This document introduces ScalaModules, a Scala DSL for simplifying OSGi development. It discusses how the low-level OSGi API can be hidden through implicit conversions, higher-order functions, and a fluent interface. Examples are provided for how to register, consume, track, and define dependencies between OSGi services in a more functional and type-safe way using the ScalaModules DSL. A live demo is included to demonstrate these capabilities.

1. SCALAMODULES
OSGi ganz einfach mit einer Scala DSL
Heiko Seeberger
Copyright WeigleWilczek 2009

2. HOUSTON, WIR HABEN EIN PROBLEM!
ServiceReference ref =
ctx.getServiceReference(Greeting.class.getName());
if (ref != null) {
try {
Object service = ctx.getService(ref);
Greeting greeting = (Greeting) service; Low-level API
if (greeting != null) {
Häßliche System.out.println(greeting.welcome());
} else {
Details }
System.out.println("No Greeting service available!");
} finally {
ctx.ungetService(ref);
}
} else {
System.out.println("No Greeting service available!");
}
2

3. WIE KÖNNTE SCALA HELFEN?
Ausdrucksstarke high-level DSL
3

4. SO ETWAS IN DER ART ...
OSGi giveMe Greeting and call welcome
4

5. WIE BAUE ICH EINE DSL?
Implicit Higher-order
Conversions Functions
Fluent API
5

6. SCALAMODULES
Scala DSL to ease OSGi development
6

7. SERVICES REGISTRIEREN
val hello = new Greeting { ... }
automatisch ctx register hello
... unter allen Interfaces
7

8. SERVICES REGISTRIEREN II
val hello = new Greeting { ... }
ctx register (hello as classOf[Greeting]) typsicher
... unter einem bestimmten Interface
8

9. SERVICES REGISTRIEREN III
val hello = new Greeting { ... }
ctx register (hello withProps ("Scala" -> "Modules"))
... mit Properties
9

10. LIVE DEMO
10

11. SERVICES KONSUMIEREN I
Funktional
ctx getOne classOf[Greeting] andApply { _.welcome } match {
case None => // Handle service not available ...
case Some(welcome) => println(welcome)
}
... nur einen einzelnen
11

12. SERVICES KONSUMIEREN II
ctx getOne classOf[Greeting] andApply {
(greeting, properties) => ...
}
... nur einen einzelnen mit Properties
12

13. SERVICES KONSUMIEREN III
ctx getMany classOf[Greeting] andApply { _.welcome } match {
case Nil => // Handle service not available ...
case welcomes => welcomes foreach { println }
}
... alle
13

14. SERVICES KONSUMIEREN IV
ctx getMany classOf[Greeting] withFilter isTrue("polite") andApply {
_.welcome
}
match {
case Nil => // Handle service not available ...
case welcomes => welcomes foreach { println }
}
... alle mit Filter
14

15. LIVE DEMO
15

16. SERVICES TRACKEN
ctx track classOf[Greeting] on {
case Adding(grt, _) => println("Adding polite Greeting: " + grt.welcome)
case Removed(grt, _) => println("Removed polite Greeting: " + grt.goodbye)
}
... mit oder ohne Properties
16

17. SERVICE-ABHÄNGIGKEITEN
ctx register { (grt: Greeting) => new GreetingReverser(grt) }
... wie DS Mandatory Dependencies
17

18. FRAGEN / DISKUSSION
18

19. DANKE
Kontakt: seeberger@weiglewilczek.com
19