This document summarizes a presentation about maximizing the power of OSGi. It introduces Declarative Services, which allows defining components and services in a simple way using annotations. Configuration Admin allows configuring components through OSGi configurations. The HTTP Whiteboard allows exposing components as web services. The Coordinator Service allows grouping related operations together. Finally, OSGi Subsystems allow packaging multiple OSGi bundles together for deployment.

1. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.© 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Maximize the power of OSGi
Carsten Ziegeler | David Bosschaert | Adobe R&D

2. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
About
David Bosschaert davidb@apache.org @davidbosschaert
• R&D Adobe Ireland
• Co-chair OSGi Enterprise Expert Group
• ISO/IEC JTC1 SC38 Cloud Computing committee member for Ireland
• Apache Felix, Aries PMC member and committer
• … other opensource projects
• Cloud and embedded computing enthusiast
2

3. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
About
Carsten Ziegeler cziegeler@apache.org @cziegeler
• RnD Adobe Research Switzerland
• Member of the Apache Software Foundation
• VP of Apache Felix and Apache Sling
• OSGi Core Platform, OSGi Enterprise, OSGi IoT Expert Groups
• Member on the board of the OSGi Alliance
• Book / article author, technical reviewer, conference speaker
3

4. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Today’s contents
§ Declarative Services
§ with Configuration Admin
§ HTTP Whiteboard
§ Coordinator
§ Subsystems
4
Image by Joadl: Lyme_Regis_harbour_02b on wikipedia

5. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.© 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Declarative Services

6. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Component Container Interaction
6
OSGi Service Registry
Declarative Services Blueprint
iPojo,
Dependency
Manager,
….
Framework API

7. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential. 7
No POJOs
Too slow
Dynamics not manageable
No dependency injection
Not suitable forthe enterprise
Notooling
OSGi Preconceptions
✔?!

8. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
The Next Big Thing
8

9. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Building Blocks
§ Components
§ Services
§ Module aka Bundle
9

10. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Game Design
10
Game Servlet
GET
POST
HTML
Game Controller
Game Bundle

11. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Game Design - API
11
public enum Level {
EASY,
MEDIUM,
HARD
}
public interface GameController {
Game startGame(final String name,
final Level level);
int nextGuess(final Game status,
final int guess);
int getMax(final Level level);
}
public class Game {
// game status
}

12. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Implementation
12
@Component
public class GameControllerImpl implements GameController {
...
import org.osgi.service.component.annotations.Component;

13. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Configuration
13
public @interface Config {
int easy_max() default 10;
int medium_max() default 50;
int hard_max() default 100;
}
Range from 1 to a configurable max value per level
Configuration (Dictionary)
easy.max = "8"
medium.max = 40L

14. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential. 14
private Config configuration;
@Activate
protected void activate(final Config config) {
this.configuration = config;
}
public @interface Config {
int easy_max() default 10;
int medium_max() default 50;
int hard_max() default 100;
}

15. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential. 15
public int getMax(final Level level) {
int max = 0;
switch (level) {
case EASY : max = configuration.easy_max(); break;
case MEDIUM : max = configuration.medium_max(); break;
case HARD : max = configuration.hard_max(); break;
}
return max;
}

16. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Game Design
16
Game Servlet
GET
POST
HTML
Game Controller
Game Bundle

17. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Web?
17
@Component( service = Servlet.class ,
property="osgi.http.whiteboard.servlet.pattern=/game")
public class GameServlet extends HttpServlet {
@Reference
private GameController controller;

18. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Unary References
18
@Reference
private GameController controller;
@Reference(cardinality=ReferenceCardinality.OPTIONAL
policy=ReferencePolicy.DYNAMIC)
private volatile GameStatistics stats;

19. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Multiple References
19
@Reference(cardinality=ReferenceCardinality.MULTIPLE)
private volatile List<Highscore> highscores;
@Reference
private final Set<Highscore> highscores =
new ConcurrentSkipListSet<Highscore>();

20. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Game Design
20
Game Servlet
GET
POST
HTML
Game Controller
Game Bundle

21. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Management
21

22. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Component Management
22

23. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Metatype I
23
@ObjectClassDefinition(
name = "Game Configuration",
description = "The configuration for the guessing game.")
public @interface Config {
@AttributeDefinition(name="Easy",
description="Maximum value for easy")
int easy_max() default 10;

24. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Metatype II
24
@Component
@Designate( ocd = Config.class )
public class GameControllerImpl
implements GameController {

25. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Declarative Services
§ Easy too use
§ Pojos
§ DI with handling dynamics
§ Integrates with Configuration Admin and Metatype
25

26. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Try it out TODAY
§ Tooling *is* available
§ Official open source implementations available
26

27. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
OSGi Coordinator

28. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
OSGi Coordinator
§ Sometimes you want to group things together
§ set multiple configuration values
-> afterwards apply
§ multiple database access calls
-> then close the connection
§ perform related operations
-> then flush the cache
§ Combining these is better
§ Use the OSGi Coordinator Service
(Chapter 130 of OSGi Enterprise specs)
28
“Red arrows in apollo formation cotswoldairshow 2010 arp” by Arpingstone
from wikipedia.org

29. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Coordinator Service
§ Coordination Initiator
§ Start a coordination implicit/explicit
§ Knows the ‘higher level’ task
§ Normally ends the coordination too
§ Participants
§ don’t have the bigger picture
§ but can add themselves as ‘interested’
§ and get notified on completion or failure
§ Both the initiator and participants can fail the
coordination
§ Similar to transactions
§ but then light
29
For implementations see: https://en.wikipedia.org/wiki/OSGi_Specification_Implementations

30. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Optimization using Coordinator Service – without API change
30
public void setConfigurations() {
for (int i=0; i<10; i++) {
setConfig(i);
}
}
private void setConfig(int i) {
System.out.println("Setting config data " + i);
System.out.println("Flush configuration");
}
setConfigurationsWithCoordinator()
Setting config data 0
Setting config data 1
Setting config data 2
Setting config data 3
Setting config data 4
Setting config data 5
Setting config data 6
Setting config data 7
Setting config data 8
Setting config data 9
Flush configuration
setConfigurations()
Setting config data 0
Flush configuration
Setting config data 1
Flush configuration
Setting config data 2
Flush configuration
Setting config data 3
Flush configuration
Setting config data 4
Flush configuration
Setting config data 5
Flush configuration
Setting config data 6
Flush configuration
Setting config data 7
Flush configuration
Setting config data 8
Flush configuration
Setting config data 9
Flush configuration
private Coordinator coordinator = ... // From Service Registry
public void setConfigurationsWithCoordinator() {
Coordination c = coordinator.begin("coord.name", 0);
try {
setConfigurations();
} catch (Exception ex) {
c.fail(ex);
} finally {
c.end();
}
}
public void setConfigurations() {
for (int i=0; i<10; i++) {
setConfig(i);
}
}
private void setConfig(int i) {
System.out.println("Setting config data " + i);
if (!coordinator.addParticipant(this))
System.out.println("Flush configuration");
}
@Override
public void ended(Coordination c) throws Exception {
System.out.println("Flush configuration");
}
@Override public void failed(Coordination c) throws Exception {}

31. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.© 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
OSGi Subsystems

32. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Package your app for deployment
§ Most applications are composed of
multiple bundles
§ Need a neat deployment package
§ Previously: proprietary solutions
32
"Airdrop pallets" by Senior Airman Ricky J. Best - defenselink.mil (search for "airdrop").
Licensed under Public Domain via Wikimedia Commons

33. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
OSGi Subsystems
§ Chapter 134 of Enterprise spec
§ Packaging of multi-bundle deployments
§ in .esa file (a zip file)
§ Optional isolation models
§ Bundles either in:
§ .esa file
§ OSGi Repository
33
Jack Kennard TSA 3-1-1 rule
https://www.flickr.com/photos/javajoba/4013349543

34. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Subsystem types
§ Features – everything shared
§ Applications – isolated
§ for ‘friendly’ multi-tenancy – keeps bundles from interfering with each other
§ Composites – configurable isolation
§ generally useful for larger infrastructure components
34
Chiot's Run
A Few Evenings of Work
flickr.com

35. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Feature Subsystems
Deployment artifacts
35
Feature
api bundle
svc bundle use bundle
feature
bundle
Feature 2
api bundle
svc bundle use bundle
feature
bundle2
Runtime Framework
feature
bundle
svc bundle
feature
bundle2
use bundle
api bundle

36. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Application Subsystems
Deployment artifacts
36
Top-level Application
Application
api bundle
svc bundle use bundle
Application 2
api bundle
svc bundle use bundle
Runtime Framework
svc bundle
svc
bundle2
api bundle
use bundle
api bundle
use bundle

37. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Build a subsystem
§ Use maven:
<project>
<artifactId>mysubsystem</artifactId>
<packaging>esa</packaging>
<dependencies>
<!– the bundles you want in your subsystem -->
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.aries</groupId>
<artifactId>esa-maven-plugin</artifactId>
<extensions>true</extensions>
<configuration>
<generateManifest>true</generateManifest>
<instructions>
<Subsystem-Type>osgi.subsystem.feature
</Subsystem-Type>
</instructions>
</configuration>
</plugin>
to produce mysubsystem.esa
37
"Sausage making-H-1" by László Szalai (Beyond silence) - Own work.
Licensed under Public Domain via Wikimedia Commons

38. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Deploy
38
https://svn.apache.org/repos/asf/felix/trunk/webconsole-plugins/subsystems
https://svn.apache.org/repos/asf/aries/trunk/subsystem/subsystem-gogo-command
…or use the Subsystem Gogo Command
g! subsystem:list
0 ACTIVE org.osgi.service.subsystem.root
1.0.0
g! subsystem:install …/feature1.esa
...
Subsystem successfully installed: feature1;
id: 1

39. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
More info on creating a subsystem
§ OSGi Enterprise R6 spec: http://www.osgi.org/Download/Release6
§ Apache Aries website http://aries.apache.org/modules/subsystems.html
§ esa-maven-plugin
http://aries.apache.org/modules/esamavenpluginproject.html
§ For examples see:
https://github.com/coderthoughts/subsystem-examples
39

40. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential.
Recipe – OSGi R6 Compendium
40
§ OSGi Declarative Services (Chapter 112)
§ OSGi Http Whiteboard Service (Chapter 140)
§ OSGi Configuration Admin (Chapter 104)
§ OSGi Metatype Service (Chapter 105)
§ OSGi Coordinator (Chapter 130)
§ OSGi Subsystems (Chapter 134)

41. © 2015 Adobe Systems Incorporated. All Rights Reserved. Adobe Confidential. 41
Q&(A)