FIPA Agents and Platform

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FIPA Agents and Platform

• M. Cossentino

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Paradigm shift in programming
agent
Abstraction level
object
procedural
assembler
time
3
How agent technology will progress over time
according to Agentlink II
Source Agentlink II Roadmap
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Past and future
Source Agentlink II Roadmap
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Past and future
Source Agentlink II Roadmap
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Agent-related concepts

• Platform
• Communication
• Ontology
• Not specifically agent concepts
• services
• applications

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Where can you find agents today

• distributed artificial intelligence,
• robotics,
• artificial life (also in video game),
• distributed object computing,
• human-computer interaction,
• intelligent and adaptive interfaces,
• intelligent search and filtering,
• information retrieval,
• etc.

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Different kind of agents

• An example of categorization
• Autonomous agents
• Biological agents
• Computational agents
• Software agents
• Task specific agents
• Entertainment agents
• Viruses
• Artificial life agents
• Robotic agents
• others to come

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Different kinds of agents

• Another categorization
• Mobile agents
• Interface agents
• Collaborative agents
• Information agents
• Reactive agents
• Hybrid agents
• Heterogeneous agents

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What is an agent

• Perhaps the most general way in which the term
  agent is used is to denote a hardware or (more
  usually) software-based computer system that
  enjoys the following properties
• autonomy agents operate without the direct
  intervention of humans or others, and have some
  kind of control over their actions and internal
  state
• social ability agents interact with other agents
  (and possibly humans) via some kind of
  agent-communication language Genesereth and
  Ketchpel, 1994
• reactivity agents perceive their environment,
  (which may be the physical world, a user via a
  graphical user interface, a collection of other
  agents, the INTERNET, or perhaps all of these
  combined), and respond in a timely fashion to
  changes that occur in it
• pro-activeness agents do not simply act in
  response to their environment, they are able to
  exhibit goal-directed behaviour by taking the
  initiative.
• From Intelligent Agents Theory and Practice of
  M. Wooldridge and N. Jennings (http//www.csc.liv.
  ac.uk/mjw/pubs/ker95/ker95-html.html)

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BDI Agents

• ALL agents (except for purely reactive agents)
  maintain an internal representation of their
  world.
• There is an explicit mental state
• Can be modified by some form of symbolic
  reasoning.
• An example BDI agents (BDI Belief, Desire,
  Intention)
• a set of beliefs about the world
• a set of goals that the agent is currently trying
  to achieve (Desires)
• a library of plans describing how to achieve
  goals and how to react to changes in beliefs
• an intention structure describing how the agent
  is currently achieving its goals and reacting to
  changes in beliefs.

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What is FIPA

• FIPA (Foundation for Intelligent Physical Agents)
  is a non-profit organization aimed at producing
  standards for the interoperation of heterogeneous
  software agents
• www.fipa.org

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Agent FIPA definition

• An agent is a computational process that
  implements the autonomous, communicating
  functionality of an application. Typically,
  agents communicate using an Agent Communication
  Language.

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FIPA Agents

• Agents communicate by exchanging messages which
  represent speech acts, and which are encoded in
  an agent-communication-language.
• Services provide support services for agents. In
  addition to a number of standard services
  including agent-directory-services and
  message-transport-services the FIPA Abstract
  Architecture defines a general service model that
  includes a service-directory-service.

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FIPA Agent Relationships to Other Elements

• Agent has an agent-name
• Agent may have agent-attributes
• Agent has an agent-locator, which lists the
  transport-descriptions for that agent
• Agent may be sent messages via a
  transport-description, using the transport
  corresponding to the transport-description
• Agent may send a transport-message to one or more
  agents
• Agent may register with one or more
  agent-directory-services
• Agent may have an agent-directory-entry, which is
  registered with an agent-directory-service
• Agent may modify its agent-directory-entry as
  registered by an agent-directory-service
• Agent may deregister its agent-directory-entry
  from an agent-directory-service.

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Concrete implementation of the FIPA Agent

• an agent may be realized in a variety of ways,
  for example as a Java component, a COM object, a
  self-contained Lisp program, or a TCL script.
• It may execute as a native process on some
  physical computer under an operating system, or
  be supported by an interpreter such as a Java
  Virtual Machine or a TCL system.
• The relationship between the agent and its
  computational context is specified by the agent
  lifecycle.

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Agents

• (FIPA) State-machine agent

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Agents a software engineering point of view

• An agent is a subsystem
• High decoupling with other subsystems (agents)
• High coherence of internal classes (behaviors of
  the same agent)
• It offers services to other agents
• FIPA agents are communication oriented
• High Standardization in communications provide
  interoperability
• Ontology
• Agent Interaction Protocols (and communicative
  acts)
• Content language

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PASSI Agent
In playing a role the agent uses one or more of
its tasks.
Each task is composed of several elementary
behaviors

• An agent may occupy several functional roles to
  achieve its goals

The instance of an agent class It is the
software implementation of an autonomous entity
capable of pursuing an objective through its
autonomous decisions, actions and social
relationships.
Elementary behavior
A series of elementary pieces of behavior
(actions) necessary for a specific purpose. Each
task carries out one of the agents decisions/
actions/ social relationships
The function temporarily assumed by the agent in
the society while pursuing a sub-goal
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Platform
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Platforms

• What is a platform
• A place where agents live
• not always needed
• Platform responsibilities
• Agent management
• creation termination
• security
• Agent communication services
• Agent directory services

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Communications (conversations)
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Agents interactions (FIPA point of view)

• Agents communicate by exchanging messages which
  represent speech acts2, and which are encoded in
  an agent-communication-language.
• The simplest for of speech act (we can refer to
  it as a message) is
• lti, act (j, C)gt
• Where
• i is the originator of the speech act (we can
  refer to it as a message),
• act is the name of the act (it communicates the
  speakers intention to the hearer)
• j is the target
• C the semantic content
• Examples of communicative acts1 (also called
  performatives)
• Query, Inform, Request, Agree, Refuse
• 1FIPA Communicative Act Library Specification.
  Foundation for Intelligent Physical Agents,
  Document FIPA00037 (2000). http//www.fipa.org/spe
  cs/fipa00037/.
• 2Searle, J.R., Speech Acts. Cambridge University
  Press, 1969.

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Messages and performatives

• Is the door open?
• Open the door (for me)
• OK! Ill open the door
• The door is open
• I am unable to open the door
• I will not open the door
• Say when the door becomes open
• Anyone wants to open the door?
• I can open the door for you..at a price
• Door? Whats that? Dont understand...

• query
• request
• agree
• inform
• failure
• refuse
• Subscribe
• cfp
• Propose
• Not-understood

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A layered model
One conversation can be composed of several
messages, each one addressing one different
performative (or communicative act)
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Conversations

• Conversations are composed by one or more
  messages
• They are ruled by agent interaction protocols
  (AIP, discussed later)
• Given a message (and its specific performative),
  the AIP defines which is the set of performatives
  that could be associated to the following
  messages
• If a message does not comply to this rule, the
  agent could not understand it

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Message elements
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Components of a message
Parameter                 Category of Parameters
performative Type of communicative acts
sender Participant in communication
receiver Participant in communication
reply-to Participant in communication
content Content of message
language Description of Content
encoding Description of Content
ontology Description of Content
protocol Control of conversation
conversation-id Control of conversation
reply-with Control of conversation
in-reply-to Control of conversation
reply-by Control of conversation
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A layered model
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Content and Content language

• The content denotes the content of the message
  equivalently denotes the object of the action.
• The content language denotes the language in
  which the content is expressed.
• FIPA content languages
• SL, CCL, KIF, RDF

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A layered model
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Agent communication Language

• The structure of a message is a key-value-tuple
  and is written in an agent-communication-language,
  such as FIPA ACL.
• The content of the message is expressed in a
  content-language, such as KIF, SL or RDF.

• The content-language may reference an ontology,
  which grounds the concepts being discussed in the
  content.

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ACL message example
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A layered model
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Transport Message

• When a message is sent it is transformed into a
  payload, and included in a transport-message.
• The payload is encoded using the
  encoding-representation appropriate for the
  transport.

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A layered model
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Message Transport Protocol

• Each agent has an agent-name. This agent-name is
  unique and unchangeable.
• Each agent has one or more transport-descriptions,
  which are used by other agents to send a
  transport-message.
• Each transport-description correlates to a
  particular form of message transport, such as
  IIOP, SMTP, or HTTP.
• A transport-message is a message expressed in a
  format (or encoding) that is appropriate to the
  transport being used.
• A set of transport-descriptions can be held in a
  locator.

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Example of transport description

• Directory entry for agent ABC
• Agent-name ABC
• Locator

Transport-type Transport-specific-address Transport-specific-property
HTTP http//www.whiz.net/abc (none)
SMTP Abc_at_lowcal.whiz.net (none)
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A layered model
Out of our scope
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Ontology
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Ontology

• Concepts
• (categories, entities of the domain)
• Predicates
• (assertions on properties of concepts)
• Actions
• (that agents can perform in the domain).

Book_in_stock
Searched_book
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Agents Interaction Protocols(AIP)
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Message Content Languages
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A proposition in RDF

• Proposition
• "The statement 'W. Richard Stevens is the author
  of TCP/IP Illustrated' is true".
•  
• lt?xml version"1.0"?gt
• ltrdfRDF xmlnsrdf"http//www.w3.org/1999/02/22-r
  df-syntax-ns"
•          xmlnsfipahttp//www.fipa.org/schemas/fi
  pa-rdf0"gt
•  
•   ltfipaPropositiongt
•     ltrdfsubjectgtTCP/IP Illustratedlt/rdfsubjectgt
•     ltrdfpredicate rdfresource"http//descript
  ion.org/schemaauthor"/gt
•     ltrdfobjectgtW. Richard Stevenslt/rdfobject/gt
•     ltfipabeliefgttruelt/fipabeliefgt
•   lt/fipaPropositiongt
• lt/rdfRDFgt

author
W. Richard Stevens
TCP/IP Illustrated
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A communication (ACLRDFRequest AIP)

• Scenario
• Mary requests John to open door 1 and door 2 and
  then wants John to inform her if he performed the
  action and what the result is.
•  
• Message 1 Request from Mary to John containing
  the description of the action,  
• Message 2 Inform from John to Mary, referring to
  the action and stating the completion of the
  action.
•  
• (request
•   sender Mary
•   receiver John
•   content (
•     lt?xml version"1.0"?gt
•     ltrdfRDF xmlnsrdf"http//www.w3.org/1999/02/
  22-rdf-syntax-ns
•              xmlnsfipa"http//www.fipa.org/schem
  as"gt
•        ltfipaAction rdfID"JohnAction1"gt
•         ltfipaactorgtJohnlt/rdfactorgt
•         ltfipaactgtopenlt/rdfactgt
•         ltfipaargumentgt
•           ltrdfbaggt
•             ltrdfligtdoor1lt/rdfligt

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A communication (ACLRDFRequest AIP)

• (inform
•   sender John
•   receiver Mary
•   content (
•     lt?xml version"1.0"?gt
•     ltrdfRDF xmlnsrdf"http//www.w3.org/1999/02/
  22-rdf-syntax-ns"
•              xmlnsfipa"http//www.fipa.org/schem
  as"gt
•  
•       ltrdfDescription about"JohnAction1"gt
•         ltfipadonegttruelt/fipadonegt
•         ltfiparesultgtdoors closedlt/fiparesultgt
•       lt/rdfDescriptiongt
•     lt/rdfRDFgt )
•   language fipa-rdf0)
•  

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The FIPA Platform
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The FIPA platform

• Agent Management System (AMS)
• The AMS provides white-page and life-cycle
  service, maintaining a directory of agent
  identifiers (AID) and agent state.
• Each agent must register with an AMS in order to
  get a valid AID.
• Directory Facilitator (DF)
• the agent who provides the default yellow page
  service in the platform.
• Message Transport System (MTS)
• the software component controlling all the
  exchange of messages within the platform,
  including messages to/from remote platforms.
• also called Agent Communication Channel (ACC)

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Agents interactions

• Agent Communication Channel All agents have
  access to at least one ACC. The ACC is the
  default communication method that connects all
  agents within an AP and between APs.

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Other topics

• Agents
• Services
• Directory services
• Starting/ finding an agent
• See FIPA-presentation.doc

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The FIPA platform implementation
The operating shell
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Jade Behaviors
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An Example

• Sender agent
• Receiver agent

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(Performative, ontology, content language,
content) This is not common in PASSI PASSI
syntax (AIP, Performative, Ontology)
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Agent Sender

• public class AgentSender extends Agent
• class SendBehaviour extends SimpleBehaviour
• private boolean finished false
• public SendBehaviour (Agent a)
• super(a)
• public void action()
• try
• System.out.println("\nEnter responder
  agent name (e.g. da0_at_myhost1099/JADE) ")
• BufferedReader buff new
  BufferedReader
• (new InputStreamReader(System.in))
• String responder buff.readLine()
• AID r new AID()
• r.setName(responder)
• ACLMessage msg new ACLMessage(ACLMessag
  e.INFORM)
• msg.setSender(getAID())
• msg.addReceiver(r)
• msg.setContent("FirstInform")
• send(msg)

• doWait(1000)
• msg.setOntology("ReceiveTest")
• msg.setContent("FourthInform")
• send(msg)
• System.out.println("\nFourth INFORM
  sent")
• finished true
• myAgent.doDelete()
• catch (IOException ioe)ioe.printStackTrace(
  )
• public boolean done()
• return finished
• protected void setup()
• SendBehaviour mysendbehaviour new
  SendBehaviour(this)
• addBehaviour(mysendbehaviour)

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Agent Receiver 1/2

• public class AgentReceiver extends Agent
• class my3StepBehaviour extends SimpleBehaviour
  
• final int FIRST 1
• final int SECOND 2
• final int THIRD 3
• private int state FIRST
• private boolean finished false
• public my3StepBehaviour (Agent a)
• super(a)
• public void action()
• switch (state)
• case FIRST if (op1()) state SECOND
• else state FIRST break
• case SECONDop2() state THIRD break
• case THIRDop3() state FIRST finished
  true
• break

• private boolean op1()
• MessageTemplate m1
• MessageTemplate.MatchPerformative(ACLMessage.INFOR
  M)
• MessageTemplate m2
• MessageTemplate.MatchLanguage("PlainText")
• MessageTemplate m3
• MessageTemplate.MatchOntology("ReceiveTest")
• MessageTemplate m1andm2 MessageTemplate.and
  (m1,m2)
• MessageTemplate notm3 MessageTemplate.not(m
  3)
• MessageTemplate m1andm2_and_notm3
• MessageTemplate.and(m1andm2, notm3)
• System.out.println( "\nAgent
  "getLocalName()" in state
• FIRST.op1 is waiting for a message matching the
• template ")
• //The agent waits for a specific message. If
  it doesn't arrive the behaviour is suspended
  until a new message arrives.
• ACLMessage msg receive(m1andm2_and_notm3)
• if (msg! null)
• System.out.println("\nAgent " getLocalName() "
  
• received the following message in state

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Agent Receiver 2/2

• private void op2()
• System.out.println("\nAgent " getLocalName() "
  in state
• SECOND.op2 is waiting for any message in next
  5000
• msec")
• //Using a blocking receive causes the block
  of all the
• //behaviours
• ACLMessage msg blockingReceive(5000)
• if(msg ! null)
• System.out.println("\nAgent "
  getLocalName() "
• received the following message in state
• SECOND.op2 ")
• System.out.println(msg.toString())
• else
• System.out.println("\nNo message received in
  
• state SECOND.op2")
• // End of op2

• private void op3()
• MessageTemplate m1
• MessageTemplate.MatchPerformative(ACLMessage.INFOR
  M)
• MessageTemplate m2
• MessageTemplate.MatchLanguage("PlainText")
• MessageTemplate m3
• MessageTemplate.MatchOntology("ReceiveTest")
• MessageTemplate m1andm2 MessageTemplate.and
  (m1,m2)
• MessageTemplate m1andm2_and_m3
• MessageTemplate.and(m1andm2, m3)
• System.out.println("\nAgent
  "getLocalName()" in state
• THIRD.op3 is blocked waiting for a message
  matching the
• template")
• //blockingReceive and template
• ACLMessage msg blockingReceive(m1andm2_and_
  m3)
• if (msg! null)
• System.out.println("\nAgent "
  getLocalName() "
• received the following message in state
  THIRD.op3

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MAS References

• Agentlink Roadmap www.agentlink.org
• Intelligent Agents Theory and Practice. M.
  Wooldridge, N. Jennings (http//www.csc.liv.ac.uk/
  mjw/pubs/ker95/ ker95-html.html)
• Objects and Agents Compared. J. Odell.
  (http//www.jot.fm/issues/issue_2002_05/column4)
• Searle, J.R., Speech Acts. Cambridge University
  Press, 1969.

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Ontology References

• What are ontologies and why do we need them. B.
  Chandrasekaran et al. (http//portal.acm.org/citat
  ion.cfm?id630436dlACMcollportal)
• Ontologies from AI Topics library of AAAI.
  http//www.aaai.org/AITopics/html/ontol.html
• Ontology Development 101 A Guide to Creating
  Your First Ontology. Natalya F. Noy and Deborah
  L. McGuinness. (http//www.ksl.stanford.edu/people
  /dlm/papers/ontology101/ontology101-noy-mcguinness
  .html)
• Designing Ontology with RDF in PASSI. M.
  Cossentino
• Modeling XML Vocabularies with UML. D. Carlson.
  (http//www.xml.com/pub/a/2001/08/22/uml.html)
• RDF (Resource Description Framework). W3C
  Consortium. (http//www.w3.org/RDF/)

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FIPA References

• FIPA website www.fipa.org
• FIPA Abstract Architecture (http//www.fipa.org/re
  pository/architecturespecs.html)
• Agent Interaction Protocols (http//www.fipa.org/r
  epository/ips.php3)
• Communication Content Languages
  (http//www.fipa.org/repository/cls.php3)
• (Design) Methodology Technical Committee
  (http//www.fipa.org/activities/methodology.html)
• Communicative Act Library Specification
  (http//www.fipa.org/specs/fipa00037/)

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JADE References

• JADE (Java Agent DEvelopment Framework)
  (http//sharon.cselt.it/projects/jade/)
• Jade Tutorial http//www.iro.umontreal.ca/vauche
  r/Agents/Jade/ JadePrimer.html
• AgentFactory http// mozart.csai.unipa.it/af