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revision 1.137 by hemppah, Thu Mar 13 11:23:49 2003 UTC revision 1.138 by hemppah, Thu Mar 13 13:18:54 2003 UTC
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1  %***********************  %***********************
2  %   K?ytet??n gradu2-tyyliluokkaa  %   Käytetään gradu2-tyyliluokkaa
3  %***********************  %***********************
4  \documentclass[a4paper,12pt, english]{gradu2}  \documentclass[a4paper,12pt, english]{gradu2}
5    
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15  \usepackage{verbatim}  \usepackage{verbatim}
16    
17  %***********************  %***********************
18  %   Tyyliluokan pakolliset m??ritykset  %   Tyyliluokan pakolliset määritykset
19  %***********************  %***********************
20  \title{Fenfire in Peer-to-Peer Environment}  \title{Fenfire in Peer-to-Peer Environment}
21    
# Line 67  vertaisverkosta Fenfire:n kannalta olenn Line 67  vertaisverkosta Fenfire:n kannalta olenn
67  \begin{document}  \begin{document}
68    
69  %***********************  %***********************
70  %   Sis?llysluettelo  %   Sisällysluettelo
71  %***********************  %***********************
72    
73  \mainmatter  \mainmatter
# Line 79  vertaisverkosta Fenfire:n kannalta olenn Line 79  vertaisverkosta Fenfire:n kannalta olenn
79  \chapter{Introduction}  \chapter{Introduction}
80    
81  Peer-to-Peer systems have recently received considerable attention in both  Peer-to-Peer systems have recently received considerable attention in both
82  academia and industry for a number of reasons. First, the lack of centralization  academia \cite{projectirisurl} and industry \cite{p2pworkinggroup}, \cite{jxtaurl} for a
83    number of reasons. The lack of centralization
84  means that the participants can form a distributed system without any investment to  means that the participants can form a distributed system without any investment to
85  centralized, high-priced hardware which would coordinate it. Second, Peer-to-Peer  centralized hardware which would coordinate it by sharing their services
86  provides new direct way to achieve interoperability between network participants.  and connecting to each other directly. Additionally, the distributed and ad hoc nature of
87  Finally, the distributed and ad-hoc nature of Peer-to-Peer improves scalability  Peer-to-Peer improves scalability and avoids single points of failure.
 and reliability againts certain kinds of faults (e.g., single point of failure).  
88    
89  There are many definitions of Peer-to-Peer networks. The Intel Peer-to-Peer  There are many definitions of Peer-to-Peer networks. The Intel Peer-to-Peer
90  Working Group defines it as ''the sharing of computer resources and services  Working Group defines it as ''the sharing of computer resources and services
91  by direct exchange between systems'' \cite{p2pworkinggroup}.  by direct exchange between systems'' \cite{p2pworkinggroup}.
92  Dave Winer \cite{winer00whatisp2p} lists several  Dave Winer \cite{winer00whatisp2p} describes Peer-to-Peer systems as
93  properties of Peer-to-Peer network, while most notably the statement  ''The user's machine is a client and a server''.
94  ''The user's machine is a client and a server'' describes best Peer-to-Peer  Schollmeier \cite{schollmeier01p2pdefinition} characterizes a Peer-to-Peer system as a system of
95  systems. Schollmeier \cite{schollmeier01p2pdefinition} characterizes a Peer-to-Peer network as a system of  distributed entities that share their own services. Thus, Peer-to-Peer systems can be characterized as distributed
96  distributed entities that share their own resources (e.g. CPU time or storage space).  systems in which all communication is symmetric and all participants entities have similar
97  To summarize, Peer-to-Peer systems can be characterized as distributed  capabilities and responsibilities. Each entity, i.e., \emph{peer}, may contribute services
98  systems in which all communication is symmetric and all participants entities have identical  to the overall system.
99  capabilities and responsibilities. Each entity, i.e., \emph{peer}, may contribute data or  
100  computing resources (e.g., unused storage) to the overall system and the welfare  In this thesis, we\footnote{Use of the plural is customary even if research
101  of the community can scale with the number of participants. Thus, each participant  paper is authored solely.} review existing Peer-to-Peer approaches, algorithms and their key properties.
102  rely on one another's services and resources, rather than solely relying on dedicated  We observe that despite of great amount of proposed Peer-to-Peer systems, all systems fall either to
 and centralized infrastructure.  
   
 One of the most important properties of any distributed computing system are efficient  
 data lookup and security. In this thesis, we\footnote{Use of the plural is customary even if research paper is authored solely.}  
 focus on these aspects in Peer-to-Peer domain.  
 Specifically, we review existing Peer-to-Peer approaches, algorithms and their key properties. We observe  
 that despite of great amount of proposed Peer-to-Peer systems, all systems fall either to  
103  loosely structured approach or tightly structured approach. We also discuss open problems in  loosely structured approach or tightly structured approach. We also discuss open problems in
104  Peer-to-Peer systems and divide problems into three sub-categories: security problems,  Peer-to-Peer systems and divide problems into three sub-categories: security problems,
105  performance problems and miscellaneous problems. In the end, we summarize all  performance problems and miscellaneous problems.  
 problems in easy-to-understand tables.  
106    
107  Next, we give an overview of Fenfire hypermedia system, which implements xanalogical storage model. We  Next, we give an overview of Fenfire project. Fenfire project is an attempt to build hyperstructured,
108  also describe briefly Storm software module of Fenfire system, which is an essential part of Fenfire's  seamlessly interoperating desktop environment. Additional features of Fenfire include innovative user
109  Peer-to-Peer functionality. We evaluate existing Peer-to-Peer approaches and  interfaces for viewing data and usage of Peer-to-Peer networking for network transparency. In Fenfire,
110  choose the best alternative to Fenfire's needs. We discover that Fenfire, xanalogical model and  all data is stored in the same format, i.e., data blocks.  All blocks have globally unique
111  tightly structured Peer-to-Peer approach all have similar method to deal with data,  identifiers and they can be referred by other blocks, i.e., pointer blocks.
112  i.e., globally unique identifiers. Finally, we propose system model for Fenfire in Peer-to-Peer  
113    After overview, we evaluate existing Peer-to-Peer approaches and
114    choose the best alternative to Fenfire's needs. Finally, we propose system model for Fenfire in Peer-to-Peer
115  environment and present yet simple but efficient algorithms to be used for data lookups in  environment and present yet simple but efficient algorithms to be used for data lookups in
116  Peer-to-Peer environment.  Peer-to-Peer environment.
117    
118  To our knowledge, this thesis is the most comprehensive work with regard to summarizing  We have attempted to comprehensively summarize existing algorithms and open problems in
119  existing algorithms and open problems in Peer-to-Peer domain. However, this  Peer-to-Peer domain. However, this thesis is not meant to be detailed work. More detailed
120  thesis is not meant to be detailed work. More detailed information can be found from genuine  information can be found from references written by original authors.
 publications written by original authors.  
   
 \section{Research problems}  
121    
122  There are three research problems related to this thesis. First research problem  There are three research problems related to this thesis. First research problem
123  is to find the most efficient way to locate and fetch Fenfire related data from the  is to find the most efficient way to locate and fetch Fenfire data blocks from the
124  Peer-to-Peer network, where Storm scroll block's identifier is given. Second, we want  Peer-to-Peer network, where block's identifier is given. Second, we want
125  to find the most efficient way to locate and fetch most recent Fenfire related data from the  to find the most efficient way to locate and fetch most recent Fenfire data block from the
126  Peer-to-Peer network, which is associated with a given pointer random string. Third problem  Peer-to-Peer network referred by a pointer block. Third problem
127  is otherwise same as the second problem, except we want to locate and fetch all Fenfire  is otherwise same as the second problem, except we want to locate and fetch Fenfire
128  related data from the Peer-to-Peer network, where given date and/or time range is given.  data block from the Peer-to-Peer network, where given date and/or time range is given.
129    
 \section{Thesis overview}  
130  This thesis is structured as follows. In next chapter, we give an overview of  This thesis is structured as follows. In next chapter, we give an overview of
131  existing Peer-to-Peer approaches, algorithms and key differences. In chapter 3, we  existing Peer-to-Peer approaches, algorithms and key differences between them. In chapter 3, we
132  address open problems in Peer-to-Peer domain and divide problems into three  address open problems in Peer-to-Peer domain and divide problems into three
133  sub-categories. Chapter 4 gives an overview of Fenfire system. In chapter  sub-categories. Chapter 4 gives an overview of Fenfire system. In chapter
134  5, we evaluate existing Peer-to-Peer approaches with regard to Fenfire system, propose a system  5, we evaluate existing Peer-to-Peer approaches with regard to Fenfire system.
135  model for Fenfire in Peer-to-Peer environment and present simple algorithms to perform data  In chapter 6, we present conclusions and future work.
 lookups in Peer-to-Peer environment. In addition, we discuss possible problems of using Fenfire  
 in Peer-to-Peer environment. In chapter 6, we present conclusions and future work.  
136    
137    
138  \chapter{Peer-to-Peer architectures}  \chapter{Peer-to-Peer architectures}
# Line 582  approach and tightly structured approach Line 570  approach and tightly structured approach
570  \endfoot  \endfoot
571    
572    
 \\ \hline  
   
573  \parbox{90pt}{Queries} &  \parbox{90pt}{Queries} &
574  \parbox{100pt}{Uncontrolled} &  \parbox{100pt}{Uncontrolled} &
575  \parbox{100pt}{Controlled}    \parbox{100pt}{Controlled}  
# Line 1656  functionality. Line 1642  functionality.
1642    
1643  \section{Overview}  \section{Overview}
1644    
1645  Fenfire project \cite{fenfireurl} is an effort to build a distributed, hyper structured user  Fenfire project \cite{fenfireurl} is an effort to build a location transparent, hyperstructured desktop
1646  interface system. Fenfire is free software and it is licensed under GNU L-GPL. Fenfire's main goal  environment. Fenfire's uses xanalogical storage model \cite{ted-xu-model} as a basis for hyperstructured
1647  is to implement xanalogical storage model \cite{ted-xu-model}. Fenfire was formerly also a implementation  media. Fenfire uses innovative user interfaces for displaying data to the end users. All data in Fenfire
1648    is stored in same format, i.e., blocks. This should allow making references between data easier and more
1649    seamlessly interoperating than in other systems. For location transparency in a distributed system, Fenfire
1650    uses Peer-to-Peer network for locating and fetching blocks.
1651    
1652    Fenfire is free software and it is licensed under GNU L-GPL.  Fenfire was formerly also a implementation
1653  of the ZigZag\texttrademark --structure, which was originally invented  of the ZigZag\texttrademark --structure, which was originally invented
1654  by Ted Nelson. Now, however, Fenfire uses Resource Description Framework (RDF) \cite{w3rdfurl}  by Ted Nelson. Now, however, Fenfire uses Resource Description Framework (RDF) \cite{w3rdfurl}
1655  for representing internal data structures and their relationships.  for representing internal data structures and their relationships.
# Line 1925  mapping function of the overlay. These s Line 1916  mapping function of the overlay. These s
1916  are sensitive to certain attacks (e.g., DDoS attack). Additionally, we prefer \emph{abstraction}  are sensitive to certain attacks (e.g., DDoS attack). Additionally, we prefer \emph{abstraction}
1917  level analysis as very recently better and better tightly structured algorihtms have been proposed.  level analysis as very recently better and better tightly structured algorihtms have been proposed.
1918  Thus, we don't want to bind our system proposal to a specific algorithm definitively as we expect  Thus, we don't want to bind our system proposal to a specific algorithm definitively as we expect
1919  that this development continues.    that this development continues.
1920    
1921  In the following subsections we assume that we know the structure of  In the following subsections we assume that we know the structure of
1922  ''virtual file'' before hand, i.e., when assembling a ''virtual file'', we know all Storm  ''virtual file'' before hand, i.e., when assembling a ''virtual file'', we know all Storm

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