OSGi Service Platform

Open Service Gateway initiative

Core Product

RBC

CIBC

ING

SYMCOR KINKOS...

... ...

Core Product 2.0

Core Product V 1.2

Core Product v1.0

RBC

CIBC IN

G

SYMCOR KINKOS...

... ...

Topics to cover

● Introduction

● Programming Model

Fundamentals Collaboration

● Eclipse Equinox

● Market Interests

What is OSGi?

● A specification of a component based service oriented platform

● A Java Framework for developing Service Applications that requires:

Reliability Large scale distribution Wide range of devices Collaborative development

● Created by collaboration of industry leaders (OSGi Alliance).

Industry Driven

● Home automation vendors (2000 - 2002)

● Automotive Infotainment and Telematics vendors (2002 - 2004)

● Mobile device vendors (2004 - now)

● Many other vertical markets (now)

Ever wonder...Eclipse IDE

QuantumPlugin

MylarPlugin

CommonsCollections

2.1.1

CommonsCollections

3.2

?

Original Motivations

● Binary software portability

Low reusability of software components● Software engineering is HARD

Software is complex Collaboration helps

● Deployment is error prone

Deployment scripts are often too complicated and unreliable Too much drama!!!

Fundamentals

Layering

Services

Life-cycle

Module (bundle)

Execution Environment

Applications

Security

Bundle

DictionaryService.jar (Bundle)

src

META-INF

lib

*.class

*.dll, *.so, etc...

*.jar

MANIFEST.MF

*.java

Bundles

● Packaging of Java library/service/application for deployment ( a jar file )

● Registers zero or more services

● Services (Java interfaces) may be implemented by multiple bundles

● Search for services registered via a (LDAP-based query language.

● Fragment bundles are like attachments to a bundle-host.

● Manifest contains important information about its bundle.

Manifest-Version: 1.0

Bundle-ManifestVersion: 2

Bundle-Name: DictonaryService Plug-in

Bundle-SymbolicName: DictonaryService

Bundle-Version: 1.0.0

Bundle-Activator: ca.intelliware.osgi.bundle.dictionary.Activator

Bundle-Localization: plugin

Import-Package: org.osgi.framework;version="1.3.0"

Export-Package: ca.intelliware.osgi.bundle.dictionary.service

Bundle-RequiredExecutionEnvironment: CDC-1.0/Foundation-1.0, OSGi/Minimum-1.1

MANIFEST.MF Sample

package ca.intelliware.osgi.bundle.dictionary;

import org.osgi.framework.BundleActivator;import org.osgi.framework.BundleContext;...import ca.intelliware.osgi.bundle.dictionary.service.DictionaryService;

public class Activator implements BundleActivator {

public void start(BundleContext context) throws Exception {Properties properties = new Properties();properties.put("Language", "English");

context.registerService(DictionaryService.class.getName(), new DictionaryServiceImpl(), properties);

}

public void stop(BundleContext context) throws Exception {}

}

<<BundleActivator>>

Registering a Servicepackage ca.intelliware.osgi.bundle.dictionary;

import org.osgi.framework.BundleActivator;import org.osgi.framework.BundleContext;import org.osgi.framework.ServiceRegistration;...import ca.intelliware.osgi.bundle.dictionary.service.DictionaryService;

public class Activator implements BundleActivator {

public void start(BundleContext context) throws Exception {Properties properties = new Properties();properties.put("Language", "English");

ServiceRegistration registration =

context.registerService(DictionaryService.class.getName(), new DictionaryServiceImpl(), properties);

}

public void stop(BundleContext context) throws Exception {}

}

Locating and using a Servicepublic class ClientActivator implements BundleActivator {

public void start(BundleContext context) throws Exception {

ServiceReference[] serviceReferences = context.getServiceReferences(DictionaryService.class.getName(),

"(Language=*)");...

ServiceReference firstServiceReference = serviceReferences[0];

DictionaryService service = (DictionaryService)context.getService(firstServiceReference);

if (service.checkWord(word)) {System.out.println(word + " was correct.");

} else {System.out.println(word + " was incorrect.");

}

context.ungetService(firstServiceReference);}

}

...

Listening to ServiceEventpublic class ServiceListenerActivator implements BundleActivator, ServiceListener {

public void start(BundleContext context) throws Exception {context.addServiceListener(this);

}

public void stop(BundleContext context) throws Exception {context.removeServiceListener(this);

}

public void serviceChanged(ServiceEvent event) {

int eventType = event.getType();String serviceName =

((String[])event.getServiceReference().getProperty("objectClass"))[0];

switch (eventType) {case ServiceEvent.MODIFIED:

System.out.println("service: " + serviceName + "has been modified.");

case ServiceEvent.REGISTERED:System.out.println("service: " + serviceName + "has been

registered.");case ServiceEvent.UNREGISTERING:

System.out.println("service: " + serviceName + "has been unregistered.");

default:break;

}}

}

Service Layer

● SOA Service Oriented Architecture Clarification:

OSGi Services != Web Services

OSGi Services are in-VM services

● Service Model

Services are POJO's in a bundle

Its interface is exported and registered in a Service Registry.

Discover and gets notified about services based on their interfaces and properties

Different bundles can register different implementations of the same interface.

● The OSGi Alliance provides many standardized services

Device Manager, Declarative Services, Event Admin, HTTP Service, Log Service, Metatype Service, Preferences Service, User Admin, Wire Admin, etc...

Life-cycle

Service

Execution

module

Demo

Life Cycle Layer

● Controlled by the System Bundle

● Provides an API for managing bundles

Install Resolve Start Stop Refresh Update Uninstall

Module

Life-cycle

Service

Execution

Life of a Bundle

Installed

Uninstalled

Resolved

Stopping

Starting

Active

Bundle

● Bundle started by an object of BundleActivator Type

● Manifest Header refer to this class

● BundleActivator Interface has 2 methods: start() and stop()

● BundleActivator gets a BundleContext provides access to the framework

● Framework provides Start Level Service to control start/stop of groups of applications

Traditional Class loading

User-DefinedClassLoader

User-DefinedClassLoader

SystemClassLoader

ExtensionClassLoader

Single Parent Delegation Model

BootstrapClassLoader

classpath

jre/ext

java.lang.*

Class loading OSGi StyleDelegation Model

BundleClassLoader

BundleClassLoader

BundleClassLoader

BundleClassLoader

ParentSystem

ClassLoader

SystemBundle

ClassLoader

importer Exporter

Bundle Space

Boot Classpath(java.lang.*)

Framework Classpath

Module Layer

● Applications and libraries are packaged in bundles (jar file)

● A classloader is assigned to each bundle for loading its classes and resources.

● Modularized Classloading

Traditional Single Parent Delegation Classloading model is inflexible

● Versioning

Raw Java cannot handle multiple versions of the same package

Life cycle

Module

Service

Execution

Manifest-Version: 1.0

Bundle-ManifestVersion: 2

Bundle-Name: DictonaryService Plug-in

Bundle-SymbolicName: DictonaryService

Bundle-Version: 1.0.0

Bundle-Activator: ca.intelliware.osgi.bundle.dictionary.Activator

Bundle-Localization: plugin

Import-Package: org.osgi.framework;version="1.3.0"

Export-Package: ca.intelliware.osgi.bundle.dictionary.service

Bundle-RequiredExecutionEnvironment: CDC-1.0/Foundation-1.0, OSGi/Minimum-1.1

MANIFEST.MF Sample

Execution Environments

● CDC-1.0/Foundation-1.0 Equals to J2ME Foundation Profile

● OSGi/Minimum-1.1 OSGi EE that is a minimal set that allows the implementation of an OSGi

Framework.

● JRE-1.1, J2SE-1.2, J2SE-1.3, J2SE-1.4● PersonalJava-1.1, PersonalJava-1.2● CDC-1.0/PersonalBasis-1.0

J2ME Personal Basis Profile

● CDC-1.0/PersonalJava-1.0 J2ME Personal Java Profile

Life-cycle

Execution

Service

Module

Programming Model

Object Oriented Model

● One of the challenges is managing dependencies, if we are not careful our objects can get quite tangled.

Object Oriented Model

● Coupling severely limits reuse.

Using a generic object can drag in a large number of other objects.

● Flexibility must be built by programmer

Plugin architectures

Service Oriented Architecture

● Separation of interface and implementation● Allows swapping in alternative implementation● Dynamically discover and bind object implementations● Components are not coupled with implementation

ClientComponent

ImplementationComponent

Service Contract

...

...

Framework

● Allows applications to share a single JVM

● Dynamic classloading

Dependencies are “wired” at runtime Compares to static classpaths

● Declarative Security

Java Security Model● Declarative bundle dependency

Coordinated via manifest headers● Independent life-cycle management of applications and

services on a single JVM instance.

Framework and Bundles

● The framework at bundle installation time:

Security check the bundle Reads the bundle's manifest Installs code and resources Resolve dependencies

● The framework at bundle runtime:

Calls the bundle's Activator to start the bundle Manages classpath Handles service dependencies Calls the bundle's Activator to stop the bundle

Layering – Bigger Picture

Courtesy of Michael Grammling

Collaborate or else...

Manifest-Version: 1.0

Bundle-ManifestVersion: 2

Bundle-Name: DictonaryService Plug-in

Bundle-SymbolicName: DictonaryService

Bundle-Version: 1.0.0

Bundle-Activator: ca.intelliware.osgi.bundle.dictionary.Activator

Bundle-Localization: plugin

Import-Package: org.osgi.framework;version="1.3.0"

Export-Package: ca.intelliware.osgi.bundle.dictionary.service

Bundle-RequiredExecutionEnvironment: CDC-1.0/Foundation-1.0, OSGi/Minimum-1.1

MANIFEST.MF Sample

Component Interaction

● Bundles collaborate through:

Service objects Package sharing

● Bundle Registry allows bundles to find and track service objects

● Framework manages the collaboration

Dependencies

● OSGi framework is a network of class loaders (one class loader per bundle).

● Complicated dependencies are “resolved” by the framework behind the scene.

CommonsCollections

Xerces

JavaMail

CommonsCollections-1.0

Xerces

Commons Collections CommonsCollections-2.0

version=1.0

version=2.0

Bundle

Exported package

imported package

Wire

Constraint

Equinox

What is Equinox

● Eclipse Project

Complete implementation of OSGi R4● Provides the base for Eclipse plug-in Architecture

Since Eclipse 3.0● Eclipse 3.2 provides additional services

Device Manager, HTTP Service, Log Service, Preferences Service, ...

● Eclipse Plug-in Development Environment (PDE) provides a environment for developing OSGi bundles.

Other OSGi implementations● ProSyst

● Knopflerfish

● Gatespace Telematics – KnopflerfishPro

● Eclipse - Equinox

● Objectweb - Oscar

● Apache - Felix

● Concierge

● Oxygen

● osxa

Bundle Repositories

● OSGi Alliance

http://bundles.osgi.org/Main/Repository● Oscar OBR

http://oscar-osgi.sourceforge.net● Knopflerfish bundle repository

http://www.knopflerfish.org/repo/index.html

Market Interests

OSGi +

●OSGi + BMW = iDrive (In-car Infotainment system)

●OSGi + Siemens VDO = RIO (In-car Infotainment system)

●OSGi + Websphere = Websphere Application Server (WAS) 6.1

●OSGi + JOnAS = JOnAS5

●OSGi + Spring = ?

... A much more comprehensive list of Markets and Solutions can be found at http://osgi.org/markets

My thoughts on OSGi

● Evolved WAY beyond the embedded markets● Version management● Encourages decoupling and collaboration● Encourages reuse● Think Product not Project● Important role technologies

OSGi + Portugese Chicken = Lunch & Learn

FIN

Questions?