Groovy Update - JavaPolis 2007

Groovy Update Guillaume Laforge G2One Dierk K önig Canoo Engineering AG

Overall Presentation Goal Learn more about the Groovy dynamic language for the JVM, what’s new in the latest version, and how you can use it in your projects!

Guillaume Laforge Groovy Project Manager JSR-241 Spec Lead Initiator of the Grails framework Co-author of Groovy in Action By Dierk König, et al. Vice-President Technology

Dierk König Canoo Engineering AG, Basel Rich Internet Applications Projects, Consulting, Training www.canoo.com Trainer, Coach, Developer, Architect Groovy- and Grails-Committer Lead author: Groovy in Action

Agenda What’s Groovy? Syntax basics Groovy APIs What’s new in Groovy 1.5? Domain-Specific Languages Integrating Groovy in your applications Summary Q&A

What’s Groovy? An award-winning alternative dynamic language for the JVM State of the Groovy Nation

Groovy – feature rich and Java friendly

Being Java friendly Groovy is Java-like Easy to learn for a Java developer  flat learning curve Simpler than Java for beginners and subject matter experts Seamless integration with Java You can mix Groovy and Java objects together Groovy class extending Java class implementing Groovy interface, and vice versa… Same strings, regex, APIs, OO, threads, security Same paradigm and platform! No impedance mismatch!

Being feature rich Fully object-oriented Properties declared easily Closures for versatile code blocks Operator overloading Native syntax for enhanced Strings, regexes, lists, ranges, enums and maps Multimethods: call the right method! GPath: XPath-like navigation in object graphs BigDecimal arithmetic by default Optional semi-colons and parenthesis GDK: a library that builds upon the JDK Perfect for Domain-Specific Languages

Lots of integrations AntHill Grails eXo Platform JBoss Seam NanoContainer Eclipse XWiki ServiceMix Tapestry Wicket TestNG SoapUI Turbine Oracle OC4J Blojsom NetBeans OpenEJB Drools 1060NetKernel RIFE GroovyRules Mule FreeMind LuxorXUL Spring Ant Maven IntelliJ IDEA Simple JSPWiki eXist Canoo WebTest Biscuit ThinG Oracle Data Integrator Struts2 Eclipse JMeter JFreeChart, IBM Project Zero, SAP Composition, …

Used in Mission-Critical applications Mutual of Omaha – Fortune 500 US Comp. 45,000 lines of Groovy (half business code / half test code) Integrated in an EJB as a risk calculation engine for insurance policies Involved Java beginners, developers, and subject matter experts Exact arithmetic support, perfect Java integration, closures  ideal for business rules expression

Books already out… more coming…

JAX 2007 Innovation Award 40 proposals / 10 nominees Groovy won the first prize Most innovative and creative project 10,000 euros donation Past winner was Spring

Syntax Basics Groovy as a Java-superset Properties, lists, maps, ranges, regex, strings, closures

Properties Support Don’t wait for Java 7/8/9  Getters / setters are boring boiler-plate code Groovy adds support for properties Declared fields get automagic accessors Example class Person { String name String firstName }

Literals for lists, maps, ranges, regex, strings List: def list = ["Groovy", "Grails"] Map: def map = [CA: "Calif.", TX: "Texas"] Ranges: def oneToTen = 1..10 Regex: assert fooooo ==~ /fo*/ Multiline strings: def s = """ multi line string""" Gstring println "My name is ${name}"

Closures Don’t wait for Java 7/8/9, get closures now! Reusable / assignable code blocks Combine, store, share data and logic Examples new File('x.txt').eachLine{ println it } [0, 1, 2].each { println it } def numbers = 1..100 def odd = { it % 2 == 1 } numbers.findAll { it > 90 } numbers.findAll( odd )

Groovy APIs Groovy Development Kit Examples: XML, SQL, Swing and Office automation

Groovy Development Kit Simplified APIs for common tasks Mocking / stubbing support XML parsing and GPath navigation SQL support with exception & resource handling Scripting Ant with the AntBuilder Create Swing UIs easily with SwingBuilder Templating support à la Velocity Script COM / ActiveX components on Windows Consume / expose XML-RPC / SOAP services Handle JXM beans as local objects

XML Parsing and GPath Navigation Given this XML snippet def xml = """ <languages> <language name="Groovy"> <feature coolness="low">SQL</feature> <feature coolness="high">Template</feature> </language> <language name="Perl"/> </languages>""“ Navigate the object graph def root = new XmlParser().parseText(xml) println root.language.feature[1].text() root.language.feature .findAll{ it['@coolness'] == "low" } .each{ println it.text() }

SQL support Easy to use JDBC thanks to closures def sql = Sql.newInstance(url, usr, pwd, driver) sql.execute("insert into table values ($foo, $bar)") sql.execute("insert into table values(?,?)", [a, b]) sql.eachRow("select * from USER") { print it.name } def list = sql.rows("select * from USER") DataSet notion: « poor-man » ORM def set = sql.dataSet("USER") set.add(name: "Johnny", age: 33) set.each { user -> println user.name } set.findAll { it.age > 22 && it.age < 42 }

SwingBuilder def theMap = [color: "green", object: "pencil"] def swing = new SwingBuilder() def frame = swing. frame ( title: 'A Groovy Swing', location: [240,240], defaultCloseOperation:WC.EXIT_ON_CLOSE) { panel { for (entry in theMap) { label (text: entry.key) textField (text: entry.value) } button (text: 'About', actionPerformed: { def pane = swing.optionPane(message: 'SwingBuilder') def dialog = pane.createDialog(null, 'About') dialog.show() }) button (text:'Quit', actionPerformed:{ System.exit(0) }) } } frame.pack() frame.show()

Automating Office Applications An additional module provide VB-like scripting capabilities with a VB-like syntax Example def outlook = new ActiveXProxy("Outlook.Application") def message = outlook.CreateItem(0) def emails = glaforge @ gmail.com def rec= message.Recipients.add(emails) rec.Type = 1 message.Display(true)

Domain-Specific Languages Why create DSLs? How to create such DSLs?

Why Create a Domain-Specific Language? Use a more expressive language than a general programming language Share a common metaphore between developers and subject matter experts Have domain experts help design the business logic of an application Avoid cluttering business code with too much boilerplate technical code Cleanly seperate business logic from application code

Putting it all together Optional parens, map syntax, props on ints move left compare indicator: ‘NIKEI’, withFund: ‘XYZ’ account.debit amount: 30.euros, in: 3.days Custom control structures with closures unless ( account.balance < 0 ) { account.debit 10.dollars } execute( withTimeoutOf: 50.seconds ) { … } Operator overloading a + b  a.plus(b) taskA | taskB  taskA.or(taskB)

Builder pattern at the syntax level Tree structures are everywhere XML, GUI components, Ant tasks, conf files… Through closure & chained method calls new MarkupBuider().invoices { invoice(id: "4") { line "product 1" line "product 2" } } Create your own « builder » Extend BuilderSupport, or FactoryBuilderSupport

What’s new in 1.5? Java 5 features New dynamic capabilities Performance improvements IDE support

What’s New? Java 5 features Annotations, generics, enums, static imports New powerful dynamic capabilities ExpandoMetaClass contributed by Grails Performance improvements Regular gains of perf. between the last releases IDE support IntelliJ IDEA, NetBeans & Eclipse

Java 5 Features Why adding Java 5 features to Groovy? To leverage Enterprise frameworks making use of annotations and generics Spring, JPA, Hibernate , Guice, TestNG, JUnit 4 Groovy is the sole alternative dynamic language for the JVM supporting annotations Groovy is Java-like, but is closer to being a Java-superset If you need annotations / generics and want to benefit from a dynamic language Look no further, Groovy is the sole option

Annotations Example Taken from JBoss Seam ’s documentation @Entity @Name("hotel") class Hotel implements Serializable { @Id @GeneratedValue Long id @Length(max=50) @NotNull String name @Override String toString() { "Hotel ${name}" } }

Enums example with a Groovy switch enum Day { SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY } def today = Day.SATURDAY switch (today) { case [Day.SATURDAY, Day.SUNDAY] : println "Weekends are cool" break case Day.MONDAY..Day.FRIDAY : println "Boring work day" break default: println "Is this a valid day?" }

New dynamic features Grails contributed the ExpandoMetaClass Easily add new behavior to existing classes Symbiotic relationship between both projects Ex: Adding a meters property to numbers Integer.metaClass.getMeters = { -> new Distance(delegate, Distance.METER) } println 3.meters

Have a look at the IntelliJ IDEA plugin!

Integrating Groovy in your Applications Why integrating Groovy in your applications? The different integration mechanisms

Why Integrating Groovy in your Apps? Groovy’s great support for testing Mocks & stubs, GroovyTestCase More concise & readable tests Handy tool in the developer toolbox Externalize business rules Business rules be written by domain experts Rules follow their own lifecycle Providing extension points in your apps For third-party plugins Customizing the app to clients’ needs

Several Integration Mechanisms The « old » Bean Scripting Framework Java 6’s scripting APIs (JSR-223) Spring dynamic language support Groovy’s own mechanisms Let’s see some of them

JSR-223 – javax.script.* from JDK 6 One API to rule them all! Dedicated Groovy engine on scripting.dev.java.net Drop it in your classpath! Example ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine gEngine = manager.getEngineByName("groovy"); String result = (String)gEngine.eval("’Foo’ * 2");

GroovyShell Easily evaluate expressions in your Java app Pass variables in and out Can provide global reusable functions Example def binding = new Binding() binding.mass = 22.3 binding.velocity = 10.6 def shell = new GroovyShell( binding ) def expression = "mass * velocity ** 2 / 2" assert shell.evaluate(expression) == 1252.814

GroovyClassLoader Most powerful integration mechanism With GCL, you can Parse and compile classes Provide a resource loader defining the location of sources Database, flat files, XML files, distant URLs… Define Java security rules To avoid System.exit(0) in an Embedded DSL! Even transform the Abstract Syntax Tree !

Spring 2.x Groovy integration Spring 2.0 provides support for alternative language bean definitions and configuration A POGO can be wired the like a POJO and be proxied You can mix languages in your Spring application POGO and POJO can be injected within each other Configuration of a POGO bean with the specific lang namespace , and a custom MetaClass <lang:groovy id="events" script-source="classpath:dsl/eventsChart.groovy" customizer-ref="eventsMetaClass" />

Let’s Wrap Up Summary Resources Q&A

Summary The Groovy dynamic language for the JVM simplifies the life of developers through powerful APIs Groovy opens some interesting perspectives towards extending your application Groovy provides seamless Java integration Groovy lets you create DSL s Groovy protects your investment in Java skills, tools, libraries, frameworks, and application platforms

Resources Groovy: http: //groovy . codehaus . org Grails: http: //grails . org Groovy blogs: http: //groovyblogs . org AboutGroovy: http: //aboutgroovy . com G2One: http://www.g2one.com Canoo: http://www.canoo.com

Q&A View JavaPolis talks @ www.parleys.com

Groovy Update - JavaPolis 2007

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