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Lecture 23 – April 11, 2002

Semester end questions

More about Bond agents

Models and languages supporting concurrency

Petri Nets

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Final Exam and Project

The final exam will be Thursday April 25,

7:00 – 9:00 PM in this class room.

The class project is due on Monday April 22 at 9 AM. See http://www.cs.ucf.edu/~dcm/Spring02Class/Projects.html for a description of the format and contents of project.

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Office Hours during the last weeks

I will be out of town Sunday April 14 till Saturday, April 20.

I will be available on Tuesday, April 24, 3 – 6 PMThursday, April 15, 4- 7 PM

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Final Exam

Open book

Comprehensive

Two hours

4-6 problems

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Final project presentations

Tuessday – April 16:7:00 – 7:20 David Aihe7:20 – 7:40 Kiran Anna 7:40 - 8:00 Temitope Alo8:00 - 8:20 Xin Bai

Thursday – April 187:00 – 7:20 Wafa Elgarath7:20 – 7:40 Shan Natarajan7:40 – 8:00 Sudipta Rashit8:00 - 8:20 Vivek Singh

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Final project presentations

Friday – April 19 CS 232 (Seminar Room)9:00 – 9:45 John Anthony9:45 – 10:30 Brian Hill10:30 – 11:15 Mathew Lowerey11:15 – 12:00 Aniruddha Tumalla

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Agent Factory

Action SchedulerSemantic Engine

S2S1

S3

Model

StrategyData Base

Resident

TupleSpace

BlueprintRepositoryBlueprint

Repository

WebServer

Local Host

Multiplane Agent

Agent

Agent Control Structure

NETWORK

ACS

ACS

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AgentFactory

InternalRepresentation of

an AgentState Machines:-states

-transitions

Strategies

Blueprint of anAgent

Model of theWorld

Agenda

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Agent Factory

Action SchedulerSemantic Engine

S2S1

Model

Resident

Modified Multiplane Agent

Modified AgentControl Structure

ACS

ACS

Agent Factory

Action SchedulerSemantic Engine

S2S1

S3

Model

Resident

Original Multiplane Agent

Original AgentControl Structure

ACS

ACS

OriginalBlueprint

SurgicalBlueprint

ModifiedBlueprint

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Agent Factory

S2S1

Model

Resident

Multiplane Agent

ACS

ACS

Agent Factory

S2S1

S3

Model

Resident

Multiplane Agent

Agent Control Structure

ACS

ACS

Beneficiary

S3

shadowof model

(i) migrate-agent (xi) success (xii) control-agent

Blueprint

(iv) migrate-agent

(x) start-agent

Agent Control Structure

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Agent transformations

Trimming.

Splitting.

Joining.

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read()take()write()

Access contolCheckpointing

Tspace server

tuples

read()waittoread()

scan()

take()

match()

consumingscan()

write()

count()

or()

index()

and()

waittotake()

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Tuplespace

CoordinatorAgent

1 4

Notify Completion

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Software Installation Workload DataGeneration

HTTP RequestGeneration

MeasurementData Analysis

MonitoringAgent

MonitoringAgent

MonitoringAgent

MonitoringAgent

MonitoringAgent

MonitoringAgent

MonitoringAgent

MonitoringAgent

MonitoringAgent

MonitoringAgent

MonitoringAgent

MonitoringAgent

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M; Petri NetModel ofSystem S

Modeling

Translation

MP; ModelProperties

SP; SystemProperties

SystemAnalysis

StaticAnalysis of

the NetModel

DynamicAnalysis of

the NetModel

Remapping

(a)

Translation

MP; ModelProperties

DynamicAnalysis of

the Net

StaticAnalysis of

the Net

(b)

S; Real-lifeSystem

M; Petri NetDescription of

a SoftwareSystem S

S; SoftwareSystem

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Place/Transition nets

In 1962 Carl Adam Petri introduced a family of graphs, called Place-Transition, P/T nets to model dynamic behavior of systems. P/T nets, are bipartite populated with tokens, that flow through the graph. A bipartite graph is one with two classes of nodes; arcs always connect a node in one class with one or more nodes in the other class. In the case of P/T nets the two classes of nodes are places and transitions; arcs connect one place with one or more transitions or a transition with one or more places.

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P/T nets

Enabling and firing of a transitionWeight of flow relations (arcs).Marked P/T netPreset and postset of a transition/place.Modeling choice and concurrency.Confusion – symmetric and asymmetricMarked graph –concurrency but no choice State graph graph – choice but no concurrencyInhibitor arcs – modeling priority

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2 1

3

p1 p2

p3

(a) (b) (c)

t1

(d) (e) (f)

2 1

3

t4

(g)(h)

(i)

p4

t3

n

nn

n(j)

2 1

3

p1 p1

p1p1

p1

p1

p1

p1

p2 p2

p2p2

p2

p2

p2

p3 p3

p3

p3

p2 p3

p3

p3

t1

t1

t1t1

t1

t1

t1 t1t1

p1

p4

p4

p4

t2t2

t2

t2

t2

t2 t2

p4

t3

t3

t3

t3

t4

t4

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P/T nets

Marking state

Finite/infinite capacity nets

Strict/weak firing rules

Extended P/T nets – P/T nets with inhibitor arcs.

Modeling exclusion.

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Properties on P/T nets

Marking independent properties of P/T nets – structural properties

Marking dependent properties of P/T nets.

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State machines

Finite state machines can be modeled by a subclass of L-labeled P/T nets called state machines (SM) with the property that

In a SM each transition has exactly one incoming and one outgoing arc or

This topological constraint limits the expressiveness of a state machine, no concurrency is possible.

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Marked graphsIn a marked graph each place has only one incoming and one outgoing arc thus marked graphs do no not allow modeling of choice.

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Confusion; free-choice and extended free-choice P/T nets.

When choice and concurrency are mixed, we end up with a situation called confusion. Symmetric confusion means that two or more transitions are concurrent and, in the same time, they are in conflict with another one.In an extended free-choice net if two transition share an input place they must share all places in their presets. In an asymmetric choice net two transitions may share only a subset of their input places.

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MarkedGraphs

Free Choice

Asymmetric Choice

Place Transition Nets

StateMachines

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Marking dependent properties

Liveness

Boundedness

Safety

Refersibility

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Firing sequence

Firing sequence

Rechability analysis

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Q

N

N

R

(a) (b)

(d)(c)

p1 p1

p1 p1

p2 p2

p2 p2p3 p3

t1 t1

t1

t1

t2 t2

t2

t2

t3