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Relating and Visualising CSP , VCR and Structural Traces
Neil Brown1 Marc Smith2
1Computing Laboratory, University of Kent, UK 2Department of Computer Science, Vassar College, NY, USA
Motivation
Relating and Visualising CSP , VCR and Structural Traces Neil Brown - - PowerPoint PPT Presentation
Relating and Visualising CSP , VCR and Structural Traces Neil Brown - - PowerPoint PPT Presentation
Relating and Visualising CSP , VCR and Structural Traces Neil Brown 1 Marc Smith 2 1 Computing Laboratory, University of Kent, UK 2 Department of Computer Science, Vassar College, NY, USA 2 November 2009 Motivation Dining Philosophers
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Motivation
Starving Dining Philosophers
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Background
Visualization: Strings and Beads
Consider the CSP system: P ||
{a,f}
Q where P = a → b → c → f → SKIP Q = a → d → e → f → SKIP
a b d f c e P Q
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Background
Visualization: Strings and Beads
Consider the CSP system: P ||
{a,f}
Q where P = a → b → c → f → SKIP Q = a → d → e → f → SKIP
a b d f c e P Q
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Background
Visualization: Strings and Beads
Consider the CSP system: P ||
{a,f}
Q where P = a → b → c → f → SKIP Q = a → d → e → f → SKIP
a b d f c e P Q
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Background
Visualization: Strings and Beads
Consider the CSP system: P ||
{a,f}
Q where P = a → b → c → f → SKIP Q = a → d → e → f → SKIP
a b d f c e P Q
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Background
CSP Observer
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Background
CSP Observer
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Background
CSP Observer
a b d f c e P Q a b d f c e P Q a b d f c e P Q a b d f c e P Q
a, b, c, d, e, f a, b, d, c, e, f a, b, d, e, c, f a, d, b, c, e, f a, d, e, b, c, f a, d, b, e, c, f
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Background
VCR Observer(s)
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Background
VCR Observer(s)
a b d f c e P Q a b d f c e P Q a b d f c e P Q a b d f c e P Q
{a}, {b, d}, {c, e}, {f} {a}, {b}, {c, d}, {e}, {f} {a}, {d}, {b, e}, {c}, {f}
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Background
Structural Observers
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Background
Structural Observers
a b d f c e P Q a b d f c e P Q a b d f c e P Q a b d f c e P Q
(a → b → c → f) || (a → d → e → f)
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Background
Traces
Three types of traces:
1 CSP traces
A sequence of individual events, recorded by the observer; events observed simultaneously are interleaved abstracts away time and space
2 VCR Traces
A sequence of event multisets; multiple observers account for different views preserves time independence; abstracts away space
3 Structural Traces
Sequential and parallel composition of the trace reflects the program’s structure preserves time independence and space
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Background
Space and Mobility
logger c
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Background
Space and Mobility
logger c logger!42 logger?42
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Background
Space and Mobility
logger c logger!42
- > c!logger
logger?42 c?logger
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Background
Space and Mobility
logger c logger!42
- > c!logger
logger?42
- > logger?43
c?logger
- > logger!43
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Background
Space and Mobility
logger c logger!42
- > c!logger
logger?42
- > logger?43
c?logger
- > logger!43
(logger!42 → c!logger) || (c?logger → logger!43) || (logger?42 → logger?43)
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Conversion
Conversion Example
CSP: P = (AB o
9 AB) ||
{b}
(b → b → SKIP) where AB = (a → SKIP) ||| (b → SKIP)
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Conversion
Conversion Example
CSP: P = (AB o
9 AB) ||
{b}
(b → b → SKIP) where AB = (a → SKIP) ||| (b → SKIP) Structural Trace Visualisation:
a b a b b b
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Conversion
Conversion Example
CSP: P = (AB o
9 AB) ||
{b}
(b → b → SKIP) where AB = (a → SKIP) ||| (b → SKIP) Structural Trace Conversion Algorithm:
a b a b b b
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Conversion
Conversion Example
Structural Trace Conversion Algorithm:
a b a b b b
VCR Trace Visualisation:
a b a b
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Conversion
Conversion Example
VCR Trace Visualisation:
a b a b
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Conversion
Conversion Example
VCR Trace Visualisation:
a b a b
CSP Trace Visualisation:
a b a b b a a b a b b a b a b a
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Example
Starving CHP Philosophers
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Example
Starving CHP Philosophers Trace
philosopher eatChicken = forever (syncBarrier eatChicken) chef a b c = forever ((syncBarrier a <&> syncBarrier b) <-> (syncBarrier b <&> syncBarrier c) <-> (syncBarrier a <&> syncBarrier c))
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Example
Starving CHP Philosophers Trace
philosopher eatChicken = forever (syncBarrier eatChicken) chef a b c = forever ((syncBarrier a <&> syncBarrier b) <-> (syncBarrier b <&> syncBarrier c) <-> (syncBarrier a <&> syncBarrier c))
chicken.0 chicken.1 chicken.2 ... (Chef) chicken.0 chicken.0 chicken.2 chicken.2 chicken.2
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Summary
Summary
Traces are useful for diagnostics and observing run-time behaviour Structural traces
Most straightforward and efficient to record Useful for observing mobility
Conversion algorithms
One Structural trace converts to many VCR traces One VCR trace converts to many CSP traces
Visualisation
Graphs to represent CSP , VCR and Structural traces Tool support will be beneficial
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Future Work
Tools to Explore Traces
prefix delta succ b c a numbers recorder d 42*(b? -> (c! || d!)) || (42*(b! -> a?) -> b!) || 42*(c! -> a?)
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Future Work
Tools to Explore Traces
prefix delta succ b c a numbers recorder d 42*(b? -> (c! || d!))
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Future Work
Challenge: Structural traces and UTP
a c b a c d b d e a g f c
Figure: Concatenation, quotient and healthiness conditions
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Future Work