Automated Versioning In OSGi

Automated Versioning in OSGi: a Mechanism for Component Software Consistency Guarantee
Jaroslav Bauml & PremekBrada
Dept of Computer Science
University of West Bohemia
Pilsen, Czech Republic

Jaroslav Bauml& PremekBrada

Jaroslav Bauml &PremekBrada

Automated Versioning in OSGi: Component Software Consistency Guarantee

Automated Versioning in OSGi: Component Software Consistency Guarantee
Reliable and Automated

Introduction
Component updates reﬂect their evolution.
Application consistency during updates
Used and suitable solution – dependencies with version ranges of providers.
BUT!!! How reliable are these version identifiers to real evolution of component?
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Brada & Bauml: Reliable Versioning
I have a new version of the Cool component
And will it work properly?
Who knows…
Ask those guys from Pilsen!

Agenda
OSGi as Research Platform
Version Identifiers and their Semantics
Subtyping as Key Solution for Automatic Versioning
Implementation
Validation – Real world example
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OSGi as ResearchPlatform – Overview
Hyped Java-based framework for service deployment and management.
Deployable unit – bundle – jar+
Two layers of Dependencies
Package/– export
Service/– import
major.minor.micro version scheme – semantics?
Rulesfor OSGi:
All incompatible changes <=> majorid++.
All backward compatible <=> minor id++.
No changes on interface <=> microid++.
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<BUNDLEFILE>META-INF/MANIFEST.MF:
Bundle-Version: 1.0.0
Bundle-Name: Apache Felix File Install
Export-Package: org.apache.felix.fileinstall;version="1.2",...
Import-Package: org.osgi.service.log;version="1.3",...
...

Subtyping as KeySolution (1)
Can use Car instead of Vehicle. Car is a subtype of …
A compatiblewithB <=>B <: A
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Difference values: NON, MUT, SPE, GEN

evaluate at leaves
combine to root:

spe ⊕ gen -> mut
mut ⊕ X -> mut
non ⊕ X -> X
Brada & Bauml: ReliableVersioning

Subtyping as KeySolution (2)
Two consecutive revisions, versions:
Rold =majold.minold.micold
Rnew = majnew.minnew.micnew
The function Diﬀerence (Rold,Rnew) is deﬁned by the rulesin the table.
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Exp.: OLD Loggerwas 1.2.4, wefoundMutation => NEW Logger‘s version = 2.0.0

ImplementationofSubtypingforOSGi(1)
Twolayers
Bundle
Java
Operations of subtyping comparison
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ImplementationofSubtypingforOSGi (2)
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Bundle layer
Simple not complete metamodel for OSGi
Java layer – JavaTypes
Custom model of Java language type system
Inspired by Java Reflection Api
But can be obtained from: reflection, bytecode inspection, custom creation, …
Caching, lazy loading, recursion in types detection

Validation – Real World Bundles
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To provide a basic validation of proposed principle, implemented tool was tested on bundles from Apache Felix archive.
Brada & Bauml: ReliableVersioning

Conclusion
Our method
allows you to ensure component consistency
possible by component type representation
as strong as type information allows (semantic changes)
“No matter how sophisticated a (versioning) scheme is, it is useless if it is not used by all components universally.”
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Thankyouforyourattention
Do not hesitate to visit usat:
http://www.kiv.zcu.cz/research/groups/dss/
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