P2P is increasingly gaining its popularity for streaming multimedia contents. The architecture of streaming has shifted from traditional client server architecture to P2P architecture. Although it is scalable and robust it faces its own challenges and problems such as churn. In tree topology frequent joining and leaving of users in search for better quality and reliable streaming makes the P2P network instable. This thesis provides an effective approach to achieve a resilient network for streaming. Relying on a single tree to receive data from single parent may leave the user deprived of getting the data if any of its ancestors leaves the network. Therefore we present an ideal solution to this problem by introducing a backup tree for the existing base tree. The backup tree is constructed based on parameter such as bandwidth and delay. In case of failure of a node, its children along the tree receive the data from the nodes of backup tree. We present an efficient algorithm for the construction of base tree as well as the backup tree which are based on normalization of two entities of nodes: bandwidth and delay. Through mathematical formulation and experimental setups we show that introducing a backup tree for an existing base tree can help provide resilience to the network. / UOIT

The purpose of my research is to examine the music industry from both the perspective of a musician and a lawyer, and draw real conclusions regarding where the music industry is heading in the 21st century. Digital technologies are overhauling the way in which musicians, record labels, and other industry professionals make a living, and my goal is to decipher what these changes mean in the long term. In light of this transformation, my research investigates whether musicians still need record labels in the digital era, and what role copyright law will continue to have in this new model.<p> The method of research for my thesis was slightly atypical. While I utilized any textbook and scholarly journal that was available on the topic, much of my most valuable research came in the form of personal interviews with some of the biggest players in the music industry, as well as various articles and studies found online.<p> My thesis argues that the roles played by artists and record labels have completely changed in the last five years, and the parties that will find success on either side of the bargaining table will be those most appreciative of and adaptive to this change. Directly related to this is the changing face of copyright in the music industry. My thesis argues that while copyright used to provide massive value from a single source in the short term, it now generates smaller amounts of value from an infinite array of sources, in the long term. The significance of this finding cannot be understated, for both artists and their investors. In this way, my research aims to be equally significant and accessible to musicians, industry professionals, and academics.

Large--scale distributed environments can be seen as a conflict between the selfish aims of the participants and the group welfare of the population as a whole. In order to regulate the behavior of the participants it is often necessary to introduce mechanisms that provide incentives and stimulate cooperative behavior in order to mitigate for the resultant potentially undesirable availability outcomes which could arise from individual actions.The history of economics contains a wide variety of incentive patterns for cooperation. In this thesis, we adopt bartering incentive pattern as an attractive foundation for a simple and robust form of exchange to re-allocate resources. While bartering is arguably the world's oldest form of trade, there are still many instances where it surprises us. The success and survivability of the barter mechanisms adds to its attractiveness as a model to study.In this thesis we have derived three relevant scenarios where a bartering approach is applied. Starting from a common model of bartering: - We show the price to be paid for dealing with selfish agents in a bartering environment, as well as the impact on performance parameters such as topology and disclosed information.- We show how agents, by means of bartering, can achieve gains in goods without altruistic agents needing to be present.- We apply a bartering--based approach to a real application, the directory services.The core of this research is the analysis of bartering in the Internet Age. In previous times, usually economies dominated by bartering have suffered from high transaction costs (i.e. the improbability of the wants, needs that cause a transaction occurring at the same time and place). Nowadays, the world has a global system of interconnected computer networks called Internet. This interconnected world has the ability to overcome many challenges of the previous times. This thesis analysis the oldest system of trade within the context of this new paradigm. In this thesis we aim is to show thatbartering has a great potential, but there are many challenges that can affect the realistic application of bartering that should be studied.The purpose of this thesis has been to investigate resource allocation using bartering mechanism, with particular emphasis on applications in largescale distributed systems without the presence of altruistic participants in the environment.Throughout the research presented in this thesis we have contributed evidence that supports the leitmotif that best summarizes our work: investigation interactions amongst selfish, rational, and autonomous agents with incomplete information, each seeking to maximize its expected utility by means of bartering. We concentrate on three scenarios: one theoretical, a case of use, and finally a real application. All of these scenarios are used for evaluating bartering. Each scenario starts from a common origin, but each of them have their own unique features.The final conclusion is that bartering is still relevant in the modern world.

Centrally controlled search engines will not be sufficient and reliable for indexing and searching the rapidly growing World Wide Web in near future. A better solution is to enable the Web to index itself in a decentralized manner. Existing distributed approaches for ranking search results do not provide flexible searching, complete results and ranking with high accuracy. This thesis presents a decentralized Web search mechanism, named DEWS, which enables existing webservers to collaborate with each other to form a distributed index of the Web. DEWS can rank the search results based on query keyword relevance and relative importance of websites in a distributed manner preserving a hyperlink overlay on top of a structured P2P overlay. It also supports approximate matching of query keywords using phonetic codes and n-grams along with list decoding of a linear covering code. DEWS supports incremental retrieval of search results in a decentralized manner which reduces network bandwidth required for query resolution. It uses an efficient routing mechanism extending the Plexus routing protocol with a message aggregation technique. DEWS maintains replica of indexes, which reduces routing hops and makes DEWS robust to webservers failure. The standard LETOR 3.0 dataset was used to validate the DEWS protocol. Simulation results show that the ranking accuracy of DEWS is close to the centralized case, while network overhead for collaborative search and indexing is logarithmic on network size. The results also show that DEWS is resilient to changes in the available pool of indexing webservers and works efficiently even in the presence of heavy query load.

The purpose of my research is to examine the music industry from both the perspective of a musician and a lawyer, and draw real conclusions regarding where the music industry is heading in the 21st century. Digital technologies are overhauling the way in which musicians, record labels, and other industry professionals make a living, and my goal is to decipher what these changes mean in the long term. In light of this transformation, my research investigates whether musicians still need record labels in the digital era, and what role copyright law will continue to have in this new model.<p> The method of research for my thesis was slightly atypical. While I utilized any textbook and scholarly journal that was available on the topic, much of my most valuable research came in the form of personal interviews with some of the biggest players in the music industry, as well as various articles and studies found online.<p> My thesis argues that the roles played by artists and record labels have completely changed in the last five years, and the parties that will find success on either side of the bargaining table will be those most appreciative of and adaptive to this change. Directly related to this is the changing face of copyright in the music industry. My thesis argues that while copyright used to provide massive value from a single source in the short term, it now generates smaller amounts of value from an infinite array of sources, in the long term. The significance of this finding cannot be understated, for both artists and their investors. In this way, my research aims to be equally significant and accessible to musicians, industry professionals, and academics.

Existing methods to utilize capacity-heterogeneity in a P2P system either rely on constructing special overlays with capacity-proportional node degree or use topology adaptation to match a node's capacity with that of its neighbors. In existing P2P networks, which are often characterized by diverse node capacities and high churn, these methods may require large node degree or continuous topology adaptation, potentially making them infeasible due to their high overhead. In this thesis, we propose an unstructured P2P system that attempts to address these issues. We first prove that the overall throughput of search queries in a heterogeneous network is maximized if and only if traffic load through each node is proportional to its capacity. Our proposed system achieves this traffic distribution by biasing search walks using the Metropolis-Hastings algorithm, without requiring any special underlying topology. We then define two saturation metrics for measuring the performance of overlay networks: one for quantifying their ability to support random walks and the second for measuring their potential to handle the overhead caused by churn. Using simulations, we finally compare our proposed method with Gia, an existing system which uses topology adaptation, and find that the former performs better under all studied conditions, both saturation metrics, and such end-to-end parameters as query success rate, latency, and query-hits for various file replication schemes.

With the progress of the network, peoples can communicate with each other easily. The popularization of the Broadband network makes many things that could be hard to achieved becoming possible. For example, video conference, distance education and on-line games have become a part of our daily life. However, most network services are client-server architecture. This kind of service need a expensive and powerful server. The restriction will makes it difficult to improve the quality of service. P2P (peer-to-peer) architecture embodies one of the key technical concepts of the internet and many internet users was attracted by it. A peer-to-peer computer network is a network that relies on computing power at the edges (ends) of a connection rather than in the network itself. It has been used in two kinds of applications which are file sharing and distributed computing. Instead of using P2P model, client-server architecture is used in muti-user conference. A software using P2P model still needs one of the users to become a server to deal with all the messages in the conference. When the number of the users increasing, the overhead of the server will increase linearly. This makes many communication softwares to limit the number of users in a conference. Therefore, most of the companies use an expensive and powerful server offering this kind of service. In this paper, we will implement a voice-conferencing system using P2P model and the technique of distributed computing. It makes the overhead of the server in logarithmic increase. In addition, we still can configure some low-end peers with a constant overhead. No mater how the number of users increase, these peers will have a constant overhead. With the good design, we can gurantee the quality of service easily.

In a P2P (Peer-to-Peer) system, every user node, i.e., the peer, may dynamically join and leave the system. In general, peers can exchange information and contribute portions of their resources to the community in a P2P system. They are treated functionally identical. Therefore, it is very important to efficiently locate the peer that stores a particular data item and make the system load balance in P2P systems. Chord is a structured P2P system which has a ring architecture, where a structured P2P system means that peers maintain information about what resources neighbor peers offer. It provides support for just one operation: to assign the data key to the peer by hashing. Therefore, we can efficiently locate the peer that stores a particular data key. However, in the Chord system, most of data keys may be assigned to the same peer by using the static hashing scheme, which results in the case that the load of the system not be balanced. Therefore, in this thesis, we propose a strategy which uses the dynamic hashing scheme to locate the data key based on the Chord architecture, and to maintain the load balance. A dynamic hashing allows the address space allocated to the file to be increased and reduced without reorganizing the whole file. The basic idea of a dynamic hashing approach is to split the current overflow bucket into two new buckets by using the next level hashing function without reorganizing the other buckets, and our proposed strategy uses such an approach. In our strategy, we use two data structures for a peer, one stores the data hashed to the current peer and the other one stores the data from its predecessor. When an overflow occurs in the bucket after insertion of a data key, we use the one hashing function to split data keys stored in the data bucket. If the capacity of the current peer is larger than that of its successor, we forward some data keys to the successor. Similarly, we also consider the case of an underflow occurs in the bucket after deletion of a data key. Therefore, the unbalanced condition of the load (even distribution of items to nodes) of the system can be improved based on our strategy. From our simulation results, we show that the load of the P2P system based on our strategy is much more balanced than that used in the Chord system, when there are few peers and a lot of data keys in the P2P system. We also show that the load based on our strategy is still more balanced than that used in the Chord system, when the data distribution becomes skew.

A Peer-to-Peer system is a distributed system whose component nodes participate in similar roles. Every user node (the peer) can exchange and contribute its resources to another one in the system. Similar to the case that peers may dynamically join and leave the system, the data will also be inserted into and removed from the system dynamically. Given a certain range, a range query will find any data item whose value within the range. For example, a range query can find all the Beatle's works between 1961 and 1968 for us. However, once the range data is distributed over a P2P system through the hash function which has been used largely in many P2P systems, the continuity of the range data is not guaranteed to exist. Therefore, finding the scattered data whose value within a certain range costs much in a P2P system. The Distributed Segment Tree method (DST) preserves the local continuity of the range data at each node by using a segment tree and can break any given range into minimum number of node intervals whose union constitutes the whole requested range. The DST method works based on the Distributed Hash Table (DHT) logic; therefore, it can be applied in any DHT-based P2P system. However, data distribution of the DST method may cause overlapping. When searching a data range, the DST method sends more number of requests than what is really needed. Although the DST method designs the Downward Load Stripping Mechanism, the load on peers still may not be balanced. The main reason of these problems is that the DST method applies the DHT logic to the P2P systems. Therefore, in this thesis, we propose a method called Structured Segment Tree (SST) that does not use the DHT logic but embeds the structure of the segment tree into the P2P systems. In fact, the P2P network topology of an SST is the structure of a segment tree. Unlike a DST, an SST can fully reflect the properties of the original segment tree. Each peer in our proposed P2P system represents a node of a segment tree. Data intervals at the same level are continuous and will not overlap with each other. The union of data intervals at a level with full nodes is totally the whole data range which the P2P system can support. When searching a data range, the SST method sends as many number of requests as needed. In addition, we add sibling links to preserve the spatial locality and speed up the search efficiency. For the issue of load balance, our SST method also performs better than the DST method. From our simulation, we show that the SST method routes less number of peers to locate the requested range data than the DST method. We also show that the load based on our method is more balanced than that based on the DST method.

Over the last few years, peer-to-peer (P2P) applications have relentlessly grown to represent a formidable component of Internet traffic. In contract to P2P networks witch used well-defined port number, current P2P applications have use of arbitrary ports. As P2P applications continue to evolve, robust and effective methods are methods are needed for P2P traffic identification. Many P2P applications are bandwidth-intensive. Understanding the Internet traffic profile is important for several reasons, including traffic engineering, network service pricing. In this Thesis, we integrated port-based method into original Classifier which is using content-based method only. Therefore, we can improve the recognition rate for Classifier and identify more applications. We also verified our Classifier recognition rate by using the results of Service Control Engine.