UNIVERSITY OF JYVÄSKYLÄ Chedar P2P platform InBCT 3.2 Peer-to-Peer communication Cheese Factory -project Research Assistant Annemari Auvinen University of Jyväskylä Agora Center

UNIVERSITY OF JYVÄSKYLÄ 2003 Generally Chedar is a Peer-to-Peer(P2P) platform for searching resources from the distributed network Resources can be i.e. computing power or files Distributed system without any central points P2P Applications Chedar IP TCP Network Chedar TCP

UNIVERSITY OF JYVÄSKYLÄ Architecture

UNIVERSITY OF JYVÄSKYLÄ 2003 Components 1/3 ChedarClient –Control interface of a Chedar node –Applications and user interfaces communicate with Chedar through the ChedarClient –Used by P2PStudio, data fusion and distributed computing applications Chedar ChedarClient P2PStudio, Data Fusion, Distibuted Computing

UNIVERSITY OF JYVÄSKYLÄ 2003 Components 2/3 ConnectionManager –Manages active connections and history data –Forwards received messages to the right component –Measures traffic: Traffic limit and meter -> Overload TopologyManager –Makes decisions which connections are dropped and where to establish a new connection –Optimizes the topology locally

UNIVERSITY OF JYVÄSKYLÄ 2003 Components 3/3 PropagationEngine –Handles the resource queries and replies Connection –Represents the TCP connection to neighboring Chedar node

UNIVERSITY OF JYVÄSKYLÄ 2003 Connections Chedar keeps a track of active and earlier connections Active connections and history data contains –Number of the neighbors –Hit values: One is increased every time the node gets reply to resource query Actual hits is increased when node selects to use the neighbor’s resource Verified hits is added when node wants to give feedback to used resource –Relayed hits Connection measures how many replies their neighbor has relayed

UNIVERSITY OF JYVÄSKYLÄ 2003 Messages Topology management messages – Connection requests and replies – NeighborList requests and replies – ServiceList requests and replies Resource requests and replies

UNIVERSITY OF JYVÄSKYLÄ 2003 Resource discovery algorithms Breadth-First Search algorithm –Query is forwarded to all node’s neighbors if there is time-to- live value left –When resource is found the node sends the reply NeuroSearch –Uses neural network for forwarding decisions Other algorithms currently under implementation –Highest degree search –Random walker –Adaptive Breadth-First Search

UNIVERSITY OF JYVÄSKYLÄ Topology Management Algorithms

UNIVERSITY OF JYVÄSKYLÄ 2003 Overtaking 1/2 Peer moves closer to the ”good” peers Overtaking percent If connection has neighbor which relayed hits proportion of all neighbors relayed hits and connection’s hits is more than the given percent a new connection to that neighbor is established and current connection is dropt Hits:2 Relayed hits:6 (60%) Relayed hits:2 (20%)

UNIVERSITY OF JYVÄSKYLÄ 2003 Overtaking 2/2 Peers which provide lots of good resources are in the middle of the network Power-law network: a few nodes with many neighbors and a lot of nodes with a few neighbors -> fault tolerant and efficient topology for searching

UNIVERSITY OF JYVÄSKYLÄ 2003 Node Selection 1. Tries to establish the connections which the peer had before leaving the network 2. History data 1. Connections with hit values and ”old” request time 2. Connections with ”old” request time or unrequested connections

UNIVERSITY OF JYVÄSKYLÄ 2003 Node Removal Selects the ”worst” connection Worst connection is a connection which has the lowest goodness value Goodness value: connections hits+its neighbors relayed hits

UNIVERSITY OF JYVÄSKYLÄ 2003 Overload estimation Connections are established and dropped based on the traffic amount flowing through the node ConnectionManager measures the traffic in the given time sequence and if it is more than the given traffic limit one connection is dropped by using Node Removal If the traffic meter is less than the limit, algorithm tries to establish a new connection by using Node Selection

UNIVERSITY OF JYVÄSKYLÄ 2003 Resource reply ”routing” Reply goes back to sender same route as it came if all nodes are still available If the node where the query came to the node is not available anymore the reply is tried to sent to the previous node If the previous node is not available the reply is sent directly to the sender Peer 3Peer 2 Peer 1 Peer 4 query reply

UNIVERSITY OF JYVÄSKYLÄ 2003 Future Point-to-Point Protocol to enable two peer-to- peer nodes to communicate with each other Topology management using a neural network for making Chedar adaptive in wide range of peer-to-peer networks New search algorithms for studying the performance of local search algorithms and the NeuroSearch