1. Daniel Lohmann Department of Computer Science IV Distributed Systems and Operating Systems Friedrich-Alexander University Erlangen-Nuremberg http://www4.cs.fau.de/~lohmann daniel.lohmann@cs.fau.de Architecture-Neutral Operating System Components

2. 2 daniel.lohmann@cs.fau.de The Tyranny of OS Architectures Architecture defines fundamental properties and policies  Module structure and interaction schemes  Scheduling and locking strategies  Interrupt handling and synchronization  Supported hardware platforms  … Architecture is considered as something static  Decisions are made at early stages of OS development  Extremely costly to adapt later

3. 3 daniel.lohmann@cs.fau.de But why... shouldn’t it be possible to configure architectural properties? Optimize a server OS for a dedicated services demands Taylor down an embedded systems OS Cope better with architectural evolution

4. 4 daniel.lohmann@cs.fau.de Interaction The Problem Architectural properties are inherent crosscutting Synchronization

5. 5 daniel.lohmann@cs.fau.de Aspect-Oriented Programming AOP has proven to be successful in dealing with crosscutting concerns With AspectC++ it is now possible to use AOP for system software development Synchronization Interaction Module BModule C Module A OS Modules Code Aspect Code «uses» Aspect Weaver http://www.aspectc.org «uses» Module BModule C Module A Generated OS Code «uses»

6. 6 daniel.lohmann@cs.fau.de The CiAO Project (CiAO is Aspect Oriented) Aspect-oriented family of operating systems  Methods: Feature modeling, static configuration, AOP  Encapsulation of policies and architectural properties Target: Embedded Systems  From deeply-embedded devices up to embedded UNIX-like systems  High level of adaptability and configurability Architectural Transparency

7. 7 daniel.lohmann@cs.fau.de The CiAO Vision: Architectural Transparency Operating System Construction Set Module BModule C «uses» Module A Synchronisation Interaction Abstract Component CodeSets of Aspects

8. 8 daniel.lohmann@cs.fau.de The CiAO Vision: Architectural Transparency Configuration 1: Procedure-based, multithreaded Module BModule CModule A Call address space Synchronisation Interaction Generated Component Code Used Aspects Semaphore Procedure call

9. 9 daniel.lohmann@cs.fau.de The CiAO Vision: Architectural Transparency Configuration 2: Message-based, one thread per module Message address space Module BModule CModule A Synchronisation Interaction Used Aspects «none» Message (local) Generated Component Code

10. 10 daniel.lohmann@cs.fau.de The CiAO Vision: Architectural Transparency Configuration 3: Message-based, one process per module Message Module BModule CModule A Synchronisation Interaction Used Aspects «none» Message (IPC) Generated Component Code

11. 11 daniel.lohmann@cs.fau.de Conclusion Architectural properties are inherent crosscutting Aspect-Oriented Software Development can help  AspectC++ brings AOP to the C/C++ world  Encapsulation without sacrificing efficiency Real chance to reach architectural transparency http://www.aspectc.org

12. Daniel Lohmann Department of Computer Science IV Distributed Systems and Operating Systems Friedrich-Alexander University Erlangen-Nuremberg http://www4.cs.fau.de/~lohmann daniel.lohmann@cs.fau.de Thanks for your attention!