Exploiting users’ social relations to forward data in opportunistic networks: The HiBOp solution

Opportunistic networks, in which nodes opportunistically exploit any pair-wise contact to identify next hops towards the destination, are one of the most interesting technologies to support the pervasive networking vision. Opportunistic networks allow content sharing between mobile users without requiring any pre-existing Internet infrastructure, and tolerate partitions, long disconnections, and topology instability in general. In this paper we propose a context-aware framework for routing and forwarding in opportunistic networks. The framework is general, and able to host various flavors of context-aware routing. In this work we also present a particular protocol, HiBOp, which, by exploiting the framework, learns and represents through context information, the users’ behavior and their social relations, and uses this knowledge to drive the forwarding process. The comparison of HiBOp with reference to alternative solutions shows that a context-aware approach based on users’ social relations turns out to be a very efficient solution for forwarding in opportunistic networks. We show performance improvements over the reference solutions both in terms of resource utilization and in terms of user perceived QoS.     

Interactive middleware architecture for lifelog based context awareness

Due to the development of IT convergence, a wide variety of information is being produced and distributed rapidly in digital form. Lifelog based context awareness is a technology that provides a service automatically based on perceived situational information in ubiquitous environments. To offer customized services to users, the technology of acquiring lifelog based context information in real time is the most important consideration. We propose the interactive middleware architecture for lifelog based context awareness in distributed and ubiquitous environments. Conventional middleware to support ubiquitous environments stores and manages the situational information and service content acquired by centralized storage or a DBMS. Centralized situational information and service content management may impede the autonomy of mobile nodes and the interoperation between different middle software. The proposed method designs a system that can distribute and manage situational information in mobile nodes using mobile devices in distributed and ubiquitous environments and share the service content between interactive middleware through publication. The application system designed in this study was used in a scenario providing situational perception based mobile service and proved to be useful.     

基于身份加密的机会网络安全路由架构

机会网络整合了容迟网络、移动自组织网络、社会网络等多种概念,可通过移动节点的相遇性机会实现消息的传输与共享,针对机会网络中目前较为流行的基于社会上下文的路由转发协议,设计了基于身份加密的安全架构来保证节点社会上下文的隐私性以及消息的机密性:通过可搜索的加密算法为每一个节点的社会属性设置相应的陷门,使得中继节点在可计算自...     

Understanding the mechanism of social tie in the propagation process of social network with communication channel

The propagation of information in online social networks plays a critical role in modern life, and thus has been studied broadly. Researchers have proposed a series of propagation models, generally, which use a single transition probability or consider factors such as content and time to describe the way how a user activates her/his neighbors. However, the research on the mechanism how social ties between users play roles in propagation process is still limited. Specifically, comprehensive summary of factors which affect user’s decision whether to share neighbor’s content was lacked in existing works, so that the existing models failed to clearly describe the process a user be activated by a neighbor. To this end, in this paper, we analyze the close correspondence between social tie in propagation process and communication channel, thus we propose to exploit the communication channel to describe the information propagation process between users, and design a social tie channel (STC) model. The model can naturally incorporate many factors affecting the information propagation through edges such as content topic and user preference, and thus can effectively capture the user behavior and relationship characteristics which indicate the property of a social tie. Extensive experiments conducted on two real-world datasets demonstrate the effectiveness of our model on content sharing prediction between users.     

MIMOSA: context-aware adaptation for ubiquitous web access

The ubiquitous computing scenario is characterized by heterogeneity of devices used to access services, and by frequent changes in the user’s context. Hence, adaptation according to the user’s context and the used devices is necessary to allow mobile users to efficiently exploit Internet-based services. In this paper, we present a distributed framework, named MIMOSA, that couples a middleware for context-awareness with an intermediary-based architecture for content adaptation. MIMOSA provides an effective and efficient solution for the adaptation of Internet services on the basis of a comprehensive notion of context, by means of techniques for aggregating context data from distributed sources, deriving complex contextual situations from raw sensor data, evaluating adaptation policies, and solving possible conflicts. The middleware allows programmers to modularly build complex adaptive services starting from simple ones, and includes tools for assisting the user in declaring her preferences, as well as mechanisms for detecting incorrect system behaviors due to a wrong choice of adaptation policies. The effectiveness and efficiency of MIMOSA are shown through the development of a prototype adaptive service, and by extensive experimental evaluations.     

P2P multicast for pervasive ad hoc networks

During the last few years, the proliferation of miniaturised devices with networking capabilities has provided the technological grounds for pervasive networking environments. It is not visionary to foresee a world of pervasive devices embedded in the environment interacting between them, and with those carried by users, via wireless communications. In addition, fostered by the diffusion of small-size, computational-rich mobile devices, the way content is generated, and accessed is changing with respect to the legacy-Internet paradigm. An ever-increasing share of the Internet content is generated directly by the users, and shared on the network (following the User-Generated Content model). While today the legacy Internet is still used to share user-generated content, it is reasonable to envision that pervasive networking technologies will represent the natural platform to support this new model. This will result in content being distributed on users’ devices rather than on centralised servers on the Internet, and in users creating ad hoc networks to share content. The p2p paradigm is particularly suitable for this scenario, because communications will occur directly among users, instead of being necessarily mediated by centralised servers. Motivated by these remarks, in this work we focus on p2p multicast services over ad hoc networks aimed at sharing content among groups of users interested in the same topics. Specifically, starting from a reference solution in legacy wired networks (Scribe), we design a cross-layer optimised protocol (XScribe) that addresses most of the Scribe problems on ad hoc networks. XScribe exploits cross-layer interactions with a proactive routing protocol to manage group membership. Furthermore, it uses a lightweight, structureless approach to deliver data to group members. By jointly using experimental results and analytical models, we show that, with respect to Scribe, XScribe significantly reduces the packet loss and the delay experienced by multicast receivers, and increases the maximum throughput that can be delivered to multicast groups.     

Why do people share their context information on Social Network Services? A qualitative study and an experimental study on users' behavior of balancing perceived benefit and risk

Despite the rapid growth of context-aware systems and ubiquitous computing, the factors influencing users' decision to share their context information in a social setting are poorly understood. This study aims to clarify why users share their context information in social network service (SNS), even while they are concerned with the potential risk at the same time. Drawing on the diverse theories of self-disclosure, we take an approach that the consideration of benefit encourages users to endure the existence of risk, and that users actively adjust the way they share their information to optimize the level of benefit and risk. In a qualitative study, we examined what kinds of risks and benefits exist in context information sharing situations and how users control them. An experiment was conducted using stimuli that simulate the actual use of SNS to investigate the effect of various context types and control types on users' expected benefit and risk and their intention to share. The results showed that both expected benefit and expected risk influenced users' intention to share. More interestingly, the effect of expected benefit was found to be stronger than that of expected risk. Moreover, different privacy control strategies were found to have induced different effects on the expected benefit and expected risk. Implications and limitations of this study were proposed at the end of this study.     

Modelling and performance analysis of content sharing and distribution in community networks with infrastructure support

We consider the problem of sharing a viral file between users in a local community network (e.g., college and office campuses). Community computing is computer networking among and between users in a geographically bounded setting for local purposes and activities. Due to the community-oriented nature of such networks, it is likely that users of a community network would like to share content. Peer-to-Peer (P2P) networks have turned out to be one of the most innovative paradigms for sharing content on the Internet. In this paper, we analyze the performance of P2P content sharing in community networks and investigate the role that infrastructure nodes (helpers) can play to enhance the performance of content sharing and distribution. We model the evolution of content demand in a community network. The use of this demand prediction model allows us to design a delicate P2P-with-helpers content distribution system. Our insights that we obtain using fluid-flow model increase our understanding of how helper provisioning affects the performance of content sharing and distribution. The derived results show that significant reduction in both the cost of distributing content and the average content download time can be realized when only few infrastructure nodes in the community network play the role helpers and cache P2P objects.     

Finding Diachronic Like‐Minded Users

User communities in social networks are usually identified by considering explicit structural social connections between users. While such communities can reveal important information about their members such as family or friendship ties and geographical proximity, just to name a few, they do not necessarily succeed at pulling like‐minded users that share the same interests together. Therefore, researchers have explored the topical similarity of social content to build like‐minded communities of users. In this article, following the topic‐based approaches, we are interested in identifying communities of users that share similar topical interests with similar temporal behavior. More specifically, we tackle the problem of identifying temporal (diachronic) topic‐based communities, i.e., communities of users who have a similar temporal inclination toward emerging topics. To do so, we utilize multivariate time series analysis to model the contributions of each user toward emerging topics. Further, our modeling is completely agnostic to the underlying topic detection method. We extract topics of interest by employing seminal topic detection methods; one graph‐based and two latent Dirichlet allocation‐based methods. Through our experiments on Twitter data, we demonstrate the effectiveness of our proposed temporal topic‐based community detection method in the context of news recommendation, user prediction, and document timestamp prediction applications, compared with the nontemporal as well as the state‐of‐the‐art temporal approaches.     

Transitive node similarity: predicting and recommending links in signed social networks

Online social networks (OSNs) like Facebook, Myspace, and Hi5 have become popular, because they allow users to easily share content. OSNs recommend new friends to registered users based on local features of the graph (i.e., based on the number of common friends that two users share). However, OSNs do not exploit the whole structure of the network. Instead, they consider only pathways of maximum length 2 between a user and his candidate friends. On the other hand, there are global approaches, which detect the overall path structure in a network, being computationally prohibitive for huge-size social networks. In this paper, we define a basic node similarity measure that captures effectively local graph features (i.e., by measuring proximity between nodes). We exploit global graph features (i.e., by weighting paths that connect two nodes) introducing transitive node similarity. We also derive variants of our method that apply to different types of networks (directed/undirected and signed/unsigned). We perform extensive experimental comparison of the proposed method against existing recommendation algorithms using synthetic and real data sets (Facebook, Hi5 and Epinions). Our experimental results show that our FriendTNS algorithm outperforms other approaches in terms of accuracy and it is also time efficient. Finally, we show that a significant accuracy improvement can be gained by using information about both positive and negative edges.     

Efficient allocation of resources in multiple heterogeneous Wireless Sensor Networks

Wireless Sensor Networks (WSNs) are useful for a wide range of applications, from different domains. Recently, new features and design trends have emerged in the WSN field, making those networks appealing not only to the scientific community but also to the industry. One such trend is the running different applications on heterogeneous sensor nodes deployed in multiple WSNs in order to better exploit the expensive physical network infrastructure. Another trend deals with the capability of accessing sensor generated data from the Web, fitting WSNs in novel paradigms of Internet of Things (IoT) and Web of Things (WoT). Using well-known and broadly accepted Web standards and protocols enables the interoperation of heterogeneous WSNs and the integration of their data with other Web resources, in order to provide the final user with value-added information and applications. Such emergent scenarios where multiple networks and applications interoperate to meet high level requirements of the user will pose several changes in the design and execution of WSN systems. One of these challenges regards the fact that applications will probably compete for the resources offered by the underlying sensor nodes through the Web. Thus, it is crucial to design mechanisms that effectively and dynamically coordinate the sharing of the available resources to optimize resource utilization while meeting application requirements. However, it is likely that Quality of Service (QoS) requirements of different applications cannot be simultaneously met, while efficiently sharing the scarce networks resources, thus bringing the need of managing an inherent tradeoff. In this paper, we argue that a middleware platform is required to manage heterogeneous WSNs and efficiently share their resources while satisfying user needs in the emergent scenarios of WoT. Such middleware should provide several services to control running application as well as to distribute and coordinate nodes in the execution of submitted sensing tasks in an energy-efficient and QoS-enabled way. As part of the middleware provided services we present the Resource Allocation in Heterogeneous WSNs (SACHSEN) algorithm. SACHSEN is a new resource allocation heuristic for systems composed of heterogeneous WSNs that effectively deals with the tradeoff between possibly conflicting QoS requirements and exploits heterogeneity of multiple WSNs.     

An adaptive quality of service aware middleware for replicated services

A dependable middleware should be able to adaptively share the distributed resources it manages in order to meet diverse application requirements, even when the quality of service (QoS) is degraded due to uncertain variations in load and unanticipated failures. We have addressed this issue in the context of a dependable middleware that adaptively manages replicated servers to deliver a timely and consistent response to time-sensitive client applications. These applications have specific temporal and consistency requirements, and can tolerate a certain degree of relaxed consistency in exchange for better response time. We propose a flexible QoS model that allows clients to specify their timeliness and consistency constraints. We also propose an adaptive framework that dynamically selects replicas to service a client's request based on the prediction made by probabilistic models. These models use the feedback from online performance monitoring of the replicas to provide probabilistic guarantees for meeting a client's QoS specification. The experimental results we have obtained demonstrate the role of feedback and the efficacy of simple analytical models for adaptively sharing the available replicas among the users under different workload scenarios.     

Thematic Schema Building for Mediation-based Peer-to-Peer Architecture

Recently, mediation tools and peer-to-peer systems have allowed an important evolution for data sharing. Mediators are now mature techniques to share structured and heterogeneous data distributed through a reasonable number of nodes. Peer-to-peer architectures open new ways to build very large and dynamic networks allowing to share unstructured data as files indexed by some keywords. We propose here to exploit the complementarity of these approaches to efficiently share structured and heterogeneous data distributed through a large set of nodes. We propose an unstructured peer-to-peer architecture handling interactions between a large set of mediators and simplifying the process of schema exchanges. We focus on the dynamic building of mediation schemas which are personalized for user needs in order to query the network. To validate our approach, we have implemented a prototype, MenT2, which integrates several schemas via mediator interactions in a simulated network.     

支持上下文感知服务的中间件原型*

提出了基于传感器网络环境的上下文感知应用开发中间件原型的体系结构MidCASE,重点阐述了中间件的体系结构设计和软件运行时基于服务的分布式运行架构.讨论了上下文感知过程中的两个关键问题,包括上下文信息建立的方法和感知过程中上下文信息与高层通信的调度模型.最后,以该中间件原型为基础,通过在医疗护理的场景下实现上下文感知应用并证明了其易用性与支撑作用.     

Architectural Components of Information–Sharing Societies

Two similar multi–agent systems have been designed to address the issue of information sharing within a multi–agent system. This paper examines the architectural components that have been added to our information–sharing societies, ACORN and MP3. Through this exploration, we conclude that these components and their underlying concepts can be added to other information–retrieval societies.
ACORN consists of a set of information–sharing locations referred to as cafés. Cafés are defined as meeting locations for like–minded agents. Like–minded agents are defined as agents that share a common set of interests. As an example, a café may contain agents that are interested in information relating to cars. A dynamic café clustering method is developed. The performance evaluation of the proposed structure for the café is presented. The concept of a fat / thin agent architecture is introduced. This agent architecture allows for minimizing network traffic as agents traverse the network in search of or distribution of knowledge. The directory server component is presented along with its relation to the fat/thin agent architecture. Finally, an anonymity service provider which allows anonymity for users is introduced.
The MP3 society exists with the sole purpose of finding MP3s throughout a given network. Through this society, the core design issues of agent verification and agent validation are addressed and solutions are presented through respective interface components.     

支持多应用任务的WSNs中间件的设计与实现

无线传感器网络作为物联网的基础设施,需要同时运行多种应用任务来满足不同用户的复杂需求。现有的无线传感器网络中间件主要是为某一类应用领域而设计和开发的,其上运行的是单一应用任务。设计了一种支持多应用任务的无线传感器网络中间件架构,并根据此架构设计与实现了整个系统与各个功能组件,整个中间件可以根据不同需求承载多种应用任务,并且通过模拟网络的实验验证了该中间件系统具有较好的可行性和实用性。     

pFusion: A P2P Architecture for Internet-Scale Content-Based Search and Retrieval

The emerging peer-to-peer (p2p) model has become a very powerful and attractive paradigm for developing Internet-scale systems for sharing resources, including files and documents. The distributed nature of these systems, where nodes are typically located across different networks and domains, inherently hinders the efficient retrieval of information. In this paper, we consider the effects of topologically aware overlay construction techniques on efficient p2p keyword search algorithms. We present the peer fusion (pFusion) architecture that aims to efficiently integrate heterogeneous information that is geographically scattered on peers of different networks. Our approach builds on work in unstructured p2p systems and uses only local knowledge. Our empirical results, using the pFusion middleware architecture and data sets from Akamai's Internet mapping infrastructure (AKAMAI), the active measurement project (NLANR), and the text retrieval conference (TREC) show that the architecture we propose is both efficient and practical     

Socially inspired search and ranking in mobile social networking: concepts and challenges

In this paper, we provide an overview of challenges in mobile search and ranking, and envision the fundamental features that should be satisfied. We argue that two principles will help improve the relevance and quality of mobile search and ranking: the first one is to examine both intrinsic content features and context of items (usage statistics and social features, etc.); and the second one lies in that no algorithms can replace the objectivity of a human being—let users define the sites that they feel are relevant, leverage their social networks, and over time see their results become highly personalized. Specifically, wireless-virtualcommunity-based mobile search and ranking architecture is proposed in this paper, in which communities act as a first class abstraction for information sharing. Then, we introduce briefly the potential procedures of achieving high relevance and quality in mobile search and ranking based on wireless virtual community.     

Socially inspired search and ranking in mobile social networking: concepts and challenges

In this paper, we provide an overview of challenges in mobile search and ranking, and envision the fundamental features that should be satisfied. We argue that two principles will help improve the relevance and quality of mobile search and ranking: the first one is to examine both intrinsic content features and context of items (usage statistics and social features, etc.); and the second one lies in that no algorithms can replace the objectivity of a human being—let users define the sites that they feel are relevant, leverage their social networks, and over time see their results become highly personalized. Specifically, wireless-virtualcommunity- based mobile search and ranking architecture is proposed in this paper, in which communities act as a first class abstraction for information sharing. Then, we introduce briefly the potential procedures of achieving high relevance and quality in mobile search and ranking based on wireless virtual community.     

Already up? using mobile phones to track & share sleep behavior

Users share a lot of personal information with friends, family members, and colleagues via social networks. Surprisingly, some users choose to share their sleeping patterns, perhaps both for awareness as well as a sense of connection to others. Indeed, sharing basic sleep data, whether a person has gone to bed or waking up, informs others about not just one's sleeping routines but also indicates physical state, and reflects a sense of wellness. We present Somnometer, a social alarm clock for mobile phones that helps users to capture and share their sleep patterns. While the sleep rating is obtained from explicit user input, the sleep duration is estimated based on monitoring a user's interactions with the app. Observing that many individuals currently utilize their mobile phone as an alarm clock revealed behavioral patterns that we were able to leverage when designing the app. We assess whether it is possible to reliably monitor one's sleep duration using such apps. We further investigate whether providing users with the ability to track their sleep behavior over a long time period can empower them to engage in healthier sleep habits. We hypothesize that sharing sleep information with social networks impacts awareness and connectedness among friends. The result from a controlled study reveals that it is feasible to monitor a user's sleep duration based just on her interactions with an alarm clock app on the mobile phone. The results from both an in-the-wild study and a controlled experiment suggest that providing a way for users to track their sleep behaviors increased user awareness of sleep patterns and induced healthier habits. However, we also found that, given the current broadcast nature of existing social networks, users were concerned with sharing their sleep patterns indiscriminately.