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Why OSGi?

by bjhargrave on Oct 06, 2011

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Presentation by Peter Kriens and BJ Hargrave at JavaOne 2011.

Presentation by Peter Kriens and BJ Hargrave at JavaOne 2011.

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Why OSGi? — Presentation Transcript

Why OSGi? BJ Hargrave, IBM Peter Kriens, aQute
Agenda• Why OSGi?• The Dream• Looking for Shoulders• Java & Packages• OSGi Bundles & Services• Conclusion
Why OSGi?
Why OSGi? Scriptorium
Why OSGi?… because there should be a better way to develop software ...
Why OSGi? 2010 2003 1996 1989 1982 1982 1975 1968 1961 Amount of software doubling every 7 yearssource: http://users.jyu.fi/~koskinen/smcosts.htm
Why OSGi?2010 2003 1996 1989 2017 1982 1982 1975 1968 1961 Amount of software doubling every 7 years source: http://users.jyu.fi/~koskinen/smcosts.htm
The Dream
The Dream• Adaptive• Flexible B C• Contracts• Robust D E F• Secure• Evolution G H I• Distributed
The Dream• Adaptive• Flexible A B C• Contracts• Robust D E F• Secure• Evolution G H I• Distributed
The Dream• Adaptive• Flexible A Ba B Bb C• Contracts• Robust D E F• Secure• Evolution G H I• Distributed
The Dream• Adaptive• Flexible A Ba Bb C• Contracts• Robust D E F• Secure• Evolution G H I• Distributed
The Dream• Adaptive• Flexible A Ba Bb C• Contracts• Robust D E F• Secure• Evolution G H I• Distributed
The Dream• Adaptive• Flexible A Ba Bb C• Contracts• Robust D E F• Secure• Evolution G H I• Distributed
The Dream• Adaptive• Flexible A Ba Bb C• Contracts• Robust D E F• Secure• Evolution G H I• Distributed
The Dream• Adaptive• Flexible A Ba Bb C• Contracts• Robust D E F• Secure• Evolution G H• Distributed
The Dream• Adaptive• Flexible A Ba Bb C• Contracts• Robust D E F• Secure• Evolution G H• Distributed
The Dream• Adaptive• Flexible A Ba Bb C• Contracts• Robust D E F• Secure• Evolution G H• Distributed
The Dream• Adaptive• Flexible A Ba Bb C• Contracts• Robust D E F• Secure• Evolution G H• Distributed
The Dream• Adaptive• Flexible A Ba Bb C• Contracts• Robust D E F• Secure• Evolution G H I v2.0• Distributed
The Dream• Adaptive• Flexible A Ba Bb C• Contracts• Robust D E F• Secure S;1.1.0• Evolution G H I v2.0• Distributed
The Dream• Adaptive• Flexible A Ba Bb C• Contracts• Robust D E F• Secure S;1.1.0• Evolution G H I v2.0• Distributed
The Dream• Adaptive• Flexible A Ba Bb• Contracts• Robust D E F• Secure S;1.1.0• Evolution G H I v2.0• Distributed
Cambridge in the 50’s
Cambridge in the 50’s“As soon as we started programming, we found toour surprise that it wasnt as easy to get programsright as we had thought.”“… the realization came over me with full force thata good part of the remainder of my life was going tobe spent finding errors in my own programs.” Maurice Wilkes
Subroutines
Subroutines Subroutines
Subroutines• Subroutine: • Focus on what, not how • Encapsulate the implementation details • Formalized the input data (arguments) • Formalized the output (return values)
Subroutines• Abstraction • Easier to understand• Less Code • Fewer Errors• Sharing • Simpler Maintenance (depends …)
Subroutines
Functions
Functions Function
Functions Input(arguments) Function
Functions Input Output(arguments) (return) Function
Functions Private Input Output(arguments) (return) Function
Then Systems Grew
Then Systems Grew
Spaghetti Code
Pittsburg 70’s
Pittsburg 70’s“ … modularization as a mechanism for improvingthe flexibility and comprehensibility of a systemwhile allowing the shortening of its developmenttime.” David Parnas
Modules
Modules Module
Modules Private FunctionsImported ExportedFunctions Functions Module
Then Systems Grew
Then Systems Grew
Sharing Proved Hard
Sharing Proved Hard
Sharing Proved Hard
Palo Alto 80’s
Palo Alto 80’s“Objects support modularity - the functioning of anobject does not depend on the internal details ofanother object. The complexity of the system isreduced by this minimization of interdependenciesof system components.” Smalltalk Team
Objects
Objects Private MembersImported ExportedMembers Members Type
Objects• Objects/Classes => Modules + • Instantiation (private data per instance) • Inheritance • Polymorphism
Then Systems Grew
Then Systems Grew
C++
Menlo Park 90’s
Menlo Park 90’s
Packages“Chapter 7 describes the structure of a program,which is organized into packages similar to themodules of Modula.” Java Language Specification
Packages Private TypesImported Exported Types Types Packages
Then Systems Grew
Then Systems Grew
And Distributed
And Distributed
And Multiplied
And Multiplied
Small Java App ...
Worldwide 00’s
Worldwide 00’s
Worldwide 00’s
Next Level of Modularity
Next Level of Modularity Functions
Next Level of Modularity Classes/Objects Functions
Next Level of Modularity Packages Classes/Objects Functions
Next Level of Modularity Bundles Packages Classes/Objects Functions
Next Level of Modularity Bundles Packages Classes/Objects Functions
Bundles Private PackagesImported ExportedPackages Packages Bundle (JAR file)
Type Coupling
Type Coupling
Download the Internet
Type Coupling
Type Coupling substitutable packages = API
Instance CouplingConsumer Bundle Provider Bundle
Instance CouplingConsumer Bundle Provider Bundle API Bundle
Instance CouplingConsumer Bundle Provider Bundle need an instance ... API Bundle
Instance CouplingConsumer Bundle Provider Bundle X need an instance ... API Bundle
Instance Coupling
Instance CouplingConsumer Bundle Provider Bundle Service API Bundle
A Dream Come True A B C D E F G H I
Why OSGi?… because it is a better way to develop software ...
Conclusion2010 2003 2017 1996 1989 1982 1982 1975 1968 1961 Amount of software doubling every 7 years source: http://users.jyu.ﬁ/~koskinen/smcosts.htm
OSGi• Legacy and backward compatibility is important• Modularizing is hard • Many popular Java patterns are fundamentally not modular• In the next 7 years, we double the amount of software• Investment in modularity has a great ROI!
OSGi Alliance• The OSGi Alliance is a non-profit that has the vision to develop a Java component model to ease software development • Comprehensive framework specification • Service specifications • An active community • Repository • Tools
Join!• Help us to achieve our vision to make software simpler to develop• Provide Requirements• Develop speciﬁcations• Help the community• OSGi Alliance restructured to provide lower-cost membership levels
Q&A