Presentation by Tom Watson (IBM) at OSGi DevCon 2012 BOF (22 March, 2012) Video recording of presentation is available at http://youtu.be/3uq729vFQEc Enterprise OSGi 4.2 standardized the use of a number of component models for developing Enterprise OSGi applications: Servlet, JSP, Blueprint, and JPA. Implementations of these specifications have since become available in many open source projects and products such as Apache Aries, Eclipse Gemini/Virgo, GlassFish, JBoss Application Server and WebSphere Application Server. Looking at a number of these environments, it's clear that when it comes to assembly and deployment there's still something missing, namely something to represent a collection of bundles (e.g. an Application). Eclipse Virgo has "PARs" and "Plans", Apache Aries has "Applications", and WebSphere Application Server has “Applications” and “Composites”. Looking further afield to kernel projects, other bundle collection concepts exist, such as Apache Karaf "Features". Each model has concepts in common, such as identity, versioning and content, but also differences like isolation and format. It is clear that this is an area of Enterprise OSGi that could benefit from standardization and hence the Subsystems specification is being created for the Enterprise OSGi 5.0 specification. Subsystems is an OSGi specification which standardizes artifacts representing collections of bundles, such as an Application. This presentation will introduce the Subsystems design. It will describe how Subsystems can be used for development and deployment of bundle collections with different isolation semantics, to address the application, composite and feature use cases seen in the OSGi community today. The OSGi framework provides a powerful runtime for the Java platform, which promotes strong modularity, versioning and dynamic management of bundles. Bundles installed in the framework are expected to collaborate and live together sharing the same service registry and public class space. Until now there was no standard way to provide additional isolation and lifecycle to a collection of bundles installed in a single framework. This presentation will discuss how the subsystems specification can be used to provide additional isolation to a collection of bundles or applications installed into the framework.

1. Subsystems:
for those occasions where bundles are just too small
Tom Watson
IBM
March 27st 2012
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COPYRIGHT © 2008-2012 OSGi Alliance. All Rights Reserved, © IBM Corp. 2012

2. Agenda
Motivation
Model
Types
Meta-data
Packaging
Life-cycle and API
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3. Motivation
Enterprise Java platforms are awash with bundle
collections
Apache Aries – Applications
Apache Geronimo - Applications
Apache Karaf – Features
Eclipse Virgo – Plans, PARs
IBM WebSphere Application Server – Applications and
Composite
Oracle GlassFish – Applications
Paremus Service Fabric – Systems
Crying out for standardization
Portability
Tools
Ecosystem
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4. Subsystem Model: Hierarchy
Subsystem Hierarchy
Each has 1 or more parents (except
root)
subsystem
root
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5. Subsystem Model: Hierarchy
Subsystem Hierarchy
Each has 1 or more parents (except
root)
Each can have many children subsystem
root
S1 S2
S3
S4 S5
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6. Subsystem Model: Hierarchy
Subsystem Hierarchy
Each has 1 or more parents (except
root)
Each can have many children subsystem
Each is contained in a Region region
root
Regions
Provides isolation for a group of one S1 S2
or more subsystems
Defined by a scoped subsystem S3
S4 S5
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7. Subsystem Model: Sharing Policies
Scoped subsystems control
the sharing policy bundle
requirement
capability
root
A B
Y Y
S1 S2
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8. Subsystem Model: Sharing Policies
Scoped subsystems control
the sharing policy bundle
A region provides isolation requirement
capability
root
A X B
Y Y
S1 S2
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9. Subsystem Model: Sharing Policies
Scoped subsystems control
the sharing policy bundle
A region provides isolation requirement
Selectively export capabilities to the capability
parent
root
exports Y
A B
Y Y
S1 S2
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10. Subsystem Model: Sharing Policies
Scoped subsystems control
the sharing policy bundle
A region provides isolation requirement
Selectively export capabilities to the capability
parent
root
Selectively import capabilities from the
parent
imports Y exports Y
A B
Y Y
S1 S2
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11. Subsystem Model: Sharing Policies
Scoped subsystems control
the sharing policy bundle
A region provides isolation requirement
Selectively export capabilities to the capability
parent
root
Selectively import capabilities
from the parent
Unscoped subsystems
share everything with other imports Y exports Y
subsystems contained in the same A B
region Y Y
S1 S2
U1 C
Y
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12. Subsystem Types: Features
Collection of Resources (e.g.
Bundles)
A C
B D
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13. Subsystem Types: Features
Collection of Resources (e.g.
Bundles)
Shared life-cycle
A C
B D
F1 F2
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14. Subsystem Types: Features
Collection of Resources (e.g.
Bundles)
Shared life-cycle
Can have children
A C
B D
F1 F2
F
F3
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15. Subsystem Types: Features
Collection of Resources (e.g.
Bundles)
Shared life-cycle
Can have children
A C
No scoping, able to share
B D
resources shared
E resource E
F1 F2
F
F3
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16. Subsystem Types: Features
Collection of Resources (e.g.
Bundles)
Shared life-cycle S1
Can have children
A C
No scoping, able to share
B D
resources shared
E resource E
Must be contained within a F1 F2
region
F
F3
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17. Subsystem Types: Features
Collection of Resources (e.g.
Bundles)
Shared life-cycle S1
Can have children
A C
No scoping, able to share
B D
resources shared
E resource E
Must be contained within a F1 F2
region
F
Examples: Karaf Features, F3
Virgo unscoped Plans
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18. Subsystem Types: Composite
Coarse-grained sub-assembly
module
X X
Y Y
C1 C2
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19. Subsystem Types: Composite
Coarse-grained sub-assembly
module
Explicit export and import of
capabilities (e.g. packages, Root
services)
Import X Import Y
Export Y Export X
X X
Y Y
C1 C2
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20. Subsystem Types: Composite
Coarse-grained sub-assembly
module
Explicit export and import of
capabilities (e.g. packages, Root
services)
Composed of Resources (e.g.
Bundles) Import X Import Y
Export Y Export X
A C
X X
B D
Y Y
C1 C2
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21. Subsystem Types: Composite
Coarse-grained sub-assembly
module
Explicit export and import of
capabilities (e.g. packages, Root
services)
Composed of Resources (e.g.
Bundles) Import X Import Y
Export Y Export X
Scoped
A C
X X
B D
Y Y
E E
C1 C2
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22. Subsystem Types: Composite
Coarse-grained sub-assembly
module
Explicit export and import of
capabilities (e.g. packages, Root
services)
Composed of Resources (e.g.
Bundles) Import X Import Y
Export Y Export X
Scoped
A C
Examples: RFC 138 Composite X X
Bundles*, WebSphere B D
Y Y
Composite Bundles E E
C1 C2
*old design prior to resolver hooks
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23. Subsystem Types: Application
Used for composing hosted
applications using
Resources (e.g. Bundles)
A C
X X
B E E B
Y Y Y Y
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24. Subsystem Types: Application
Used for composing hosted
applications using
Resources (e.g. Bundles)
Scoped
A C
X X
B E E B
Y Y Y Y
A1 A2
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25. Subsystem Types: Application
Used for composing hosted
applications using
Resources (e.g. Bundles) C Root
Scoped
No exporting capabilities,
implicit imports of
dependencies A
X X
C
B E E B
Y Y Y Y
A1 A2
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26. Subsystem Types: Application
Used for composing hosted
applications using
Resources (e.g. Bundles) C Root
Scoped
No exporting capabilities,
implicit imports of
dependencies A
X X
C
Examples: Aries Application, B E E B
Virgo Scoped Plans,
Virgo PARs Y
A1
Y Y
A2
Y
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27. Example Combination
Subsystem Types can be A1 A2
G H
mixed ‘n’ matched X X
F F
Example shows:
Features used to assemble a Composite
C1
Composite providing a ‘platform’ to
Applications
A C
X X
B D
Y Y
E E
F1 F2
Root
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28. Subsystem Meta-data
Manifest format with relaxed rules
OSGI-INF/SUBSYSTEM.MF
Some headers unique to Subsystem type
Common concepts use same headers
Headers cover:
Identity and type
Content
Sharing policy
Human readable information
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29. Subsystem Meta-data: Identity Headers
Identified by
symbolic name Manifest-Version: 1.0
Subsystem-ManifestVersion: 1.0
version Subsystem-SymbolicName:
my.first.subsystem
Subsystem-Version: 1.0.0
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30. Subsystem Meta-data: Type Header
Type governs the sharing policy
Standard Types:
Manifest-Version: 1.0
osgi.subsystem.application Subsystem-ManifestVersion: 1.0
osgi.subsystem.composite Subsystem-SymbolicName:
my.first.subsystem
osgi.subsystem.feature Subsystem-Version: 1.0.0
Subsystem-Type:
One directive specified for osgi.subsystem.application;
controlling where dependencies provision-policy:=acceptDependencies
are installed
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31. Content
Identifies the resources contained
in the Subsystem Manifest-Version: 1.0
Subsystem-ManifestVersion: 1.0
Resources identified by name, Subsystem-SymbolicName:
my.first.Subsystem
version (range) and type Subsystem-Version: 1.0.0
Composites only allow fixed versions Subsystem-Type:
osgi.subsystem.application;
Standard types provision-policy:=acceptDependencies
Subsystem-Content:
osgi.bundle (default) an.osgi.bundle1;version="[1.0, 1.1)",
osgi.fragment an.osgi.subsystem;
type=osgi.subsystem.application;
subsystem types version="[1.2, 1.3)"
Can be optional
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32. Explicit Sharing Manifest-Version: 1.0
Subsystem-ManifestVersion: 1.0
Subsystem-Name: A Composite Subsystem
Subsystem-Description:
This is a Composite Subsystem
Subsystem-SymbolicName: my.first.composite
Subsystem-Version: 1.0.0
Subsystem-Type: osgi.subsystem.composite
Subsystem-Content:
Composite subsystems share an.osgi.bundle1;version="[1.0, 1.0]",
an.osgi.bundle2;version="[1.0, 1.0]"
nothing unless explicitly Subsystem-ExportService:
stated exported.service.Interface;
filter:="(color=blue)"
Re-use existing bundle Subsystem-ImportService:
headers where applicable imported.service.Interface
Export-Package:
Not applicable for implicitly an.exported.pkg;version="1.0"
isolated subsystems (i.e. Import-Package:
an.imported.pkg;version="[1.0, 2.0)"
Features and Applications) Require-Bundle:
a.required.bundle;
bundle-version="[1.0, 2.0)"
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33. Informational
Headers for humans Manifest-Version: 1.0
Subsystem-ManifestVersion: 1.0
Subsystem-Name: First Subsystem
Subsystem-Description:
This is my first ever Subsystem and
it's sooo cool.
Subsystem-SymbolicName:
my.first.subsystem
Subsystem-Version: 1.0.0
Subsystem-Type:
osgi.subsystem.application;
provision-policy:=acceptDependencies
Subsystem-Content:
an.osgi.bundle;version="[1.0, 1.1)",
an.osgi.subsystem;
type:=osgi.subsystem.application;
version="[1.2, 1.3)"
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34. Portability
Subsystem Manifests are
portable to a point
Target Environment + Transitive
Dependencies must support the Subsystem Definition
required resource implementation
types (e.g. Blueprint, WAB, DS, etc)
Deployment manifests may be Dependencies
portable
Different Target Environments likely to
require different Transitive Target Environment
Dependencies
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35. Packaging
Packaged in a Subsystem my.first.subsystem.esa
Archive
A zip file with .esa extension: OSGI-INF/SUBSYSTEM.MF
Subsystem Manifest (optional)
OSGI-INF/DEPLOYMENT.MF
Deployment Manifest (optional)
Resources
(optional) an.osgi.bundle-1.0.0.jar
an.osgi.bundle2-1.0.0.jar
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36. Subsystem Service
Life-cycle management A1 A2
Install, start, stop, uninstall
G H
Each subsystem logically F F
has it’s own Subsystem A1 A2
service
Navigation C1
getParents, getChildren, getConstituents
Introspection A C1, F1, F2 C
(A1, A2)
getHeaders, getState, getSymbolicName,
getVersion, getLocation B D
F1 F2
(ALL) Root
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37. Subsystem Lifecycle: Installing
Root Subsystem Service
(Subsystem)
Root
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38. Subsystem Lifecycle: Installing
Root Subsystem Service
used to install subsystems
A1
installing
install()
(Subsystem)
Root
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39. Subsystem Lifecycle: Installing
Root Subsystem Service
used to install subsystems
Repository based provisioning
A1
installing
install()
(Subsystem)
Root
A, B, C, D,
E, F, G
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40. Subsystem Lifecycle: Installing
Root Subsystem Service
used to install subsystems
Repository based provisioning
Content Resources (specified by A1
Subsystem-Content header) A
B
installing
install()
(Subsystem)
Root
A, B, C, D,
E, F, G
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41. Subsystem Lifecycle: Installing
Root Subsystem Service
used to install subsystems
Repository based provisioning
Content Resources (specified by A1
Subsystem-Content header) A
Dependencies B
installing
E install()
(Subsystem)
F
Root
A, B, C, D,
E, F, G
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42. Subsystem Lifecycle: Installing
Root Subsystem Service
used to install subsystems
Repository based provisioning
Content Resources (specified by A1
Subsystem-Content header) A
Dependencies B
installed
E
(Subsystem)
F
Root
A, B, C, D,
E, F, G
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43. Subsystem Lifecycle: Installing
Root Subsystem Service
used to install subsystems
Repository based provisioning
Content Resources (specified by A1 A2
Subsystem-Content header) A C
Dependencies B D
Share capabilities installed installed
E G
(Subsystem)
F
Root
A, B, C, D,
E, F, G
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44. Subsystem Lifecycle: Starting
Subsystem Service
used to start subsystems start()
A1 A2
A C
B D
E G
F
Root
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45. Subsystem Lifecycle: Starting
Subsystem Service
used to start subsystems start()
Effect on referenced resources
A1 A2
A C
B D
starting
E G
F
Root
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46. Subsystem Lifecycle: Starting
Subsystem Service
used to start subsystems start()
Effect on referenced resources
Dependencies are started when one A1 A2
subsystem that uses them is
started A C
B D
starting
E G
F
Root
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47. Subsystem Lifecycle: Starting
Subsystem Service
used to start subsystems start()
Effect on referenced resources
Dependencies are started when one A1 A2
subsystem that uses them is
started A C
Content resources are started
B D
starting
E G
F
Root
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48. Subsystem Lifecycle: Starting
Subsystem Service
used to start subsystems start()
Effect on referenced resources
Dependencies are started when one A1 A2
subsystem that uses them is
started A C
Content resources are started
B D
active
E G
F
Root
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49. Subsystem Lifecycle: Starting
Subsystem Service
used to start subsystems
Effect on referenced resources
Dependencies are started when one A1 A2
subsystem that uses them is
started A C
Content resources are started
B D
active active
E G
F
Root
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50. Subsystem Lifecycle: Stopping
Subsystem Service
used to stop a subsystem stop()
A1 A2
A C
B D
active active
E G
F
Root
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51. Subsystem Lifecycle: Stopping
Subsystem Service
used to stop a subsystem stop()
Effect on referenced resources
A1 A2
A C
B D
stopping started
E G
F
Root
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52. Subsystem Lifecycle: Stopping
Subsystem Service
used to stop a subsystem stop()
Effect on referenced resources
Content resources are stopped A1 A2
A C
B D
stopping started
E G
F
Root
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53. Subsystem Lifecycle: Stopping
Subsystem Service
used to stop a subsystem stop()
Effect on referenced resources
Content resources are stopped A1 A2
Dependencies are stopped when no
subsystems that use them are A C
active
B D
stopping started
E G
F
Root
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54. Subsystem Lifecycle: Stopping
Subsystem Service
used to stop a subsystem
Effect on referenced resources
Content resources are stopped A1 A2
Dependencies are stopped when no
subsystems that use them are A C
active
B D
resolved started
E G
F
Root
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55. Subsystem Lifecycle: Stopping
Subsystem Service
used to stop a subsystem stop()
Effect on referenced resources
Content resources are stopped A1 A2
Dependencies are stopped when no
subsystems that use them are A C
active
B D
resolved started
E G
F
Root
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56. Subsystem Lifecycle: Stopping
Subsystem Service
used to stop a subsystem
Effect on referenced resources
Content resources are stopped A1 A2
Dependencies are stopped when no
subsystems that use them are A C
active
B D
resolved resolved
E G
F
Root
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57. Subsystem Lifecycle: Uninstalling
Subsystem Service
used to uninstall a subsystem uninstall()
A1 A2
A C
B D
resolved resolved
E G
F
Root
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58. Subsystem Lifecycle: Uninstalling
Subsystem Service
used to uninstall a subsystem uninstall()
Effect on referenced resources
A1 A2
A C
B D
uninstalling resolved
E G
F
Root
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59. Subsystem Lifecycle: Uninstalling
Subsystem Service
used to uninstall a subsystem uninstall()
Effect on referenced resources
Content resources are uninstalled A1 A2
A C
B D
uninstalling resolved
E G
F
Root
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60. Subsystem Lifecycle: Uninstalling
Subsystem Service
used to uninstall a subsystem uninstall()
Effect on referenced resources
Content resources are uninstalled A1 A2
Dependencies are uninstalled when
no subsystem is installed that uses C
them
D
uninstalling resolved
E G
F
Root
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61. Subsystem Lifecycle: Uninstalling
Subsystem Service
used to uninstall a subsystem
Effect on referenced resources
Content resources are uninstalled A1 A2
Dependencies are uninstalled when
no subsystem is installed that uses C
them
D
uninstalled resolved
G
F
Root
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62. Subsystem Lifecycle: Uninstalling
Subsystem Service
used to uninstall a subsystem uninstall()
Effect on referenced resources
Content resources are uninstalled A1 A2
Dependencies are uninstalled when
no subsystem is installed that uses C
them
D
uninstalled resolved
G
F
Root
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63. Subsystem Lifecycle: Uninstalling
Subsystem Service
used to uninstall a subsystem
Effect on referenced resources
Content resources are uninstalled A1 A2
Dependencies are uninstalled when
no subsystem is installed that uses
them
uninstalled uninstalled
Root
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64. Summary
Subsystems are the standard way to manage groups of
resources
Repository based provisioning of subsystem content and
dependencies
Subsystem types define sharing semantics
API enables management of Subsystem life-cycle
Standardized meta-data and packaging (.esa file)
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65. Trademarks
ational Business Machines Corp., registered in many jurisdictions worldwide.
tered trademarks of Oracle and/or its affiliates.
companies. A current list of IBM trademarks is available on the Web at “Copyright
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