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[Gzz-commits] gzz/Documentation/misc/hemppah-progradu mastert...
From: |
Hermanni Hyytiälä |
Subject: |
[Gzz-commits] gzz/Documentation/misc/hemppah-progradu mastert... |
Date: |
Wed, 21 May 2003 03:01:56 -0400 |
CVSROOT: /cvsroot/gzz
Module name: gzz
Changes by: Hermanni Hyytiälä <address@hidden> 03/05/21 03:01:56
Modified files:
Documentation/misc/hemppah-progradu: masterthesis.tex
Log message:
Steven's comments
CVSWeb URLs:
http://savannah.gnu.org/cgi-bin/viewcvs/gzz/gzz/Documentation/misc/hemppah-progradu/masterthesis.tex.diff?tr1=1.203&tr2=1.204&r1=text&r2=text
Patches:
Index: gzz/Documentation/misc/hemppah-progradu/masterthesis.tex
diff -u gzz/Documentation/misc/hemppah-progradu/masterthesis.tex:1.203
gzz/Documentation/misc/hemppah-progradu/masterthesis.tex:1.204
--- gzz/Documentation/misc/hemppah-progradu/masterthesis.tex:1.203 Mon May
5 04:21:04 2003
+++ gzz/Documentation/misc/hemppah-progradu/masterthesis.tex Wed May 21
03:01:55 2003
@@ -39,15 +39,16 @@
\abstract{
-In this thesis, we review existing Peer-to-Peer approaches, algorithms and
their
-key properties. We summarize open problems in Peer-to-Peer systems and divide
-problems into three sub-categories. We observe that there are many problems
with
-either no solutions at all, or only practically unrealizable ones.
-
-Then, we give an overview of the Fenfire system. We evaluate existing
-Peer-to-Peer approaches-- loosely and tightly structured overlays-- with regard
-to Fenfire's needs. Finally, we propose simple methods to efficiently find
Fenfire
-data from Peer-to-Peer network.
+In this thesis, first we review existing Peer-to-Peer approaches, algorithms
and their
+key properties. We summarize open problems in Peer-to-Peer systems and divide
these
+problems into three sub-categories. We realize that there are many problems
and few
+practical solutions, and some problems have no solution at all.
+
+Then, we provide an overview of the Fenfire system. The Fenfire system is a
free
+software effort to build a location transparent, hyperstructured desktop
environment.
+We evaluate existing Peer-to-Peer approaches-- loosely and tightly structured
overlays-- with regard
+to Fenfire's needs. Finally, we propose simple methods to efficiently locate
Fenfire
+data from Peer-to-Peer networks.
}
\tiivistelma{
Tässä opinnäytetyössä esittelemme olemassaolevia vertaisverkkoja, algoritmeja
ja
@@ -85,7 +86,7 @@
without any investment to centralized hardware by sharing their services and
connecting to each
other directly. Peer-to-Peer systems can be characterized as distributed
systems in which all
communication is symmetric and all participant entities have similar
capabilities and responsibilities
-\cite{oram01harnessingpower}. Schollmeier \cite{schollmeier01p2pdefinition}
describes Peer-to-Peer system as a system of
+\cite{oram01harnessingpower}. Schollmeier \cite{schollmeier01p2pdefinition}
describes a Peer-to-Peer system as a system of
distributed entities that share their own services.
Each entity, i.e., \emph{peer}, may contribute services to the overall system.
The distributed
and ad hoc nature of Peer-to-Peer improves scalability and avoids single
points of failure.
@@ -93,29 +94,29 @@
The Fenfire project is an attempt to build a hyperstructured, seamlessly
interoperating desktop
environment. In the Fenfire system, all data is stored as blocks.
Each block has a globally unique identifier and it can be referred, by pointer
blocks.
-Other features of the Fenfire include innovative user
+Other features of Fenfire include innovative user
interfaces for viewing data. The applicability of Peer-to-Peer networking with
Fenfire for network
transparency is currently under investigation.
-Three research problems are discussed in this thesis: first, finding the most
efficient
-way to locate and fetch Fenfire data blocks from a Peer-to-Peer network, when
the block's
+Three research problems are discussed in this thesis: First, finding the most
efficient
+way to locate and fetch Fenfire data block from a Peer-to-Peer network when
the block's
identifier is given. Second, we want to find the most efficient way to locate
and fetch the most
recent Fenfire data block from a Peer-to-Peer network referred by a pointer.
The third problem
is similar to the second problem, except we want to locate and fetch the
Fenfire
-data block, when date and or time range is given.
+data block when a date and or time range is given.
In this thesis, we evaluate existing Peer-to-Peer approaches and
-evaluate them to Fenfire's needs. We start by reviewing existing Peer-to-Peer
approaches,
-algorithms and their key properties. Our insight is that despite the great
amount of proposed
-Peer-to-Peer systems, we are able to classify \emph{all} systems either to
loosely or
-tightly structured approach. We also discuss open problems in
+evaluate them, based on Fenfire's needs. We start by reviewing existing
Peer-to-Peer approaches,
+algorithms and their key properties. Our insight is that, despite the great
amount of proposed
+Peer-to-Peer systems, we are able to classify \emph{all} systems either as
loosely or
+tightly structured approaches. We also discuss open problems in
Peer-to-Peer research and divide problems into three sub-categories: security,
performance, and miscellaneous
-problems. We attempt to comprehensively summarize existing algorithms and open
problems in
-Peer-to-Peer domain. This thesis doesn't give detailed information about
reviewed algorithms nor
+problems. We attempt to comprehensively summarize existing algorithms and open
problems in the
+Peer-to-Peer domain. This thesis does not provide detailed information about
reviewed algorithms nor
open problems. More detailed information can be found from the references.
-Finally, we give an overview of the Fenfire project, and evaluate Peer-to-Peer
approaches to Fenfire's
-needs. Finally, we propose simple but yet efficient methods to be used for
data lookups in Peer-to-Peer
+Finally, we give an overview of the Fenfire project, and compare Peer-to-Peer
approaches to Fenfire's
+needs. Finally, we propose simple yet efficient methods that could be used for
data lookups in a Peer-to-Peer
environment.
\chapter{Peer-to-Peer architectures}
@@ -126,18 +127,18 @@
\section{Brief history and overview}
The Internet was originally established in the late 1960s \cite{253741}. 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
+of the ARPANET-project was to share information resources among military
computers
+in 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,
+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 the
starting point
of both the Peer-to-Peer concept and the Internet
\cite{oram01harnessingpower}.
The most popular form of modern Peer-to-Peer computing is file-sharing. In
this scenario,
-participants of Peer-to-Peer network share their file resources with other
participants.
-This is a form of distributed file system (e.g.,
\cite{levy90distributedfilesystems}).
+participants of Peer-to-Peer networking share their file resources.
+This is form of a distributed file system (e.g.,
\cite{levy90distributedfilesystems}).
A modern Peer-to-Peer system is composed of an \emph{application} level
overlay network, i.e.,
-network operates at the application level and forms a logical network overlay
on top of physical
+the network operates at the application level and forms a logical network
overlay on top of the physical
network with regard to the ISO-OSI reference model (e.g., \cite{800902}).
Figure \ref{fig:application_level}
illustrates the Peer-to-Peer application level overlay network.
Compared to ARPANET's Peer-to-Peer functionality, modern Peer-to-Peer systems
@@ -155,41 +156,42 @@
-In the development of modern Peer-to-Peer systems, lot of influences have been
derived from
+In the development of modern Peer-to-Peer systems, many influences have come
from
outside of computer science. First, it is interesting to realize that chemical
properties of biological cells, the Internet, ad hoc
Peer-to-Peer systems, and social network self-organize based on the same
principles \cite{albert-02-statistical, albert-00-tolerance, watts00dynamics}.
Second, the
association between social relationships among people and Peer-to-Peer overlay
topology has been
-studied recently \cite{watts00dynamics, kleinberg99small, nips02-Kleinberg}.
-This insight is motivated by Milgram \cite{milgram67smallworld}, who noticed
that people are very effective in
-locating other people in a wide scale based on local knowledge. This
phenomenon is called as
+recently studied \cite{watts00dynamics, kleinberg99small, nips02-Kleinberg}.
+This insight is motivated by Milgram \cite{milgram67smallworld}, who noticed
that people very effectively
+locate other people on a wide geographic scale based on local knowledge. This
phenomenon is called
''small-world phenomenon''. As a consequence, many modern Peer-to-Peer systems
have applied similar techniques when constructing and maintaining the
application level
overlay network.
-In the end, however, we observe that there are only two approaches in which
all modern Peer-to-Peer
-systems fall: the loosely structured approach and the tightly structured
approach.
+In the end, however, we observe that there are only two approaches in modern
Peer-to-Peer
+systems: the loosely structured approach and the tightly structured approach.
By structure, we refer to the topology of the overlay network, i.e., how the
connections between participating peers are created
and maintained. In the following sections, we will discuss in more detail the
properties of these approaches.
\section{Loosely structured}
-In the loosely structured approach the construction and the maintenance of the
overlay is controlled
+In the loosely structured approach the construction and maintenance of the
overlay is controlled
loosely. The placement of services and the topology of overlay is random. The
data lookup model in loosely structured systems is
-not very efficient, because of unstructured properties of the overlay. Data
lookup model is a combination of methods which
+not very efficient because of unstructured properties of the overlay. The data
lookup model is a combination of methods which
are used for locating data in the overlay.
-\subsection{Skecth of definition}
+\subsection{Proposed definition}
-In this subsection, we try to introduce a \emph{sketch} of formal definition
of the loosely structured overlay. This
-model is based on original Gnutella overlay network with power-law
improvements.
+In this subsection, we try to \emph{sketch out} a formal definition of the
loosely structured overlay. This
+model is based on the original Gnutella overlay network with power-law
improvements. Please notice that the
+definition proposal is not used elsewhere in this thesis.
-Let $S$ be the aggregate of all services $s$ in system. Let $P$ be the
aggregate of
-all peers $p$ in system. Then, $\forall s \in S$, there is a provider of the
service,
+Let $S$ be the aggregate of all services $s$ in the system. Let $P$ be the
aggregate of
+all peers $p$ in the system. Then, $\forall s \in S$, there is a provider of
the service,
expressed as $p = \delta(s)$. Every $p$ has neighbor(s), named as $p_n$, which
is $P$ = \{$p \in P: \exists neighbor$, which is randomly chosen from $P$\}.
-Summary index maintains indices of other peers, $si o= \gamma(\delta(s))$.
-Then, $\forall$ regular peer $p$, there is a super peer, $sp$, and it has a
index of
+The summary index maintains indices of other peers, $si o= \gamma(\delta(s))$.
+Then, $\forall$ regular peer $p$, there is a super peer, $sp$, and it has an
index of
regular peer's content $P$ = \{$p \in P: \exists sp$,
where $sp$ = $\delta(\gamma(\delta(s))) \wedge (p = \delta(s))$\}
@@ -296,13 +298,14 @@
approach the overlay is constructed deterministically, which all participating
peers have to follow; the topology of the
overlay and the placement of services is controlled tightly.
-\subsection{Sketch of definition}
+\subsection{Proposed definition}
-In this subsection, we try to introduce a \emph{sketch} of formal definition
of the tightly structured overlay, such as
-identifiers, identifier space and the mapping function.
+In this subsection, we try to \emph{sketch out} a formal definition of the
tightly structured overlay, such as
+identifiers, identifier space and the mapping function. Please notice that the
+definition proposal is not used elsewhere in this thesis.
Let $S$ be the aggregate of all services $s$ in the system. Let $P$ be the
aggregate of
-all peers $p$ in system. Let $I$ be the aggregate of all identifiers $i$ in
system.
+all peers $p$ in the system. Let $I$ be the aggregate of all identifiers $i$
in the system.
Let $IS$ be the aggregate of all identifier points $ip$ in system. Then,
$\forall s \in S$,
there is a provider of the service, expressed as $p = \delta(s)$. Service's
identifier
is defined as $i = \iota(s)$. Coordinate point is defined as $ip =
\zeta(\iota(s))$.