©2003 aqute, all rights reserved tokyo, august 2003 : 1 osgi service platform tokyo august 28, 2003...

©2003 aQute, All Rights Reserved Tokyo, August 2003 : 1

OSGiService PlatformTokyo August 28, 2003

Peter KriensCEO aQute, OSGi Fellow

www.aQute.biz

Mail [email protected] pkriensTel +33 467871853


What is the OSGi Service Platform?

• A Java framework for developing remotely deployed service applications, that require:

– Reliability– Large scale distribution– Wide range of devices– Collaborative

• Created through collaboration of industry leaders

• Spec 3.0 publicly available at www.osgi.org


Release 3 Planned Extensions

Framework

OSGi Specifications Content

Execution Environment

Devic

e M

anag

er

Log

Serv

ice

Http

Ser

vice

R1

User

Adm

in

Serv

ice T

rack

er

Conf

igur

atio

n Ad

min

Pref

eren

ces

Serv

ice

Pack

age

Adm

in

Perm

issio

n Ad

min

R2

Conn

ecto

r Ser

vice

Posit

ion

XML

Pars

er S

ervic

e

UPnP

Ser

vice

Jini S

ervic

e

Wire

Adm

in

Mea

sure

men

t

Star

t Lev

el

URL

Hand

ler

R3


Essentials

• Reliable– Large-scale deployments fail without extremely high reliability

• Portable– Attract third-party developers to create essential innovative services

• Dynamic– Allow configuration to adapt to user & operator needs over time

• Secure– Protect service providers from each other– Guarantee a prescribed quality of service

• Scalable– Members have very different configurations for their deployment of

OSGi frameworks


Core Functions

• Life Cycle Management– Install, Start, Stop, Update, Uninstall

• Dynamic Service Registry

• Version management

• Open remote management architecture

• Strict separation of specifications and implementations – multiple implementations


OSGi Environment

Hardware

BundleBundle

Bundle

Operating System

OSGi

Java VM

Bundle (Application)

Driver Driver Driver

= service interfaceexported and importedby bundles


Framework

• Allows applications to share a single Java VM

• Manages applications– Life cycle, Java Packages, Security, Dependencies

between applications

• Service registry for collaboration

• Extensive notification mechanism

• Policy free


Framework Entities

OSGi Framework

Bundle A{}

= service, java interface

Bundle B{}

Bundle C{}


Bundles

• A bundle is the deliverable application– Like a Windows EXE file

• Contains programs + resources

• A bundle registers zero or more services– A service is specified in a Java interface and may be implemented

by multiple bundles

• Searches can be used to find services registered by other bundles– Query language (filters)

• The Framework itself is represented as the system bundle


Cooperative Model

• Bundles can cooperate through:– service objects– package sharing

• A dynamic registry allows a bundle to find and track service objects

• Framework fully manages this cooperation– Dependencies, security

• More than an Applet, MIDlet, Xlet runner


Cooperative Model

JAVA

Operating System

Hardware

Java Application Manager

Serviceregistry

packagespackages

Midlet,Xlet,

orApplet

Midlet,Xlet,

orApplet

No native code

No management bundlesServiceregistry

packagespackages No package management

(versions!)

No cooperation


Service Specifics

• A service is an object registered with the Framework by a bundle to be used by other bundles

• The semantics and syntax of a service are specified in a Java interface

service


Services & Java Interfaces

LogBundle

IBMLog

MotorolaLog

implements

Gets from Framework (with query)

interface

public interface Log { public void log(String s);}

SimpleLog

public class SimpleLog implements Log { public void log(String s) { System.out.println( s ); }}


Dependencies

• The Framework manages the dependencies between bundles

• Bundles that are installed and started will register services

• Framework will automatically unregister services when a bundle stops

• Event notifications for all important events


Dependencies

Framework

Bundle C{ }

Bundle A{ }

Bundle B{ }

Install A

start

events: install

events: register


Framework

Dependencies

Bundle C{ }

Bundle B{ }

Uninstall

stop

events: uninstall

events: unregister

Bundle A{ }


The Classpath in OSGi

• Each bundle has its own class loader

• Bundles can only shares packages when:– Import and export clauses in the manifest match– Have permission to do so for those packages

• The framework manages the overall CLASSPATH for bundles

• Assures that all bundles use the same class (of the same version)

• Tracks shared usage of packages between between bundles


Native code

• JAR file contains both Java classes + native code

• Matching of correct operating system, processor and language

• Life cycle bound to bundles life cycle

• Requires Java 1.2 support

• Notice that JAR format is only delivery format


OSGi Security

• Separates bundles from each other, in all aspects

• Optional– Base Framework API not linked to java.security

• OSGi uses a single (1) protection domain per bundle

• Framework is policy free

• Administration is done via the Permission Admin service


Remote Management

• Framework provides mechanisms, but is policy free

• Management policy provided by a bundle specific to the operator: – Called a Management Bundle

• Management policies made/selected by the operator

• Enables standardized OSGi management bundles from network management vendors


LocalEthernet

LocalPowernet

Management, protocols or API?

AccessNet

OSGiEnvironment

ManagementSystem

= Bundle

Private protocolfor example:SNMP,CIM, SyncML, etc.


Conclusion

• Open specification process, not a patented API

• Java Based

• Cooperative

• (Remote) Managed

• Secure

• Component Market

• Contact www.aQute.biz for further information

©2003 aqute, all rights reserved tokyo, august 2003 : 1 osgi service platform tokyo august 28, 2003...

Documents

rights reserved tokyo

service interface

java interface service

osgi service platform

system bundle slide

service providers

service specifics

java framework