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revision 1.14 by hemppah, Thu Nov 28 12:52:52 2002 UTC revision 1.15 by hemppah, Thu Nov 28 14:01:45 2002 UTC
# Line 87  is made greater than the sum of its part Line 87  is made greater than the sum of its part
87  Many defitions of P2P have been proposed in P2P community. The Intel P2P Working Group \cite{p2pworkinggroup}  Many defitions of P2P have been proposed in P2P community. The Intel P2P Working Group \cite{p2pworkinggroup}
88  defines P2P as "the sharing of computer resources and services by direct exchange between systems". Ross Lee  defines P2P as "the sharing of computer resources and services by direct exchange between systems". Ross Lee
89  Graham \cite{graham02lecture} defines P2P through three requirements: 1) System has an operational computer  Graham \cite{graham02lecture} defines P2P through three requirements: 1) System has an operational computer
90  of server quality; 2) System has an addressing system independent of DNS \cite{rfc1101}; 3) System is able  of server quality; 2) System has an addressing system independent of DNS; 3) System is able
91  to cope with variable connectivity. O'Reilly's Clay Shirky proposes that "P2P is a class of applications  to cope with variable connectivity. O'Reilly's Clay Shirky proposes that "P2P is a class of applications
92  that takes advantage of resources - storage, cycles, content, human presence - available at the edges  that takes advantage of resources - storage, cycles, content, human presence - available at the edges
93  of the Internet. Because accessing the decentralized resources means operating in a environment of unstable  of the Internet. Because accessing the decentralized resources means operating in a environment of unstable
# Line 113  of P2P versus centralized, client-server Line 113  of P2P versus centralized, client-server
113  [Figure 1. Insert picture]  [Figure 1. Insert picture]
114    
115  However, more detailed comparison of P2P systems and client-server approach is significantly more complex  However, more detailed comparison of P2P systems and client-server approach is significantly more complex
116  along many dimensions: "There is no clear border between a client-server and a P2P model. Both models can be  because: "There is no clear border between a client-server and a P2P model. Both models can be
117  built on a spectrum of level of characteristics, functionality, organizations, components, protocols etc. Furthermore,  built on a spectrum of level of characteristics, functionality, organizations, components, protocols etc. Furthermore,
118  one mode can be built on top of the other or parts of the components can be realized in one or the other model. Finally,  one mode can be built on top of the other or parts of the components can be realized in one or the other model. Finally,
119  both models can execute on different types of platforms and both can server as an underlying base for traditional  both models can execute on different types of platforms and both can server as an underlying base for traditional
# Line 123  and what it is not. It is extremely inte Line 123  and what it is not. It is extremely inte
123    
124  \subsection{A brief history}  \subsection{A brief history}
125    
126  The Internet has been originally established in the late 1960s \cite{oram01harnessingpower}.  The Internet has been originally established in the late 1960s. The objective of the ARPANET-project was to
127  The aim of the ARPANET-project was to share computers' resources around the  share computers' resources around the United States. The most challenging purpose of ARPANET was to
128  United States. The most challenging purpose of ARPANET was to integrate different kinds of  integrate different kinds of existing network technologies with one common network architecture. The
129  existing network technologies with one common network architecture. The ARPANET connected  ARPANET connected the first few hosts together not in client/server relationship, but rather as
 the first few hosts together not in client/server relationship, but rather as  
130  equal networking peers. This could be seen as starting point both of P2P systems and  equal networking peers. This could be seen as starting point both of P2P systems and
131  Internet [REFERENCE NEEDED!!!].  Internet \cite{oram01harnessingpower}.
132    
133  While most early distributed applications can be considered P2P, e-mail systems and Usenet  While most early distributed applications can be considered P2P, file transfer protocol (FTP), Usenet and Telnet
134  News were probably the most extensively used. In both cases, local server created connections to  systems were probably the most extensively used. A Telnet client logged into a server, and
135  other peer servers to deliver messages into the user's mail box or into a spool box  an FTP client downloaded and sent data to a file server. In the case of Usenet, peer servers connected
136  containing messages from the newsgroups. The File Transfer Protocol (FTP) can be considered as a  to other peers to deliver messages into the user's mail box or into a spool box containing messages from
137  predecessor to today's file-sharing P2P systems. Eventually, the Archie indexing system, was developed to  the newsgroups. Altough  single application could be seen as was client/server relationship, the usage model as a
138    whole were symmetric. Every computer on the ARPANET could create connections to any other computer and use
139    each other's resources. The symmetry is what made the ARPANET so novel. As a implication, early ARPANET
140    made possible to create more complex systems as DNS \cite{rfc1101}.
141    
142    In subsequent years, the Internet has become more restricted to client/server based applications. In
143    recent years, however, P2P systems have emerged a significant social and technical phenomenon. It could
144    be possible the Internet could revert to its initial symmetrical form. At the end, FTP can be considered as
145    a predecessor to today's file-sharing P2P systems. The Archie, global indexing system, was developed to
146  provide a central search infrastructure over existing FTP servers. Napster \cite{napsterurl} is a good  provide a central search infrastructure over existing FTP servers. Napster \cite{napsterurl} is a good
147  example of this kind of approach in modern P2P file-sharing systems.  example of this kind of approach in modern P2P file-sharing systems.
148    
149  \subsection{Characteristics of P2P}  \subsection{Characteristics of P2P}
150    
151    Decentralization
152    Scalability and adapion
153    Anonymity and Autonomy
154    Self-organization
155    Cost Of ownership
156    ad-hoc connectivity
157    accountability
158    reputation
159    
160  \subsection{Adaptations of P2P}  \subsection{Adaptations of P2P}
161    
162  \subsection{Models of P2P}  \subsection{Models of P2P}

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