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CSE-538-Mobile Agent Technology

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					CSE-538: Mobile Agent Technology:
    Concepts and Applications




                 Dr. R. B. Patel
         Dept of Computer Engineering,
        M. M. University Mullana-133203
                Haryana, INDIA
        Email: patel_r_b@indiatimes.com
          Website: www.drrbpatel.org
                   Life in a Highly-Connected World
                                                           Internet
•   Interconnected networks
•   Distributed data                                                    Perimeter

•   Mobile workers                             Customers                          Intranet

•   Business extranets                                     Web Server                 `




•
                                                                              `


    Remote access
•   Web services                                       X    Extranet
                                                                                  Infrastructure
                                                                                      Servers
                                                             Server
•   Wireless
•   Mobile smart devices, etc.                                    Remote Access
                                                                    Gateway


                                                             Remote
                                                            Employees




Microsoft Confidential – Provided under NDA.
                                                                                             2
  Current trends leading to Mobile Agent Technology
                 Increased need
Information    for personalization
                                          Server-side
  overload
                                                                    Mobile code
                    “Customization”       Too many unique,
                                      dispersed clients to handle    to server
Diversified                                                           or proxy
population
                                         Proxy-based        Multiple
                                                          sites to visit

                                                                      Mobile
Bandwidth              Avoid large                                    Agents
   gap                  transfers
                                         Mobile code
                                                                          Avoid
                                          to client
                                                                          “star”
Mobile users          Disconnected                                      itinerary
and devices             Operation
                                                           High
                                                          latency              3
                Mobile Agent
A Mobile Agent (MA) is an autonomous program
that can migrate under its own or host control
from one node to another in a heterogeneous
network.
In other words, the program running at a host can
suspend its execution at an arbitrary point, transfer
itself to another host (or request the host to
transfer it to its next destination) and resume
execution from the point of suspension.
Once it is launched by a user, can travel from node to
node autonomously, and can continue to function even
if the user is disconnected from the network.

                                                     4
         Continued...

                        Server
Client




               Server   Server



                                 5
Distributed System Structuring Mechanisms
                     Call to server procedure
         Client                                   Server       Data
                              results
                                                 Procedure


                        Client Server

                                    Procedure

       Client                                    Server       Data
                         results

                  Remote Evaluation


      Client                                    Server       Data
                  Procedure

                  Code on Demand
                                                                      6
     Remote Evaluation (REV) v/s MA

• A one hop solution
• Mobile agents an extension of REV
• REV involves just a movement of code from one
  host to another host which is capable of caring
  out the process where as for MA we have active
  entities been shipped over the network (data,
  code and execution state).
• Performance wise both will have same
  performance except that MA’s execution
  environment is comparatively heavy.
                                                    7
         Process Migration v/s MA

• Not the desire of the process to move, but
  the desire of the distributed operating
  system to have it moved.
• Mainly to improve load distribution, fault
  resilience, parallelism and so on.
• The programmer (user) has neither control
  nor visibility of migrating process.

                                               8
         Interaction Model
                Request

     Client                   Server

               Response
    Client/server communication

              Mobile Agent

                              Request

Client                                  Server
                             Response

    Mobile Agent Communication
                                                 9
              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
                                                       10
  approach to software design
               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
                                                11
  Experts say: Agent should display
• Autonomy
   – system does its work in a largely pro-active manner, without
     explicit control from the user at every step
   – In practice, most agents will check with the user, at least for
     major decisions and actions
• Intelligence
   –   system does something smart
   –   exhibits behavior that humans would consider intelligent
   –   typically solving some non-trivial problem, and
   –   exhibiting some kind of learning, i.e., the ability to adapt
       and improve over time

                                                                12
  Experts say: Agent should display
• Cooperation
  – the system collaborates, minimally with the user,
    and usually with other agents, to perform the
    task.


 Based on this criterion, we can categorize
 agents into the four classes
 [see figure]

                                                13
       Part-View of Agent Topology
                                      Collaborative
Collaborative                         Learning
Agents                                Agents

          Cooperate           Learn




                 Autonomous      Interface
Smart                            Agents
Agents                                        14
                       Agent – Non Agent
According to above classification
• Should exhibit at least two of the above features to a reasonable degree
• those in the non-overlapping area of the circles are not considered to be
  Software Agents
• Non-Agent examples
   – expert system
        • exhibit intelligence
        • not cooperation or autonomy
    – a web indexing robot
        • might be autonomous,
        • may not very intelligent
    – a distributed system
        • might display some collaboration among the components
        • may be neither autonomous nor intelligent



                                                                    15
         Classification of Agents
• Single-Agent vs. Multi-Agent (Collaborative)
   – A multi-agent system involves a collection of agents
     collaborating to perform a task.
   – This model is more complex, but more modular, and is
     well-suited for concurrent or distributed tasks.
• Static vs. Mobile
   – Static agents work on a single system,
   – mobile agents (also known as "bots") move from
     system/node to system/node.
   – Depending on the degree of autonomy and the nature of
     the task, mobile agents may keep sending intermediate
     status to the base server/agent submitter if required.
                                                            16
     Classification of Agents(Contd.)
• Homogeneous vs. Heterogeneous
   – Both are multi-agent systems
   – In a homogeneous system: agents are all similar
   – In a heterogeneous system: agents are of different types.
• Deliberative vs. Reactive
   – A deliberative agent has an explicit representation of its domain
       • and uses symbolic reasoning to do its task.
       • often has an explicit representation of its own beliefs, desires and
         intentions and uses these in its reasoning.
   – Deliberative agents involve explicit programming of the knowledge
     and problem-solving in the conventional way, and is the way most
     agents currently work.




                                                                                17
   Classification of Agents(Contd.)


– A reactive agent consists of many agents,
   • each of which has a very simple stimulus-response type
     behavior.
   • A single agent typically has no clue about the actual task to be
     performed, but the collective action of the group has an
     emergent behavior which causes the required task to be
     accomplished.
– This type of behavior is found in ant and bee colonies,
  where each insect works independently and seemingly
  chaotically, but the overall effect is quite dramatic.
– Hybrid agents are those which combine more than one
  philosophy within the same agent.

                                                                    18
  Classification of Agents (Contd.)
Agent Technology is Reactive school of thought
• Real-world problem-solving
   – rarely involves explicit and elaborate reasoning and planning,
   – more of local responses based on the current situation, which keeps
     changing.
• Advantage
   – allows a simple model
   – potentially more responsive to rapid change and to automatic learning.
• Disadvantage
   – black-box model
   – does not allow inspection and debugging of knowledge



                                                                    19
       Different types of agents
• Agents exist in a multi-dimensional space
• A representative flat-list
  – Collaborative agents
  – Interface agents
  – Mobile agents
  – Information/Internet agents
  – Reactive agents
  – Hybrid agents
  – Smart Agents

                                              20
       Collaborative Agents
• Collaborative Agents emphasize
  autonomy, and collaboration with other
  agents to perform their tasks.
• They may need to have “ social ” skills
  in order to communicate and negotiate
  with other agents.

                                            21
             Collaborative Agents
• Example
   – Plead Project at MMU.
   – Visitor-Hoster:
       • helps a human secretary to plan the schedule of visitors to MMU
       • matches their interests with the interests and availability of the
         faculty and staff.
       • organized as a number of agents that retrieve the relevant pieces of
         information from several different real-world information sources,
         such as finger, online library search, etc.
• Collaborative agents are good for problems
   – too large for a single system,
   – inherently distributed in nature.
   – main challenge
       • coordination among multiple agents, particularly when they are
         autonomous and heterogeneous.


                                                                     22
     Interface (Personal) Agents
• Emphasize autonomy, and learning in order to
  perform useful tasks for their owners.
• Examples
   – personal assistants that handle your appointments
   – Office Agents in Microsoft Office.
• focus is more on interacting with the user
   – "learn" to serve the user better,
      • by observing and imitating the user,
      • through feedback from the user, or
      • by interacting with other agents.
   – The main challenge here is how to assist the user without
     bothering him, and how to learn effectively.
• normally have a distinctive personality,
                                                          23
   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



                                              24
   Objects and Agents – An Analogy
• Agents have control of whether or not to perform
  any given action
• Request actions rather than invoke methods




                                                25
      Agents - Current Research and Industry
• theories, architectures, languages, systems
• agent (internal structure) and multi-agents
  (collaboration, teamwork)
• still thriving research -> emerging industry
• >20 companies including IBM, BT, HP, Microsoft,
  Fujitsu, AgentSoft, Verity, AOS, Extempo, ...
• >50 research laboratories worldwide
• organizations coordinating international agent research:
  Agent Society, AgentLink, Agents-in-Melbourne

                                                      26
                     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   27
   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


                                         28
     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
                                                                29
          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
                                               30
         Mobile Agent Myths
• MYTH #3: Wide deployment of agent
  environments is unlikely to emerge….
   – Because agent’s 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



                                             31
           Mobile Agent Myths
• FACT #3 : No …Because…
   – JVM’s and ORB’s exist in each browser (most
     MA applications are developed in Java and the
     OMG’s 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
                                                      32
     “interoperable agent environments”
        Mobile Agent Myths

• MYTH #4: Most things that mobile
  agents can do, static agents can do as
  well
• FACT #4: True…but the
  performance benefits associated with
  mobile agents can be higher
                                     33
      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.

                                         34
         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


                                        35
           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


                                                 36
            Why Mobile Agents?

•   Reduce the network load
•   Encapsulate protocols
•   Execute asynchronously and autonomously
•   Adapt dynamically
•   Naturally heterogeneous
•   Robust and fault-tolerant

                                              37
             Gateway
                               BH       AH v '           Continued…



                                                                  U
 U                             Failed
                            communication
                                link

                   C                             N
      AH u

                                                  AH v
 V                                                                    U



C - Current host, U -Unvisited host, V -Visited host, N - Next host


 Reroute the agent on communication link failure
                                                                          38
                 Agent Mobility
Agent objects are composed of a combination of code and data.
Agent Object mobility means the network transportation of
code, data and state information, detailing where the agent has
been and what it has accomplished, as well as where it is going
and what it still has to do.
Some platforms also provides interfaces allowing agents to
create other agents and clone themselves at remote sites.




                                                         39
                     Procedure     Continued…
                         +
                       State
Client                                         Server      Data


                                              Procedure
                   Mobile Agents                  +
                                                State
    Procedure
        +                                    Server       Data
      State


                                             Procedure
                                                 +
                                               State
                                 Procedure
                                     +
                                   State        Server      Data
Server      Data




                                                                   40
            Agent Mobility Patterns

• Itinerary: the set of sites that an MA has to visit
   – static
   – dynamic


• Order: the order in which an MA visits sites in its
  itinerary.
   – static
   – dynamic

                                                        41
                 Continued…



• Static Itinerary Dynamic Order (SIDO)
• Static Itinerary Static Order (SISO)
• Dynamic Itinerary (DI)
  – Dynamic Itinerary implies dynamic order




                                              42
           Static Itinerary Static Order
 H1   H2    H3    H4          H1       H2     H3    H4
      Itinerary                         Order


        C


       H1          H2        H3             H4

                                        •   Sequential CS
Applicable Implementation Strategies    •   Sequential MA
                                        •   Parallel CS
                                        •   Parallel MA
                                                         43
       Static Itinerary Dynamic Order
  H1   H2       H3   H4                H1       ?
       Itinerary                        Order

            C


         H1               H2   H3             H4



                                       •    Sequential CS
Applicable Implementation Strategies   •    Sequential MA
                                       •    Parallel CS
                                       •    Parallel MA
                                                        44
                 Dynamic Itinerary
       H1        ?                     H1       ?
    Itinerary                          Order

            C



            H1       H2         H3             H4


                                        •   Sequential CS
Applicable Implementation Strategies    •   Sequential MA
                                        •   Parallel CS
                                        •   Parallel MA
                                                        45
          Mobile Agent Itineraries

We have defined itineraries according to the manner in
which the different hosts listed in it, are to be visited.
These itineraries are flexible to recover the communication
failures.
    Serial Itinerary: it support multihop agents
    Virtual Serial Itinerary: it supports twohop agents
    Parallel Itinerary: support two hop agents
    Complex Itinerary: multihop agents with integrated
    two hop sub agents (clones).


                                                         46
                         Serial Itinerary

AS            AH1             AH2                 AHn




     Serial itinerary
     Virtual path, in case of unreachable hosts




                                                  47
      Virtual Serial Itinerary
              C1            AH1                 Cn
                                          AH2        AHn
                       C2
          1        2               n

AS   AH

                                  Child Agent




                                                     48
     Parallel Itinerary

                          AH1


AS        AH              AH2



                          AHn


                                49
        Complex Serial Itinerary
               AH 1                  AH1   AH2         AHp



 AH i          AH 2

                             AHi+1

               AHm




AS      AH 1          AH 2                 AH n




                                                  50
              Agent- Agent Communication
o In a Mobile Agent System (MAS), the communication
  service is responsible for all remote interactions that take
  place between its distributed components, such as inter-
  agent communication, agent transfer, etc.
o Communication enables the agents in a MAS to exchange
  information, on the basis of which they coordinate their
  actions and cooperate with each other.
o This raises the important question of what communication
  protocols and mechanisms are conducive to enhance
  collaboration between communicating agents.
o Agents can directly exchange messages, or they can
  organize themselves into a federated system and
  communicate through special facilitator agents, or they can
  broadcast or multicast messages.
                                                            51
              Direct Communication

o Directed communication is used in most existing agent
  MASs.
o It involves establishing direct physical links with other
  agents using a protocol such as TCP/IP.
o A physical link implies that the agent has to be aware of
  other agents in the system.
o Agent addresses may be obtained either as part of received
  broadcast messages from other agents or from a centralized
  object, which is like a directory service where all agents
  register.
o A message sender agent can access the addresses of
  receiver agents by looking at this centralized object.
                                                           52
     Broadcast and Multicast Communication

In situations where a message has to be communicated to
   all agents in the environment, or the sender agent does
   not know who the recipient will be (like when it
   announces a task and has to choose from all possible
   agents that can perform that task) then it has two
   choices: it can either physically broadcast or multicast
   the message to all agents in the system, or it can
   maintain individual communication links with them
   and send each a directed message using the TCP/IP or
   other Protocol.


                                                          53
                     Federated System
o When the number of agents in a system becomes very
  large (e.g. in an Internet-like setting) the cost and
  processing involved in directed communication is
  prohibitive.
o A popular alternative to directed communication that
  eliminates these difficulties is to organize the set of agents
  into a federated system.
o Agents do not directly communicate with each other.
o A set of agents has a facilitator, who is kept informed
  about their individual needs and abilities.
o Agents can also send and receive application-level
  information and requests to these facilitators.
o Facilitators use the information provided by these agents
  to transform these application-level messages and route
  them to appropriate AHs.

                                                             54
             Federated System
Agent Host                          Agent Host
Agent        Agent               Agent       Agent

     Facilitator                     Facilitator




                   Facilitator
Agent Host


   Agent             Agent           Agent

                                                     55
            Agent Naming and Locating
Global network environment divided into network domains,
  regions (subnetworks) and AHs (local sites). Each network
  domain contains a Domain management server (DMS) it
  has information of all other DMSs in the global network.
  Each DMS
  Maintains information about all the regions in a network
  domain.
  Opens channel to share information of its regions with
  other network domains.
  Helps to identify the region (subnetwork) in which an
  agent is present.
  Maintains Domain Agent Database (DAD).
  DAD is responsible for maintaining current location
  information about all the agents that were created in that
  domain or transited though it.

                                                         56
                 Continued...
Region maintains information about all its AHs.
An AH can be a member of an existing region or
can start in a new region.
Each region maintains a Region Agent Database
(RAD) at an AH running at the gateway of a
subnetwork, and contains current location
information about each agent that was created in
that region.
Gateway host acts as Agent Name Server (ANS),
which manages the RAD.
ANS is responsible for maintaining uniqueness of
agent name, created in that region. Whenever a
new agent is created and registered in the RAD
of its birth region.
                                            57
                   Continued...
                    DMS
                                      INTERNET
                      Gateway

                          Site

                      Subnetwork/
                        Region
                            Network Domain 3     Network Domain 2

                                    AH
                                               Network domain
                                    DAD
                                               Region (subnetwork)
Network Domain 1                    RAD

          Distributed Environment
                                                          58
                            Continued...
Migration of an agent from one network domain to another is always
accomplished through the DMS.
During inter domain migration, the agent updates the location information in
DAD of parent domain and registers in DAD of the target network domain.
During intra region migration agent has to update its location information in
the RAD of that region.
During inter region migration agent has to update in the location information
in RAD of present region and register RAD of the target region specifying to
which host in that region it is migrating.
Agent naming is compliant with the MASIF (Mobile Agent System
Interoperability Facility) standard.
Agent naming is transparent and location independent




                                                                           59
       Modified Mobile Agent Paradigm
              Mobile Agent with Task




User    Agent                   Agent Host with
       Submitter                Stationary Agent




               Mobile Agent’s Result

                                                   60
              Why Proposed Mobile Agent Paradigm?

                                 H                  H

                                …                   …


AL                  H            H                  H

User               HA
                                 H                  H
H = Host, AL= Agent Launcher
                                  HB
                                                    H
     Result
                                                    HC

                                                         61
     Why Proposed Mobile Agent Paradigm?
                  (contd.)
Assume an agent MA1 of sizeS a         KB is received at stageH A m,

clones are forwarded to stages H B and n           clones to stage H C .

Assume that BR1 , BR 2 , BR3 ,..., BR m  and CR1 , CR2 , CR3 ,..., CRn 

KB of result data is generated by the cloned agents at stageH B and
H C , respectively, and stage H A generates a result ofAR KB.



                                                                     62
Why Proposed Mobile Agent Paradigm?
             (contd.)
In the old paradigm the total amount of data
traveling back to AL is m        n
          Dold  S a  AR  mS a   BR  nS a   CR
                                 i 1               i 1
                                         m      n
            S a 1  m  n   AR   BR   CR
                                        i 1   i 1

 Whereas in the new paradigm we have
                                        m           n
                   Dnew  AR   BR   CR
                                        i 1    i 1


 For large sizes of agent code Sa and large number of clones n
 and m, it can be seen that the saving in network bandwidth is
 substantial.                                             63
    Agent Host                                                              P
                             Cloning
                             Manager
                                           Resource
                                           Account
                                                                            M
                  Network                  Manager     Agent                A
                  Address                              Reply                D
                  Manager                             Manage r
                                                                            E
          Signature                  Host                  Persistence
          Manager                    Driver                 Manager         -
             Agent
                                                                            S
            Manager                                       Security          F
                                                          Manager
                        User                    Broker                      A
                                     Task       Manager
                       Manager      Manager                                 R
                                                                            C
                                                                            H
   Agents                     Service             Agent Receiver          I
   Objects                                        Agent to Agent
   Application                 Bridge               Communication
                                                  Message Queue Processor   T
                                                                            E
                                 Network
                                                                            C
                                                                            T
                            Agent Submitter                                 U
                                                                            R
                                                                            E
                                   User

                                                                            64
       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...
                                       65
              Mobile Agent Applications

•   Information retrieval
•   Peer-to-Peer Computing
•   Intelligent Supervisor
•   Load Balancing
•   Mobile Computing
•   Grid Computing
•   Intelligent environments
•   Distributed communities
     – networks of mobile and fixed people, devices and applications
     – Virtual communities for e-business, e-commerce, e-government
        and e-education, etc.



                                                                       66
    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, ...
                                              67
        Mobile agents in E-commerce
• Shopping Agent
  – Customer-driven market place
  – Elimination of large amount of information exchange
    over the network
• Salesman Agent
  – Supplier-driven market place
  – For products with short shelf-life, advertising a product,
    ..
  – Network delays in servicing orders is reduced
• Auction Agent
  – Supports disconnected operations and quicker response
                                                            68
            Architecture of E-Commerce Prototype
       Buyer
                           Buyer's agent
          Buyers
           GUI

                     Product
                                           List of shops
                     Request
                                            to visit and
                   Template as
                      XML
                                             dockyards                    SHOP


SHOP
                   SHOP
                      Shopkeeper                               Salesman
                                                Shops        Salesman
                                                                 agent
                          s                                  Salesman
                                                agent        agent
                         GUI                                 agent



                            Sales                   DB      Local         Product
                       Transaction Log         DB          services       Catalog


                                                                                    69
          How Mobile Agents Help

• Map directly to real life situations
• Need a generic execution environment
• Can work in both modes
   – push
   – pull
• Can work offline
• Provide local interactions
• Provide multi-hop solutions

                                         70
                                    Paper Setting

                                                        = Paper Setter Nodes
Comprehensive Question Paper                            = Install Agent
                                                        = Fetch Agent


       5


                            4




                                                                      3
      Paper Assembler           1
                                                    2   Cloning

        6
                                                             Partial Question
                                                                  Paper
                                                                    71
   To Distribution Center
                         Paper Setting: Details
                         NS
        Launcher
                              Controller GUI
                                                  NS = Name Server
Fetch
                                                  N = Paper Setter Node
Agent

               Install
               Agent

                   Cloning



                               GUI
                   N-                                  N-
                   1                                   2



                   NS                                 NS




                                                                          72
                     Distribution and Testing

                                                           List of Students enrolled
                Single copy of paper                                  …
Distribution           1                              2              …
                                       Exam Center
  Server                               Distribution
                                          Server
                       5
                                                               c9611060
               Each copy returned

                                                          Separate Copy per user
                              4
               Answered and Returned                       3
                                               Each Candidate get a Copy




                                                                               73
              Evaluation and Result Compilation


              Objective Questions Evaluator
c9611060
                                                                      Examiner B


                     Distributor
              Distribution Server



                                    Examiner A                        Examiner C



                                                      Examiner D
    Results
                                      Agents collaborate to produce the
      …                               final result
      …                                                                   74
            Concluding Remarks
• Mobile Agents provide effective and flexible mechanisms for structuring
  distributed systems viz., distance evaluation
• Advantages
   – Fast response times
   – Handling objective and subjective contents
   – Application level multicasting
   – Dynamic upgradation of applications
   – Centralized control and management of logistics
• Some Issues
   – Reliability
   – Persistence
   – Security
   – Infrastructures


                                                                            75
Thanking You
     ?


               76

				
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posted:8/9/2012
language:English
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Description: mobile computing