
}
QCON 2010 - 60

...Game example...
...
void drop(item) {
if (inventory?.remove(item)) {
currentRoom?.contents << item
println "You dropped the $item"
} else {
println "You don't have the $item"
}
© ASERT 2006-2010

}
def propertyMissing(String name) {
if (metaClass.respondsTo(this, name)) {
this."$name"()
}
name
}
}
...
QCON 2010 - 61

...
...Game example...
Room plainRoom = new Room(description:'a plain white room',
contents:['dagger', 'emerald', 'key'])
Player player = new Player(currentRoom:plainRoom)
player.with{
inv
look
take dagger
inv
© ASERT 2006-2010

look
take emerald
inv
look
take key
drop emerald
inv
look
}
assert player.inventory == ['dagger', 'key'] QCON 2010 - 62

...Game example
...

// now try some error conditions
plainRoom.description = null
player.with {
drop gold
take gold
drop emerald
© ASERT 2006-2010

take emerald
take emerald
look
}

QCON 2010 - 63

Grails Criteria
// Account is a POJO in our domain/model

def c = Account.createCriteria()
def results = c {
like("holderFirstName", "Fred%")
and {
between("balance", 500, 1000)
eq("branch", "London")
© ASERT 2006-2010

}
maxResults(10)
order("holderLastName", "desc")
}
// source: Grails doco: 5. Object Relational Mapping (GORM): 5.4.2 Criteria

QCON 2010 - 64

Grails Criteria Example
// Book is a POJO in our domain/model

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

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

book = Book.findByReleaseDateBetween( firstDate, secondDate )
© ASERT 2006-2010

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

QCON 2010 - 65

Grails Bean Builder Example
bb.beans {
marge(Person) {
name = "marge"
husband = { Person p ->
name = "homer"
age = 45
props = [overweight:true, height:"1.8m"]
}
children = [bart, lisa]
© ASERT 2006-2010

}
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 QCON 2010 - 66

Groovy Lab Example
// 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
© ASERT 2006-2010

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))
QCON 2010 - 67

Operator Overloading Example
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
© ASERT 2006-2010

QCON 2010 - 68

Type Transformation Example
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) {
© ASERT 2006-2010

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() }
QCON 2010 - 69

AST Builder
• Numerous approaches, still evolving.
“From code” approach:

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

• Produces:
BlockStatement
-> ReturnStatement
-> MethodCallExpression
-> VariableExpression("this")
-> ConstantExpression("println")
-> ArgumentListExpression
-> ConstantExpression("Hello World")

Topics
• Groovy Intro
• Web Services
• Writing DSLs
© ASERT 2006-2010

Groovy Testing
• Polyglot Groovy
• More Info
QCON 2010 - 71

Types of Testing

Unit Testing
Mock/interaction testing Techniques
State-based testing Testing DSLs
ATDD/BDD
Data-driven
Logic-driven
© ASERT 2006-2010

Integration Testing
Model-driven
Performance
testing
Acceptance Testing
All-pairs &
Web drivers
combinations
Non-web drivers
Gpars
Test runners

QCON 2010 - 72

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
© ASERT 2006-2010

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

Groovy and Testing Tool Spectrum*
Utilities Runners
AllPairs, Combinations Native Groovy, JUnit, TestNG, Spock, EasyB,
Polyglot languages JBehave, Cucumber, Robot Framework
Logic programming
Threads, Parallel /
Web Database SOAP / Other
Concurrency libraries
Drivers Drivers REST Drivers
Data-driven libraries
Drivers
Networking libraries WebTest DbUnit FEST
© ASERT 2006-2010

XML Processing GroovyWS
WebDriver DataSets Email
Read/write files /
JWebUnit SqlUnit XML-RPC FTP
Excel / Word / CSV
Reporting, Logging Tellurium groovy.sql CXF AntUnit
Selenium JPA Axis2 Telnet
HtmlUnit JDO JAX-WS SSH
Tools Watij BigTable JAX-RS Exec
iTest2, SoapUI, Twist, HttpBuilder JDBC
IDEs, JMeter, Text Cyberneko
editors, Recorders,
Sahi, Build Tools, CI

* Tools/libraries/frameworks don't always neatly fall into one category – still useful conceptually QCON 2010 - 74

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)
–
© ASERT 2006-2010

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

HtmlUnit: Testing New Blog Post...
@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 title
assert 'Welcome to SimpBlog' == page.titleText
© ASERT 2006-2010

// fill in blog entry and post it
def 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()

...

QCON 2010 - 76

...HtmlUnit: Testing New Blog Post

...

// check blog post details
assert result.getElementsByTagName('h1').item(0).
textContent.matches('Post.*: Bart was here.*')
def h3headings = result.getElementsByTagName('h3')
© ASERT 2006-2010

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 - 77

WebTest testing Web Sites
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")
}
}
© ASERT 2006-2010

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}")
}
}
}
QCON 2010 - 78

WebTest testing Emails
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")
}
}
© ASERT 2006-2010

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')
}
}
QCON 2010 - 79

Spock Testing Framework...
© ASERT 2006-2010

QCON 2010 - 80

...Spock Testing Framework
• Testing framework for Java and Groovy
• Highly expressive specification language
– No assertion API
– No record &
replay @Speck
mocking API @RunWith(Sputnik)
– No class PublisherSubscriberSpeck {
superfluous def "events are received by all subscribers"() {
© ASERT 2006-2010

annotations def pub = new Publisher()
– Meaningful def sub1 = Mock(Subscriber)
assert error def sub2 = Mock(Subscriber)
messages pub.subscribers << sub1 << sub2

when:
pub.send("event")

then:
– Extensible 1 * sub1.receive("event")
– Compatible 1 * sub2.receive("event")
with JUnit }
reportingwise }
QCON 2010 - 81

Spock Example...
import 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 shoul
© ASERT 2006-2010

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
form.getSelectByName('category').getOptions().find { it.text == category
form.getSelectByName('author').getOptions().find { it.text == author }.se
form.getTextAreaByName('content').setText(content)
result = form.getInputByName('btnPost').click()
subheadings = result.getElementsByTagName('h3')
para = result.getByXPath('//TABLE//TR/TD/P')[0]
...
QCON 2010 - 82

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

and:
// Optional use of 'and:'
para.textContent == content
© ASERT 2006-2010

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

QCON 2010 - 83

EasyB
• Description: BDD, Rspec-like testing library
narrative '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'
© ASERT 2006-2010

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
}
} QCON 2010 - 84

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

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"
© ASERT 2006-2010

and "I have selected 'Bart' as the author"
and "I click the 'Create Post' button"
then "I expect the entry to be posted"
}

QCON 2010 - 85

...EasyB Example...
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", {
© ASERT 2006-2010

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.getInputByName('title').setValueAttribute(
'Bart was here (and so was EasyB)')
}

...
QCON 2010 - 86

...EasyB Example...
...
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(
}

and "I click the 'Create Post' button", {
}
© ASERT 2006-2010

then "I expect the entry to be posted", {
// check blog post details
assert result.getElementsByTagName('h1').item(0).textContent.matches('Post.*: Bart wa
assert h3headings.item(1).textContent == 'Category: Home' // traditional style
h3headings.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.firstChild
assert para.textContent == 'Cowabunga Dude!'
// para.shouldHave textContent: 'Cowabunga Dude!'
}
}

QCON 2010 - 87

...EasyB Example...
© ASERT 2006-2010

QCON 2010 - 88

...EasyB Example
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 easyb is preparing to process 2 file(s)
© ASERT 2006-2010

Post Blog Entry Feature Running simp blog initial story (SimpBlogInitialStory.groovy)
for feature Scenarios run: 1, Failures: 0, Pending: 1, Time elapsed: 1.049 sec
As a Blogger Running simp blog story (SimpBlogStory.groovy)
I want to be able to post a blog Scenarios run: 1, Failures: 0, Pending: 0, Time elapsed: 1.356 sec
So that I can keep others informed
given we are on the create blog entry page 2 total behaviors ran (including 1 pending behavior) with no failures
easyb execution passed
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

QCON 2010 - 89

Cucumber
# language: en
• Description Feature: Addition
In order to avoid silly mistakes
– Loose coupling As a math idiot
between text spec I want to be told the sum of two numbers

and step defns Scenario Outline: Add two numbers
Given I have entered <input_1> into the calculator
And I have entered <input_2> into the calculator
When I press <button>
Then the stored result should be <output>

Examples:
© ASERT 2006-2010

| input_1 | input_2 | button | output |
| 20 | 30 | add | 50 |
| 2 | 5 | add | 7 |
| 0 | 40 | add | 40 |
# language: en
Feature: Division
In order to avoid silly mistakes
Cashiers must be able to calculate a fraction

Scenario: Regular numbers
Given I have entered 3 into the calculator
And I have entered 2 into the calculator
When I press divide
Then the stored result should be 1.5
QCON 2010 - 90

Cucumber Example...

# 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
© ASERT 2006-2010

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.*"

QCON 2010 - 91

...Cucumber Example...
© ASERT 2006-2010

QCON 2010 - 92

...Cucumber Example
this.metaClass.mixin(cuke4duke.GroovyDsl)

Given ~/we are on the create blog entry page/, { ->
}

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

When(~'I have entered "(.*)" as the content') {String content ->
© ASERT 2006-2010

}

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") { ->
}

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)
}
QCON 2010 - 93

...Cucumber Data Driven Example
© ASERT 2006-2010

QCON 2010 - 95

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
© ASERT 2006-2010

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 clauses
QCON 2010 - 96

JBehave Example...

import org.jbehave.scenario.Scenario
© ASERT 2006-2010

import org.jbehave.scenario.steps.Steps

class NewPostScenario extends Scenario {
NewPostScenario() {
super([new CreateBlogSteps()] as Steps[])
}
} Scenario:


QCON 2010 - 97

...JBehave Example
import org.jbehave.scenario.steps.Steps
import org.jbehave.scenario.annotations.*

class CreateBlogSteps extends Steps {
def page, form, result

@Given("we are on the create blog entry page")
void gotoEntryPage() {
}
© ASERT 2006-2010

@When('I have entered "$title" as the title')
void enterTitle(String title) {
form.getInputByName('title').
setValueAttribute(title + ' (and so was JBehave)')
}

@When('I have entered "$content" as the content')
void enterContent(String content) {
}
...
Example uses HtmlUnit which must be added to CLASSPATH QCON 2010 - 98

Topics
• Groovy Intro
• Web Services
• Writing DSLs
© ASERT 2006-2010

• Groovy Testing
Polyglot Groovy
 Other languages, other styles
• More Info QCON 2010 - 99

Polyglot Programming...

@Grab('org.clojure:clojure:1.0.0')
import clojure.lang.Compiler
import clojure.lang.RT ...
def jy = getEngine("jython")
def src = new File('temp.clj') jy?.eval('''
src.text = ''' def factorial(n):
(ns groovy) i=fact=1
© ASERT 2006-2010

(defn factorial [n] while i <= n:
(if (< n 2) fact=fact*i
1 i=i+1
(* n (factorial (- n 1)))) return fact
'''
result = factorial(4)
src.withReader { reader -> ''')
Compiler.load reader println jy?.result
}

def fac = RT.var('groovy', 'factorial')
println fac.invoke(4)
QCON 2010 - 100

...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
© ASERT 2006-2010

• 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

Functional Programming in Groovy
• Java functional programming goodness
– Normal OO methods
– Ability to have immutable types
– Some concurrency building blocks
• Closures for greater flexibility
© ASERT 2006-2010

– 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

Functional Programming…

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

// define and use infinite streams
© ASERT 2006-2010

def 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 - 103

…Functional Programming…

import fj.data.Stream

//some metaprogramming to make fj mesh well with Groovy
Stream.metaClass.filter = { Closure c ->
delegate.filter(c as fj.F) }
Stream.metaClass.getAt = { n ->
delegate.index(n) }
© ASERT 2006-2010

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 - 104

…Functional Programming

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

// some metaprogramming to make Closures mesh well with
// fj functions and products
Stream.metaClass.filterTail = { Closure c ->
delegate.tail()._1().filter(c as fj.F) }
Stream.metaClass.static.cons = { h, Closure c ->
© ASERT 2006-2010

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
QCON 2010 - 105

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:
def numbers = [31,-41,59,26,-53,58,97,-93,-23,84]
© ASERT 2006-2010

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"

QCON 2010 - 106

... Enabling a functional style …
• A first attempt at a more functional style:

def numbers = [31,-41,59,26,-53,58,97,-93,-23,84]
© ASERT 2006-2010

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"

QCON 2010 - 107

• 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:
© ASERT 2006-2010

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

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

QCON 2010 - 108

• An even more functional style
mss = max º sum* º (flatten º tails* º 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]
© ASERT 2006-2010

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

Notes:
– sum() is one-level flatten in Groovy, flatten() is recursive
– Metaprogramming allowed us to enhance all Lists
List.metaClass {
inits{ (0..<delegate.size()).collect{ delegate[0..it] } }
tails{ delegate.reverse().inits() }
}
Source: http://hamletdarcy.blogspot.com/2008/07/groovy-vs-f-showdown-side-by-side.html
QCON 2010 - 109

...Constraint/Logic Programming...
// 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 = [ Found a solution:
© ASERT 2006-2010

'Mixed fruit' : 215, 7 * Mixed fruit
'French fries' : 275, Found a solution:
'Side salad' : 335, 1 * Mixed fruit
'Hot wings' : 355, 2 * Hot wings
'Mozzarella sticks' : 420, 1 * Sampler plate
'Sampler plate' : 580
]
def numOrdered = new IntegerVariable[menu.size()]
def priceEach = new int[menu.size()]
def sum = 1505
...
QCON 2010 - 111

...Constraint/Logic Programming
...
menu.eachWithIndex { name, price, i ->
// number ordered >= 0
// number ordered * price <= sum
numOrdered[i] = makeIntVar(name, 0, sum.intdiv(price))
priceEach[i] = price
}
m.addConstraint(eq(scalar(numOrdered, priceEach), sum))
© ASERT 2006-2010

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()
}
QCON 2010 - 112

ModelJUnit...
// require modeljunit.jar
import nz.ac.waikato.modeljunit.coverage.*
import nz.ac.waikato.modeljunit.*

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

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

boolean coin25Guard() {state <= 75}
© ASERT 2006-2010

@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()
QCON 2010 - 113

...ModelJUnit...
...
done (0, coin50, 50)
done (50, coin25, 75)
done (75, coin25, 100)
done Random reset(true)
done (50, coin25, 75)
done (75, coin25, 100)
done (100, vend, 0)
...
© ASERT 2006-2010

done (50, coin50, 100) Metrics Summary:
done (100, vend, 0) action coverage: 3/3
done (0, coin25, 25) state coverage: 5/5
done (25, coin25, 50) transition coverage: 7/8
done Random reset(true) transition-pair coverage: 8/12
...
done (50, coin25, 75)
done (75, coin25, 100)
done (100, vend, 0)
done (50, coin25, 75)
...
QCON 2010 - 114

ScalaCheck
• Description
– Tool for testing Scala, Java and Groovy programs
– Based on property specifications and automatic
random test data generation
> scala -classpath ScalaCheck-1.5.jar
Welcome to Scala version 2.7.6.final
© ASERT 2006-2010

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")
QCON 2010 - 116

ScalaCheck: SimpBlog Case Study...
class SimpBlogChecker {
static postAndCheck = null
static clean(s) { s.replace('', '').replace('n', 'n') }
static ResultHolder postAndReturn(String title, String content,
String author, String category) {
if (!postAndCheck) postAndCheck = new GroovyShell().parse('''
def page = new WebClient().getPage('http://localhost:8080/postForm')
def form = page.getFormByName('post')
form.getInputByName('title').setValueAttribute(title)
© ASERT 2006-2010

form.getSelectByName('category').getOptions().find {
it.text == category }.setSelected(true)
form.getSelectByName('author').getOptions().find {
it.text == author }.setSelected(true)
def result = form.getInputByName('btnPost').click()
def titleResult = result.getElementsByTagName('h1').item(0).textContent
def categoryResult = h3headings.item(1).textContent
def authorResult = h3headings.item(2).textContent
def para = result.getByXPath('//TABLE//TR/TD/P')[0]
def contentResult = para.textContent
return new ResultHolder(titleResult, contentResult, authorResult, categoryResult)
''')
...

QCON 2010 - 117

...ScalaCheck: SimpBlog Case Study...
...
def binding = new Binding()
binding.setVariable('title', title)
binding.setVariable('content', clean(content))
binding.setVariable('author', author)
binding.setVariable('category', category)
postAndCheck.binding = binding
postAndCheck.run()
}
}
© ASERT 2006-2010

class ResultHolder {
String title, content, author, category
ResultHolder(String title, String content,
String author, String category) {
this.title = title
this.content = content
this.author = author
this.category = category
}
}

> groovyc SimpBlogChecker.groovy
QCON 2010 - 118

//CheckSimpBlog.scala

import org.scalacheck.Prop._
import org.scalacheck.ConsoleReporter.testStatsEx
import org.scalacheck.Test.check
import org.scalacheck.Arbitrary._
import org.scalacheck.Gen._

object CheckSimpBlog {
© ASERT 2006-2010

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 - 119

...
val enterFieldsAcceptedAndEchoedProperty = forAll(fieldsGen)(
fields =>
{
val (title, content, author, category) = fields
val result = SimpBlogChecker.postAndReturn(title, content, author, category)
result.getTitle contains title
result.getContent contains content
result.getAuthor contains author
result.getCategory contains category
}
)
© ASERT 2006-2010

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.
QCON 2010 - 120

Topics
• Groovy Intro
• Web Services
• Writing DSLs
© ASERT 2006-2010

• Groovy Testing
• Polyglot Groovy
Parallel Processing
• More Info
QCON 2010 - 122

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
© ASERT 2006-2010

• 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 actors
QCON 2010 - 123

Fibonacci…
START = 8
END = 16
fib = {n -> n < 2 ? n : fib(n - 1) + fib(n - 2) }
(START..END).each {num ->
println "n:$num => ${fib(num)}"
}
© ASERT 2006-2010

QCON 2010 - 124

…Fibonacci…
import java.util.concurrent.*

CUTOFF = 12 // not worth parallelizing for small n
THREADS = 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 ->
© ASERT 2006-2010

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()

QCON 2010 - 125

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
© ASERT 2006-2010

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 Clojure
QCON 2010 - 126

gpars/GParallelizer...

// run multiple closures in parallel
Asynchronizer.withAsynchronizer {
assert [10, 20] == AsyncInvokerUtil.doInParallel(
{calculateA()},
{calculateB()}
)
© ASERT 2006-2010

}

// multiply numbers asynchronously
Parallelizer.withParallelizer(5) {
def result = [1, 2, 3, 4, 5].collectAsync {it * 2}
assert result == [2, 4, 6, 8, 10]
}

QCON 2010 - 127

...gpars/GParallelizer...

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

final def x = new DataFlowVariable()
final def y = new DataFlowVariable()
final def z = new DataFlowVariable()
© ASERT 2006-2010

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

thread { x << 10 }

thread { y << 5 }

QCON 2010 - 128

...gpars/GParallelizer...

// actor support
import static org.gparallelizer.actors.pooledActors.PooledActors.*

def me = actor {
friend.send('Hi')
react(10.seconds) {
© ASERT 2006-2010

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

QCON 2010 - 129

...gpars/GParallelizer
// safe support
import 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
© ASERT 2006-2010

}

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()
QCON 2010 - 130

gpars for testing
@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'],
© ASERT 2006-2010

['Food', 'Lisa', 'Content 4']
]

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

private postAndCheck(category, author, content) {
...
QCON 2010 - 131

Topics
• Groovy Intro
• Web Services
• Writing DSLs
© ASERT 2006-2010

• Groovy Testing
• Polyglot Groovy
Enterprise Groovy
• More Info
QCON 2010 - 132

Integration with Spring...

// 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
© ASERT 2006-2010

// 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')

QCON 2010 - 133

...Integration with Spring
// 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
© ASERT 2006-2010

@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')
QCON 2010 - 134

Dependency Injection: Guice
import com.google.inject.*

@ImplementedBy(CalculatorImpl)
interface Calculator {
def add(a, b)
}

@Singleton
class CalculatorImpl implements Calculator {
private total = 0
© ASERT 2006-2010

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

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

def injector = Guice.createInjector()
// ...
QCON 2010 - 135

Topics
• Groovy Intro
• Web Services
• Writing DSLs
© ASERT 2006-2010

• Groovy Testing
• Polyglot Groovy
More Info
QCON 2010 - 136

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
© ASERT 2006-2010

• 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

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