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Execution Architecture

Foundations of Software Architecture : Module 4. Execution Architecture. John Reekie University of Technology, Sydney. Contributors. Lian Loke, University of Technology, Sydney Rohan McAdam, Honeywell Inc. . Terms of Use: Creative Commons Attribution-ShareAlike 2. 5

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Execution Architecture

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  1. Foundations of Software Architecture : Module 4 Execution Architecture John Reekie University of Technology, Sydney Contributors Lian Loke, University of Technology, Sydney Rohan McAdam, Honeywell Inc. Terms of Use: Creative Commons Attribution-ShareAlike 2.5 http://creativecommons.org/licenses/by-sa/2.5/

  2. An elephant with a view • Structure • Compute nodes • Processes • Subsystems • Activity • Behavior • Communication The execution architecture focuses on the “run-time” structures that exist in the system.

  3. Conceptual vs execution Conceptual Architecture Execution Architecture Domain-level responsibilities Unit of concurrent activity Component Invocation relationship Flow of information Connector View Single view Multiple views

  4. Component relationships This is a simplified and idealized (but useful) diagram.

  5. When you do it Inception Elaboration I Elaboration II Conceptual architecture Execution architecture Implementation architecture A close-up view of a possible Unified Process instance.

  6. What is concurrent activity? • When two actions occur “simultaneously”. • In actuality, the activities are time-sliced into a single processor. • Concurrency needs are often related to time: • Waiting for something • Working at the same time • When does the event occur?

  7. When to use concurrency Locate components on different processors ++ Scalability Waiting for a slow external device ++ Performance Independent development and compilation of components ++ Maintainability

  8. Processes and threads • A more “concrete” execution unit than concurrent subsystems • Map directly to operating system processes and threads Process Thread Own memory space Shared memory space Communicate by shared data structures Communicate via IPC, pipes, sockets Visible to most O/S utilities Not so visible

  9. Activity stereotypes • How is concurrent activity initiated? • By user action • By an active thread or threads of control • In response to a request

  10. Communication • Arrows indicate an invocation relationship • Synchronous • Asynchronous • Callback

  11. Concurrent subsystems • A large-grained unit of execution • Database • Web/application server • Real-time disk recorder • A concurrent subsystem may: • Exhibit significant (and complex) internal concurrency • Consist of a number of processes, which may be both static and dynamic

  12. Concurrent subsystems view • Contains only concurrent subsystems • The highest-level execution view of the system A simple audio processing system

  13. An example • A foley and sound-editing system

  14. Process view • Shows only processes • A process is the real unit of deployment • The process view shows exactly how the software system is allocated to hardware units • Operating system utilities “understand” processes • May be more palatable to traditional systems designers - ?

  15. Dynamic concurrency • Processes or threads are created and destroyed in response to operating conditions Dynamic concurrency is best illustrated by judicious use of use-case maps!

  16. To deploy v.t. • de·ploy (dĭ –ploi´)v.de·ployed,de·ploy·ing,de·ploys v.tr. • 1. • To position (troops) in readiness for combat, as along a front or line. • To bring (forces or material) into action. • To base (a weapons system) in the field. • 2.To distribute (persons or forces) systematically or strategically. • 3.To put into use or action: “Samuel Beckett's friends suspected that he was a genius, yet no one knew... how his abilities would be deployed” (Richard Ellmann). http://www.dictionary.com

  17. Shrink-wrap Buy a piece of software and install it on your own computer

  18. Client-managed Buy one or more pieces of software and install it on your own servers and clients

  19. Physical architecture • A simple audio-processing embedded system The physical architecture shows the key hardware elements of the system—as relevant to the software architecture

  20. Deployment view A deployment view shows the mapping of software elements onto hardware elements

  21. Deployment example • A concurrent subsystems view overlaid on a (simplified) physical view • Processes map to a single processing node • Subsystems map to one or more processing nodes • Replication to show scalability

  22. That’s all folks! • Questions or comments?

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