Scala is an alternative JVM language with both object-oriented and functional programming paradigms. Scala development with the Java EE 7 platform is definitely possible and can be a pleasant experience. If you have uncertainty about how Scala can fit around the Java EE 7 platform, then this session aims to illustrate the huge benefit that Scala adoption can bring to the platform. Many other developers are taking advantage and the challenge of the JVM’s capability of being a vessel for multi-language programming. You no longer have to write every single project using Java, even if you like Lambdas experiences. For the developer and engineering terms that feeling a little braver than usual, Scala is attractive as it is strongly typed and lets you set the gauge on how object oriented or how functional you want to be. You will learn how to reuse the annotations and creating Scala plain object safely and concisely. This session will highlight and contrast the experience I had developing Scala solutions with Java EE, and there will be plenty of advice about using the functional programming features against the Java object oriented API. Scala language overview Java EE 7 architecture and design Using Gradle as a build tool How to create beans in Scala with dependency injection JAX-RS endpoints Servlet Endpoints JMS Messaging Scala adoption advice and hints for sustainable team development

1. Scala and Java EE 7 Development
Experiences
Peter A. Pilgrim
Independent Contractor, Java Champion

2. Biography
■ Completed Java Sybase
course in 1998
■ Founded JAVAWUG
2004-2010
■ Independent Contractor
■ Blue-chip business:
Digitas Lbi, Barclays
Retail, Transform

3. September 2013
Java EE 7
Developer
Handbook

4. • Overview of Scala
• Java EE 7 architecture and design
• Using Gradle as a build tool
• How to create beans in Scala with dependency injection
• JAX-RS endpoints
• Servlet Endpoints
• JMS Messaging
• Scala adoption advice and hints for sustainable team
development

5. “The right architecture to the right application. Not all of us work
for Facebook or Twitter. If you look at their "web site" the
navigation is quite simple… For them, statelessness and NoSQL is
mandatory. But when you work on a "web application” then you
deal with complex flow management. Their problem is elsewhere :
fewer users but complex long time running transactional flows.
Stateful architecture are mandatory.
Antonio Gonclaves
Why Java EE Lost and Spring Won
http://java.dzone.com/articles/why-java-ee-lost-and-spring

7. Scalable Language
12/05/2014 XeNoNiQUe.co.uk (c) 2011 7
Still has a very bright future
Purely Object-Oriented
Statically-typed
Functional
JVM Language

8. Typing Derived from “Pascal” Tree of
Computer Language
<variableName> [: [ <Type> ]
personName: String
taxRate: Float
density: Double
found: False
persion: Person
May 12, 2014 Xenonique ©2013 8

9. Variables and Values
Assignment less programming
Prefer val over var
var x = 10.0; x = 10 + x
val y = 10.0
val z: Float = x
var t: Int = 42; t = t * 2
9

10. Scala Class
class Person (
val firstName: String
val lastName: String,
val height: Float,
val age: Int ) {
// Write your definition here
}
May 12, 2014 Xenonique ©2013 10

11. Instances of Scala Classes
val p1 = new Person( "Billy",
"Mitchell", 5.10F, 42 )
val p2 = new Person( "Kat",
"Moon", 5.8F, 39 )
May 12, 2014 Xenonique ©2013 11

12. Companion Objects
object Person {
private records = List[Person]()
def apply(fn: String, ln: String,
h: Float, a: Int): Person = {
val p = new Person(fn, ln, h, a );
records = p :: records.reverse // O(1)
return p
}
def recordCount() = records.size
}
May 12, 2014 Xenonique ©2013 12

13. Case Classes
class Transmission( driveTrain:
String )
May 12, 2014 Xenonique ©2013 13

14. Scala Functions
val isEven: (Int => Boolean) = (k: Int) => k % 2 == 0
• Functions are values, values are object
• Ergo, functions are objects in Scala
May 12, 2014 Xenonique ©2013 14

15. Scala Code
def uniqueSorted[Symbol]( p: List[Symbol] ): List[Symbol] = {
val myOrdering =
Ordering.fromLessThan[Symbol](
_.toString < _.toString )
var acc = SortedSet.empty(myOrdering)
def compress0( q: List[Symbol] ): Unit = {
q match {
case Nil => Nil
case x :: xs => { acc += x ; compress0(xs) }
}
}
May 12, 2014 Xenonique ©2013 15

16. Functions are First Class
• In Scala, functions are first class citizens
• Functions can return functions
May 12, 2014 Xenonique ©2013 16

17. SBT
• SBT is the de-facto build tool
• Works with Maven
• Incremental Compilation +1
• DSL written in Scala +1
• Plugins Available +1
• Complex to Understand -1
May 12, 2014 Xenonique ©2013 17

18. Gradle
• Gradle is written in Groovy
• Gradle is a DSL too +1
• Easier to Grok +1
• Since v1.4 Gradle support incremental
compilation through Zinc
• Not the de-facto standard -1
May 12, 2014 Xenonique ©2013 18

19. ENTERPRISE
DEVELOPMENT
Modern Practice

22. Java EE 7 Framework Updates
Interface Boundary
Endpoints
JAX RS 2.0
JMS 2.0
Bean Validation 1.1
Management and
Storage
EJB 3.2
CDI 1.1
JPA 2.1
Web and HTML
Service Endpoints
Servlet 3.1
WebSocket 1.0
JSF 2.2
JSON 1.0

23. CDI and Scala
trait Processor {
def process( payload: DataValue ) : Unit
/* ... */
}
@ApplicationScoped
class DatastarProcessor extends Processor {
@Inject var dataStore: DataStore = _
override def process( payload: DataValue): Unit = {
// Do something here
}
}

24. What about Java SE 8?
public interface PaymentIssuer {
public void allocate( int id );
}

25. What about Java SE 8?
@ApplicationScoped
public class CreditCardTicketTracker() {
@Inject PaymentIssuer issuer;
public void doWork(
List<Ticket> ticketBatch ) {
}
}

26. What about Java SE 8?
public void doWork( List<Ticket> ticketBatch ) {
DateTime dt = new DateTime().minusDays(2);
ticketBatch.stream()
.filter(
t -> t.isAvailable() &&
t -> t.paymentType == PaymentType.CreditCard &&
t.concertDate.before( dt ) )
.map( t -> p.getAllocationId() )
.forEach( allocationId -> issuer.allocate(allocationId));
}

27. Write Annotations as Java
// In the Java source tree (src/main/java)
import javax.inject.Qualifier;
import javax.interceptor.InterceptorBinding;
import java.lang.annotation.*;
import static java.lang.annotation.ElementType.*;
@Qualifier
@InterceptorBinding
@Target({METHOD, TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface PermanentStorage { }
public @interface CachedStorage { }
public @interface TransientStorage { }

28. Stock CDI Advice
• CDI does works very well with Scala POJOs
• CDI cannot instantiate companion objects!
• CDI beans must have a default constructor
• CDI does not understand case classes (but
see later …)

29. CDI Setter Injection
• Take advantage of Scala’s @BeanProperty
annotation
@BeanProperty
var liveStatus:String = “Default”
@Inject
def setLiveStatus(a:String):Unit=???

30. CDI Scopes
// Prefer CDI scopes if you use JSF in Java EE
import javax.enterprise.context.RequestScoped
import javax.enterprise.context.SessionScoped
import javax.enterprise.context.ApplicationScoped
// Instead of
import javax.faces.bean.RequestScoped
import javax.faces.bean.SessionScoped
import javax.faces.bean.ApplicationScoped

31. Last Advice on CDI Proxies
• Scala POJOs need a lifecycle scope
• Always create default no args constructor
• Cannot be final or have final members
– (Interaction between Java and Scala)

32. JSF Managed Beans
import javax.enterprise.context.RequestScoped
import javax.inject.Named
@Named @RequestScoped
class BasicFlow {
def serveResponse() = "endState.xml"
}

33. JSF XHTML Facelet View
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html ...>
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:ui="http://xmlns.jcp.org/jsf/facelets"
xmlns:f="http://xmlns.jcp.org/jsf/core”>
<h:head> ... </h:head>
<h:body> ... </h:body>
</html>

34. JSF XHTML Facelet View
<h:body> ...
<h:form>
<h:commandButton
action="#{basicFlow.serveResponse}”
value="Invoke Action" />
</h:form>
</h:body>

35. Demo CDI and Scala

36. Produces JMS Connections in Scala
class JMSResourceProducer {
@Resource(name = "jms/OrderConnectionFactory")
private orderConnectionFactory: QueueConnectionFactory = _
@Produces @Order @Resource(name = "jms/OrderQueue")
private orderQueue: Queue = _
@Produces @Order
def createOrderConnection(): QueueConnection =
orderConnectionFactory.createQueueConnection()
@Produces @Order
def createOrderSession(@Order conn:QueueConnection): QueueSession
= conn.createQueueSession(true, Session.AUTO_ACKNOWLEDGE)
}

37. Scala and JAX-RS
• JAX-RS 2 annotations work with Scala
POJOS out of the box
• Annotate on public methods
• @GET, @POST, @PUT, @DELETE
• @Produces, @Consumes

38. Use Qualifiers in Scala
// In the Scala source tree (src/main/scala)
@ApplicationScoped
@PermanentStorage
class DatastarProcessor extends Processor {
@Inject
var dataStore: DataStore = _
override def process( payload: DataValue):
Unit = { /* ... */ }
}

39. JAX-RS
@Path("/alldata")
class AllDataServiceEndpoint {
@Inject var fastService: FastService = _
@Inject var predictorService: PredictorService = _
@Context var request: HttpServletRequest = _
@Path("/item")
@GET @Produces(Array(APPLICATION_JSON))
def listServices = ???
}

40. JAX-RS
def listServices = {
val listServices =
(fastService.configuredAllServices ++
predictorService.configuredAllServices)
map { makeElement( _ ) }
Response.ok(listServices,
MediaType.APPLICATION_JSON).build
}
}

41. Jackson, Scala & JSON Support
• JAX-RS works well with Scala POJOs
• JAX-RS and Java EE 7 provides JSON
providers only for Java POJOs
• Use Jackson JSON Providers for seamless
support of case classes

42. Jackson Scala JAX-RS
@Singleton
@Provider
@Consumes(
Array(MediaType.APPLICATION_JSON,
"application/*+json", "text/json"))
@Produces(
Array(MediaType.APPLICATION_JSON,
"application/*+json", "text/json"))
class JacksonScalaContextResolver extends
JacksonJaxbJsonProvider(
JacksonScalaContextResolver.getObjectMapper,
JacksonJaxbJsonProvider.DEFAULT_ANNOTATIONS)

43. Jackson Scala JAX-RS
object JacksonScalaContextResolver {
def getObjectMapper: ObjectMapper = {
val mapper = new ObjectMapper with ScalaObjectMapper
mapper.registerModule(new DefaultScalaModule)
mapper.configure(
DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES,
false)
mapper.setSerializationInclusion(Include.NON_NULL);
mapper
}
}

44. Open Source Integration Testing
Peter Muir, David Blewin and Aslak Knutsen and from Red Hat JBoss.

45. Demo Alternative

46. Demo Servlets, CDI & EJB

47. Java EE 7 Demo

48. EXECUTIVE SUMMARY
Digital by Default with Java

49. “If you're frustrated that you're not getting picked, one
plan is to up your game, to hustle harder, ... But in the
era of picking yourself, it seems to me that you're
better off finding a path that doesn't require you get
picked in order to succeed.”
Seth Godin,
Getting Picked (‘need to’ versus ‘want to’)

50. Run It Yourself
• https://github.com/peterpilgrim/javacro
• Download the source code, build and run
• Feedback, welcomed!

51. Thank You!
The book:
http://www.packtpub.com/java-ee-7-
developer-handbook/book
Blog:
http://xenonique.co.uk/blog/
Twitter:
@peter_pilgrim

52. Creative Commons Attributions
http://www.flickr.com/photos/holstphoto/3371060720/
Photo of "Chip Pattern" by Ryan Holst, March, 2009
http://www.flickr.com/photos/scarygami/5489773527/lightbox/
Photo of "Pattern" by Scarygami
http://www.flickr.com/photos/christianhaugen/3486381680/sizes/l/in/photostream/
Photo of "Patterns in the Sand" by Christian Haugen
http://www.flickr.com/photos/krunkwerke/3840127296/
Photo of a series of punch cards which are strung together, to
control the pattern woven by the Jacquard loom. John R. Southern

53. Creative Commons Attributions
http://www.flickr.com/photos/josefstuefer/43867840/
Proof of Pattern messh "untitled" in tan by Josef Stuefer
http://www.flickr.com/photos/josefstuefer/43972554/
Proof of Pattern mesh "untitled" in blue by Josef Stuefer
http://www.flickr.com/photos/scott1723/6290151038/
Alter photo of "Tug of War 3" by Scott Anderson