Using Mobile Agents for Network Resource Discovery in P2P Network

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Using Mobile Agents for Network Resource
Discovery in P2P Network

• Zhengzheng Wan

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Reference

• 1 Shirky, C, What is P2PAnd what isnt .
  OReilly Network, 24/11/2000
• 2Napster, Inc., http//www.napster.com
• 3SETI_at_Home, http//setiathome.ssl.berkeley.edu
• 4ICQ, Inc, http//www.icq.com
• 5eMikolo Networks, Inc., http//www.emikolo.com
• 6Groove, Groove Networks Inc.,
  http//www.grove.net
• 7Caglayan, A. and Harrison, C. Agent
  Sourcebook. Wiley Computer Publishing, 1997

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Reference (Contd.)

• 8 Green, S.et al., Software Agents A review,
  Department of Computer Science, Trinity College
  Dublin, 1997
• 9 Danny B.Lange and Mitsuru Oshima, Seven Good
  Reasons for Mobile Agents, Communications of the
  ACM, vol.42, No.3, March 1999.
• 10 Dan Connolly, Mobile Code Systems,
  http//www.w3.org/MobileCode/
• 11 General Magic, Inc., http//www.genmagic.com/
  

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Background

• Peer to Peer network is the movement away from
  traditional client server model to a network
  where each participating device is acting as both
  client and the server 1
• some of the main advantage of P2P are greater
  storage, more computer cycles and greater
  bandwidth.

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What is a Software Agent?

• No consensus definition yet
• Since agents can play roles in many different
  types of applications and since current agent
  research is so varied, there may never be a
  consensus
• But several key concepts have emerged

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Software Agent (Contd.)

• Lets look at some definitions
• An agent is a component of software and/or
  hardware which is capable of acting exactingly in
  order to accomplish tasks on behalf of its user
  (Nwana, 1996)
• An agent is a computer system, situated in
  some environment, that is capable of flexible
  autonomous action in order to meet its design
  objectives (Jennings, Sycara and Wooldridge, 1998)

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Stationary Agent

• Executes only on the system where it begins
  execution (Software agent)
• If it needs information on another system, or
  needs to interact with an agent on another
  system, it uses a standard client-server
  communication mechanism such as RPC, RMI, DCOM,
  CORBA

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Mobile Agent

• Not bound to the system where it begins execution
• Can move from one system to another within the
  network
• Transports both its code and its state with it
• Decide itself where to go, what to do, how long
  to exist. (Autonomous)

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Why use Mobile Agents?

• MA reduce the need for bandwidth.
• Peers perform multiple interactions over the
  communication channel, this generate the network
  traffic. MA allows the interactions among the
  peers to be packaged together and sent as a
  discrete piece of network traffic. Allows these
  interactions take place locally.

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Why use MA? (Contd.)

• Encapsulate all the required data within
  themselves.
• Once a MA arrives on a computer with all its
  data, and need not to communicate with any other
  computers. Compared to conventional search
  protocol in which all the raw data travels over
  the network to be processed. MA reduce the
  network traffic by mo

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Why use MA (Contd.)

• Mobile agents are asynchronous.
• When a mobile agent is dispatched there is no
  need to wait for it to return. The original peer
  does not need to remain connected to the network
  while the mobile agents are out

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Why use MA (Contd.)

• MA is autonomous.
• MA is learning about the network as it
  progresses through it. The mobile agent will
  visit peers that were unknown when it was
  originally dispatched. At each peer it can make
  the decisions based on its history of visited
  peers and the current peer.

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Why use MA (Contd.)

• Mobile agents have either new or more recent
  information about the resources. Information is
  being disseminated at every peer that the mobile
  agent visits.
• MA maybe easily be cloned and dispatched in
  different directions.
• MA based solution is very fault tolerant

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What is Resource

• something that may have a perceived value to
  somebody or something.
• Source available in each peer

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Current research solutions

• Napster
• Gnutella
• KaZaA
• Project Juxtaposition

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Peer Discovery Algorithm

• The algorithm is making a trade-off between a
  more detailed network discovery and a more
  efficient and practical network discovery.
• The main algorithm is used to decide how the MA
  will behave in its search for other peers

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Creator peer

• A mobile agent is created on a peer wishing
  to participate in the network. This peer is known
  as the creator peer for that particular mobile
  agent and all its future clones. The mobile agent
  updates itself with information about its creator
  peer.

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Two important parameters

• A journey-time for the MA. It is set in terms of
  the maximum number of peers that may be visited
  before it returns to its creator peer
• Branching factor. It is used to determine how
  many times the MA maybe cloned at any peers.
• Control the depth and breadth of the search.

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Algorithm (1)

• The mobile agent is given the address of some
  other peers participating in the network.
• The number of addresses provided should be small
  and should be less than the branching factor.
• These addresses should come from different
  sources.

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Algorithm (2)

• Mobile agent clones itself enough times to allow
  a mobile agent to be sent to each of these peer.

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Algorithm (3)

• After arriving at each peer. MA decrements its
  journey-time, and updates the peer with the
  information about its creator peer.
• Updates itself with information on the current
  peer.

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Algorithm (3) (Contd.)

• If two mobile agents from the same creator peer
  arrive at the current peer within a preset time
  period. The second MA destroys itself.
• It keeps the information up to date and
  prevents peers form cycles from having to deal
  repeatedly with the MA from the same creator peer

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Algorithm (4)

• If the MAs journey-time has expired, it returns
  to its creator peer and updates its creator peer
  with all the information in has collected on its
  journeys.
• MA clones itself enough times to allow a clone of
  itself to be sent to each peer that was known to
  the current peer.

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Implementation

• Implementing the mobile agent based solution
  using the Aglet Software Development Kit (ASDK)
  with the patch supplied by K.Muniandy2

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Aglets

• Aglets is a Java mobile agent platform and
  library.
• Aglets has been developed at the IBM Tokyo
  Research Laboratory (TRL) from Mitsuro Oshima and
  Danny Lange.

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Aglets (Contd.)

• Aglets includes both a complete Java mobile agent
  platform, with a stand-alone server called
  Tahiti, and a library that allows developer to
  build mobile agents.
• Its source is totally opened and is hosted on
  sourceforge.net

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Architecture

• The general architecture of our proposed
  solution is built upon the existing Aglets
  architecture. The solution developed by us is an
  Aglet based protocol to be used as part of a
  larger solution rather than a stand-alone
  application.

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Architecture (Contd.)
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DiscoveryAglet

• DiscoveryAglet is the MA that travels the
  network. It implements the peer discovery
  algorithm.
• The Aglet takes its state with it by using
  its instance variables which can be type of
  boolean, int, string or vector. These classes are
  all part of the standard Java Virtual Machine. No
  need to transmit them with MA, save time and
  bandwidth.

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AgletContext

• AgletContext class is part of ASDK. It is needed
  to maintain and manage Aglets within a secure
  environment.
• Aglet can communicate with other objects that are
  within the AgletContext.
• Provides methods allowing other objects to be
  placed within it.

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PeerResource

• It is an object that holds the information about
  all resources at the current peer.
• It is placed within the AgletContext. MA within
  AgletContext can access it

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PeerApplication

• A stand-alone java application that encapsulates
  all the software components.
• Use Tahiti, the default mobile agent server that
  comes with the ASDK.
• Use a new EmbeddedAgletServer containing an
  embedded mobile agent server, all the
  funcitonality needed to use the discoveryaglets.
  .

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Conclusion

• Characters of MA
• A MA solution
• Advantage of this solution
• Aglets
• Architecture of the solution and its
  implementation using Aglets

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Thank you!