CS5233 Components – Models and Engineering · Seite 3 OSGI – what, why and who What OSGi is: OSGi is about building systems from components OSGi - Components work together in

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CS5233Components – Models and Engineering(Komponententechnologien) Master of Science (Informatik)

OSGI - Introduction

Prof. Dr. Th. Letschert

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OSGI – what, why and who

What OSGi stands for

once: OSGi : Open Service Gateway Initiative

now: OSGi is a name for a Dynamic Module System for Java

Slides on OSGi are based on

– OSGi Alliance: OSGi Service Platform Core Specification OSGi 2009

– J. McAffer, P. Vanderlei, S. Archer: OSGi and Equinox, Addison-Wesley 2010

– Wütherich/Hartmann/Kolb/Lübken, Die OSGI Service Platform – Dpunkt Verlag, 2008

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What OSGi is:

OSGi is about building systems from components

OSGi - Componentswork together in a systemcan be managed (installed / removed)

… at runtime

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What OSGi is:

OSGi is a component framework for Java

OSGi-componentsare called bundlesare units of resourcescan be installedhave managed mutual dependenciesare independent units can export services and run processesrun in an OSGi-container

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What OSGi is:

OSGi is a (a set of) specification(s)

by the OSGi-Alliance (founded 1999)with wide adoption outside the alliance

developed in expert groupsCore platform (CPEG)

Vehicle (VEG) OSGi in vehicles

Mobile (MEG) OSGi in mobile devices

Enterprise (EEG) OSGi in enterprise solutions

Residential (REG) OSGi in home automation

structured into 2 documentsCore Specification : frameworkService Compendium : standard services

actual version 4.1

Alcatel-Lucent Aplix Corporation

Deutsche Telekom

Ericsson Mobile Platforms AB Hitachi, Ltd.

IBM Corporation LinkedIn

Makewave

Mitsubishi Electric Corporation NEC Corporation

NTT

Oracle Corporation Paremus, Ltd.

Progress Software ProSyst Software GmbH

Qualcomm

Red Hat SAP AG

Siemens AG Siemens Enterprise Communications

Software AG

Sonatype Inc. SpringSource (a Division of VMware)

Sun Microsystems, Inc.

Telcordia Technologies, Inc. TIBCO Software Inc.

Westell Inc.

http://www.osgi.org

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Where OSGi came from

Requirement for a component model for devices

Installable Software services Software deployment and management Security

Originally aimed at home automation Set top boxes, DSL-Modems, ··· building equipment and

appliances

Used in several areas for years automotive mobile devices

Adopted by Eclipse for Eclipse 3.0

Currently widespread useOSGi Scenario: Refrigerator that runs

software form different vendors. Each of them may independently install new

version of software modules.

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OSGi and Java

OSGi has a focus on Java

Bundles usually contain class-files

Bundles may contain JNI code e.g. SWT-bundles in Eclipse

Communication with non-Java devises is possible

Script language support may be provided

Java execution environmentRequirements on a JVM to support OSGi framworksfulfilled by several JVMs (SE und ME)

related JSRs:JSR 232: Mobile operational ManagementJSR 291: Dynamic component support for Java SE

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OSGi and Eclipse

Eclipse is a main adopter of OSGi

Eclipse and OSGi in 2003 OSGi: a consortium of vendors in the area of embedded systems with the aim to

provide a platform for inter-vendor compatible components called bundles.

Eclipse: a consortium of vendors in the area of software tools with the aim to provide a platform for inter-vendor compatible components called plugins.

2003: Eclipse Project Equinox initiated Aim: Resolve problems of Eclipse's runtime behavior

Leverage of (then) current work on management and provisioning Available technologies considered

JMX Java Management Extensions Avalon Component framework : Apache project, 1999 – 2004, still active

follower projects eg. Excalibur

OSGi Decision to use OSGi

A number of changes and extension of the OSGi specification where developed Based on IBMs OSGi-Impl. SMF (Service Management Framework),

Equinox runtime was developed and replaced Eclipse runtime

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OSGi and Eclipse

Eclipse and OSGi together changed the (software) world

Eclipse ~> OSGi OSGi: from niche to mainstream:

a mature good technology became the marketing it deserved OSGi got a complete new market: all mayor Java application server are (or are in

the process of being) ported to OSGi

OSGi ~> Eclipse gain of a mature component model Eclipse/Equinox adoption outside Eclipse (embedded systems)

OSGi + Eclipse Proof for everyone: Working runtime component systems can exist

OSGi is not the first component system but it is the first with wide range of followers

OSGi's original target market - “home gateways” - never where of any relevance but the strict constraints of them forced the development of a technology of widespread usage

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OSGi Survey

Service platform: Container, Bundles, Services

OSGi Service Platform: Component technology consisting of

Bundle ~ ComponentSet of classes and resources that

have defined interfaces (provided / used services)may be installed (deployed) / de-installed at runtime

Service ~ Component interfaceServices are provided by bundles that register them with the container

Services are used by bundles that request them from the container

Some Services are standard-services provided by the container

Container ~ OSGi FrameworkRuntime environment for bundles

Life-cycle management of bundles

Service-management

Provider of standard services

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OSGi Survey

OSGi application

A set of bundles each bundle may contribute in any way:provide libraries, start threads, open sockets, open DBs, ····

no “main”-bundle: all bundles are peers

no hierarchy: no bundle within a bundle

Bundle A

Bundle DBundle C

Bundle B

OSGi-Application

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OSGi Survey

OSGi application vs Java application

OSGi-Application: A set of bundles with mutual dependencies declared and resolved through defined interfaces

Java application: Dependencies are between (more granule) classes. They are declared using class-names and resolved using names, the position of a package / jar within the classpath, the loader that was used to load the using class, the loader that was used to load the used class, ···

Bundle A

Bundle DBundle C

Bundle B

OSGi-Application Java-Application

Jar

package

class

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OSGi Survey

Logical Layers according to the OSGi Specification

Module LayerDefines bundles: the basic components

Life-cycle Management LayerLife-cycle of bundles: states, actions, state transitions

Service LayerService definition, how to provide or use services

Security LayerSecurity related definitions

Execution Environment

Module Layer

Lifecycle Mngmt

Service Layer

Securty

ServicesOSGiFramework

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OSGi adoption

OSGi is a technology for enterprise servers

Enterprise servers based on OSGi➢ IBM WebSphere Application Server ➢ Sun Glassfish V3➢ Oracle WebLogic Server ➢ Redhat JBoss➢ SAP Netweaver Application Server (announced) ➢ ···

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OSGi adoption

OSGi is a technology for automotive electronics

➢ BMW➢ Bombardier➢ Siemens VDO ➢ Volvo➢ Windriver ➢ ···

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What do you need:

an OSGi container (open source examples):➢ Equinox

OSGi-container implementation developed and used by Eclipse

➢ Apache FelixOSGi-container implementation by the Apache Foundation

➢ KnopflerfishOSGi-container implementation developed by Makewave

➢ ...

http://eclipse.org/equinox/

http://felix.apache.org/

http://www.knopflerfish.org/

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OSGi with Equinox / The console

see Equinox QuickStart Guide http://eclipse.org/equinox/documents/quickstart.php

Equinox is part of Eclipse and can be activated without further downloads– Start the Equinox osgi-console:

java -jar /path/to/eclipse/plugins/org.eclipse.osgi_3.5.2.jar -console

osgi>

– This starts the equinox implementation of the OSGi container and opens a console

– The console may also be used with eclipse itself:

/path/to/eclipse/eclipse -console

http://eclipse.org/equinox/documents/quickstart.php

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Th Letschert


Commands (Examples)

– help List all available commands.

– ss List of all bundles together with their state and id.

– ss <string> List all bundles with names containing that string.

– start <id> Start up the bundle with a given id.

– stop <id> Stop the bundle with the given id.

– install <url> Install the bundle that the URL refers to.

– uninstall <id> Uninstall the bundle with the given id.

– diag <id> Show resolution problems for bundle with given id.

– exit Exit

For more information use the help command

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Th Letschert


Usage Example: install http-server as eclipse bundles

> java -jar org.eclipse.osgi_3.5.2.jar -consoleosgi> install file:/path/to/eclipse/plugins/org.eclipse.osgi.services_3.2.0.v20090520-1800.jarBundle id is 1 osgi> install file:/path/to/eclipse/plugins/org.eclipse.equinox.ds_1.1.1.R35x_v20090806.jar

Bundle id is 2 osgi> install file:/path/to/eclipse/plugins/javax.servlet_2.5.0.v200806031605.jarBundle id is 3 osgi> install file:/path/to/eclipse/plugins/org.eclipse.equinox.util_1.0.100.v20090520-1800.jarBundle id is 4osgi> install \ file:/path/to/eclipse/plugins/org.eclipse.equinox.http.servlet_1.0.200.v20090520-1800.jarBundle id is 5osgi> install file:/path/to/eclipse/plugins/org.mortbay.jetty.util_6.1.15.v200905182336.jarBundle id is 6osgi> install file:/path/to/eclipse/plugins/org.mortbay.jetty.server_6.1.15.v200905151201.jar

Bundle id is 7osgi> setprop org.osgi.service.http.port=8888Setting Properties: org.osgi.service.http.port = 8888

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Th Letschert

Usage Example: install eclipse bundles (cont)

osgi> start 1 osgi> start 2osgi> start 3osgi> start 4osgi> start 5osgi> start 6osgi> start 7osgi> ssFramework is launched.id State Bundle0 ACTIVE org.eclipse.osgi_3.5.2.R35x_v201001261 ACTIVE org.eclipse.osgi.services_3.2.0.v20090520-18002 ACTIVE org.eclipse.equinox.ds_1.1.1.R35x_v200908063 ACTIVE javax.servlet_2.5.0.v2008060316054 ACTIVE org.eclipse.equinox.util_1.0.100.v20090520-18005 ACTIVE org.eclipse.equinox.http.servlet_1.0.200.v20090520-18006 ACTIVE org.mortbay.jetty.util_6.1.15.v2009051823367 ACTIVE org.mortbay.jetty.server_6.1.15.v200905151201osgi>

now a http server is up and running(of course it has no files to serve)

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Th Letschert

OSGi adoption :

OSGi survey report 2009 / Java developers on OSGi

➢ Are you familiar with the OSGi Service Platform?

92% have heard of OSGi

➢ Are you currently developing systems to be deployed to an OSGi runtime?

70.9% were using OSGi

➢ Do you have plans to develop systems that are to be deployed to an OSGi runtime within the next 6 – 12 months?

82.7% are planning to use it in the next 6 - 12 months

➢ Are you familiar with the available OSGi products and services

83.5% were familar with OSGi products and services

➢ Which OSGi implementations are you currently using or evaluating?

Equinox, Felix are the leaders

http://osgi.dzone.com/articles/osgi-survey-results

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Th Letschert

OSGi adoption : OSGi survey report 2009 / Java developers on OSGi

Which of the following types of systems are you planning to deploy within an OSGi runtime?

64.8% web apps17.2% embedded development15.6% mobile development50.4% for rich clients13.6% aren't using OSGi at all.

What are the benefits you hope to achieve using OSGi?

83.9% greater modularity56.6% hot deployment51.4% manageable runtime environment68.6% better dependency management57.3% bundle versioning63.5% plugin architecture10.2% nothing


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Th Letschert

OSGi adoption : OSGi survey report 2009 / Java developers on OSGi (cont.)

Which of the following types of systems are you planning to deploy within an OSGi runtime?

64.8% web apps17.2% embedded development15.6% mobile development50.4% for rich clients13.6% aren't using OSGi at all.

What are the benefits you hope to achieve using OSGi?

83.9% greater modularity56.6% hot deployment51.4% manageable runtime environment68.6% better dependency management57.3% bundle versioning63.5% plugin architecture10.2% nothing


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OSGI – Bundle

Th Letschert

Bundle Bundles are runtime components, i.e. plugins Eclipse plugins are (special) bundles Incarnation : Jar-file containing:

➢ Content: classes, resources ➢ Meta-information: Bundle-specific meta-information

Content➢ mainly packages identified by name and version➢ hidden from other bundles➢ unless explicitly exported and explicitly imported by other bundles

Meta-information Manifest file (mandatory)

➢ as Jar manifest file META-INF/MANIFEST.MF➢ file-content structured following the jar-specification➢ with specific OSGi headers

Optional meta-information in optional directories e.g.:➢ OSGi-INF: XML-files describing (declarative services)➢ OSGi-OPT: security / i18n related specifications

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OSGI – Bundle

Th Letschert

Example: Bundle org.eclipse.core.runtime-v20090525.jar and its manifest file

Manifest-Version: 1.0Bundle-Localization: pluginBundle-RequiredExecutionEnvironment: CDC-1.0/Foundation-1.0,J2SE-1.3

Bundle-SymbolicName: org.eclipse.core.runtime; singleton:=trueRequire-Bundle: org.eclipse.osgi;bundle-version="[3.5.0,4.0.0)";visibi lity:=reexport,org.eclipse.equinox.common;bundle-version="[3.5.0,4.0. 0)";visibility:=reexport,org.eclipse.core.jobs;bundle-version="[3.2.0 ,4.0.0)";visibility:=reexport,org.eclipse.equinox.registry;bundle-ver sion="[3.4.0,4.0.0)";visibility:=reexport,org.eclipse.equinox.prefere nces;bundle-version="[3.2.0,4.0.0)";visibility:=reexport,org.eclipse. core.contenttype;bundle-version="[3.3.0,4.0.0)";visibility:=reexport, org.eclipse.core.runtime.compatibility.auth;bundle-version="[3.2.0,4. 0.0)";resolution:=optional,org.eclipse.equinox.app;bundle-version="[1 .0.0,2.0.0)";visibility:=reexportBundle-Activator: org.eclipse.core.internal.runtime.PlatformActivatorExport-Package: org.eclipse.core.internal.preferences.legacy;x-interna l:=true,org.eclipse.core.internal.runtime;x-friends:="org.eclipse.cor e.runtime.compatibility",org.eclipse.core.runtime;version="3.4.0"Bundle-Version: 3.5.0.v20090525Bundle-ActivationPolicy: lazyBundle-Vendor: %providerNameBundle-Name: %pluginName

· · ·

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OSGI – Bundle

Th Letschert

Manifest file contains information about the bundle in headers:

Identification: bundles identify themselvesheader: Bundle-SymbolicName

header: Bundle-Version

Export: Bundles may export packages Exported packages form the bundle's API Packages not exported are private Packages are exported with their name and a optional version number

(packages are versioned independently)header: Export-Package

Example:

Export-Package: org.eclipse.core.internal.preferences.legacy;x-interna l:=true,org.eclipse.core.internal.runtime;x-friends:="org.eclipse.cor e.runtime.compatibility",org.eclipse.core.runtime;version="3.4.0"

package org.eclipse.core.runtime is exported with version number 3.4.0

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OSGI – Bundle

Th Letschert


Import

Bundles may use packages exported packages only if they explicitly import them using the package name

Version: Each import may be qualified with a version or a version range :lower and upper bound of versions for the imported packageVersion range spec. mathematically “[a,b)” “(“ ~ exclusive “[“ ~ inclusive

header: Import-Package

Example (from org.eclipse.equinox.http.servlet_1.0.200.v20090520-1800.jar)

Import-Package: javax.servlet;version="2.3",javax.servlet.http;version="2.3",org.osgi.framework;version="1.3.0",org.osgi.service.http;version="1.2.0"

all imports are labeled with exact versions

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OSGI – Bundle

Th Letschert


Requirement Bundles may specify a dependency on entire bundles Simplifies imports May be used to express dependency on on-Java resources Widely used in Eclipse because it maps to the import statements of eclipse's

original plugin concept Version: Requirements may be qualified with a version or a version range header: Required-Bundle

Example (from org.eclipse.core.runtime-v20090525.jar)

Require-Bundle: org.eclipse.osgi;bundle-version="[3.5.0,4.0.0)";visibi lity:=reexport,org.eclipse.equinox.common;bundle-version="[3.5.0,4.0. 0)";visibility:=reexport,org.eclipse.core.jobs;bundle-version="[3.2.0

,4.0.0)";visibility:=reexport,org.eclipse.equinox.registry;bundle-ver sion="[3.4.0,4.0.0)";visibility:=reexport,org.eclipse.equinox.prefere nces;bundle-version="[3.2.0,4.0.0)";visibility:=reexport,org.eclipse. core.contenttype;bundle-version="[3.3.0,4.0.0)";visibility:=reexport, org.eclipse.core.runtime.compatibility.auth;bundle-version="[3.2.0,4. 0.0)";resolution:=optional,org.eclipse.equinox.app;bundle-version="[1 .0.0,2.0.0)";visibility:=reexport

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OSGI – Bundle

Th Letschert

Resolving dependencies between bundles

Dependencies are resolved using language rules and classloaders

Dependencies between bundles are resolved at runtime Visibility follows usual Java language rules (public, protected, ···) Mechanism: Each bundle is equipped with it's own class loader when being

installed

class name

bundle class loaderclass

class+

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OSGI – Bundle

Th Letschert

Lifecycle

Instances of a bundle are created by installing them in a container / framework.

Installed bundles have a lifecycle manged by the framework.

The difference between a bundle and its installment is usually not made explicit. The noun “bundle” may refer to a bundle or to an installed bundle (a bundle instance). OSGi Spec differentiates between Bundle - deployed instance - and bundle - jar file.

For each Bundle (an installed bundle) there is a Bundle-object that is managed by the framework

Each Bundle goes through a lifecycle controlled by the framework A Bundle has to listen and react on lifecycle events

deploy / install,activate, stop

update, uninstall

OSGi framework

bundleBundleBundle

lifecycleevents

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OSGI – Bundle

Th Letschert

BundleBundle

Diagr: OSGi Service Platform Spec. 4.2

OSGi framework

bundle

deploy / install,activate, stop

update, uninstall

Bundle lifecycle

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OSGI – Bundle

Th Letschert

Lifecycle installed: initial state of an (installed) bundle

resolved: all dependencies are resolved, all classes are available, bundle is ready to be started

starting: the bundle is in the process of starting,method BundleActivator.start is called but did not return

active: bundle is active and running, method BundleActivator.start was called and did return

stopping: the bundle is in the process of being stopped, method BundleActivator.stop was called but did not yet return

uninstalled: the bundle has been uninstalled, it is no longer available for use of the framework

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OSGI – Bundle

Th Letschert

Bundle Context Upon activation a bundle gets a bundle context

The bundle context represents the framework as seen by the bundle

The bundle context is used by the bundle to:

get information about the framework install other bundles information about other bundles access persistent storage access the service registry access the event subscription

Framework

BundleBundle

Bundle Context(proxy to the framework)

Bundle

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OSGI – Bundle

Th Letschert

Events Types of events

Bundle events: report state changes of a bundle Service events: report service registration, un-registration, modification Framework events: report changes in the framework (starting, stopping)

Bundle listener registered by the bundle at the bundle context called when the bundles stage changes

Framework listener registered by the bundle at the bundle context called when a framework event occurs

Framework

BundleBundle

Bundle Context

Listener

Event

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OSGI – Service

Th Letschert

Services Types of bundle interaction

Via direct references to classes provided by other bundles Via Services: Access mediated by a service registry Via Extension points (only Equinox)

Service Service name: name of an interface Service definition: a public interface defined in an exported package of a

bundle

Service implementation: Object of a class that implements the interface (within the same or a different bundle) The service class usually is not exported.

Service registration: Service implementer registers the object under the name of the interface

Service usage: A service consumer imports the package containing the interface

looks up – using the name – the service registry for a matching object

uses the service object

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Bundle / Equinox – Extensions

Th Letschert

Extension and Extension Point

Extension Point: a complementary bundle collaboration mechanism. Bundle-local registration mechanism.

Defined and implemented in Equinox

Inheritance of Eclipse's pre-OSGi time

Bundles declare extension points

Other bundles provide extensions to an extension point

Extensions and extension points are declared in XML (file plugin.xml)

BundleBundle

BundleBundle

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OSGi – Framework

Th Letschert

Framework

framework = runtime = container = platform

Specified in “OSGi Service Platform Core Specification” as part of an OSGi-compliant device responsible for managing bundles, services and their dependencies

Structured into “layers”: Execution Environment (EE) Module Lifecycle Service Security

Framework layers, their interaction and responsibilities(OSGi Service Platform Spec. 4.2 )

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OSGi – Framework

Th Letschert

Life cycle state diagram

Diagr.: OSGi Service Platform Spec. 4.2

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OSGi – Framework

Th Letschert

Life cycle of a framework

Outside of the specification: Classes that implement a framework must be made available through the class path or a special class loader.

Launcher: a launcher (outside the specification) launches the framework by using the factory and a framework object:

Factory: A framework implementation must provide a factory class which can create a framework object

Framework life cycle refers to a framework object installed: the framework has been created starting: the framework has been initialized, none of its bundles are active active: services and event handling is active, framework object has a

bundle context object, framework services are available, all bundles are started

stopping: shutdown is initiated

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OSGi – Framework

Th Letschert

Launching a framework

Launching a framework(OSGi Service Platform Spec. 4.2 )

Documents

CS5233 Components – Models and Engineering · Seite 3 OSGI – what, why and who What OSGi is: OSGi is about building systems from components OSGi - Components work together in