Open Services Gateway Initiative slides from Kiev JavaDay 2012 (27 October) Conference

1. OSGi platform
Yuriy Shapovalov
EPAM Systems

2. What is it?
“The Open Services Gateway initiative framework is a
module system and service platform for the Java programming
language that implements a complete and dynamic component model,
something that as of 2012 does not exist in standalone Java/VM
environments.” – Wikipedia
OSGi Platform

3. … module system …
“The Open Services Gateway initiative framework is a
module system and service platform for the Java programming
language that implements a complete and dynamic component model,
something that as of 2012 does not exist in standalone Java/VM
environments.” – Wikipedia
OSGi Platform

4. … service platform …
“The Open Services Gateway initiative framework is a
module system and service platform for the Java programming
language that implements a complete and dynamic component model,
something that as of 2012 does not exist in standalone Java/VM
environments.” – Wikipedia
OSGi Platform

5. … for Java programming language …
“The Open Services Gateway initiative framework is a
module system and service platform for the Java programming
language that implements a complete and dynamic component model,
something that as of 2012 does not exist in standalone Java/VM
environments.” – Wikipedia
OSGi Platform

6. …complete and dynamic component model …
“The Open Services Gateway initiative framework is a
module system and service platform for the Java programming
language that implements a complete and dynamic component
model, something that as of 2012 does not exist in standalone
Java/VM environments.” – Wikipedia
OSGi Platform

7. … does not exist in standalone Java/VM …
“The Open Services Gateway initiative framework is a
module system and service platform for the Java programming
language that implements a complete and dynamic component
model, something that as of 2012 does not exist in standalone
Java/VM environments.” – Wikipedia
OSGi Platform

8. OSGi history
o Initially was developed as an embedded platform for the “home
gateway”;
o and make it easier to deploy Java application on embedded devices
o OSGi Alliance was formed in 1999, and it has following mission:
• Maintaining and publishing OSGi specification
• Certifying implementations
• Organizing events.
o Specification target was: “Define Java-based service platform, full
dynamic component model”
• Because JVM does not support natively dynamic module system
– starting, stopping, updating application at runtime
• JAR dependencies management missing
OSGi Platform
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9. The Dream
o Adaptive
B
C
D
E
F
G
H
I
o Flexible
o Contracts
o Robust
o Secure
o Evolution
o Distributed
OSGi Platform
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10. The Dream
 Adaptive
o Flexible
A
B
C
D
E
F
G
H
I
o Contracts
o Robust
o Secure
o Evolution
o Distributed
OSGi Platform
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11. The Dream
 Adaptive
o Flexible
A
B
C
D
E
F
G
H
I
o Contracts
o Robust
o Secure
o Evolution
o Distributed
OSGi Platform
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12. The Dream
 Adaptive
 Flexible
A
Ba
Bb
C
o Contracts
o Robust
D
E
F
G
H
I
o Secure
o Evolution
o Distributed
OSGi Platform
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13. The Dream
 Adaptive
 Flexible
A
Ba
Bb
C
o Contracts
o Robust
D
E
F
G
H
I
o Secure
o Evolution
o Distributed
OSGi Platform
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14. The Dream
 Adaptive
 Flexible
A
Ba
Bb
C
 Contracts
o Robust
D
E
F
G
H
I
o Secure
o Evolution
o Distributed
OSGi Platform
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15. The Dream
 Adaptive
 Flexible
A
Ba
Bb
C
 Contracts
o Robust
D
E
F
G
H
I
o Secure
o Evolution
o Distributed
OSGi Platform
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16. The Dream
 Adaptive
 Flexible
A
Ba
Bb
C
 Contracts
 Robust
D
E
G
F
H
o Secure
o Evolution
o Distributed
OSGi Platform
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17. The Dream
 Adaptive
 Flexible
A
Ba
Bb
C
 Contracts
 Robust
D
E
G
F
H
o Secure
o Evolution
o Distributed
OSGi Platform
17/42

18. The Dream
 Adaptive
 Flexible
A
Ba
Bb
C
 Contracts
 Robust
D
E
G
F
H
 Secure
o Evolution
o Distributed
OSGi Platform
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19. The Dream
 Adaptive
 Flexible
A
Ba
Bb
C
 Contracts
 Robust
D
E
G
F
H
 Secure
o Evolution
o Distributed
OSGi Platform
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20. The Dream
 Adaptive
 Flexible
A
Ba
Bb
C
 Contracts
 Robust
D
E
F
G
H
I v2.0
 Secure
o Evolution
o Distributed
OSGi Platform
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21. The Dream
 Adaptive
 Flexible
A
Ba
Bb
C
 Contracts
 Robust
D
E
F
G
H
I v2.0
 Secure
 Evolution
o Distributed
OSGi Platform
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22. The Dream
 Adaptive
 Flexible
A
Ba
Bb
C
 Contracts
 Robust
D
E
F
G
H
I v2.0
 Secure
 Evolution
o Distributed
OSGi Platform
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23. The Dream
 Adaptive
 Flexible
A
Ba
Bb
 Contracts
 Robust
D
E
F
 Secure
 Evolution
 Distributed
G
OSGi Platform
I v2.0
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24. What is an OSGi application
o Collection of bundles integrated via Service interfaces
o Bundles may be independently developed and deployed
o Bundles and their associated services may appear or
disappear at any time
o Resulting application follows a Service-Oriented
Component Model approach
o Combines Ideas from both component and service orientation
OSGi Platform
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25. Architecture abstraction
o Application is a set of independent components,
collaborating between each other in a service orienting
way.
Application
A
C
D
B
E
OSGi Platform
F
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26. Architecture abstraction
o Application implement reduced functionality, all
additional features implements as plug-ins
C
A
Application
B
D
E
OSGi Platform
F
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27. Architecture abstraction
o or even…
Application
A
B
A
C
B
D
E
OSGi Platform
D
E
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28. Next level of modularity
Subroutines
(50’s)
×
×
×
×
Focus on “what”, not “how”
Encapsulate the implementation details
Formalize the input data (arguments)
Formalize the output data (return values)
OSGi Platform
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29. Next level of modularity
Input (arguments)
function
Output (return)
Then systems grew…
Functions
Subroutines
(50’s)
Spaghetti Code
OSGi Platform
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30. Next level of modularity
Imported Functions
Module
Exported Functions
Then systems grew…
Modules
(70’s)
Functions
Subroutines
(50’s)
Sharing Proved Hard
OSGi Platform
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31. Next level of modularity
Imported Members
Type
Exported Members
Then systems grew…
Classes/Objects (80’s)
Modules
(70’s)
Functions
Subroutines
(50’s)
OSGi Platform
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32. Next level of modularity
Imported Types
Packages
(90’s)
Type
Exported Types
Then and multiplies
…… systems grew…
and distributed
Classes/Objects (80’s)
Modules
(70’s)
Functions
Subroutines
(50’s)
OSGi Platform
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33. Next level of modularity
Small Java App …
OSGi Platform
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34. Next level of modularity
Bundles
Packages
(00’s)
(90’s)
Classes/Objects (80’s)
Modules
Imported Packages
Bundle
(JAR file)
Exported Packages
(70’s)
Functions
Subroutines
(50’s)
OSGi Platform
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35. Bundle
o A Bundle - is a module in OSGi terminology
o What is a bundle?
• Simply a JAR file plus module metadata
• Modules metadata is stored in META-INF/MANIFEST.MF
• Define what the module provides and require
o What does a bundle JAR contain?
• Java classes (i.e., standard JAR file content)
• Resources (e.g., configuration files, images, etc.)
• Native code
• Embedded JAR files
• Bundles have their own class path
OSGi Platform
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36. OSGi architecture
Application composite
(Bundles)
OSGi Layer
Service
Bundle
Bundle
Bundle
Life Cycle
Bundle
Bundle
Module
Bundle
Bundle
Security
Java VM
OS / Hardware
OSGi Platform
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37. Life cycle of bundles
INSTALLED
STARTING
RESOLVED
ACTIVE
UNINSTALLED
STOPPING
OSGi Platform
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38. Services System
o Services are simple POJOs with a published service interface
o Coupling to the framework is isolated to the Activator and
collaborators
o Services may bind to other services through their published
interfaces
o The framework provides a standard Service Factory mechanism
track
publish
Bundle A
Bundle B
Service Registry
track
publish
Bundle C
Service
OSGi Platform
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39. OSGi Bundle Manifest
Bundle-ManifestVersion: 2
Bundle-SymbolicName: org.foo.simplebundle
Bundle-Version: 1.0.0
Bundle-Activator: org.foo.Activator
Bundle-ClassPath: .,org/foo/embedded.jar
Bundle-NativeCode: libfoo.so; osname=Linux; processor=x86,
foo.dll; osname=Windows 7; processor=x86
Import-Package:o sgi.service.log; version="[1.0.0,1.1.0)";
resolution:="optional"
Export-Package: org.foo.service; version=1.1; vendor="org.foo:";
exclude:="*Impl", org.foo.service.bar; version=1.1; uses:="org.foo.service"
OSGi Platform
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40. OSGi Bundle Manifest
Bundle-ManifestVersion: 2
Bundle-SymbolicName: org.foo.simplebundle
Bundle-Version: 1.0.0
Indicates semantic
Bundle-Activator: org.foo.Activator and syntax
Bundle-ClassPath: .,org/foo/embedded.jar
Bundle-NativeCode: libfoo.so; osname=Linux; processor=x86,
foo.dll; osname=Windows 7; processor=x86
Import-Package:o sgi.service.log; version="[1.0.0,1.1.0)";
resolution:="optional"
Export-Package: org.foo.service; version=1.1; vendor="org.foo:";
exclude:="*Impl", org.foo.service.bar; version=1.1; uses:="org.foo.service"
OSGi Platform
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41. OSGi Bundle Manifest
Bundle-ManifestVersion: 2
Bundle-SymbolicName: org.foo.simplebundle
Bundle-Version: 1.0.0
Bundle-Activator: org.foo.Activator
Indicates semantic
Globally unique ID
and syntax
Bundle-ClassPath: .,org/foo/embedded.jar
Bundle-NativeCode: libfoo.so; osname=Linux; processor=x86,
foo.dll; osname=Windows 7; processor=x86
Import-Package:o sgi.service.log; version="[1.0.0,1.1.0)";
resolution:="optional"
Export-Package: org.foo.service; version=1.1; vendor="org.foo:";
exclude:="*Impl", org.foo.service.bar; version=1.1; uses:="org.foo.service"
OSGi Platform
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42. OSGi Bundle Manifest
Bundle-ManifestVersion: 2
Bundle-SymbolicName: org.foo.simplebundle
Bundle-Version: 1.0.0
Bundle-Activator: org.foo.Activator
Bundle-ClassPath: .,org/foo/embedded.jar
Bundle-NativeCode: libfoo.so; osname=Linux; processor=x86,
Life cycle entry
foo.dll; osname=Windows 7; processor=x86
point
Import-Package:o sgi.service.log; version="[1.0.0,1.1.0)";
resolution:="optional"
Export-Package: org.foo.service; version=1.1; vendor="org.foo:";
exclude:="*Impl", org.foo.service.bar; version=1.1; uses:="org.foo.service"
OSGi Platform
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43. OSGi Bundle Manifest
Bundle-ManifestVersion: 2
Bundle-SymbolicName: org.foo.simplebundle
Bundle-Version: 1.0.0
Bundle-Activator: org.foo.Activator
Bundle-ClassPath: .,org/foo/embedded.jar
Bundle-NativeCode: libfoo.so; osname=Linux; processor=x86,
foo.dll; osname=Windows 7; processor=x86
Internal bundle
Import-Package:o sgi.service.log; version="[1.0.0,1.1.0)";
class path
resolution:="optional"
Export-Package: org.foo.service; version=1.1; vendor="org.foo:";
exclude:="*Impl", org.foo.service.bar; version=1.1; uses:="org.foo.service"
OSGi Platform
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44. OSGi Bundle Manifest
Bundle-ManifestVersion: 2
Bundle-SymbolicName: org.foo.simplebundle
Bundle-Version: 1.0.0
Native code
Bundle-Activator: org.foo.Activator dependencies
Bundle-ClassPath: .,org/foo/embedded.jar
Bundle-NativeCode: libfoo.so; osname=Linux; processor=x86,
foo.dll; osname=Windows 7; processor=x86
Import-Package:o sgi.service.log; version="[1.0.0,1.1.0)";
resolution:="optional"
Export-Package: org.foo.service; version=1.1; vendor="org.foo:";
exclude:="*Impl", org.foo.service.bar; version=1.1; uses:="org.foo.service"
OSGi Platform
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45. OSGi Bundle Manifest
Bundle-ManifestVersion: 2
Bundle-SymbolicName: org.foo.simplebundle
Bundle-Version: 1.0.0
Bundle-Activator: org.foo.Activator
Optional
Bundle-ClassPath: .,org/foo/embedded.jar
dependency on a
package version
Bundle-NativeCode: libfoo.so; osname=Linux; processor=x86,
range
foo.dll; osname=Windows 7; processor=x86
Import-Package: osgi.service.log; version="[1.0.0,1.1.0)";
resolution:="optional"
Export-Package: org.foo.service; version=1.1; vendor="org.foo:";
exclude:="*Impl", org.foo.service.bar; version=1.1; uses:="org.foo.service"
OSGi Platform
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46. OSGi Bundle Manifest
Bundle-ManifestVersion: 2
Bundle-SymbolicName: org.foo.simplebundle
Bundle-Version: 1.0.0
Bundle-Activator: org.foo.Activator
Bundle-ClassPath: .,org/foo/embedded.jar
Provided package with
Bundle-NativeCode: libfoo.so; osname=Linux; processor=x86,
foo.dll; osname=Windows 7;arbitrary attribute and
processor=x86
excluded classes
Import-Package:o sgi.service.log; version="[1.0.0,1.1.0)";
resolution:="optional"
Export-Package: org.foo.service; version=1.1; vendor="org.foo:";
exclude:="*Impl", org.foo.service.bar; version=1.1; uses:="org.foo.service"
OSGi Platform
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47. OSGi Bundle Manifest
Bundle-ManifestVersion: 2
Bundle-SymbolicName: org.foo.simplebundle
Bundle-Version: 1.0.0
Bundle-Activator: org.foo.Activator
Bundle-ClassPath: .,org/foo/embedded.jar
Bundle-NativeCode: libfoo.so; osname=Linux; processor=x86,
Provided package with
foo.dll; osname=Windows 7; processor=x86
dependency on
Import-Package:o sgi.service.log; exported package
version="[1.0.0,1.1.0)";
resolution:="optional"
Export-Package: org.foo.service; version=1.1; vendor="org.foo:";
exclude:="*Impl", org.foo.service.bar; version=1.1; uses:="org.foo.service"
OSGi Platform
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48. Declarative Services
o Declarative services provides a minimally intrusive way to:
• Define components that provide and use services
• Automate dependency resolution and maintenance
package foo.impl;
public class HelloImpl implements foo.HelloService {
LogService log;
protected void setLog(LogService l) {
log = l;
}
protected void unsetLog(LogService l) {
log = null;
}
public void sayHello(String s) {
log.log(LogService.LOG_INFO, "Hello " + s);
}
}
OSGi Platform
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49. Declarative Services
o Declarative services component metadata:
<?xml version="1.0" encoding="UTF-8"?>
<component name="example.hello">
<implementation class="foo.impl.HelloImpl"/>
<service>
<provide interface="foo.HelloService"/>
</service>
<reference name="LOG"
interface="org.osgi.service.log.LogService"
bind="setLog"
unbind="unsetLog"
/>
</component>
OSGi Platform
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50. OSGi implementations
o Specification it is good, but without implementation it
is a dead stuff
o The most popular open source implementation is:
• Equinox
• Apache Felix
• Knopflerfish
OSGi Platform
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51. OSGi in Enterprise (as example)
o Why?
• Create modular and reusable software
• Create evolvable software
• Create line of products
o What?
•
•
•
•
•
•
Desktop Applications
Web Applications
Service Layers
Content Management Systems
Embedded and Mobile Applications
Cloud Applications
OSGi Platform
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52. Conclusions
o Java needs improved modularity support
• Lagging behind .NET in this area for years
• The OSGi framework provides it now
o Importance and relevance of OSGi is growing
• Industry support for mobile applications
• Significant uptake in the enterprise space
OSGi Platform
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53. Questions?
OSGi Platform
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