A few case studies of companies using Groovy.

1. Groovy in the Enterprise:
Case Studies
Guillaume Laforge
VP Technology
G2One, Inc.
glaforge@g2one.com

2. Guillaume Laforge
Groovy Project Manager
• Spec Lead of JSR-241
Initiator of the Grails framework
Co-author of Groovy in Action
VP Technology at G2One
• The Groovy / Grails company
• Training, support, consulting
Evangelizing Groovy, Grails and DSLs
• JavaOne, JavaPolis, QCon, JAX, Sun TechDays...

3. Goal of this talk
Discover real-world Groovy
usage in the Enterprise
to better understand:
•How you can leverage Groovy
in your own environment
•How to integrate Groovy
in your applications

4. Agenda
About Groovy and Grails
Groovy usage patterns
Integrating Groovy in your applications
Case studies

5. About Groovy and Grails
Groovy, a dynamic language for the JVM
Grails, an agile web application framework

6. Groovy is...
The fastest dynamic language for the JVM
• that integrates seamlessly with Java
without any impedance mismatch
An Apache-licensed Open Source project
• successful project hosted at Codehaus
Aiming at simplifying the life of developers
• by bringing expressiveness and productivity boosts
• by borrowing good ideas from other languages
An innovative and creative project

7. Java-like on steroids
Syntax derived from the Java 5 grammar
• Flat learning curve for Java developers
• Supports both static and dynamic typing
Support Java 5 features
• Annotations, generics, static imports, enums...
• Sole dynamic language to support this!
GInterface
JInterface
Real full Java / Groovy interop <<implements>>
<<implements>>
JClass
GClass
• Joint compiler
• or can be evaluated on the fly JClass GClass

8. A Java program
import java.util.List;
import java.util.ArrayList;
class Erase {
private List filterLongerThan(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(quot;Tedquot;);
names.add(quot;Fredquot;);
names.add(quot;Jedquot;);
names.add(quot;Nedquot;);
System.out.println(names);
Erase e = new Erase();
List shortNames= e.filterLongerThan(names, 3);
System.out.println(shortNames.size());
for (inti= 0; i< shortNames.size(); i++) {
String s = (String) shortNames.get(i);
System.out.println(s);
}
}
}

9. A Groovy program
import java.util.List;
import java.util.ArrayList;
class Erase {
private List filterLongerThan(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(quot;Tedquot;);
names.add(quot;Fredquot;);
names.add(quot;Jedquot;);
names.add(quot;Nedquot;);
System.out.println(names);
Erase e = new Erase();
List shortNames= e.filterLongerThan(names, 3);
System.out.println(shortNames.size());
for (inti= 0; i< shortNames.size(); i++) {
String s = (String) shortNames.get(i);
System.out.println(s);
}
}
}

10. A more idiomatic Groovy solution
def names = [“Ted”, “Frend”, “Jed”, “Ned”]
println names
def shortNames = names.findAll {
it.size() <= 3
}
println shortNames.size()
shortNames.each { println it }

11. Features at a glance...
Don’t wait for Java 7, 8, 9
• closures, properties, collection & regex literals
Operator overloading
• Just method calls: plus(), multiply(), etc.
• BigDecimal arithmetics by default
Metaprogramming — useful for DSLs
• Property / method calls interception
Optional semicolons and parentheses
SQL, Ant, XML, templates, Swing, JMX...

12. Lots to read to learn more!

13. Grails

14. Groovy usage patterns
A tool in the developer toolbox
A full stack web application framework
An extension point in your application
Domain-Specific Languages

15. Pattern: Developer tool
Great support for unit
testing and mock objects
• Nice way to introduce Groovy in a project
Shell scripting reusing all your JARs
• Easy to control Ant task for custom builds
Template engine for code generation needs
Excellent XML parsing and creation support
Easy JDBC for import/export database scripts

16. Pattern: CoC web app development
Convention over Configuration
• Productive in minutes with scaffolding
• No useless configuration, focus on what matters
• Dir. layout, naming conventions, transparent wiring...
Grails = Groovy + Spring + Hibernate + ...
• Groovy is the glue to write
 your views (Groovy Server Pages)
 your controllers
 your services
 your domain classes

17. Pattern: Application extension point
Customize or extend your application at
extension points through Groovy scripting
Create plugins adding new functionality
Add / Update business rules at runtime
• See also Domain-Specific Languages
Personalize your reporting screens
• With Groovy templates
Remote introspection of your app
• Embed a remote Groovy shell

18. Pattern: Domain-Specific Language
Use a more expressive language
• than a general purpose language
Share a common metaphore between
developers and subject matter experts
Domain experts can help write the rules!
Avoid boilerplate technical code
Cleanly seperate business logic
from application plumbing code

19. Integrating Groovy
in your applications
JSR-223, one API to rule them all
Spring dynamic beans
Groovy’s own mechanisms

20. JSR-223: javax.script.*
One API to rule them all
Groovy engine JAR at scripting.dev.java.net
• drop it in your classpath
ScriptEngineManager mgr =
new ScriptEngineManager();
ScriptEngine eng =
mgr.getEngineByName(“Groovy”);
String result =
(String)eng.eval(“‘foo’*2”);

21. Spring 2 dynamic language beans
Spring 2 provides support for alternative
language bean definitions & implementations
• POGOs can be wired, proxied, injected in POJOs
Configuration with the <lang:*> namespace
• <lang:groovyid=’bean’
script-source=’classpath:com.foo.GBean’
customizer-ref=’specialMetaClass’/>
Groovy beans can be “refreshed”

22. Groovy’s own mechanisms
Several integration mechanisms
• Eval, GroovyShell, GroovyScriptEngine
• def binding = new Binding()
binding.mass = 22.3
binding.velocity = 10.6
def shell = new GroovyShell()
def expr = “mass * velocity ** 2 / 2”
assert shell.evalute(expr) == 1252.814
GroovyClassLoader for more advanced
integration scenario

23. Case studies
Groovy and Grails Success Stories

24. Grails Examples
LinkedIn
BSkyB showbiz portal

25. LinkedIn
Main site
• Java / Tomcat / Spring / Hibernate / custom MVC
But their corporate solutions are in Grails
• Private portals for recruiters, for premium customers
with focused needs
Why Grails?
• Needed a more productive webapp framework with
rapid prototyping capabilities
• Needed deep integration with their Java backend
 custom session, reuse business services, SSO

26. showbiz
Biggest UK satellite
broadcaster
• also known as BSkyB
• owned by News Corp.
Developed their showbiz website on Grails
• 186+ million page views per month
• “Grails just scales” ™
Currently rewriting their main portal in Grails

27. Groovy as a Developer Tool
Patterson Institute for Cancer Research
French Ministry of Justice
Canoo WebTest

28. Patterson Institute for Cancer Research
Manchester University / Cancer Research UK
Groovy in two projects
• X:Map: a Genome browser
 using a 54GB tileset for Google Maps
• exonmap: microarrays analysis program
Groovy used to
• Fetch latest genome sequencing information (FTP)
• Homogenize data sources
• Scan databases, extrapolate and filter data

29. Code generation
Groovy was used as a developer tool
• but no line of Groovy in production code
Groovy XML
Parsers
XMI
UML
Groovy
Template
Engine

30. Canoo WebTest
Open Source tool for automating testing
of web applications
 invoke “http://google.com”
verifyTitle “Google”
setInputField name: ‘q’,
value: ‘WebTest’
clickButton “I’m feeling lucky”
verifyTitle “Canoo WebTest”

31. Groovy as a Language for
Application Extension Points
CodeStreet Market Data Studio
Hyperic HQ

32. codestreet
Market Data Works simplifies
• capturing, auditing
• editing Reuters market data
Traders can use Groovy
• modify market data feeds
• record and replay feeds
• test evolutionary scenario

33. Groovy

34. Hyperic HQ: open source web infrastructure
monitoring and management suite
• used in Spring Application Management Suite
Big Groovy-based plugin infrastructure
• script deployments, server reboots, threshold alerts,
resources monitoring, etc...
• agent side: custom handling of monitored resources
• also embeds a Groovy console for interactive work
• plugins updatable / reloadable at runtime

35. Groovy for
Business Rules and DSLs
Mutual of Omaha
National Cancer Institute
IRSN
OCTO Technology

36. Mutual of Omaha
US Fortune 500 insurance company
Risk calculation engine in Groovy
part of a mission-critical application
50,000 lines of Groovy code
• half business rules, half test code
Module part of a large EJB-based application
Choice of Groovy
• Business rules readability, maintenance by IT and
Subject Matter experts, seamless Java integration

37. Mutual of Omaha
On business rules readability...
• Groovy’s BigDecimal support
• Simple interpolation formula
 (d*(b-c)+e*(c-a))/(a-b)
BigDecimal uMinusv = upperBound.subtract(value);
BigDecimal vMinusl = value.subtract(lowerBound);
BigDecimal uMinusl = upperBound.subtract(lowerBound);
return lowerValue.multiply(uMinusv).
add(upperValue.multiply(vMinusl)).
divide(uMinusl, 10, BigDecimal.ROUND_HALF_UP);
(lowerValue * (upperBound-value) + upperValue * (value-lowerBound) ) / (upperBound-lowerBound)

38. National Cancer Institute
Cancer registry management
• Organizes large amounts of medical records
• JBoss / Oracle / Hibernate / Struts application
Groovy used in several places
• As an architecture validation system — dev. tool
 ensure proper layer seperation, if not, fail the build
• Param validation for customizing reporting screens
• Business rules to edit and validation medical records
 validity of fields, of set of fields, of records
 check / fix / improve the patient files
 700k patient files * 1,300 edits

39. Nuclear safety organization
Scientific context, with intensive
and complex computation needs
Matlab/Mathematica-like DSL on top of super
efficient Java custom math library
• Thin Groovy DSL layer
• Enjoyed a math-like syntax for matrices, seamless
integration with Java
• Groovy’s operator overloading mechanism
• Friendlier to scientists and mathematicians
• Application targets 200-300 engineers & researchers

40. Human Resources DSL
Architecture / Agile consultancy
• Needed a way to track consultant skills & knowledge
 pay raises, finding the right person for the gig, etc...
Developed a DSL to represent skills
• Textual DSL transformed into a treemap-like graphics
• Integrated in Confluence as a plugin
 the plugin parses and generates an in-memory model
 a servlet renders graphics to embed in the wiki pages
 a Confluence macro renders everything on the wiki page
• Leverages Confluence’s search capabilities

41. Human Resources DSL
etre {
idees {
capture 1
formule 1
produit 1
}
organisation {
controle 1
abandonne 1
aligne 1
}
engagement {
euros 1
gens 1
idees 1
enseigner 1
}
}
faire {
...
}

42. Summary

43. Summary
Groovy is a successful, mature and
performant dynamic language for the JVM
Provides several interesting usage patterns
• Developer tool, CoC webapp development,
application extension mechanism,
DSLs & business rules externalization
Used in production for mission-critical
applications, and integrated in many
frameworks

44. Questions & Answers
glaforge @ .com