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Santosh Kumar. Why OSGi matters for Enterprise Java Infrastructures. Agenda. Introduction to OSGi Why is OSGi technology important How OSGi matters for Infrastructure OSGi Enterprise spec OSGi in Cloud Q&A. OSGi Key for Infrastructure. Take away from this session.

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Santosh Kumar

Why OSGi matters for Enterprise Java Infrastructures

  • Introduction to OSGi
  • Why is OSGi technology important
  • How OSGi matters for Infrastructure
  • OSGi Enterprise spec
  • OSGi in Cloud
  • Q&A
take away from this session


Key for Infrastructure

Take away from this session
  • Overall understanding to view OSGi as THE module system for Java
  • Understanding of what this OSGi Enterprise spec is all about
  • Should be able to start experimenting with it themselves using one of the available implementations
what is osgi


Consider as Universal


What is OSGi
  • OSGi - Open Services Gateway initiative
    • Technology is the dynamic module system for Java™.
    • Provides a service-oriented, component-based environment for developers
    • Offers standardized ways to manage the software lifecycle.
    • Support for building modular dynamic and extensible systems
lets put things in perspective
Lets put things in perspective…
  • The Complexity & Scale of Software requires:
    • 1. Service Oriented

As complexity and size


Need for higher level of

abstract programming

why osgi

Jar as unit does

not have modularity

Why OSGi?
  • 2. Modularity
    • Java Platform Modularity
      • Classes encapsulate data
      • Packages contain classes
      • Jars contain packages
    • Class visibility:
      • private, package private, protected,public
    • No “jar scoped” access modifiers.
    • No means for a jar to declare its dependencies.
    • No versioning.
    • Jars have no modularization characteristics
      • At runtime, global classpath to search
why osgi1
Why OSGi?
  • 3. Versioning
    • Enterprise Apps have isolated classpaths but…
    • Across apps - each archive typically contains all the libraries required by the application
        • Common libraries/frameworks get installed with each application
        • Multiple copies of libraries in memory
    • Within apps - 3rd party libraries consume other libraries leading to version conflicts
overall architecture

Module (Bundle)




Operating System

Overall Architecture

OSGi as

module system





= service

osgi the dynamic module system for java
OSGi –The Dynamic Module System for Java
  • OSGi specifies a modular architecture for dynamic component based systems
  • • Execution Environment
  • • Module Layer
  • • Life Cycle Layer
  • • Service Layer

OSGi introduces


as modules

module layer

Bundle as module


separation of concerns

Module layer
  • Bundle - unit of module
  • Packaged as JAR - classes + manifest + resources
  • - Versioning support
  • - Dependency specification
  • - JAR with MIME type : application/vnd.osgi.bundle
  • OSGi enforces modularity in bundles
osgi classloading
OSGi ClassLoading
  • Each bundle has its own classloader / classpath. More efficient for large systems
  • Multiple versions of bundles supported concurrently
service layer
Service Layer
  • Defines a publish/find/bind service model
    • Fully dynamic
    • Intra VM
    • service registry
  • A service is a normal Java object published under one or more Java interfaces with additional metadata with the service registry
  • Bundles can register services, search for them, or receive notifications when their registration state changes.
  • Service lifecycle is highly dynamic
    • Service may be published or unpublished at any time
service orientation
Service Orientation

OSGi intrinsically

supports SOA

Service Registry



Service Description

Service Provider

Service Consumer


life cycle
Life Cycle
  • API to control the security and life cycle operations of bundles
  • Install, uninstall, start, stop bundles dynamic without restarting applications
what does the osgi framework provide
What does the OSGi Framework provide?
  • Horizontal Software Integration Platform
  • Component Oriented Architecture
    • Module (Bundles)
    • Package sharing and version management
    • Life-cycle management and notification (events)
  • Service Oriented Architecture
    • Publish/find/bind intra-VM service model
    • Life-cycle notification (events)
framework features
Framework Features
  • Runs multiple applications and services
  • Single VM instance
  • Separate class loader per bundle
    • Class loader network
    • Independent namespaces
    • Class sharing at the Java package level
  • Lifecycle management of bundles
  • Intra VM publish/find/bind service model
  • Java Permissions to secure framework
where osgi is used
Where OSGi is used
  • Equinox
    • Reference implementation of core framework and various services
    • Base runtime for all of Eclipse (rich client, server side and embedded)
  • Felix - Ships with GlassFish
  • Application servers : Websphere, JBoss etc
  • SOA Virtualization Platform : TIBCO Active Matrix
    • widespread use in desktop and servers
does enterprise java need osgi
Does Enterprise Java need OSGi?
  • Current challenges
    • Lots of Libraries To Manage
    • Designed for Extensibility
    • Dynamic Deployment, Uptime
    • Well-defined coherent modules
    • Simplify unit of reuse
osgi in enterprise
OSGI in Enterprise
  • Integration of established Java Enterprise Edition technologies into an OSGi Environment
  • Multiple, interoperable, dependency injection based component models
  • Distributed service model for multiple service platforms and external heterogeneous systems
  • Database persistence support
  • Enterprise-class life cycle and configuration management
osgi enterprise spec v4 2
OSGi Enterprise Spec V4.2
  • Brings Enterprise technologies and OSGi together - OSGi Enterprise Expert Group (EEG)
  • Using existing Java SE/EE specifications:
    • JTA, JPA, JNDI, JMX, WebApps, SCA
    • Framework integrates with the Java EE programming model
  • Adds Spring-derived component model and dependency injection container – Blueprint Container




what s happening with osgi ee
What’s happening with OSGi EE
  • Apache “Aries” - new Apache incubator project
    • deliver set of pluggable Java components enabling an enterprise OSGi application programming model.
  • Eclipse Enterprise Modules (“Gemini”)
    • collection of subprojects, each of which is an implementation or integration of an enterprise-level technology
  • Virgo - Dynamic Enterprise Application Platform
    • provide a runtime platform for development of server-side enterprise applications
blueprint components and service
Blueprint Components and Service
  • Specifies a Dependency Injection container, standardizing established Spring conventions
  • Specifies components can be wired together within a bundle
  • Components can be published as services to the service registry
  • Components configuration and dependencies injected them Blueprint component container ( part of the runtime environment)
  • Configuration and dependencies declared in XML “module blueprint”
blueprint components and service1
Blueprint Components and Service
  • •Extended for OSGi: publishes and consumes components as OSGi services
  • Blueprint standardizes the configuration metadata, and brings governance to the specification of the component model.
  • Simplifies unit test outside either Java EE or OSGi r/t.
  • The Blueprint DI container is a part of the server runtime (compared to Spring which is part of the application.)

dependencies injected



Blueprint managed bundle

Blueprint managed bundle

Blueprint Components(POJO)

the java persistence api
The Java Persistence API
  • JPA is a POJO based Object Relational Mapping Framework
  • – defines an API for persisting
  • objects into a Relational Database
  • – API for retrieving Objects
  • from the database
  • JPA - rich API for mapping
  • arbitrarily complex objects to the underlying database tables
the jpa service specification
The JPA Service Specification
  • An OSGi specification for making JPA work in an OSGi framework
  • Core concepts:
  • > Persistence Bundle : An OSGi bundle containing managed classes a persistence descriptor and a Meta-Persistence manifest header
  • > Meta-Persistence header : – A header that defines the locations of persistence descriptors in a bundle
  • > EntityManagerFactory service : An EntityManagerFactory available as an OSGi service
  • > Persistence Client : A bundle that makes use of an EntityManagerFactory service.
  • > EntityManagerFactory builder : A factory for incomplete persistence units
remote services
Remote Services
  • Extending the OSGi framework to configure existing distributed computing software systems
  • Describes how to distribute OSGi services
  • Ability for OSGi services to invoke services running in other JVMs
  • Support enterprise application topologies for availability, reliability, and scalability

Enables Distributed


web applications specification
Web Applications Specification
  • Defines how to support the Servlet 2.5 and JavaServer Pages (JSP) 2.1 specifications in OSGi
  • Provide deployment of existing and new web applications to Servlet containers operating on the OSGi service platform
  • Specification defines the Web Application Bundle, a bundle that performs the same role as the WAR in Java EE
web applications specification1
Web Applications Specification
  • WAB uses the OSGi life cycle and class/resource loading rules instead of the standard Java EE environment
  • Details web application packaged as a WAR may be installed into an OSGi Service Platform
sca configuration
SCA Configuration
  • Provides an assembly model for distributed applications and systems using a service oriented architecture
  • Components that are assembled can be written in different technologies for example Java EE, BPEL, C++, and scripting languages
  • Execute on different machines, and can communicate through different protocols and technologies
  • Declarative application metadata to enable reflection of an SCA component type definition
sca configuration1
SCA Configuration
  • Remote Services specification provides an extendable model for configuration types
  • SCA Configuration Type Specification defines such a configuration type
osgi on cloud
OSGi on Cloud
  • Investigation underway to find possibility of using OSGi in the context of cloud computing (RFP 133 Cloud Computing)


Software as a Service


Platform as a Service


Infrastructure as a Service

osgi on cloud1
OSGi on Cloud
  • Value of OSGi : ability to address the following
  • - Dependency management
  • - Provisioning/Configuration (Remote services API)
  • - Extensible, modular system
  • - Dynamic replacement of components

Major Java infrastructures

support OSGi modular


support apps designed &

deployed as bundles



Key for Infrastructure

Bundle as module


separation of concerns


Consider as Universal



OSGi increasingly

relevant to Enterprise

OSGi and Cloud

Synergy having interesting


  • OSGi Core Spec
  • OSGi Enterprise Spec

That’s all folks


Thank You

Santosh Kumar