We collected mobility traces of 84,208 avatars spanning 22 regions over two months in Second Life, a popular networked virtual en- vironment. We analyzed the traces to characterize the dynamics of the avatars mobility and behavior, both temporally and spatially. We discuss the implications of the our findings to the design o f peer-to-peer networked virtual environments, interest management, mobility

The novelty of the peer-to-peer (P2P) paradigm relies on two main concepts: cooperation among users and resource sharing. There are many applications based on peer-to-peer paradigm, but the most popular one is the file sharing. We can classify the file sharing application into centralized systems, (having a central server), and decentralized systems. Another classification would be structured and unstructured systems,

Purpose – This article examines peer-to-peer sharing platform business models, their sources of competitive advantage, and the roles, motivations, and behaviors of key actors in their ecosystems.
Design/methodology/approach – This paper uses a conceptual approach that is rooted in the service, tourism and hospitality, and strategy literature.
Findings – First, this paper defines key types of platform business models in the sharing economy and describes their characteristics. In particular, we propose the differentiation between sharing platforms of capacity-constrained versus capacity-unconstrained assets and advance five core properties of the former. Second, we contrast platform business models with their pipeline business model counterparts to understand the fundamental differences between them. One important conclusion is that platforms cater to vastly more heterogeneous assets and consumer needs, and therefore, require liquidity and analytics for high quality matching. Third, we examine the competitive position of platforms and conclude that their widely taken “winner takes it all” assumption is not valid. Primary network effects are less important once a critical level of liquidity has been reached and may even turn negative if increased listings raise friction in the form of search costs. Once a critical level of liquidity has been reached, a platform’s competitive position depends on stakeholder trust and service provider and user loyalty. Fourth, we integrate and synthesize the literature on key platform stakeholders of platform businesses (i.e. users, service providers, and regulators) and their roles and motivations. Finally, directions for further research are advanced.
Practical implications – This article helps platform owners, service providers, and users understand better the implications of sharing platform business models and how to position themselves in such ecosystems.
Originality/value – This article integrates the extant literature on sharing platforms, takes a novel approach in delineating their key properties and dimensions, and provides insights into the evolving and dynamic forms of sharing platforms including converging business models.

Structured peer-to-peer (P2P) networks is becoming popular for their advantages of high scalability and good performance. These networks are based on the Distributed Hash Tale or DHT mechanism to establish and maintain a certain topology. However, while adopting structured P2P network for wireless environment, one have to deal with the phenomenon of frequent join and leave of mobile nodes, namely churn. In this study, we focus on modification of Chord, a well-known DHT protocol, in order to

With the rise of peer-to-peer (P2P) file sharing applications there has been an increasing interest in understanding the popularity and use of P2P. In this study, we look at P2P use on the University of Southern California’s campus network throughout a 14-hour period. We quantify the volume of traffic from P2P activity as well as the number of campus hosts involved in P2P at USC. Since port-matching techniques often fail for P2P applications, we estimate traffic based on both port-based and connection-pattern based techniques. We do not have access to packet data and so these measures provide only bounds on P2P traffic. In addition, while we identify P2P sharing, we cannot comment the types of data being shared (either music or data, restricted or freely available). We find that 3–13% of active hosts on campus participate in P2P, and that this traffic accounts for 21–33% of the bytes transferred to and from our campus.

With the increasing popularity of the World Wide Web, end-user applications are moving from the desktop to the browser. More and more applications that we have come to know as desktop applications are now making their way into the web. This has made online collaboration a key aspect for many applications. Collaborative applications like Facebook, Flickr and Google Docs are just an early hint of how we can benefit from users being able to share data. Still, collaborative features are not easy to implement in web applications. Most web programming environments aim at easy user interface creation and persistence, but not for online collaboration and pushing data from one user to another. The Lively Kernel is a highly dynamic web programming platform and runtime environment developed at Sun Microsystems Laboratories. By utilizing the Lively Kernel platform, it is easy to implement desktop like applications for the web using JavaScript. In this paper we summarize the experiences from adding peer-to-peer collaboration into the Lively Kernel. These additions include persistent data storage, communication channels between users and user identification.

Eigenvector computations are an important building block for computing authority, trust, and reputation scores in social networks and other graphs. In peer-to-peer networks or other forms of decentralized settings (such as multi-agent platforms), this kind of analysis needs to be performed in a distributed manner and requires bilateral data exchanges between peers. This gives rise to the problem that dishonest peers may cheat in order to manipulate the computation's outcome.

The communication as we know it is about to change, the simple peer-to-peer voice type of calls being replaced by a mix of different media belonging to the same session. Networkbased speech processing technologies are increasingly used, adding flexibility, speed and naturalness to various telecom services. For instance, text-to-speech (TTS) synthesis is already incorporated into commercial telephony applications, but in most of the cases the services offered are not real-time. This paper proposes a solution in building up a network-based media processing environment and designing a multi-threaded and multi-process TTS engine, integrated with the rest of the network by means of flexible and standardized signaling protocols. As a particular application of the proposed approach, we present a convergent real-time telecom service, combining instant messaging, presence and TTS in a single new experience.

— many file sharing systems exists today. The abundance of content on the web is in itself a huge problem to comprehend. The existence and wide scale use of peer-to-peer file sharing systems, which let users share files, folders, directors to entire drives makes the problem of finding relevant information a daunting task. With the increasing number of file sharing systems, there are challenges in providing users with useful recommendations about interesting products and services, which suit their tastes and behaviors. In this paper we propose a simple, extensible Peer-to-Peer (P2P) based content recommendation architecture. Keywords—Peer-to-peer file sharing systems, content recommendation systems, DC++, NS2, TCL, log mining I.

Existing approaches for modelling the Internet delay space predict end-to-end delays between two arbitrary hosts as static values. Further, they do not capture the characteristics caused by geographical constraints. Peer-to-peer (P2P) systems are, however, often very sensitive to the underlying delay characteristics of the Internet, since these characteristics directly influence system performance. This work proposes a model to predict lifelike delays between a given pair of end hosts. In addition to its low delay computation time, it has only linear memory costs which allows large scale P2P simulations to be performed. The model includes realistic delay jitter, subject to the geographical position of the sender and the receiver. Our analysis, using existing Internet measurement studies reveals that our approach seems to be an optimal tradeoff between a number of conflicting properties of existing approaches.

The extraction and recognition of facial expression has been the topic of various researches subject to enable smooth interaction between computer and their users. In this way, computers in the future will be able to offer advice in response to the mood of the users. Humans tend to attribute human qualities to computers. It is expected that people, when using their natural communicational skills, can perform cognitive tasks with computers in a more enjoyable and effective way. For these reasons human-like embodied conversational agents (ECAs) as components of user interfaces have received a lot of attention. In this article, we propose a collective and collaborating e-learning system on the peer to peer network, using the PECS model (Physics, Emotion, Cognition, and Social status) integrated on the Emotional Embodied Conversational Agent (EECA). In order to handle difficulties of learner, to guarantee a more available support at distance and to carry over relevant support due to the learner's emotional state. We describe an affective dialogs with an EECA. We present an update of Emotional Markup Language (EML).

Peer-to-peer (P2P) overlay networks have recently become one of the hottest topics in OS research. These networks bring with them the promise of harnessing idle storage and network resources from client machines that voluntarily join the system; self-configuration and automatic load balancing; censorship resistance; and extremely good scalability due to the use of symmetric algorithms. However, the use of unreliable client machines leads to two defects of these systems that precludes their use in a number of applications: storage is inherently unreliable, and lookup algorithms have long latencies. In this paper we propose a design of a robust peer-to-peer storage service, composed not of client nodes, but server nodes that are dedicated to running the peer-to-peer application. We argue that our system overcomes the defects of peer-to-peer systems while retaining their nice properties with the exception of utilizing spare resources of client machines. Our system is capable of surviving arbitrary failures of its nodes (Byzantine faults) and we expect it to perform and scale well, even in a wide-area network.

Web 2.0 is the adoption of open technologies and architectural frameworks to facilitate participative computing. Web 2.0 has the potential to deliver rich peer-to-peer interactions among users, enable collaborative value creation across business partners and create dynamic new services and business models. With the emergence of new information technology it is necessary for organizations to redefine and reassess the new technology and its business value. Extant research does not provide managers guidance on how they can utilize their web 2.0 presence to add value creating activities for the organization. In this research we develop a conceptual foundation for the value propositions enabled by web 2.0 technologies. We provide taxonomy of features, capabilities and organizational value added activities. We develop a model of Web 2.0 capabilities and the nature of value adding services they can provide.

to design a community healthcare information network for all 450,000 citizen in the State of Geneva, Switzerland, connecting public and private healthcare professionals. Requirements include the decentralized storage of information at the source of its production, the creation of a virtual patient record at the time of the consultation, the control by the patient of the access rights to the information, and the interoperability with other similar networks at the national and european level. a participative approach and real-world pilot projects are used to design, test and validate key components of the network, including its technical architecture and the strategy for the management of access rights by the patients. a distributed architecture using peer-to-peer communication of information mediators can implement the various requirements while limiting to an absolute minimum the amount of centralized information. Access control can be managed by the patient with the help of a medic...

Spam is one of the major problems of today email systems. While many solutions have been proposed to automatically detect and filter spam, spammers are getting more and more technically sophisticated and aware of internal workings of anti-spam systems, finding ways to disguise their emails to get around the different controls that can be enforced. In this paper, we propose a decentralized privacypreserving approach to spam filtering. Our solution exploits robust digests to identify messages that are a slight variation of one another and a structured peer-to-peer architecture between mail servers to collaboratively share knowledge about spam.

In recent times, coupled with the emergence of the new cloud paradigm, a number of security related issues have emerged. Therefore, trust and reputation management has become unavoidable challenge in this new cloud computing paradigm. Cloud computing represents a shared and statistical service model that allows software, platform and infrastructure to be shared as service, with high degree of openness and autonomy. Consequently these high degree of openness and autonomy impose the need for surveillance of the services, and profer nearly an ideal condition for a spread of unauthentic files. Although peer- to-peer (P2P) models and their applications are popular depending on their domain of applicability, protecting peer's security remain a challenge. As a result, this research paper presents a novel Peer-to-Peer reputation- based trust management model in a cloud provisioning environment. To validate the proposed model, a simulation environment with different peers and service pro...

Wireless sensor networks (WSNs) have many potential applications [1, 5] and unique challenges. They usually consist of hundreds or thousands small sensor nodes such as MICA2, which operate autonomously; conditions such as cost, invisible deployment and many application domains, lead to small size and limited resources sensors [2]. WSNs are susceptible to many types of physical attacks [1] and most of traditional networks security techniques are unusable on WSNs[2]; due to wireless and shared nature of communication channel, untrusted transmissions, deployment in open environments, unattended nature and limited resources [1]. So, security is a vital requirement for these networks; but we have to design a proper security mechanism that attends to WSN's constraints and requirements. In this paper, we focus on security of WSNs, divide it (the WSNs security) into four categories and will consider them, include: an overview of WSNs, security in WSNs, the threat model on WSNs, a wide v...

Web services have the potential to dramatically reduce the complexities and costs of software integration projects. The most obvious and perhaps most significant difference between Web services and traditional applications is that Web services use a common communication infrastructure, XML and SOAP, to communicate through the Internet. The method of communication introduces complexities to the problems of verifying and validating Web services that do not exist in traditional software. This paper presents a new approach to testing Web services based on data perturbation. Existing XML messages are modified based on rules defined on the message grammars, and then used as tests. Data perturbation uses two methods to test Web services: data value perturbation and interaction perturbation. Data value perturbation modifies values according to the data type. Interaction perturbation classifies the communication messages into two categories: RPC communication and data communication. At present, this method is restricted to peer-to-peer interactions. The paper presents preliminary empirical evidence of its usefulness.

The use of peer-to-peer (P2P) applications is growing dramatically, which results in several serious problems such as the network congestion and traffic hindrance. In this paper, a method is proposed to identify the P2P traffic based on the machine learning. The novelty of the proposed method is that it utilizes only the size of packets exchanged between IPs within seconds. By investigating the ratio between the upload and download traffic volume of several P2P applications, a characteristic library is constructed. Then the unknown network traffic can be recognized online using this library. The distinguished features of the proposed method lie in that fast computation, high identification accuracy, and resource-saving capability. Finally, experiment results show the satisfactory performance of the proposed method.

A peer-to-peer database management system(P2PDBMS) is a collection of autonomous data sources, called peers. In this system each peer augments a conventional database management system with an inter-operability layer (i.e. mappings/policies) for sharing data and services. Peers exchange data in a pair-wise fashion on-the-fly in response to a query without any centralized control. Generally, the communication link between two peers is insecure and peers create a temporary session while exchanging data. When peers exchange highly confidential data between them over an insecure communication network, such as the Internet, the data might be trapped and disclosed by the intruders. In a P2PDBMS there is no centralized control for data exchange, hence we cannot assume any central third party security infrastructure (e.g. PKI) to protect confidential data. So far, there is currently no available/existing security protocol for secured data exchange in P2PDBMS. In this paper we propose three models for secure data exchange in P2PDBMSs and the corresponding security protocols. The proposed protocol allows the peers to compute their secret session keys dynamically during data exchange based on the policies between them. Our proposed protocol is robust against the man-in-the middle attack, the masquerade attack, and the reply attack.

Peer-to-Peer (P2P) networks offer reliable and efficient services in different application scenarios. In particular, structured P2P protocols (like Chord [1]) have to handle changes in the overlay topology fast and with as little signaling overhead as possible. This paper analyzes the ability of the Chord protocol to keep the network structure up to date, even in environments with high churn rates, i.e. nodes joining and leaving the network frequently. High churn rates occur, e.g., in mobile environments, where participants have to deal with the limited resources of their mobile devices, such as short battery lifetimes or high comnmunication costs. In this paper, we analyze different design parameters and their influence on the stability of Chord-based network structures. We also present several modifications to the basic Chord stabilization scheme, resulting in a much more stable overlay topology.

Today, research in electronic negotiations focuses on negotiation protocols that support the negotiation of only a few properties. These protocols are mainly designed for automated negotiations between software agents. However, for peer-to-peer negotiations in business-to-business electronic marketplaces, such protocols are less appropriate. For example, negotiations about multiple attributes, complex attribute combinations, or frame contracts require more sophisticated support of the involved interactions and communication acts. In this paper we present a novel approach to the eective support of electronic negotiations among human negotiators. Our approach is based on the following observation. The outcome of a successful negotiation process is a business contract. The contract evolves during the negotiation, coordinated through the exchange of structured messages such as oers, requests, quotations, counteroers, and acceptances. Therefore, each negotiation between business partners involves the exchanges of documents and messages. Furthermore, documents and messages are interrelated in that a message leads to a new contract version which itself is the medium for a new negotiation step and thus initiates a new message. In contrast to the current practice of separate management of messages and documents, we create a powerful framework for eective negotiation support in electronic marketplaces by combining communication and document management. Our approach enables monitoring of contractual obligations and traceability of both documents and messages and their interrelations. Ó

In this work, we address the problem of locally estimating the size of a Peerto-Peer (P2P) network using local information. We present a novel approach for estimating the size of a peer-to-peer (P2P) network, fitting the sum of new neighbors discovered at each iteration of a breadth-first search (BFS) with a logarithmic function, and then using Lambert’s W function to solve a root of a ln(n)+b−n = 0, where n is the network size. With rather little computation, we reach an estimation error of at most 10 percent, only allowing the BFS to iterate to the third level.

In this paper, we propose the design of VoroNet, an objectbased peer to peer overlay network relying on Voronoi tessellations, along with its theoretical analysis and experimental evaluation. VoroNet differs from previous overlay networks in that peers are application objects themselves and get identifiers reflecting the semantics of the application instead of relying on hashing functions. This enables a scalable support for efficient search in large collections of data. In VoroNet, objects are organized in an attribute space according to a Voronoi diagram. VoroNet is inspired from the Kleinberg's small-world model where each peer gets connected to close neighbours and maintains an additional pointer to a long-range neighbour. VoroNet improves upon the original proposal as it deals with general object topologies and therefore copes with skewed data distributions. We show that VoroNet can be built and maintained in a fully decentralized way. The theoretical analysis of the system proves that routing in VoroNet can be achieved in a poly-logarithmic number of hops in the size of the system. The analysis is fully confirmed by our experimental evaluation by simulation.

Internet was designed for network services without any intention for secure communication. Exponential growth of internet and its users have developed an era of global competition and rivalry. Denial of service attack by multiple nodes is capable of disturbing the services of rival servers. The attack can be for multiple reasons e. g. extortion or to beat the rivals. Peer

This paper presents a framework for multimodal human-robot interaction. The proposed framework is being implemented in a personal robot called Maggie, developed at RoboticsLab of the University Carlos III of Madrid for social interaction research. The control architecture of this personal robot is a hybrid control architecture called AD (automatic-deliberative) that incorporates an emotion control system (ECS). Maggie's main goal is to interact establish a peer-to-peer relationship with humans. To achieve this goal, a set of human-robot interaction skills are developed based on the proposed framework. The human-robot interaction skills imply tactile, visual, remote voice and sound modes. The multi-modal fusion and synchronization are also presented in this paper

The paper describes a novel social network-based open educational resource for learning foreign languages in real time from native speakers, based on the predefined teaching materials. This virtual learning platform, named i2istudy, eliminates misunderstanding by providing prepared and predefined scenarios, enabling the participants to understand each other and, as a consequence, to communicate freely. The system allows communication through the real time video and audio feed. In addition to establishing the communication, it tracks the student progress and allows rating the instructor, based on the learner's experience. The system went live in April 2014, and had over six thousand active daily users, with over 40,000 total registered users. Currently monetization is being added to the system, and time will show how popular the system will become in the future.

The interrelatedness between computer systems, networks, code, and traditional law and legal frameworks continues to pose a number of important and vexed questions. This report will consider one area of the relationship: legal recognition of distributed ledger technology (DLT) or blockchain applications. Specifically, registers appended to blockchains (thereby creating “blockchain registries”), and “smart contracts” executed on blockchains

Already a popular application in the Internet, IPTV is becoming, among the service providers, a preferred alternative to conventional broadcasting technologies. Since many of the existing deployments have been done within the safe harbor of telco-owned networks, IP multicast has been the desired streaming solution. However, previous studies showed that the popularity of the TV channels follows the Pareto principle, with the bulk of TV channels being watched only by a small fraction of viewers. Recognizing the potential scalability issues, we believe that multicast streaming approach may not be desirable for unpopular TV channels, especially when there are many such channels in the provider's service package. For this reason, the peer-to-peer content distribution paradigm is seen as an alternative, in particular for non-popular content. In order to analyze its viability, in this paper we perform a comparative analysis between IP multicast and a peer-to-peer overlay using unicast connections as streaming approaches, in the context of channels with different degrees of popularity. The analysis targets the bandwidth utilization, video quality and scalability issues, and our findings show that while multicast is always more efficient, peer-to-peer has a comparable performance for unpopular channels with a low number of viewers.

A lot of attention has recently been focused oti Peer-topeer file sharing systems. Cniitella is CI fully distribiited peer-to-peer protocol, without the need for N central entity. This increcises the reliability of the system by uvoicfitig ci single point of failure as well making it more immune to legal attack. The two main featiires of the Gnutella protocol, discoven of peers and searching for files are implemented by passing diflerent ypes of messages behveeri the nodes of the Gtiiitella overlay network. Due to its fully distribiited nature, Gnittella relies on flooding to route most of these messages, which immediately raises the question of cost and scalabiliu. I n this paper, we study these aspects of the Gniitelki protocol by niecins of sitnulation, also considering the injluence of the topology ofthe Gnutella network.

... 5: Scalable Video Coding (in integrated form with ITU-T Rec. H.264 | ISO/IEC 14996-10). JointVideo Team (JVT), Doc. JVT-R201, Jan. 2006. 4. Luby, M., Stockhammer, T., Watson, M., Gasiba, T., and Xu, W. Raptor Codes for Reliable Download Delivery in Wireless Broadcast ...

People continuously try to improve their quality of life and technologies have an important role on it. Money transaction between mobile devices is bored and a difficult operation to perform since there is not a simple and safe way to do it. Near field communication (NFC) is a new secure shortrange wireless connectivity technology, can play an important role on this kind of issues, and it is very easy to use. In upcoming years the NFC technology can offer an important contribution to simplify some daily operations, such as payments and money transactions. This paper focused on NFC technology and proposes a peer-to-peer based application that demonstrates the usage of NFC and Bluetooth technologies for money transaction between mobile devices. NFC technology is used with a simple gesture that triggers a lot of background operations. A solution is proposed, evaluated, and demonstrated and it is ready for use. It demonstrates the NFC availability for secure and easy communication and authentication in mobile applications.

A fundamental problem that confronts peer-to-peer applications is to efficiently locate the node that stores a particular data item. This paper presents Chord, a distributed lookup protocol that addresses this problem. Chord provides support for just one operation: given a key, it maps the key onto a node. Data location can be easily implemented on top of Chord by associating a key with each data item, and storing the key/data item pair at the node to which the key maps. Chord adapts efficiently as nodes join and leave the system, and can answer queries even if the system is continuously changing. Results from theoretical analysis and simulations show that Chord is scalable, with communication cost and the state maintained by each node scaling logarithmically with the number of Chord nodes. of nearby servers, anonymity, search, authentication, and hierarchical naming. Despite this rich set of features, the core operation in most peer-to-peer systems is efficient location of data items. The contribution of this paper is a scalable protocol for lookup in a dynamic peer-to-peer system with frequent node arrivals and departures.

The peer-to-peer (P2P) Internet online hybrid test system has been developed for the seismic simulation of a structure. In this study, the stability and accuracy of the system are investigated analytically by studying the spectral radius of the recursive matrix of the test scheme featuring a two-round quasi-Newton test scheme. The applicability of the system is further examined by exploring the seismic responses of a complex structure, a steel-encased reinforced concrete (SRC) structure with a steel tower on the top. The structure is divided into two numerical substructures and one tested part for hybrid test. The numerical substructures are simulated by sophisticated finite element method (FEM) models with material nonlinearities to capture local plastifications. Two types of FEM programs, namely OpenSEES and ABAQUS, which are suitable for the SRC part and the steel tower, respectively, are employed. The results demonstrate that the P2P system is able to simulate complex structures with significant nonlinearities. As compared with the previous study in which two elastic numerical substructures were considered, increase in the number of iterations in this study is not significant, because the associated nonlinearities are limited due to the small time interval adopted in the test. Copyright © 2007 John Wiley & Sons, Ltd.

Expressing and recognizing emotional behavior of human play an important role in communication systems. Facial expression analysis is the most expressive way to display human emotion. Three types of facial emotion are recognized and classified: happy, sad, anger. Depending on the emotion, the music player will play the song accordingly which eliminates the time-consuming and tedious task of manually segregating or grouping songs into different lists and help in generating an appropriate playlist based on individual's emotional features. This paper implements an efficient extraction of facial points using Beizer Curves which is more suitable for use in mobile devices. To enhance the audibility level of audio and memory shortage group play concept is also introduced. More than one android mobiles communicate with each other through Peer to Peer connection using Wi-Fi direct. Along with music player editing features like audio trimming and precise voice recording. Later the customized audio file can be set as alarm, ringtone, notification tones. Since all the emotional recognition is done for the real time images, it outperforms well than the any other existing face recognition algorithms or music play applications.

Collaborative Filtering (CF) technique has been proved to be one of the most successful techniques in recommender systems in recent years. However, most existing CF based recommender systems worked in a centralized way and suffered from its shortage in scalability as their calculation complexity increased quickly both in time and space when the record in user database increases. In this article, we first propose a distributed CF algorithm called PipeCF together with two novel approaches: significance refinement and unanimous amplification, to further improve the scalability and prediction accuracy. We then show how to implement this algorithm on a Peer-to-Peer (P2P) structure through distributed hash table method, which is the most popular and efficient P2P routing algorithm, to construct a scalable distributed recommender system. The experimental data show that the distributed CF-based recommender system has much better scalability than traditional centralized ones with comparable prediction efficiency and accuracy. q