[Gzz-commits] gzz/Documentation/misc/hemppah-progradu mastert...

[Hermanni Hyytiälä]

CVSROOT:        /cvsroot/gzz
Module name:    gzz
Changes by:     Hermanni Hyytiälä <address@hidden>      03/02/26 09:28:20

Modified files:
        Documentation/misc/hemppah-progradu: masterthesis.tex 

Log message:
        Overview

CVSWeb URLs:
http://savannah.gnu.org/cgi-bin/viewcvs/gzz/gzz/Documentation/misc/hemppah-progradu/masterthesis.tex.diff?tr1=1.84&tr2=1.85&r1=text&r2=text

Patches:
Index: gzz/Documentation/misc/hemppah-progradu/masterthesis.tex
diff -u gzz/Documentation/misc/hemppah-progradu/masterthesis.tex:1.84 
gzz/Documentation/misc/hemppah-progradu/masterthesis.tex:1.85
--- gzz/Documentation/misc/hemppah-progradu/masterthesis.tex:1.84       Wed Feb 
26 07:54:08 2003
+++ gzz/Documentation/misc/hemppah-progradu/masterthesis.tex    Wed Feb 26 
09:28:20 2003
@@ -149,22 +149,31 @@
 We also discuss open issues and future work. Finally, we present conclusions 
in chapter
 6.
 
-\chapter{Peer-to-Peer schemes}
+\chapter{Peer-to-Peer architectures}
+In this chapter we give brief history and overview of Peer-to-Peer networks, 
+review most important Peer-to-Peer protocols and list key differences between 
+two main approaches.
 
 \section{Overview}
 
-
-Approaches:
-1) centralized (napspter, audiogalaxy: search index on single server, p2p file 
transer between clients)
-1) decentralized, but structured (DHTs, SWAN, gnutella superpeers/peer 
clusters)
-3) decentralized and unstructured (gnutellas, freenet)
-
-\cite{levy90distributedfilesystems}
-\cite{339345}
-\cite{albert-02-statistical}
-\cite{albert-00-tolerance}
-\cite{balakrishanarticle03lookupp2p}
-
+The Internet has been originally established in the late 1960s. The objective 
+of the ARPANET-project was to share computers' resources among military 
computers
+around the United States. The most challenging purpose of ARPANET was to 
integrate 
+different kinds of existing network technologies with one common network 
architecture. 
+The ARPANET connected the first few hosts together not in client/server 
relationship, 
+but rather as equal networking \emph{peers}. This could be seen as starting 
point 
+both of Peer-to-Peer concept and the Internet \cite{oram01harnessingpower}. 
+
+In subsequent years, the Internet became more restricted to client--server 
based 
+applications. In recent years, however, Peer-to-Peer systems have again 
emerged 
+room in computing world. Indeed, Peer-to-Peer has had significant social and 
technical 
+attention in academia, industry and media. Already deceased Napster 
\cite{napsterurl}, 
+launched in 1999, was a new starting point for modern Peer-to-Peer computing. 
After
+Napster, hundreds of Peer-to-Peer systems have been developed and proposed. 
+
+Modern Peer-to-Peer system is composed of \emph{application} level overlay 
network.
+Figure \ref{fig:application_level} illustrates the analogy of Peer-to-Peer 
network with
+regard to OSI model.
 
 \begin{figure}
 \centering
@@ -172,6 +181,44 @@
 \caption{Peer-to-Peer Application Level Overlay}
 \label{fig:application_level}
 \end{figure}
+
+Compared to ARPANET's Peer-to-Peer functionality, today's Peer-to-Peer systems
+are ad-hoc, i.e. peers join and leave the system constantly in a dynamic 
manner. This
+fact constitutes challenging requirements for efficient construction and 
maintenance
+of the overlay network. Even more demanding tasks are how to perform efficient 
data
+lookup and maintain security in a varying distributed environment. The most 
popular
+form of modern Peer-to-Peer computing is file-sharing. In this scenario, 
participants
+of Peer-to-Peer network share their resources to other participants while 
obtaining
+more resources from others. This can been seen as a variant of distributed 
filesystem
+(see, e.g., \cite{levy90distributedfilesystems}). 
+
+In a development of modern Peer-to-Peer systems, lot of influences has been 
attained from 
+other research areas than computer science. There has been done research 
regarding 
+to ad-hoc nature of complex networks \cite{albert-02-statistical}, 
\cite{albert-00-tolerance}, \cite{watts00dynamics}. 
+It's interesting to realize that chemical properties of cells, the Internet, 
ad-hoc 
+Peer-to-Peer networks, have in common that they all self-organize based on 
same 
+principles.  Furthermore, the assocation between social connections among 
people 
+and Peer-to-Peer overlay topology has been studied recently  
\cite{watts00dynamics}, 
+\cite{kleinberg99small}, \cite{nips02-Kleinberg}. This insight is motivated
+by Milgram, how noticed that people are very effective to locate other people 
in a wide scale, 
+based on local knowledge. This phenomenon is called as ''small-world 
phenomenon'' 
+\cite{milgram67smallworld}. As a consequence, many modern Peer-to-Peer systems
+have applied techniques outside of computer science when constructing and 
maintaining
+the application level overlay network.
+
+In the end, however, there are two main approaches in which all modern 
Peer-to-Peer
+systems fall: loosely structured approach and tightly structured approach. In 
loosely
+structured approach the construction and the maintenance of the overlay is-- 
as the name
+suggests- is controlled loosely. This approach gives freedom for participating 
peers
+to perform certains tasks in Peer-to-Peer network. On the other hand, tightly 
structured
+approach has some rules, which all participating peers have obey. In next 
sections,
+we discuss in more detail both approaches, they disadvantages and advantages, 
and
+key differences. 
+
+\cite{balakrishanarticle03lookupp2p}
+
+
+
 
 
 \section{Centralized}