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\chapter{Introduction} |
\chapter{Introduction} |
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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 |
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communication is symmetric and all participants have identical capabilities and responsabilities. |
academia and industry for a number of reasons. First, the lack of centralization |
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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 |
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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 |
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participant rely on one another services and resources, rather than solely relying on dedicated |
provides new, direct way to achieve interoperability between network participants. |
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centralized infracstructure. |
Finally, the distributed and ad-hoc nature of Peer-to-Peer improves scalability |
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and reliability againts certain kinds of faults (e.g., single point of failure). |
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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 |
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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 |
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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 |
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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 |
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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 |
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networks. |
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footnote:use of the plural is customary even if research paper is authored solely |
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To summarize, Peer-to-Peer systems can be characterized as distributed |
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systems in which all communication is symmetric and all participants have identical |
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capabilities and responsabilities. Each \emph{peer} may contribute data or |
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computing resources (e.g., unused storage) to the overall system and the welfare |
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of the community can scale with ne number of participants. Thus, each participant |
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rely on one another services and resources, rather than solely relying on dedicated |
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and centralized infracstructure. |
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One of the most important properties of any distributed computing system are efficient |
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data lookup and security. In this thesis, we \footnote{Use of the plural is customary even if research paper is authored solely.} |
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focus on these aspects in Peer-to-Peer domain. |
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Specifically, we review existing Peer-to-Peer approaches, protocols and their properties. We observe |
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that despite of greate amount of proposed Peer-to-Peer systems, all systems fall either |
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loosely structured approach or tightly structured approach. Then, we discuss open problems in |
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Peer-to-Peer networks and divide problems into three sub-categories: security related problems, |
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performance related problems and miscellaneous problems. In the end, we summarize all |
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problems in easy-to-understand tables. |
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Next, we give an overview of our Fenfire system, which implements xanalogical storage model. We |
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also describe briefly Storm design and urn-5 concept, which are essential to Fenfire's |
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Peer-to-Peer functionality. We evaluate existing Peer-to-Peer approaches and |
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choose the best alternative to our needs. Finally, we propose effective but yet simple |
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algortihms to be used with our Fenfire system in Peer-to-Peer environment. |
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To our knowledge, this thesis is the most comprehensive work with regard to summarizing |
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existing Peer-to-Peer protocols and open problems in Peer-to-Peer domain. However, this |
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thesis is not meant to be detailed work. More information can be found from genuine |
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publications written by original authors. |
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\section{Research problems} |
\section{Research problems} |
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There are three research problems related to this thesis. First research problem |
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is to find the most efficient way to locate and fetch Fenfire related data from the |
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a)* Mist? riippuu ja kuinka nopeaa nykyisill? algoritmeilla |
Peer-to-Peer network, where Scroll block's identifier is given. Second, we want |
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on tietyn storm-blokin haku mist? tahansa? |
to find the most efficient way to locate and fetch most recent Fenfire related data from the |
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the Peer-to-Peer network, which is associated with a given urn-5 random string. Final problem |
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--> Distributed hash, esim. CAN, Chord jne. (Overview) |
is otherwise same as the second problem, except we want to locate and fetch all Fenfire |
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related data from the Peer-to-Peer network, where given date and/or time range is given. |
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- summarize current research, specifically on problems |
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where we cannot trust any servers, and where |
When comparing different Peer-to-Peer approaches and protocols, we will examine their |
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probability distributions for the blocks are used. |
scalability, efficiency, space requirements for neighbor connections and overhead |
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Bibtex references. |
associated with system maintenance. When we have solutions to our research |
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problems, we will use best solutions as examples in our algorithm proposals. |
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b)* Mist? riippuu ja kuinka nopeaa nykyisill? algoritmeilla |
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on tiettyyn urn-5 -nimeen liitetyn uusimman blokin haku |
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(jossa uusin blokki allekirjoitettu annetulla avaimella) |
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c)* Mist? riippuu ja kuinka nopeaa nykyisill? algoritmeilla |
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on tiettyyn urn-5 -nimeen liitetyn annettuna aikana |
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olleen blokin haku ("Hesarin etusivu 3.6.-02")? |
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(jossa blokki allekirjoitettu annetulla avaimella) |
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*=Näiden jälkeen voidaan miettiä, voidaanko systeemiä tehdä |
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ilman hierarkiaa (Tumbler). |
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"Mistä riippuu" = Skaalautuvuus (verkokoko, datamäärä, levinneisyys, verkon kytkeytyvyys) |
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\section{Thesis overview} |
\section{Thesis overview} |
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This thesis is structured as follows. In next chapter, we give an overview of |
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definition \cite{p2pworkinggroup} |
existing Peer-to-Peer approaches, protocols and key differences. In chapter 3, we |
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definition \cite{graham02lecture} |
address open problems in Peer-to-Peer domain and divide problems into three |
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definition \cite{winer00whatisp2p} |
sub-categories. Chapter 4 gives an overview of our Fenfire system. In chapter |
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5 we evaluate existing Peer-to-Peer approaches with regard to Fenfire system and |
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propose simple algorithms perform data lookups in Fenfire's Peer-to-Peer enviroment. |
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We also discuss open issues and future work. Finally, we present conclusions in chapter |
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6. |
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\chapter{Peer-to-Peer schemes} |
\chapter{Peer-to-Peer schemes} |
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