Taems%20/%20MASS%20Technical%20Overview

1
Taems / MASS Technical Overview

• Bryan Horling
• University of Massachusetts
• bhorling_at_cs.umass.edu

Régis Vincent SRI vincent_at_ai.sri.com
2
Overview

• Taems - a language for modeling the quantitative
  behavior of tasks and task interactions
• MASS - a simulation environment that uses Taems
  as the basis of agent activity

3
Source and Licensing

• Java implementations of Taems and MASS are
  available
• Java 1.3
• Source is included
• Apache 2.0 License
• http//mas.cs.umass.edu/download.html
• (Forthcoming from GITI as well)

4
Documentation

• Implementation
• JavaDoc APIs available online
• Topic-specific HOWTOs online
• Sample code in JAF distribution
• These slides
• Concepts
• Taems white paper
• Various publications (see Taems and MASS
  webpages)
• http//mas.cs.umass.edu/

5
High-Level Overview
Agent
Agent
Agent
New Taems Structure Action Started Communication
Action Completed Communication
MASS
Manages Time Simulates Method Execution Enforces
Taems Semantics Reports Activity Results
6
Taems at a glance

• Task groups represent goals
• Tasks represent a sub-goal
• Methods are executable primitives
• Resources model resource state
• Interrelationships model interactions between
  nodes
• QAFs specify how quality is accrued from sub-tasks

7
Inside a Taems Structure

• Directed graph, made up of nodes
• Each node has a set of defined properties
• Methods have outcomes
• Interrelationships define effect, etc.
• These fields are explained in the white paper

method name Vacuum-Floor agent Me supertasks
Clean-Floor quality_distribution 5.0 1.0
duration_distribution 10.0 1.0 cost_distribution
0.0 1.0
facilitates name Facilitates_1 from
Vacuum-Floor to Wash-Floor quality_power 0.3
1.0 duration_power 0.2 1.0 cost_power 0.0 1.0
nodes
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Constructing Taems Structures

• Textual Taems (ttaems)

(spec_agent (label Me) ) (spec_task_group
(label Clean-Kitchen) (agent Me) (subtasks
Clean-Floor Wash-Counters Put-Away-Dishes)
(qaf q_sum) ) (spec_task (label Clean-Floor)
(agent Me) (subtasks Vacuum-Floor
Wash-Floor) (supertasks Clean-Kitchen) (qaf
q_max) ) (spec_task (label Put-Away-Dishes)
(agent Me) (subtasks Slow-And-Safe
Quick-And-Dirty) (supertasks Clean-Kitchen)
(qaf q_exactly_one) )
(spec_method (label Vacuum-Floor) (agent
Me) (supertasks Clean-Floor) (outcomes
(Outcome_1 (density 1.0)
(quality_distribution 5.0 1.0)
(duration_distribution 10 1.0)
(cost_distribution 0 1.0) )
) ) (spec_method (label Wash-Floor) (agent
Me) (supertasks Clean-Floor) (outcomes
(Outcome_1 (density 1.0)
(quality_distribution 7.0 1.0)
(duration_distribution 15 1.0)
(cost_distribution 0 1.0) )
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Constructing Taems Structures

• Visual Editor - taemsview

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Pre-Taems

• Preprocessed Taems (ptaems)
• Taems template language
• Parameterizable, dynamically generate many
  structures from one specification
• Conceptually similar to C preprocessor directives
• Variables (define)
• Control structures (e.g., if, while)
• Functions (e.g., sum, prod, random_float)

foo.ptaems
foo.ttaems
foo
parameters
preprocess
parse
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Reading Taems

• Taems library includes a parser
• ReadTTaems reader new ReadTTaems(null)
• Taems task reader. readTTaems(stream)
• pTaems
• PreProcessorParser parser new
  PreProcessorParser(stream)
• PreProcessor preprocessor parser.Input()
• Hashtable parameters new Hashtable()
• String processed preprocessor.toTTaems(parameter
  s)
• Taems task readTTaems(new StringReader(processed
  ))
• Parsers are created by JavaCC, source is included

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Writing Taems

• Taems object may be converted to its textual
  representation
• For communication, storage, etc.
• String text task.toString()
• String text task.toTTaems(Taems.V1_0)
• Individual nodes may be stringified similarly
• Taems object is also serializable

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Visualizing Taems

• Taems object is a JPanel
• Simply add it to a frame to visualize
• JFrame frame new JFrame("Taems Task
  Structure")
• frame.getContentPane().add(task,
  BorderLayout.CENTER)
• frame.setVisible(true)
• Display is updated as changes are made
• Can also edit using this interface (danger!)

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Accessing Nodes

• Node is the base class for most Taems structures
  (tasks, methods, IRs, resources, etc.)
• The Taems object itself is a container for Node
  objects (among other things)
• for (Enumeration e task.getNodes()
  e.hasMoreElements() )
• Node node (Node)e.nextElement()
• if (node instanceof Task ((Task)node).isTaskG
  roup()) n
• // end countTaskGroups
• Graph structure exists in the relationships each
  Node possesses, e.g.,
• Task.getSubtasks()
• TaskBase.getSupertasks()
• Interrelationship.getFrom() getTo()

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Modifying Nodes

• All of the structures characteristics can be
  modified using accessors
• Task.setQAF()
• Method.addOutcome()
• Interrelationship.setEndpoints()
• Resource.setState()
• Node.setAgent()
• Interrelationship.setActive()
• ConsumesInterrelationship.setConsumes()
• etc
• These can be used to read and change structural
  properties

16
Analyzing Taems

• Finding classes of nodes
• Enumeration e t.findNodes(new Resource())
• while (e.hasMoreElements())
• Resource r (Resource)e.nextElement()
• // end resourceWalker
• Enumeration e t.findNodes(new Node(Foobar))
  
• while (e.hasMoreElements())
• Node r (Node)e.nextElement()
• // end foobarFinder
• Automatic state propagation
• (e.g., cost, quality, duration)
• method.setCurrentQuality()
• taskgroup.getCurrentQuality()

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Things not covered here

• Schedule, ScheduleElement
• For storing activity schedules
• Commitments
• Represent results of coordination
• Attributes
• For tagging nodes with arbitrary data
• Nonlocal methods
• Actions that one cannot perform locally
• Merging Taems structures
• See Taems.unionTaems

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MASS

• Interface/GUI
• Demo
• Time/pulse driven
• Pulse cycle
• Scripting

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MASS GUI
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Features

• Resources modeling
• Scripting capabilities
• Separate actual and perceived states
• what the participants believe may not be true
• Time and Event based
• Logging
• Deterministic
• to allow for the re-testing of modified components

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Clock

• Centralized (at simulation controller)
• Discrete, pulse-based
• During each cycle
• a pulse is sent to each attached client
• each client converts the pulse to actual CPU time
• upon completion, each client responds to the
  simulator
• when all responses have been received, simulation
  continues

start
finished
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Event Queue

• Event based system
• simulated execution
• message transfer
• environmental
• Events have both a start and duration time
• During each cycle
• the list of extant events is retrieved for that
  time slot
• each event is given a time slice to run in

events
1
2
3
4
1
2
time
3
4
5
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Scripting

• Highly customizable scripting language
• Format
• Script, ScriptClassName, ScriptSpecificName,
  Data
• Assertion, Assertion1ClassName, Data
• Assertion, Assertion3ClassName, Data
• Reaction, Reaction1ClassName, Data
• Reaction, Reaction2ClassName, Data
• Over 50 pre-defined scripts
• Assertion, AgentConnected, AgentWaterHeater
• Assertion, ResourceLevelCompare,
  Resource1Kitchen_Temp, Opgt, Resource2LivingRoom
  _Temp
• Reaction, SendMessage, AgentWaterHeater,
  Perfask, CWdisconnect, ControlTrue
• Reaction, SendCommitment, Labeltests,
  Importance30, MinQuality60, EarliestStartTime10
  , Deadline20, TimeSatisfied450, ToAgent
• Example
• Script, AndScript, Agent Disconnect Status,
• Assertion, NumAgentConnected, Oplt, Value5
• Assertion, Time, Opgt, Value10
• Reaction, Write, LineStopping Simulation!

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MASS Agents

• GITI/Grid Agent
• CoABS grid agent
• Interfaces to MASS
• Available shortly
• JAF (Java Agent Framework)
• Component-based agent framework
• Uses Taems
• Available at http//mas.cs.umass.edu

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BACKUP
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MASS Interface

• Hand-shake
• A-gtS (register sender ExampleAgent type
  control content receiver simulator language
  KQML)
• S-gtA (tell sender simulator type control
  content (Name ExampleAgent ) receiver
  ExampleAgent language KQML)
• Init
• S-gtA (tell sender simulator type control
  content (RandomSeed 889210829049 ) receiver
  ExampleAgent language KQML)
• S-gtA (tell sender simulator type control
  content (Time 0 ) receiver ExampleAgent
  language KQML)
• Pulsing
• S-gtA (tell sender simulator content (pulse)
  type control reply-with (pulse) receiver
  ExampleAgent language KQML)
• A-gtS (reply sender ExampleAgent in-reply-to
  pulse content (ack pulse) receiver simulator
  language KQML)

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MASS Interface 2

• New TAEMS structure
• A-gtS (tell sender ExampleAgent content
  (AddTaems.) receiver simulator language KQML)
• Execution of method
• Activation
• Termination
• Query of resources
• S-gtA (reply sender simulator content (R1 value
  min max) in-reply-to ??? receiver ExampleAgent
  type control language KQML)
• Reset
• S-gtA (ask sender simulator content (reset)
  receiver ExampleAgent type control reply-with
  (reset) language KQML)

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MASS Interface 3

• Inter-agent communications
• Point-to-point
• Broadcast