BindForge & ScalaModules: Scala DSLs to ease OSGi development.

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)
“customerRepository” :: bind [impl.CustomerRepositoryImpl]
bind [CustomerService, impl.CustomerServiceImpl] spec {
property(“customerRepository”) = ref(“customerRepository”)
}

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?