Maximise the Power of OSGi - Carsten Ziegeler & David Bosschaert

© 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

© 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

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

Today’s contents
§  Declarative Services
§  with Configuration Admin
§  HTTP Whiteboard
§  Coordinator
§  Subsystems
4
Image by Joadl: Lyme_Regis_harbour_02b on wikipedia

Declarative Services

Component Container Interaction
6
OSGi Service Registry
Declarative Services Blueprint
iPojo,
Dependency
Manager,
….
Framework API

© 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
✔?!

The Next Big Thing
8

Building Blocks
§  Components
§  Services
§  Module aka Bundle
9

Game Design
10
Game Servlet
GET
POST
HTML
Game Controller
Game Bundle

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
}

Implementation
12
@Component
public class GameControllerImpl implements GameController {
...
import org.osgi.service.component.annotations.Component;

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

private Config configuration;
@Activate
protected void activate(final Config config) {
this.configuration = config;
}
int medium_max() default 50;
int hard_max() default 100;
}

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;
}

Game Design
16
Game Servlet
GET
POST
HTML
Game Controller
Game Bundle

Web?
17
@Component( service = Servlet.class ,
property="osgi.http.whiteboard.servlet.pattern=/game")
public class GameServlet extends HttpServlet {
@Reference
private GameController controller;

Unary References
18
@Reference
private GameController controller;
@Reference(cardinality=ReferenceCardinality.OPTIONAL
policy=ReferencePolicy.DYNAMIC)
private volatile GameStatistics stats;

Multiple References
19
@Reference(cardinality=ReferenceCardinality.MULTIPLE)
private volatile List<Highscore> highscores;
@Reference
private final Set<Highscore> highscores =
new ConcurrentSkipListSet<Highscore>();

Game Design
20
Game Servlet
GET
POST
HTML
Game Controller
Game Bundle

Management
21

Component Management
22

Metatype I
23
@ObjectClassDefinition(
name = "Game Configuration",
description = "The configuration for the guessing game.")
@AttributeDefinition(name="Easy",
description="Maximum value for easy")

Metatype II
24
@Component
@Designate( ocd = Config.class )
public class GameControllerImpl
implements GameController {

Declarative Services
§  Easy too use
§  Pojos
§  DI with handling dynamics
§  Integrates with Configuration Admin and Metatype
25

Try it out TODAY
§  Tooling *is* available
§  Oﬃcial open source implementations available
26

OSGi Coordinator

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

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

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
Flush configuration
setConfigurations()
Flush configuration
Flush configuration
Flush configuration
Flush configuration
Flush configuration
Flush configuration
Flush configuration
Flush configuration
Flush configuration
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))
}
@Override
public void ended(Coordination c) throws Exception {
}
@Override public void failed(Coordination c) throws Exception {}

OSGi Subsystems

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

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

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

Feature Subsystems
Deployment artifacts
35
Feature
api bundle
svc bundle use bundle
feature
bundle
Feature 2
api bundle
feature
bundle2
Runtime Framework
feature
bundle
svc bundle
feature
bundle2
use bundle
api bundle

Application Subsystems
Deployment artifacts
36
Top-level Application
Application
api bundle
Application 2
api bundle
Runtime Framework
svc bundle
svc
bundle2
api bundle
use bundle
api bundle
use bundle

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

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

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

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)

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Maximise the Power of OSGi - Carsten Ziegeler & David Bosschaert

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