With the release of the OSGi Enterprise Specification we now have defined what an application is in the context of OSGi rather than a traditional application server, think JEE. Running multiple applications in the same OSGi framework requires some form of isolation and visibility boundaries, which the subsystem specifications describes in detail. In a real world example of implementing a enterprise integration solution based on OSGi we found that the complexity of the metadata demanded by the subsystems spec can be overwhelming and hindering to customers. In this talk we outline an alternative approach to providing application isolation that is based on the location of the artifacts. The implementation relies on the same OSGi framework hooks as does the Subsystems specification. We will demonstrate the simplicity and advantages of the solution in comparison to the Subsystems spec. Any enterprise vendor considering adoption of OSGi is facing this very same problem and will be on the lookout for the best solution on behalf of their customers. We expect the audience to gain a better understanding of the current landscape and the alternatives in implementations. Bio: Tim is a Principal Architect at TIBCO Software Inc. working on the next generation of the flag ship enterprise integration product BusinessWorks. This award winning product has base of over 4000 customers around the globe. In his role he is responsible for the application hosting environment based on OSGi and the administration of the product. Tim has served as the co-chairman of the OSGi Enterprise Expert Group since its inception in 2006. He has been a regular speaker at EclipseCon/OSGi DevCon since 2007.

1. © Copyright 2000-2014 TIBCO Software Inc.
Application Isolation
Is there an alternative to Subsystems?
Tim Diekmann!
Principal Architect
TIBCO Software Inc.
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2. © Copyright 2000-2014 TIBCO Software Inc.
Disclaimer
Any of the TIBCO ActiveMatrix BusinessWorks materials presented here is
subject to change without notice. This document is TIBCO proprietary
information.
!
This document (including, without limitation, any product roadmap or
statement of direction data) illustrates the planned testing, release and
availability dates for TIBCO products and services. This document is
provided for informational purposes only and its contents are subject to
change without notice.
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TIBCO makes no warranties, express or implied, in or relating to this
document or any information in it, including, without limitation, that this
document, or any information in it, is error-free or meets any conditions
of merchantability or fitness for a particular purpose.
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Overview
• why multiple applications
• brief history of approaches
• OSGi solution
• why another solution
• Alternative OSGi solution
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Why multiple applications?
… in a single JVM that is
• save memory (objects and classes)
• reduce management and monitoring overhead
• save CPU on startup and load of applications
• multiple applications vs multi-tenancy
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very brief History
• web resources
• web applications
• JEE application servers
• application servers like Apache Karaf, Eclipse
Virgo, Paremus Service Fabric, IBM WebSphere,
etc.
• what are applications?
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“Application software is all the computer
software that causes a computer to perform
useful tasks beyond the running of the computer
itself.”
Wikipedia - http://en.wikipedia.org/wiki/Application_software
Application Definition

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* in the context of this presentation, Java, and OSGi
• packaged software deployed to an app server:
• versioned unit of release/maintenance
• providing coherent business function
• with a common life cycle
• possibly modular in composition
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my Application Definition*

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Problems
• no isolation
• same OS process, OutOfMemoryErrors, in-memory access
to other application data
• trade-off between sharing versus protecting
• no accounting
• unwanted side effects
• unit of certified deliverable
• cannot possibly test all potential interactions
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Approaches
• servlet bridge
• nested / child OSGi frameworks
• Apache Karaf
• Eclipse features
• Eclipse Virgo
• IBM WebSphere, Paremus Service Fabric
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• Deployment Admin Service, Application Admin Service (older)
• nested OSGi framework
• Subsystems
• part of Enterprise Specification, introduced in R5
• based on experience in Eclipse Equinox, Virgo, Apache Aries, and
others
• explicit model of sharing policies: share all, share selected, share
nothing
• visibility boundaries for services, packages, events
• implementation boundary already provided by OSGi service model
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OSGi Approaches

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• rich metadata supports large number of use cases
• common life cycle for constituents
• declarative approach
• independent of OSGi implementation
• reduces memory consumption by sharing
• supports dynamic resolution and installation of applications
• unresolved deployment
• SUBSYSTEM.MF vs DEPLOYMENT.MF
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Advantages

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SUBSYSTEM.MF
Example of Subsystems Metadata
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Manifest-Version: 1.0!
Subsystem-ManifestVersion: 1.0!
Subsystem-Name: Bank Account!
Subsystem-SymbolicName: com.mybank.account.app!
Subsystem-Version: 1.0!
Subsystem-Type: osgi.subsystem.application!
Subsystem-Content: !
com.mybank.account.bankWeb; version=1.0.0,!
com.mybank.account.bankAccount; version=1.0.0,!
com.mybank.account.common; version=1.0.0,!
com.mybank.account.utility; version=1.0.0!
Use-Bundle: com.mybank.account.admin;version="[1.0.0,2.0.0)"!
Subsystem-ExportService: com.mybank.account.service.AccountService!
Subsystem-ImportService:!
com.mybank.security.UserAuthService;filter="(security=strong)"

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Drawbacks
• complicated
• complex policy definitions
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Drawbacks
• complicated
• complex policy definitions
• configuration vs convention
• missing tooling: details exposed to users, application developers
• issues with common infrastructure services
• e.g. Configuration Admin, Event Admin, Declarative Services, Blueprint and other extenders
• application is aware of subsystem environment, not functional in OSGi environment
without it
• modular applications require updates of metadata in multiple places
• think distributed application development
• dynamic changes to the application
• subsystem needs to be started to share code
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SUBSYSTEM.MF
Drawbacks
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Manifest-Version: 1.0!
Subsystem-ManifestVersion: 1.0!
Subsystem-Name: Bank Account!
Subsystem-SymbolicName: com.mybank.account.app!
Subsystem-Version: 1.0!
Subsystem-Type: osgi.subsystem.application!
Subsystem-Content:!
com.mybank.account.bankWeb; version=1.0.0,!
com.mybank.account.bankAccount; version=1.0.0,!
com.mybank.account.common; version=1.0.0,!
com.mybank.account.utility; version=1.0.0!
Use-Bundle: com.mybank.account.admin;version="[1.0.0,2.0.0)"!
Subsystem-ExportService: com.mybank.account.service.AccountService!
Subsystem-ImportService:!
com.mybank.security.UserAuthService;filter="(security=strong)"

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Subsystems Improvements
• enhancements worked out in RFC 201 scheduled for
a later release of the Enterprise Specification
• header localization
• weaving hook integration / interaction
• provide deployment manifest at install time
• improve API for management agent
• determine service dependencies of applications
• revisit rules for preferred provider and application resolution
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Alternative
• use existing ResolverHook, BundleCollisionHook,
EventHook, FindHook etc
• model common infrastructure, shared libraries,
applications based on file system location
• use bundle location to identify source
• apply visibility rules based on location
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Layering
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OSGi framework
JVM
Product Infrastructure
Shared SW Shared SW
Application Application Application

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File System Layout
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OSGi framework
JVM
Product Infrastructure
Shared SW Shared SW
Application Application Application
$JAVA_HOME
~/product/lib
~/libs
~/apps

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Solution
• file system is source of truth for deployment
• use the JVM as-is with its boot and ext class loaders
• place product code in one folder or structure
• e.g. system or product
• place common infrastructure code in separate folder
• place shared libraries in separate folders
• not necessarily part of the product, separate lifecycle
• place applications in separate folders
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Visibility Boundaries
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OSGi framework
JVM
Product Infrastructure
Shared SW Shared SW
Application Application Application

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Advantages
• simple
• understandable
• changeable, flexible
• structured by location in file system
• no other metadata required
• unless you want to model other dependencies and
visibility boundaries
• compatible
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Implementation
• different strategies possible
• multi-tier level visibility
• sensitive vs public services and code
• visibility boundaries enforced via ResolverHooks,
EventHooks, FindHooks, even WaevingHooks
• change strategy via configuration
• support multiple singletons if required by business
logic, e.g. static variables in common classes
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Disadvantages
• may not support all complex use cases
• requires additional metadata to support finer grain
sharing policies
• too simple?
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TIBCO ActiveMatrix BusinessWorksTM 6
Real World Example

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• ESB product, hosting multiple applications in single
OSGi based runtime environment
• install product in one folder
• install applications in a different folder
• determine visibility and accessibility based on
folder location
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TIBCO BusinessWorksTM 6

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Entitites
• product
• BusinessWorks 6
• palettes (part of the product)
• ~16 Palettes
• product extensions
• palettes like salesforce.com, Twitter, etc.
• applications
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Folder Layout
product layout:
system contains all product code
ext contains links to product extensions
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application layout:
grouped in AppSpaces
versioned
contains code and configuration

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Visibility Boundaries
• product is self-contained in system folder
• does not get wired outside of system folder
• product extensions are able to see and use anything in
product folder
• can also supply their own versions of infrastructure bundles
• visible to all applications
• palettes sit above product and product extensions
• applications sit above palettes
• can provide infrastructure that is confined to application
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Visibility Boundaries
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OSGi framework
JVM
BW framework
Application Application Application
BW extensions BW palettes

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Applications
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Application
Module
Module
Module
Application
Module
Module
Module

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Specifics
• separate public from internal APIs
• product internals are hidden from upper layers
• application support provided by Eclipse based designer
• additional application metadata
• application identification and versioning
• dependency management
• same hotfix mechanism for product as well as
applications and extensions
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Hotfixing
• simple, file system based
• system/hotfix folder repeats structure under system
• any files in hotfix override files in original location
• works for outer flat class path as well as OSGi class
path environments
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the end
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questions?

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References
• OSGi Alliance, http://www.osgi.org
• OSGi Core Specification, http://www.osgi.org/Download/File?url=/download/r5/
osgi.core-5.0.0.pdf
• Enterprise Specification, http://www.osgi.org/Download/File?url=/download/r5/
osgi.enterprise-5.0.0.pdf
• Introduction to Java Multitenancy, http://www.ibm.com/developerworks/library/j-
multitenant-java/
• Apache Aries, https://aries.apache.org
• wikipedia.org, http://en.wikipedia.org/wiki/OSGi
• Equinox Regions, Mind the Gap Blog, http://underlap.blogspot.com/2011/02/stumbling-
towards-better-design.html
• Paremus Service Fabric, http://www.paremus.com/products/products_psf.html
• TIBCO ActiveMatrix BusinessWorks 6, http://www.tibco.com/products/automation/
application-integration/activematrix-businessworks/default.jsp
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