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

[Hermanni Hyytiälä]

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Changes by:     Hermanni Hyytiälä <address@hidden>      03/05/21 03:01:56

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        Documentation/misc/hemppah-progradu: masterthesis.tex 

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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

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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 $ip = 
\zeta(\iota(s))$.