Agent communication languages

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• Agent communication languages
• Roope Raisamo (rr_at_cs.uta.fi)Dept. of Computer
  and Information SciencesUniversity of Tampere
  
• http//www.cs.uta.fi/rr/

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Agent communication ACL

• ACL (FIPA, Foundation of Intelligent Physical
  Agents)
• Defines the environment in which the agents act
• Agent-Agent Communication happens through a
  well-defined Agent Communication Channel
• Agent Management System handles the creation and
  deletion of agents, and takes care of access
  rights and privileges
• Directory Facilitator knows all the agents and it
  is asked for a given agent

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Agent communication KQML

• ARPA Knowledge Sharing Effort developed KQML
  (Knowledge Query and Manipulation Language)
• a common inter-agent communication language
• defines the format of the messages to recognize
  agents, create data channels and exchange
  messages
• Has been more common than FIPA/ACL

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Agent communication KQML

• KQML does not define semantics of messages
• three layers communicaion, message and content
  layers
• KQML is based on the Speech Acts theory
• "How to Do Things With Words" Austin
  1961Austin, J.L. 1961. How to Do Things With
  Words, Harvard University Press.

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The structure of KQML message

• (ltperformativegt
• contentltstatement/speechactgt
• senderltnamegt
• receiverltnamegt
• languagelttextgt
• ontologylttextgt
• )

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Important speech acts Finin, 1993
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Facilitator broker
ask(x)
Agent 1
Agent 2
tell(x)
Agent 2
Agent 1
1. advertise(ask(x))
5. tell(x)
3. ask(x)
2. broker(ask(x))
Facilitator
4. tell(x)
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Facilitator matchmaker
4. ask(x)
Agent 2
Agent 1
5. tell(x)
1. advertise(ask(x))
3. reply(x)
Facilitator
2. recommend(ask(x))
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Facilitator feeder
Agent 2
Agent 1
2. tell(x)
3. tell(x)
Facilitator
1. subscribe(ask(x))
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KQML examples

• (ask-one
• content (PRICE IBM ?price)
• receiver stock-server
• language standard_prolog
• ontology NYSE-TICKS
• )

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KQML examples

• (subscribe
• content (stream-all
• content (PRICE IBM ?price))
• receiver stock-server
• language standard_prolog
• ontology NYSE-TICKS
• )

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KQML Examples

• (monitor
• content (PRICE IBM ?price)
• receiver stock-server
• language standard_prolog
• ontology NYSE-TICKS
• )

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Knowledge Interchange Format (KIF)

• KIF Gensereth and Fikes, 1992 is a syntax for
  inter-agent communication
• KIF is often used to present information in KQML
  messages
• A product of DARPA (Defense Advanced Research
  Projects Agency) Knowledge Sharing Effort

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KIF syntax

• KIF is based on predicate logic. It supports the
  following definitions
• objects
• functions
• relationships of objects
• rules
• meta information

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KIF syntax

• Syntax is related to LISP (prefix notation)
• Is not meant to present information in an
  application but only to communicate it to other
  applications
• Makes it possible to transfer information between
  agents
• An example of a KIF rule
• (gt (EventName AGENTSTARTING)(SetIndentifiedIn
  tervalAlarm NETSCAPE 20 minutes))

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KIF syntax

• Variables
• individual values ?name
• arrays _at_name
• Operators
• term operators
• rule operators
• clause operators
• definition operators
• Constants (other than variables and operators)
• numbers, characters, strings, constant objects,
  constant functions, constant relationships, logic
  expressions

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KIF syntax

• Four types of expressions
• Terms describe objects
• Clauses describe facts
• Rules describe allowed events
• Definitions define constants
• Clauses can be composed of constants, terms and
  other clauses

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KIF Examples

• (GetStockPrice ?price)(IntegerCompare ?price gt
  150)
• (gt (AND (AND (EventName StockAdapterStockPriceE
  vent)(GetStockEventCount ?count))
  (IntegerCompare ?count 2))(AND (AND (AND
  (TurnOffIdentiedIntervalAlarm IBM)(StockAdapter
  Show Turned off the alarm.
  ))(SetIdentifiedIntervalAlarm HSY 20
  minutes))(StockAdapterShow Alarm for Hershey.
  )))

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Summary

• Agent communication languages allow agents to
  cooperate and interact with each other
• Centralized registering services and a common
  language make this possible
• FIPA/ACL is gaining markets, KSE/KQML has been
  used for years but usually in academic
  environments