Agents

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Agents Mobile Agents

• Introduction Agents Mobile Agents 1

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Agents - The Concept

• software system which acts intelligently on
  your behalf
• convenient metaphor
• situated in an environment and exhibit behaviour
  which can be viewed as
• pro-active, autonomous, communicative,
  persistent, mobile, benevolent,
  adaptive/learning, collaborative, reactive,
  deliberative, ...
• stronger notions of agency mentalistic notions
  such as knowledge, beliefs, desire, intention,
  goals, and a logic for reasoning with them
• Cutting out the hype a kind of software and an
  approach to software design

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Agent Definitions

• Mission Impossible ?
• No consensus on a single definition
• New Buzzword
• Everybody wants to call their software Agents!
• Many synonyms just to add to the confusion ?
• knowbots, softbots, personal assistants

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What the Gurus Say

• Wooldridge and Jennings
• A computer system situated in some environment
• Capable of Autonomous Action to meet its design
  objectives in this environment
• Autonomy ability to act without direct human
  intervention

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Objects and Agents An Analogy

• Objects encapsulate state, Agents encapsulate
  state execution behaviour
• Objects have no control over the execution of
  methods
• Invocation of method m on object o involuntary
  whether object o likes it or not

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Objects and Agents An Analogy

• Agents have control of whether or not to perform
  any given action
• Request actions rather than invoke methods

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Agents - Current Research and Industry

• theories, architectures, languages, systems
• agent (internal structure) and mult-agents
  (collaboration, teamwork)
• still thriving research -gt emerging industry
• gt20 companies including IBM, BT, HP, Microsoft,
  Fujitsu, AgentSoft, Verity, AOS, Extempo, ...
• gt40 books on software agents at Amazon
• gt50 research laboratories worldwide
• organizations coordinating international agent
  research
• Agent Society, AgentLink, Agents-in-Melbourne
  

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Agents - Applications

• many due to
• appeal of the agent abstraction
• agent research spans disciplines artificial
  intelligence, distributed computing, software
  engineering (ABSE), sociology, psychology,
  economics, object-oriented systems, artificial
  life, game theory, ...
• a sampling...

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The Internet and the WWW

• impetus for information agents
• gathering, filtering, sharing, monitoring,
  recommending, comparing information
• guiding Web surfers
• email filtering, autoresponders (e.g., Snoop,
  Smartbot)
• technologies NL processing, XML/HTML, machine
  learning, knowledge engineering
• E.g.s Verity, Autonomy, AgentSoft, CiFi, ...

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Electronic Commerce

• automate CBB stages including
• product advertising, product brokering,
  merchant brokering, negotiation, purchase and
  delivery, customer services
• examples for brokering and negotiation
• PersonaLogic, Firefly, BargainFinder, Jango,
  Kasbah, AuctionBot, Tete-a-tete, ShopBot
• needs standards for unambiguous definition of
  commerce-related information such as goods,
  services, customer and business profiles,
  electronic forms

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Business Process Management

• streamline business processes in a more flexible
  and robust manner
• e.g. ADEPT Jennings et al
• agents representing entities negotiate for
  services from each other
• negotiation rules
• applied to BT process for installing a network at
  a customers premises
• prototypes based on mobile agents intra- and
  inter-organizational workflows, supply-chain
  management in virtual enterprises, project
  management

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Entertainment

• visual manifestation of agent properties
• e.g.s (life-like interactive animated
  characters) Creatures game Grand and Cliff,
  Extempo, Microsofts Persona Project (3D,
  conversational parrot)
• believable agents - illusion of life for objects

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Pilot Training

• DSTO and AAIIs SWARMM system
• agents model pilot reasoning and tactics in air
  battle simulations
• plan and meta-plan language

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Manufacturing

• agents systems for
• controlling manufacturing robots
• managing factory production processes
• e.g. YAMS
• each factory and factory component is represented
  by an agent
• automates delegation of production orders via
  bidding between agents

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And More...

• agents for telecommunications network modelling
  and QoS management
• medical informatics e.g., multi-agent based
  distributed health care systems
• communityware agents represent people in virtual
  communities
• distributed data mining

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Agents - Standardization

• Agent Communication Languages
• KQML, ...
• Agent Lifecycle Management, etc...
• Organizations creating specifications
• FIPA gt40 participants including Alcatel, BT,
  Hitachi, NEC, Siemens, IBM, Sun Microsystems,
  Telia,...
• OMG e.g. MASIF

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Important Types of Agents

• Collaborative
• Interface
• Mobile
• Information / Internet
• Others Reactive, Hybrid, Smart
• Many Classification Schemes Typologies exist gt
  to come in the next lecture

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What is a Mobile Agent ?

• Software program
• Moves from machine to machine under its own
  control.
• Suspend execution at any point in time, transport
  itself to a new machine and resume execution
• Once created, a mobile agent autonomously decides
  which locations to visit and what instructions to
  perform
• Continuous interaction with the agents
  originating source is not required
• HOW?
• Implicitly specified through the agent code
• Specified through a run-time modifiable itinerary

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Evolution

• BOTTOMLINE Mobile Agents are a distributed
  computing paradigm
• End point in the incremental evolution of mobile
  abstractions such as mobile code, mobile objects,
  mobile processes.
• Mobile Code transfers code
• Mobile Object transfers code data
• Mobile Process transfers
• code data thread state
• Mobile Agent transfers
• code data thread authority of its owner

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RPC Vs Mobile Agents

• Remote Procedure Calls (RPC)
• One computer calls procedures on another
• Messages Requests and Responses
• Procedure is remote i.e. it is local to the
  machine that performs it
• Client and Server agree in advance on the
  protocol for communication
• Continuous on-going interaction and communication
  between the client and server

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RPC Vs Mobile Agents

• Mobile Agents
• Instead of calling a procedure, supply the
  procedure as well
• Messages Mobile Agent ( procedure data
  state)
• Sending computer may have begun the procedure
  and the receiving computer will continue the
  procedure
• On-going interaction, but NO on-going
  communication

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Applets, Servlets and Mobile Agents

• Applet Downloaded from server to client
• Servlet Uploaded from client to server
• Mobile Agents Detached from client, can have
  multiple hops

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Advantages of the Mobile Agent Paradigm

• reduce bandwidth consumption and network loads
• allow dynamic deployment of application
  components to arbitrary network sites
• encapsulate protocols
• execute asynchronously and autonomously
• can adapt by moving
• run on heterogeneous platforms
• most distributed applications fit naturally into
  the mobile agent model
• intuitively suitable for mobile users and
  disconnected operations
• Mobile agents combine the strengths of techniques
  such as RPC, java applets etc. into a single,
  convenient framework

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Mobile Agent Myths

• MYTH 1 Mobile agents are risky to use.
• FACT 1 No different to allowing remote
  access or accepting email that contains active
  entities
• MYTH 2 Mobile agent paradigm needs a killer
  application to survive
• FACT 2 Any technology needs time to mature.
  Several applications rather than one killer
  application can also contribute towards pushing
  this technology further

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Mobile Agent Myths

• MYTH 3 Wide deployment of agent environments is
  unlikely to emerge.
• Because agents execute within a given
  environment. It is unlikely for such agent
  environments to be available on a base of
  computers world wide that is large enough to make
  MA applications truly ubiquitous

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Mobile Agent Myths

• FACT 3 No Because
• JVMs and ORBs exist in each browser (most MA
  applications are developed in Java and the OMGs
  MASIF standards rely on CORBA compliant
  interfaces)
• Development of PUSH technology can enable
  uninvited agents to execute on servers that are
  willing to accept them
• MA toolkits are typically small in size and so
  are easy and inexpensive to download them on
  servers where they do not already exist
• Emerging standards are likely to lead to
  interoperable agent environments

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Mobile Agent Myths

• MYTH 4 Most things that mobile agents can do,
  static agents can do as well
• FACT 4 Truebut the performance benefits
  associated with mobile agents can be higher

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Mobile Agent Myths

• MYTH 5 The Mobile Agent paradigm can solve all
  distributed computing issues
• FACT 5 NO! Mobile Agents are not a substitute
  for client-server techniques. The two techniques
  augment each other and very often a combination
  of the two is the most appropriate.

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Levels of Mobility

• Weak Mobility
• When moving a mobile agent carries code data
  state
• Data State - global or instance variable
• On moving, execution has to start from the
  beginning

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Levels of Mobility

• Strong Mobility
• When moving a mobile agent carries
• code data state execution state
• Data State - global or instance variable
• Execution State local variables and threads
• On moving, execution can continue from the point
  it stopped on the previous host

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Mobile Agent Toolkits

• What a DBMS is to Data, a Mobile Agent Toolkit is
  to Mobile Agents
• Provides the infrastructure for mobile agents
• to interact with the underlying computer system
  provide a home, a place, a context for
  agents to reside in and perform their tasks on a
  given host
• to move from host to host
• to communicate with each other, with users and
  with host servers
• to maintain privacy and integrity (of agents as
  well as hosts)
• Current trend Java based

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Java Lingua Franca for Mobile Agent Toolkits

• BENEFITS
• Platform independence
• Secure execution
• Dynamic class loading
• Multi-threaded programming
• Object serialisation

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Java Lingua Franca for Mobile Agent Toolkits

• LIMITATIONS
• Inadequate support for resource control
• No protected references need for a proxy object
  to shield access to public methods
• No support for preservation and resumption of
  execution state

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IBMs Aglet Toolkit

• An Applet-like programming model for mobile
  agents
• Java (as many mobile agent toolkits are! )
• Aglet Agent Applet
• Aglets API facilitates mobile technology
• Aglet mobile java object that visits aglet
  enabled hosts in a computer network
• An Aglet Instance of a Java class extending the
  Aglet Class

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IBMs Aglet Toolkit

• An Aglet
• Aglet state (values in variables)
• Aglet code (class implementation)
• Autonomous runs its own thread after arriving
  at a host
• Reactive responds to incoming messages
• Weak Mobility

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IBMs Aglet Mobile Agent System

• System elements host, engine, context, proxy,
  aglet
• Aglet Transfer Protocol e.g. atp//hostnameport/
  context/
• AgletID system-given globally unique identifier
  for life

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IBMs Aglet Mobile Agent System
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IBMs Aglet System

• Proxy representative of an aglet.
• Shields and protects an aglet from direct access
  to its public methods
• Provides location transparency for the object
• Context an aglets work place.
• A server can have several contexts.
• Named
• Stationary
• Message objects exchanged between aglets
• Synchronous and Asynchronous messaging (using
  FUTURE REPLY)

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The Aglet Model

• Operations on aglets
• creation within a context. Assign id,
  initialise and execute.
• run
• cloning identical copy in the same context.
  Different id and execution thread
• dispatching move from one context to another
  where execution will re-start (i.e. threads do
  not migrate)
• retraction pull from current context and insert
  into the context from which retraction was
  requested

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The Aglet Model

• activation deactivation temporary halt and
  store in secondary storage
• disposal halt execution and remove from current
  context
• Event-based control via user-defined methods
  onCreation, onDisposing, onCloning,
  onDispatching, onReverting, onArrival,
  onActivation, onDeactivating,
• Messaging between aglets messaging via proxy, a
  message invokes a method

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Several Other Toolkits

• Gossip - Tryllian
• Grasshopper IKV Technologies
• DAgents - Dartmouth University
• Voyager - ObjectSpace
• MOA - Mobile Objects and Agents - The Open Group
  Research Institute
• Concordia - Mitsubishi Electric Lab
• JSeal, Gypsy, Gossip Many, many more

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Why Mobile Agents for Ubiquitous Environments

• The Metaphor of an Agent
• Mobility, Frequent Disconnections and Resource
  Limitations
• Dynamic environment computational resources,
  battery power, memory, bandwidth (with frequent
  disconnections) limited and varying for the same
  computer and across computers set of computers
  in a domain varying
• move/off-load (multiple) computations to other
  sites (e.g., processing at database, Web and WAP
  servers) no need to maintain connection,
  depleting resources, move to discovered resources
• software components only when and where needed
  cope with limited memory, zero-maintenance mobile
  computers, different versions for different
  hardware characteristics
• BUTthe issues are
• The need for mobility to be integrated with
  reasoning, proactivity and autonomy
• Trade-offs of intelligence vs. computational
  efficiency

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Mobile Agent Toolkits for Ubiquitous Environments

• Grasshopper
• JADE-Leap
• Mobile Agent Environment (MAE)
• AbiMA
• AgentFactory WAY
• MyCampus
• JAM
• Nuin
• CALMA

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Mobile Agent Toolkits for Ubiquitous Environments
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CALMA Context-Aware Light Weight Mobile BDI
Agents
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Agent Applications in Ubiquitous Environments

• Ubiquitous Data Analysis
• Interactions with Web Services or Web
  Applications
• Delivering Services to Mobile Users
• Users service environment can follow users
  mobile device (e.g., VHE, NetChaser)
• Agents move to mobile devices to perform tasks
  (e.g., monitor and gather information from
  deployed mobile devices)

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Other Mobile Agent Applications

• WWW Information Retrieval
• Electronic Marketplaces
• Distributed Data Intensive Applications
• Space Presence ?
• Others Network Management, Distributed Database
  Access

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Current Areas of Work

• mobile agent theories Pi-calculus extensions,
  Mobile Ambients, Agent Itineraries
• mobile agent model some component-based,
  AI-based
• mobile agent infrastructure environment
  supporting mobile agents - security, naming,
  domain crossing, etc
• mobile agent programming languages, toolkits,
  abstractions
• mobile agent applications mobile agent
  standards OMGs MASIF, FIPA

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Research Issues

• Security protect host from agents, protect
  agents from agents, protect agents from host
• Performance if Java or Python, performance
  penalities with interpretation (esp. for
  performance critical applications), but not for
  long?
• Strong mobility move full execution state
  (stacks etc), stacks not accessible with current
  Java?
• MA management
• how control and manage deployed agents
• issues fault tolerance (e.g., agent fails, host
  fails), recalling agents, tracking agents,
  servicing agents (esp. longer living agents)