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revision 1.107 by hemppah, Tue Mar 4 10:00:17 2003 UTC revision 1.108 by hemppah, Tue Mar 4 11:05:58 2003 UTC
# Line 1018  and replicas should be located physicall Line 1018  and replicas should be located physicall
1018    
1019  Currently, trust in Peer-to-Peer systems is based on \emph{reputation}. Current repuation methods focus either  Currently, trust in Peer-to-Peer systems is based on \emph{reputation}. Current repuation methods focus either
1020  on the semantic properties, or data management properties of the trust model. Some research has been  on the semantic properties, or data management properties of the trust model. Some research has been
1021  done on reputation models in Peer-to-Peer systems, such as \cite{aberer01trust}. Implementations  done on reputation models in Peer-to-Peer systems, such as \cite{aberer01trust}, \cite{cornelli02reputableservents}.
1022  include Advogato \cite{advogatourl}. None of the current proposals or implementations based on reputation address trust  Implementations include Advogato \cite{advogatourl}. None of the current proposals or implementations
1023  in a trustworthy way.  based on reputation address trust in a reliable way.
1024    
1025  Optimal solution for trust in Peer-to-Peer systems would be certificate based security methods.  Optimal solution for trust in Peer-to-Peer systems would be certificate based security methods.
1026  Quite recently, widely used Public Key Infrastructure (PKI) has been deployed in distributed  Quite recently, widely used Public Key Infrastructure (PKI) has been deployed in distributed
# Line 1248  more research is required to make latenc Line 1248  more research is required to make latenc
1248    
1249    
1250    
1251  \cite{crespo02semanticoverlay}  
1252  Locality \cite{keleher-02-p2p}  Locality \cite{keleher-02-p2p}
1253    
1254    
# Line 1286  and Clustering with their search optimiz Line 1286  and Clustering with their search optimiz
1286  While it is expected that web-like searches can be layered on top of tightly structured overlay, much  While it is expected that web-like searches can be layered on top of tightly structured overlay, much
1287  more research is required to make indexing and searching more efficient.  more research is required to make indexing and searching more efficient.
1288    
 \cite{ramanathan02goodpeers}  
1289    
1290  Improve Freenet performance with small worlds \cite{zhang02using}  Improve Freenet performance with small worlds \cite{zhang02using}
1291    
# Line 1354  for monitoring health of tightly structu Line 1353  for monitoring health of tightly structu
1353    
1354  \section{Miscellaneous problems in Peer-to-Peer}  \section{Miscellaneous problems in Peer-to-Peer}
1355    
1356  \subsection{Frameworks}  In this section we discuss miscellaneous problems related to Peer-to-Peer systems.
   
 \cite{zhao03api}  
 \cite{frise02p2pframework}  
 \cite{babaoglu02anthill}  
 \cite{rhea03benchmarks}  
   
 \subsection{Social behaviour}  
 \cite{cornelli02reputableservents}  
 \cite{oram01harnessingpower}  
 \cite{golle01incentivesp2p}  
   
 Notes from from \cite{hearn02mojonation}  
   
 1) Attack resistance  
 2) malicious nodes  
 3) mutual distrust  
 4) motivation to cooperate  
1357    
1358    \subsection{Programming guidelines and benchmarks}
1359    
1360    All existing Peer-to-Peer systems have rather different interfaces even they common points and
1361    components. More important, all existing Peer-to-Peer systems incompatible with each other. One
1362    of the most important area of future research is to create common programming abstractions, i.e.
1363    interfaces, design patters and frameworks. Also, equal benchmarks are needed for comparing
1364    different algorithms. Recently, there have been few proposals towards common programming
1365    guidelines. This list includes \cite{zhao03api}, \cite{frise02p2pframework}, \cite{babaoglu02anthill}.
1366    Early experiments with Peer-to-Peer benchmarking include \cite{ratnasamy02routing} and \cite{rhea03benchmarks}.
1367    
1368  \subsection{Usage patterns}  \subsection{Social behaviour}
 \cite{saroiu02measurementstudyp2p}  
 \cite{krishnamurthy01earlymeasurements}  
   
 Research on *usage patterns* haven't been done. However, there have been some research  
 focusing on file popularity in in www and p2p networks: file popularity follows the zipf/harmonical distribution)  
1369    
1370    Very frequent assumption in Peer-to-Peer systems is that peers are willing to cooperate. Another belief
1371    is that all peers would behave equally, i.e. all peers both consume resources and contributes resources.
1372    However, these assumptions are not true as several studies show peers rather consume than contribute and
1373    and peers are unwilling to cooperate \cite{saroiu02measurementstudyp2p}, \cite{oram01harnessingpower},
1374    \cite{hearn02mojonation}.
1375    
1376    Somewhat surprisingly little research has been in this area, especiaclly when considering
1377    the possible impact of this \emph{unwanted socical behaviour} to performance of Peer-to-Peer
1378    system. However, problem is addressed by Golle et al. \cite{golle01incentivesp2p}. Some
1379    research has been focused on semantic properties of the overlay in order to increase
1380    cooperation among participating peers \cite{crespo02semanticoverlay}. Ramanathan et al.
1381    \cite{ramanathan02goodpeers} and Bernstein et al. \cite{bernstein03selection} use
1382    empirical metrics and decision trees when teaching peers to make better decisions
1383    when contacting other peers in Peer-to-Peer system. Alpine is an example of
1384    Peer-to-Peer system, which uses empirical metrics for peer selection.
1385    
1386    
1387    \subsection{Simulating the Peer-to-Peer system}
1388    
1389    Very little research has been done on simulating the global Peer-to-Peer system. Presumably, this
1390    is due to complex nature of Peer-to-Peer system, which makes comprehensive simulations very
1391    diffucult. Floyd et al. has been studying the simulation of the Internet in \cite{504642}. Authors
1392    state that simulating the Internet is very challenging task, because of Internet's heterogeneity
1393    and rapid change. Obviously, these factors exist also in Peer-to-Peer system even with higher
1394    rates.
1395    
1396    As long as global simulations of Peer-to-Peer systems are lacking, we cannot we make any further
1397    analysis e.g., on usage patterns in Peer-to-Peer systems. Presumedly, however, we can assume that
1398    queries follow the Zipf-like distributions both in the Internet and in Peer-to-Peer systems.
1399    
1400  \section{Summary}  \section{Summary}
1401    

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