osgi service platform open service gateway initiative
TRANSCRIPT
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?