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revision 1.79 by hemppah, Wed Feb 26 09:35:10 2003 UTC revision 1.80 by hemppah, Wed Feb 26 12:27:35 2003 UTC
# Line 80  vertaisverkosta tietoa Fenfire:n liittye Line 80  vertaisverkosta tietoa Fenfire:n liittye
80    
81  \chapter{Introduction}  \chapter{Introduction}
82    
83  Peer-to-Peer (Peer-to-Peer) systems can be characterized as distributed systems in which all  Peer-to-Peer systems have recently received noteworthy attention in both
84  communication is symmetric and all participants have identical capabilities and responsabilities.  academia and industry for a number of reasons. First, the lack of centralization
85  Each participant may contribute data or computing resources (such as unused storage) to the overall  means that participants can form a distributed system without any investment to
86  system, and the welfare of the community can scale with ne number of participants. Therefore each  centralized, high-priced hardware which would to coordinate it. Second, Peer-to-Peer
87  participant rely on one another services and resources, rather than solely relying on dedicated  provides new, direct way to achieve interoperability between network participants.
88  centralized infracstructure.  Finally, the distributed and ad-hoc nature of Peer-to-Peer improves scalability
89    and reliability againts certain kinds of faults (e.g., single point of failure).
90  Peer-to-Peer systems have recently received significant attention in both academia and industry for a number  There are many definitions of Peer-to-Peer networks. The Intel Peer-to-Peer
91  of reasons. First, the lack of decentralization means that participants can form a Peer-to-Peer system without any  Working Group defines is as ''the sharing of computer resources and defines
92  investment to high-priced hardware to coordinate it. Moreover, Peer-to-Peer systems provides aggregation of enormous  and services by direct exchange between systems''. Dave Winer \cite{winer00whatisp2p} lists several
93  resources and way to achieve interoperability. Finally, the distributed nature of Peer-to-Peer improves scalability  properties of Peer-to-Peer network, while most notably the statement
94  and reliability againts certain kinds of faults, e.g. single point of failure.  ''The user's machine is a client and a server'' describes best Peer-to-Peer
95    networks.
96  footnote:use of the plural is customary even if research paper is authored solely  
97    To summarize, Peer-to-Peer systems can be characterized as distributed
98    systems in which all communication is symmetric and all participants have identical
99    capabilities and responsabilities. Each \emph{peer} may contribute data or
100    computing resources (e.g., unused storage) to the overall system and the welfare
101    of the community can scale with ne number of participants. Thus, each participant
102    rely on one another services and resources, rather than solely relying on dedicated
103    and centralized infracstructure.
104    
105    One of the most important properties of any distributed computing system are efficient
106    data lookup and security. In this thesis, we \footnote{Use of the plural is customary even if research paper is authored solely.}
107    focus on these aspects in Peer-to-Peer domain.
108    Specifically, we review existing Peer-to-Peer approaches, protocols and their properties. We observe
109    that despite of greate amount of proposed Peer-to-Peer systems, all systems fall either
110    loosely structured approach or tightly structured approach. Then, we discuss open problems in
111    Peer-to-Peer networks and divide problems into three sub-categories: security related problems,
112    performance related problems and miscellaneous problems. In the end, we summarize all
113    problems in easy-to-understand tables.
114    
115    Next, we give an overview of our Fenfire system, which implements xanalogical storage model. We
116    also describe briefly Storm design and urn-5 concept, which are essential to Fenfire's
117    Peer-to-Peer functionality. We evaluate existing Peer-to-Peer approaches and
118    choose the best alternative to our needs. Finally, we propose effective but yet simple
119    algortihms to be used  with our Fenfire system in Peer-to-Peer environment.
120    
121    To our knowledge, this thesis is the most comprehensive work with regard to summarizing
122    existing Peer-to-Peer protocols and open problems in Peer-to-Peer domain. However, this
123    thesis is not meant to be detailed work. More information can be found from genuine
124    publications written by original authors.
125    
126  \section{Research problems}  \section{Research problems}
127    
128    There are three research problems related to this thesis. First research problem
129    is to find the most efficient way to locate and fetch Fenfire related data from the
130   a)* Mist? riippuu ja kuinka nopeaa nykyisill? algoritmeilla  Peer-to-Peer network, where Scroll block's identifier is given. Second, we want
131             on tietyn storm-blokin haku mist? tahansa?  to find the most efficient way to locate and fetch most recent Fenfire related data from the
132    the Peer-to-Peer network, which is associated with a given urn-5 random string. Final problem
133          --> Distributed hash, esim. CAN, Chord jne. (Overview)  is otherwise same as the second problem, except we want to locate and fetch all Fenfire
134    related data from the Peer-to-Peer network, where given date and/or time range is given.
135              - summarize current research, specifically on problems  
136                where we cannot trust any servers, and where  When comparing different Peer-to-Peer approaches and protocols, we will examine their
137                probability distributions for the blocks are used.  scalability, efficiency, space requirements for neighbor connections and overhead
138                Bibtex references.  associated with system maintenance. When we have solutions to our research
139            problems, we will use best solutions as examples in our algorithm proposals.
         b)* Mist? riippuu ja kuinka nopeaa nykyisill? algoritmeilla  
            on tiettyyn urn-5 -nimeen liitetyn uusimman blokin haku  
            (jossa uusin blokki allekirjoitettu annetulla avaimella)  
   
         c)* Mist? riippuu ja kuinka nopeaa nykyisill? algoritmeilla  
            on tiettyyn urn-5 -nimeen liitetyn annettuna aikana  
            olleen blokin haku ("Hesarin etusivu 3.6.-02")?  
            (jossa blokki allekirjoitettu annetulla avaimella)  
   
         *=Näiden jälkeen voidaan miettiä, voidaanko systeemiä tehdä  
         ilman hierarkiaa (Tumbler).  
           
         "Mistä riippuu" = Skaalautuvuus (verkokoko, datamäärä, levinneisyys, verkon kytkeytyvyys)  
   
140    
141  \section{Thesis overview}  \section{Thesis overview}
142    This thesis is structured as follows. In next chapter, we give an overview of
143  definition \cite{p2pworkinggroup}  existing Peer-to-Peer approaches, protocols and key differences. In chapter 3, we
144  definition \cite{graham02lecture}  address open problems in Peer-to-Peer domain and divide problems into three
145  definition \cite{winer00whatisp2p}  sub-categories. Chapter 4 gives an overview of our Fenfire system. In chapter
146    5 we evaluate existing Peer-to-Peer approaches with regard to Fenfire system and
147    propose simple algorithms perform data lookups in Fenfire's Peer-to-Peer enviroment.
148    We also discuss open issues and future work. Finally, we present conclusions in chapter
149    6.
150    
151  \chapter{Peer-to-Peer schemes}  \chapter{Peer-to-Peer schemes}
152    

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