17-811 Self-Healing Systems: Class Discussion Summary

Summary of Class Discussion for April 21 by Sukanya Ratanotayanon

Formal approach
        - how to specify system using logic algebra
        - how to make a structure and behavior of component

Specifying Distributed SW Arch.
        - Darwin can be view as a specific architectural style
        - How could people use darwin to specify public/subscribe ?
                - specify a special connector
                - model event as a component
        - Distinction between binding and connector
                - acme/ explicitly specify connector
                - darwin/ binding implicit in the interface
        - Dynamic component creation
                - how to terminate
                - how to do the dynamically configuration
        - Fig 9.
                - no port in the box outside poller
                        - no explicit binding specify
                        - may be because it's dynamically created
        - what criteria to choose the dynamic instantiation
        - using ¶-calculus for binding
                - underscore = port/channel
                - binding = handshaking two components at runtime
                - behavior refers to binding of components not how they interact
        - How do they specify a specific system change
                - conic = a shell to do binding and unbinding
        - how to have binding from outside & inside from multiple port
                - acme - could specify a special type of binding
                        - but not provide the solid tool for binding
                        - binding does not provide semantic in understanding the communication
                          between outside component
                        - capture more abstract idea than binding
                        - can think of binding as semantic link
                - for architecture-based, there's a need to change the structure at runtime
                - Pi calculus
                        - flexible
                        - can execute but not really analyzable ( to flexible to reason about the system)

Architecture Primitives for Distributed and Mobility
        - want to specify the movement in the system, moving or resource change
        - specify what the component do at runtime
        - User component
                - is designed as - 1 input/ 1 output / 4 action
                - makes a state transition to local state with input, and throw the output according to the state change

        - Connector
                - example connector in paper - being a channel that connect the components
                - take multiple name and rename it to one name to represent them
                - can define behavior with the action in connector
        - How to adapt to component moving
                - environment told component about change
                - component can make it own decision where to go when the environement change

Another approach to formal stuff

                        -----------------
                        |                        |
                        |         Spec       |
                        |            <--      |
                        -----------------
                                |  |
                                |  | Refinement
                        -----------------
                        |       -->           |
                        |     System       |
                        |                       |
                        -----------------
        - define a certain relationship between spec and system
        control example
        - given all behavior in spec, can it causes system to become deadlock