Oracle-based Mode-change Propagation in Hierarchical Components.

Transcription

1 Oracle-based Mode-change Propagation in Hierarchical Components. Tomas Pop, Frantisek Plasil, Matej Outly, Michal Malohlava, Tomas Bures CHARLES UNIVERSITY IN PRAGUE faculty of mathematics and physics

2 Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 2 Motivation Example Civilization search

3 Motivation Example Civilization search Phases of execution Init, Search, TDisc Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 3

4 Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 4 Motivation Example Civilization search Several phases of execution INIT, Search, TDisc Corresponding architecture Architecture variants

5 Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 5 Motivation Example Civilization search Several phases of execution INIT, Search, TDisc Corresponding architecture Architecture variants

6 Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 6 Motivation Mass production of hardware Cents matter Optimization for minimal software resource demands Use only what is needed Allows for deployment on low-cost hardware Mode switching at run-time

7 Problem Statement Switching of architecture variants (modes) in component based control systems is challenging Must not be demanding at run-time Mode relevant information is spread among multiple components E.g., state of multiple sensors and other components Handwritten architecture modifications are complex and error prone Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 7

8 Challenges Relation specification in respect to composability Generation of mode-transition automata for composed system Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 8

9 What Will Be the Seminar About? Formal model allowing for an efficient mode switching in hierarchical component system Composability of the mechanism Not polluting existing interfaces Feasible and predictable time and space complexity Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 9

10 Strategy Identify relevant part of state of component Set of properties Model relations between these Make it composable in the hierarchy Determine active sub-components based on mode (property of the parent component) Generate mode transition automata for the whole application (at deployment time) <Author>, D3S Seminar, <Date> <Title> 10

11 Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 11 Proposed Approach - Property networks Component is associated with a set of properties

12 Proposed Approach - Property networks Components are associated with a set of properties Property values are bounded by relations Directed graph Propagation Local change has an impact where relevant Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 12

13 Mapping State of Network to Arch. Variant Each component has a mode property Component mode is Set of child subcomponents used Component attributes e.g. real-time scheduling info Local change of property value Is propagated by the network Influence valuation of properties where relevant Also the ones representing mode Determines new application architecture Change propagation possibly demanding But can be pre-computed to an Oracle at deployment time Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 13

14 Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 14 Proposed Approach - Property networks Interpretation C 1 - capplication C 2 cbrain C 3 csearchstrategy p 4 mode Brain p 5 groundtype p 6 mode SearchStrategy

15 After a Change Run is started Until the network stabilize No further changes Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 15

16 Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 16 Network Run Stabilization a) will stabilize b) will stabilize c) will not stabilize

17 Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 17 Triggering Event and Network Run Event Property value assignment from component code E.g., color seen by a camera changes The network propagates the event until it stabilizes (network run) Relation with changed inputs is reevaluated Similar to shifting tokens in Petri Nets Stabilization - no further changes of property valuations If not, bad relation design (oscillation) Checked by development tools

18 Worst Case Property Network Run Length Exponential in the number of properties Possibly all the possible valuations Knowing initial state and all the possible events, all the possible runs can precomputed at deployment time Oracle (mode transition automata) At run-time, the oracle is queried in a constant time Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 18

19 Oracle Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 19

20 At Run-time - Overview Component can change value of a property that is associated with it via API After each change The oracle is queried for new valuation of all properties The valuation is changed Runtime framework takes responsibility for modifications of the architecture according to oracle hints Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 20

21 Implementation and Experience Introduction to existing SOFA-HI component system takes a feasible effort Tools for network relations design necessary Checking for well-formed property networks No oscillation Model seems to be intuitive In the case study, 13 properties <Author>, D3S Seminar, <Date> <Title> 21

22 Overview Property networks allows for highly deterministic architectural modifications Pre-computed oracle New variant in constant time Oscillation is not possible at runtime Time and space complexity is feasible Constant time and 2kB for presented case-study Does not pollute interfaces and business logic It is orthogonal to them <Author>, D3S Seminar, <Date> <Title> 22

23 Thank You, Questions Tomas Pop, CBSE 2012 Oracle-based Mode-change Propagation in Hierarchical Components 23