Why Have The OSGi Specifications Been Based On Java

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Why Have The OSGi Specifications Been Based On
Java Technology?ByPeter Kriens, CEO
aQuteOSGi Technology Officer
www.aQute.se
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Content

• Interpreted and Compiled languages
• Detailed look at Issues
• Comparison with .NET
• Conclusion

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Interpreted Languages

• Interpreter/VM is between source code and CPU
• Java is an interpreter with a defined executable
  format VM

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Portability
Interpreted
Compiled
Java
Source code
Source code
Source code
Compiler
javac
Interpreter
VM
VM
Interpreter
CPU
CPU
CPU
CPU
CPU
CPU

• Interpreters are easier to port to other
  environments
• No Source Code changes required

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Illegal Access To Memory
Interpreted
Compiled
Java
Source code
Source code
Source code
Compiler
javac
Interpreter
VM
CPU
CPU
CPU

• No Illegal Access Reduces security threats,
  Improves stability
• No (more) memory exceptions and buffer overruns

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Versioning
Interpreted
Compiled
Java
Source code
Source code
Source code
Compiler
javac
Interpreter
VM
CPU
CPU
CPU

• Solves many version issues Simpler deployment
• No More Requires version 5.12.1.4-kwt
• Interpreters use symbolic linking more robust

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Type Problems Detection
Interpreted
Compiled
Java
Source code
Source code
Source code
Compiler
javac
Interpreter
VM
CPU
CPU
CPU

• Early detection of bugs improved productivity
• Accidental and intended type violations
• Java finds all type errors, and many early

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Performance
Interpreted
Compiled
Java
Source code
Source code
Source code
Compiler
javac
Interpreter
VM
CPU
CPU
CPU

• Pre-processing reduces overhead faster startup
• Compiled code is most efficient
• JIT techniques can reduce the performance gap

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Too Many Libraries ...

• Foundation library One App for all platforms!
• Problems increase exponentially!
• Java very well defined, including run-time

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Do It Right versus Performance

• Cannot perform hacks security versus performance
• Traditional code has hacks that perform well
• Hacks increase maintenance cost and field problems

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Life Cycle Management

• Loading policy defined in application code
  Flexibility
• Used by the OSGi specifications
• Policies implemented by application code

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Security
Application A
Verify permissions for resource x
Application B
Application C
method foo
SecurityManager
resource x

• Language includes security check Safe code
• Prevents against viruses and worms
• First language with built-in security architecture

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But What About Microsofts .NET ?
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What is .NET?
Windows CE .NET
SOAP
.NET Passport
C
Windows Forms
ADO.NET
Visual Studio .NET
CLI
CLR
Microsoft .NET speech
ASP.NET
Web Services
Visual Basic .NET
.NET Framework
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Java versus .NET CLI/CLR

• Java VM technology is similar to .NET C
• But the Java environment is
• More mature
• Not controlled by a single vendor JCP
• Applicable for embedded devices
• Coherent environment (single syntax)
• Exists for virtually every OS in existence, today
• Runs the OSGi specifications!

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Conclusion

• Portability
• Safety and security features
• Increased productivity
• Class loaders make OSGi possible
• Interpreted language is the right choice for the
  OSGi
• Should we use Java today again?
• YES!

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Questions ? Contact Peter.Kriens_at_aQute.se