The document discusses BindForge and ScalaModules, which are Scala DSLs that can be used to ease OSGi development. BindForge is an OSGi module framework that allows configuration to be written in Scala. ScalaModules provides concepts and abstractions for common OSGi tasks like service registration, consumption, and tracking using a Scala API. Examples are given of how to perform common OSGi development tasks like binding implementations to interfaces, exporting/importing services, consuming services, and tracking service changes using the Scala DSLs.

1. OSGi on Scala
BindForge & ScalaModules: Scala DSLs to ease OSGi development
Roman Roelofsen (ProSyst), Heiko Seeberger (WeigleWilczek)

2. Why?
• OSGi is a great module system
• Scala is a great language
• Compiles to Java bytecode
• Object-functional programming style
• Why wait for Java 7 (or 8)? Use Scala now!
• Let’s combine them to ease OSGi development

3. What?
• BindForge - Module Framework
• ScalaModules - DSL for OSGi development in Scala

4. BindForge
• Module Framework
• Dependency Injection, OSGi service abstraction, etc.
• Useful for Java and Scala development
• Configuration is written in Scala
• Based on
• Scala
• Guice
• Peaberry

5. Example Scenario
CustomerRepository CustomerService
CustomerRep.Impl CustomerServiceImpl
Customer Bundle
LogService
OSGi Log Service Bundle

6. Example Scenario
// repository
interface CustomerRepository
class CustomerRepositoryImpl implements CustomerRepository
// service
interface CustomerService
class CustomerServiceImpl implements CustomerService {
public void setCustomerRepository(CustomerRepository cr) {
...
}
public void setLogService(LogService ls) {
...
}
}

7. Bundle Configuration
• MANIFEST.MF
BindForge-Config: com.acme.app.MyConfig
• /OSGI-INF/bindforge/config.scala
package com.acme.app
class MyConfig extends org.bindforge.Config {
...
}

8. Binding Interfaces to
Implementations
CustomerRepository CustomerService
CustomerRep.Impl CustomerServiceImpl
Customer Bundle

9. Binding Interfaces to
Implementations
package com.acme.app
class MyConfig extends org.bindforge.Config {
bind [CustomerRepository, impl.CustomerRepositoryImpl]
bind [CustomerService, impl.CustomerServiceImpl]
}

10. Inject Bindings
CustomerRepository CustomerService
CustomerRep.Impl CustomerServiceImpl
Customer Bundle

11. Inject Bindings
(by type)
bind [CustomerRepository, impl.CustomerRepositoryImpl]
bind [CustomerService, impl.CustomerServiceImpl] spec {
property(“customerRepository”)
}

12. Inject Bindings
(by name)
val customerRepo = bind [impl.CustomerRepositoryImpl]
bind [CustomerService, impl.CustomerServiceImpl] spec {
property(“customerRepository”) = customerRepo
}

13. Export Customer Service
CustomerRepository CustomerService
CustomerRep.Impl CustomerServiceImpl
Customer Bundle

14. Export Customer Service
bind [CustomerRepository, impl.CustomerRepositoryImpl]
bind [CustomerService, impl.CustomerServiceImpl] spec {
exportService
property(“customerRepository”)
}

15. Export Customer Service
(with Properties)
bind [CustomerRepository, impl.CustomerRepositoryImpl]
bind [CustomerService, impl.CustomerServiceImpl] spec {
exportService(“vendor” -> “acme”, “security” -> “none”)
property(“customerRepository”)
}

16. Import LogService
CustomerRepository CustomerService
CustomerRep.Impl CustomerServiceImpl
Customer Bundle
LogService
OSGi Log Service Bundle

17. Import LogService
bind [LogService] importService
bind [CustomerRepository, impl.CustomerRepositoryImpl]
bind [CustomerService, impl.CustomerServiceImpl] spec {
exportService
property(“customerRepository”)
property(“logService”)
}

18. Full Configuration
package com.acme.app
class MyConfig extends org.bindforge.Config {
bind [LogService] importService
bind [CustomerRepository, impl.CustomerRepositoryImpl]
bind [CustomerService, impl.CustomerServiceImpl] spec {
exportService
property(“customerRepository”)
property(“logService”)
}
}

19. What?
• BindForge - Module Framework
• ScalaModules - DSL for OSGi development in Scala

20. ScalaModules
• For Scala developers (and Java geeks)
• General OSGi concepts, e.g. service handling
• Compendium services, e.g. Configuration Admin

21. Register a Service
Greeting hello = new Greeting() {
afe
es
public String welcome() {
yp
return quot;Hello!quot;;
tt
}
no
public String goodbye() {
return quot;See you!quot;;
}
};
context.registerService(Greeting.class.getName(), hello, null);

22. Register a Service
context registerAs classOf[Greeting] theService new Greeting {
override def welcome = quot;Hello!quot;
override def goodbye = quot;See you!quot;
}

23. Register a Service
with Properties
Greeting welcome = new Greeting() {
se
o
public String welcome() {
rb
ve
return quot;Welcome!quot;;
}
public String goodbye() {
return quot;Good bye!quot;;
}
};
Dictionary<String, Object> properties = new Hashtable<String, Object>();
properties.put(quot;namequot;, quot;welcomequot;);
context.registerService(Greeting.class.getName(), welcome, properties);

24. Register a Service
with Properties
context registerAs classOf[Greeting] withProperties
Map(quot;namequot; -> quot;welcomequot;) theService new Greeting {
override def welcome = quot;Welcome!quot;
override def goodbye = quot;Goodbye!quot;
}

25. Consume a single Service
ServiceReference reference =
context.getServiceReference(Greeting.class.getName());
if (reference != null) {
try {
Object service = context.getService(reference);
Greeting greeting = (Greeting) service;
if (greeting != null) {
System.out.println(greeting.welcome());
} else {
noGreetingService();
}
} finally {
context.ungetService(reference);
inv
}
olv
} else {
ed
noGreetingService();
}

26. Consume a single Service
context getOne classOf[Greeting] andApply {
_.welcome
} match {
case None => noGreetingService()
case Some(welcome) => println(welcome)
}

27. Consume many Services
with their Properties
try {
ServiceReference[] refs = context.getServiceReferences(
Greeting.class.getName(), null);
if (refs != null) {
for (ServiceReference ref : refs) {
Object service = context.getService(ref);
Greeting greeting = (Greeting) service;
if (greeting != null) {
Object name = (ref.getProperty(quot;namequot;) != null)
? ref.getProperty(quot;namequot;)
: quot;UNKNOWNquot;;
String message = name + quot; says: quot; + greeting.welcome();
System.out.println(message);
}
}
ver
} else {
y inv
noGreetingService();
olv
}
ed
} catch (InvalidSyntaxException e) { // Do something meaningful ...
}

28. Consume many Services
with their Properties
context getMany classOf[Greeting] andApply {
(greeting, properties) => {
val name = properties.get(quot;namequot;) match {
case None => quot;UNKNOWNquot;
case Some(s) => s
}
name + quot; sais: quot; + greeting.welcome
}
} match {
case None => noGreetingService()
case Some(welcomes) => welcomes.foreach { println }
}

29. Consume Services
using a Filter
try {
ServiceReference[] refs = context.getServiceReferences(
Greeting.class.getName(), quot;(name=*)quot;);
if (refs != null) {
for (ServiceReference ref : refs) {
Object service = context.getService(ref);
Greeting greeting = (Greeting) service;
if (greeting != null) {
System.out.println(greeting.welcome());
ver
}
y
}
inv
} else {
olv
ed
noGreetingService();
aga
}
in
} catch (InvalidSyntaxException e) { // Do something meaningful ...
}

30. Consume Services
using a Filter
context getMany classOf[Greeting] withFilter quot;(name=*)quot; andApply {
_.welcome
} match {
case None => noGreetingService()
case Some(welcomes) => welcomes.foreach { println }
}

31. Track Services
ServiceTracker tracker = new ServiceTracker(context, Greeting.class.getName(), null) {
@Override
public Object addingService(ServiceReference reference) {
Object service = super.addingService(reference);
Greeting greeting = (Greeting)service;
System.out.println(quot;Adding Greeting: quot; + greeting.welcome());
return service;
}
@Override
public void removedService(ServiceReference reference, Object service) {
Greeting greeting = (Greeting)service;
System.out.println(quot;Removed Greeting: quot; + greeting.welcome());
and
super.removedService(reference, service);
aga
}
in
};
tracker.open();

32. Track Services
greetingTrack = context track classOf[Greeting] on {
case Adding(greeting, _) => println(quot;Adding Greeting: quot; + greeting.welcome)
case Modified(greeting, _) =>
case Removed(greeting, _) => println(quot;Removed Greeting: quot; + greeting.goodbye)
}

33. Service Dependencies
context registerAs classOf[Command] dependOn classOf[Greeting] theService {
greeting => new Command {
...
}
}

34. And now?
• Forge ahead at www.bindforge.org
• And get fluent at www.scalamodules.org
• Please give feedback:
• What do you like?
• What do you not like?
• What feature would you like to see implemented?