Why OSGi?
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The document discusses why OSGi is important for developing software. It notes that the amount of software is doubling every 7 years, making modularity and flexibility more critical. OSGi aims to provide a better way to develop software that is adaptive, flexible, uses contracts and services, supports evolution and distribution. It discusses the history of concepts like subroutines, modules, objects, and packages that aimed to improve modularity. OSGi bundles take this further by allowing modularization at the package and service level. This achieves the dream of fully decoupled modules through the use of APIs and services. OSGi is presented as an important investment to support modularity as software growth continues exponentially.
Why OSGi?
- 1. Why OSGi? BJ Hargrave, IBM Peter Kriens, aQute
- 2. Agenda • Why OSGi? • The Dream • Looking for Shoulders • Java & Packages • OSGi Bundles & Services • Conclusion
- 3. Why OSGi?
- 4. Why OSGi? Scriptorium
- 5. Why OSGi? … because there should be a better way to develop software ...
- 6. Why OSGi? 2010 2003 1996 1989 1982 1982 1975 1968 1961 Amount of software doubling every 7 years source: http://users.jyu.fi/~koskinen/smcosts.htm
- 7. 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
- 8. The Dream
- 9. The Dream • Adaptive • Flexible B C • Contracts • Robust D E F • Secure • Evolution G H I • Distributed
- 10. The Dream • Adaptive • Flexible A B C • Contracts • Robust D E F • Secure • Evolution G H I • Distributed
- 11. The Dream • Adaptive • Flexible A Ba B Bb C • Contracts • Robust D E F • Secure • Evolution G H I • Distributed
- 12. The Dream • Adaptive • Flexible A Ba Bb C • Contracts • Robust D E F • Secure • Evolution G H I • Distributed
- 13. The Dream • Adaptive • Flexible A Ba Bb C • Contracts • Robust D E F • Secure • Evolution G H I • Distributed
- 14. The Dream • Adaptive • Flexible A Ba Bb C • Contracts • Robust D E F • Secure • Evolution G H I • Distributed
- 15. The Dream • Adaptive • Flexible A Ba Bb C • Contracts • Robust D E F • Secure • Evolution G H I • Distributed
- 16. The Dream • Adaptive • Flexible A Ba Bb C • Contracts • Robust D E F • Secure • Evolution G H • Distributed
- 17. The Dream • Adaptive • Flexible A Ba Bb C • Contracts • Robust D E F • Secure • Evolution G H • Distributed
- 18. The Dream • Adaptive • Flexible A Ba Bb C • Contracts • Robust D E F • Secure • Evolution G H • Distributed
- 19. The Dream • Adaptive • Flexible A Ba Bb C • Contracts • Robust D E F • Secure • Evolution G H • Distributed
- 20. The Dream • Adaptive • Flexible A Ba Bb C • Contracts • Robust D E F • Secure • Evolution G H I v2.0 • Distributed
- 21. 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
- 22. 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
- 23. The Dream • Adaptive • Flexible A Ba Bb • Contracts • Robust D E F • Secure S;1.1.0 • Evolution G H I v2.0 • Distributed
- 24. Cambridge in the 50’s
- 25. Cambridge in the 50’s “As soon as we started programming, we found to our surprise that it wasn't as easy to get programs right as we had thought.” “… the realization came over me with full force that a good part of the remainder of my life was going to be spent finding errors in my own programs.” Maurice Wilkes
- 26. Subroutines
- 27. Subroutines Subroutines
- 28. Subroutines • Subroutine: • Focus on what, not how • Encapsulate the implementation details • Formalized the input data (arguments) • Formalized the output (return values)
- 29. Subroutines • Abstraction • Easier to understand • Less Code • Fewer Errors • Sharing • Simpler Maintenance (depends …)
- 30. Subroutines
- 31. Functions
- 32. Functions Function
- 33. Functions Input (arguments) Function
- 34. Functions Input Output (arguments) (return) Function
- 35. Functions Private Input Output (arguments) (return) Function
- 38. Spaghetti Code
- 39. Pittsburg 70’s
- 40. Pittsburg 70’s “ … modularization as a mechanism for improving the flexibility and comprehensibility of a system while allowing the shortening of its development time.” David Parnas
- 41. Modules
- 42. Modules Module
- 43. Modules Private Functions Imported Exported Functions Functions Module
- 49. Palo Alto 80’s
- 50. Palo Alto 80’s “Objects support modularity - the functioning of an object does not depend on the internal details of another object. The complexity of the system is reduced by this minimization of interdependencies of system components.” Smalltalk Team
- 51. Objects
- 52. Objects Private Members Imported Exported Members Members Type
- 53. Objects • Objects/Classes => Modules + • Instantiation (private data per instance) • Inheritance • Polymorphism
- 56. C++
- 57. Menlo Park 90’s
- 58. Menlo Park 90’s
- 59. Packages “Chapter 7 describes the structure of a program, which is organized into packages similar to the modules of Modula.” Java Language Specification
- 60. Packages Private Types Imported Exported Types Types Packages
- 63. And Distributed
- 64. And Distributed
- 65. And Multiplied
- 66. And Multiplied
- 67. Small Java App ...
- 68. Worldwide 00’s
- 69. Worldwide 00’s
- 70. Worldwide 00’s
- 71. Next Level of Modularity
- 72. Next Level of Modularity Functions
- 73. Next Level of Modularity Classes/Objects Functions
- 74. Next Level of Modularity Packages Classes/Objects Functions
- 75. Next Level of Modularity Bundles Packages Classes/Objects Functions
- 76. Next Level of Modularity Bundles Packages Classes/Objects Functions
- 77. Bundles Private Packages Imported Exported Packages Packages Bundle (JAR file)
- 78. Type Coupling
- 79. Type Coupling
- 81. Type Coupling
- 82. Type Coupling substitutable packages = API
- 83. Instance Coupling Consumer Bundle Provider Bundle
- 84. Instance Coupling Consumer Bundle Provider Bundle API Bundle
- 85. Instance Coupling Consumer Bundle Provider Bundle need an instance ... API Bundle
- 86. Instance Coupling Consumer Bundle Provider Bundle X need an instance ... API Bundle
- 88. Instance Coupling Consumer Bundle Provider Bundle Service API Bundle
- 89. A Dream Come True A B C D E F G H I
- 90. Why OSGi? … because it is a better way to develop software ...
- 91. Conclusion 2010 2003 2017 1996 1989 1982 1982 1975 1968 1961 Amount of software doubling every 7 years source: http://users.jyu.fi/~koskinen/smcosts.htm
- 92. 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!
- 93. 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
- 94. 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
- 95. Q&A