2011 31st International Conference on Distributed Computing Systems Workshops最新文献

{"title":"Approximation and Inapproximation for the Influence Maximization Problem in Social Networks under Deterministic Linear Threshold Model","authors":"Zaixin Lu, Wei Zhang, Weili Wu, B. Fu, D. Du","doi":"10.1109/ICDCSW.2011.33","DOIUrl":"https://doi.org/10.1109/ICDCSW.2011.33","url":null,"abstract":"Influence Maximization is the problem of finding a certain amount of people in a social network such that their aggregation influence through the network is maximized. In the past this problem has been widely studied under a number of different models. In 2003, Kempe emph{et al.} gave a $(1-{1 over e})$-approximation algorithm for the emph{linear threshold model} and the emph{independent cascade model}, which are the two main models in the social network analysis. In addition, Chen emph{et al.} proved that the problem of exactly computing the influence given a seed set in the two models is $#$P-hard. Both the emph{linear threshold model} and the emph{independent cascade model} are based on randomized propagation. However such information might be obtained by surveys or data mining techniques, which makes great difference on the properties of the problem. In this paper, we study the Influence Maximization problem in the emph{deterministic linear threshold model}. As a contrast, we show that in the emph{deterministic linear threshold model}, there is no polynomial time $n^{1-epsilon}$-approximation unless P=NP even at the simple case that one person needs at most two active neighbors to become active. This inapproximability result is derived with self-contained proofs without using PCP theorem. In the case that a person can be activated when one of its neighbors become active, there is a polynomial time ${eover e-1}$-approximation, and we prove it is the best possible approximation under a reasonable assumption in the complexity theory, $NP notsubset DTIME(n^{loglog n})$. We also show that the exact computation of the final influence given a seed set can be solved in linear time in the emph{deterministic linear threshold model}. The Least Seed Set problem, which aims to find a seed set with least number of people to activate all the required people in a given social network, is discussed. Using an analysis framework based on Set Cover, we show a $O($log$n)$-approximation in the case that a people become active when one of its neighbors is activated.","PeriodicalId":133514,"journal":{"name":"2011 31st International Conference on Distributed Computing Systems Workshops","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115043609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scale-free Networking without Routing Tables","authors":"J. Garcia-Luna-Aceves","doi":"10.1109/ICDCSW.2011.70","DOIUrl":"https://doi.org/10.1109/ICDCSW.2011.70","url":null,"abstract":"Summary form only given. The traditional approach to routing in ad hoc networks consists of maintaining routing tables listing entries for all or selected network destinations. Unfortunately, because the identifiers assigned to nodes (e.g., IP addresses or MAC addresses) in a network with mobile nodes have nothing to do with the topology of the network, network-wide dissemination of updates or queries must be used to maintain such tables, which renders the signaling of the routing protocols unscalable. This talk describes a new approach for scale-free routing that is called SURF (Scale-free Untethered Routing Framework). With SURF, the network itself assigns identifiers to nodes and updates these identifiers as the nodes move. The identifiers define a total ordering in the network with respect to one or multiple root nodes, which means that one or multiple routes from any source to any destination are defined automatically by the identifiers of the two nodes. To allow the sources to learn the identifiers of the destinations, a publish-subscribe distributed directory service is provided, such that a destination publishes its existence at an anchor node and a destination subscribes to destinations by contacting the proper anchors. The talk will show how SURF can be applied to different types of specialized networks, including those in which relay nodes have severe constraints (size, processing power, energy consumption).","PeriodicalId":133514,"journal":{"name":"2011 31st International Conference on Distributed Computing Systems Workshops","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115067120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploiting Rush Hours for Energy-Efficient Contact Probing in Opportunistic Data Collection","authors":"Xiuchao Wu, Kenneth N. Brown, C. Sreenan","doi":"10.1109/ICDCSW.2011.23","DOIUrl":"https://doi.org/10.1109/ICDCSW.2011.23","url":null,"abstract":"In many potential wireless sensor network applications, the cost of the base station infrastructure can be prohibitive. Instead, we consider the use of mobile devices carried by people in their daily life to collect sensor data opportunistically. As the movement of these mobile nodes is, by definition, uncontrolled, contact probing becomes a challenging task, particularly for sensor nodes which need to be aggressively duty-cycled to achieve long life. It has been reported that when the duty-cycle of a sensor node is fixed, SNIP, a sensor node-initiated probing mechanism, performs much better than mobile node-initiated probing mechanisms. Considering that the intended applications are delay-tolerant, mobile nodes tend to follow some repeated mobility patterns, and contacts are distributed unevenly in temporal, SNIP-RH is proposed in this paper to further improve the performance of contact probing through exploiting Rush Hours during which contacts arrive more frequently. In SNIP-RH, SNIP is activated only when the time is within Rush Hours and there are enough data to be uploaded in the next probed contact. As for the duty-cycle, it is selected based on the mean of contact length that is learned on line. Both analysis and simulation results indicate that under a typical simulated road-side wireless sensor network scenario, SNIP-RH can significantly reduce the energy consumed for probing the contacts, that are necessary for uploading the sensed data, or significantly increase the probed contact capacity under a sensor node's energy budget for contact probing.","PeriodicalId":133514,"journal":{"name":"2011 31st International Conference on Distributed Computing Systems Workshops","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117329281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cross-Examination of Datacenter Workload Modeling Techniques","authors":"Christina Delimitrou, C. Kozyrakis","doi":"10.1109/ICDCSW.2011.45","DOIUrl":"https://doi.org/10.1109/ICDCSW.2011.45","url":null,"abstract":"Data center workload modeling has become a necessity in recent years due to the emergence of large-scale applications and cloud data-stores, whose implementation remains largely unknown. Detailed knowledge of target workloads is critical in order to correctly provision performance, power and cost-optimized systems. In this work we aggregate previous work on data center workload modeling and perform a qualitative comparison based on the representativeness, accuracy and completeness of these designs. We categorize modeling techniques in two main approaches, in-breadth and in-depth, based on the way they address the modeling of the workload. The former models the behavior of a workload in specific system parts, while the latter traces a user request throughout its execution. Furthermore, we propose the early concept of a new design, which bridges the gap between these two approaches by combining some features from each one. Some first results on the request features and performance metrics of the generated workload based on this design appear promising as far as the accuracy of the model is concerned.","PeriodicalId":133514,"journal":{"name":"2011 31st International Conference on Distributed Computing Systems Workshops","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129456701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Case for Hardware Protection of Guest VMs from Compromised Hypervisors in Cloud Computing","authors":"Jakub Szefer, R. Lee","doi":"10.1109/ICDCSW.2011.51","DOIUrl":"https://doi.org/10.1109/ICDCSW.2011.51","url":null,"abstract":"Cloud computing, enabled by virtualization technologies, is becoming a mainstream computing model. Many companies are starting to utilize the infrastructure-as-a-service (IaaS) cloud computing model, leasing guest virtual machines (VMs) from the infrastructure providers for economic reasons: to reduce their operating costs and to increase the flexibility of their own infrastructures. Yet, many companies may be hesitant to move to cloud computing due to security concerns. An integral part of any virtualization technology is the all-powerful hyper visor. A hyper visor is a system management software layer which can access all resources of the platform. Much research has been done on using hyper visors to monitor guest VMs for malicious code and on hardening hyper visors to make them more secure. There is, however, another threat which has not been addressed by researchers -- that of compromised or malicious hyper visors that can extract sensitive or confidential data from guest VMs. Consequently, we propose that a new research direction needs to be undertaken to tackle this threat. We further propose that new hardware mechanisms in the multi core microprocessors are a viable way of providing protections for the guest VMs from the hyper visor, while still allowing the hyper visor to flexibly manage the resources of the physical platform.","PeriodicalId":133514,"journal":{"name":"2011 31st International Conference on Distributed Computing Systems Workshops","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129177671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preserving Social Locality in Data Replication for Online Social Networks","authors":"Khanh Nguyen, Cuong H. Pham, D. Tran, Feng Zhang","doi":"10.1109/ICDCSW.2011.14","DOIUrl":"https://doi.org/10.1109/ICDCSW.2011.14","url":null,"abstract":"An on line social network usually requires many servers to store its user data so that a large number of users can be served. The data should also be replicated across the servers to provide a high degree of availability in case failures occur. In this paper we discuss the importance of social locality in the replication procedure. To substantiate this importance, we propose and evaluate a replication method that can significantly improve the system efficiency by leveraging the social relationships of the data.","PeriodicalId":133514,"journal":{"name":"2011 31st International Conference on Distributed Computing Systems Workshops","volume":"14 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125599140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Weighted Average Based External Clock Synchronization Protocol for Wireless Sensor Networks","authors":"Amulya Ratna Swain, R. Hansdah","doi":"10.1504/IJSNET.2012.050075","DOIUrl":"https://doi.org/10.1504/IJSNET.2012.050075","url":null,"abstract":"Clock synchronization is an extremely important requirement of wireless sensor networks(WSNs). There are many application scenarios such as weather monitoring and forecasting etc. where external clock synchronization may be required because WSN itself may consists of components which are not connected to each other. A usual approach for external clock synchronization in WSNs is to synchronize the clock of a reference node with an external source such as UTC, and the remaining nodes synchronize with the reference node using an internal clock synchronization protocol. In order to provide highly accurate time, both the offset and the drift rate of each clock with respect to reference node are estimated from time to time, and these are used for getting correct time from local clock reading. A problem with this approach is that it is difficult to estimate the offset of a clock with respect to the reference node when drift rate of clocks varies over a period of time. In this paper, we first propose a novel internal clock synchronization protocol based on weighted averaging technique, which synchronizes all the clocks of a WSN to a reference node periodically. We call this protocol weighted average based internal clock synchronization(WICS) protocol. Based on this protocol, we then propose our weighted average based external clock synchronization(WECS) protocol. We have analyzed the proposed protocols for maximum synchronization error and shown that it is always upper bounded. Extensive simulation studies of the proposed protocols have been carried out using Castalia simulator. Simulation results validate our theoretical claim that the maximum synchronization error is always upper bounded and also show that the proposed protocols perform better in comparison to other protocols in terms of synchronization accuracy. A prototype implementation of the proposed internal clock synchronization protocol using a few TelosB motes also validates our claim.","PeriodicalId":133514,"journal":{"name":"2011 31st International Conference on Distributed Computing Systems Workshops","volume":"568 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132518351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modelling of Cloud Computing Centers Using M/G/m Queues","authors":"Hamzeh Khazaei, J. Misic, V. Mišić","doi":"10.1109/ICDCSW.2011.13","DOIUrl":"https://doi.org/10.1109/ICDCSW.2011.13","url":null,"abstract":"Cloud computing is a new computing paradigm, whereby shared resources such as infrastructure, hardware platform, and software applications are provided to users on-demand over the internet (Cloud) as services. Successful provision of infrastructure-as-a-service (IaaS) and, consequently, widespread adoption of cloud computing necessitates accurate performance evaluation that allows service providers to dimension their resources in order to fulfil the service level agreements with their customers. In this paper, we describe an analytical model for performance evaluation of cloud server farms, and demonstrate the manner in which important performance indicators such as request response time and number of tasks in the system may be assessed with sufficient accuracy.","PeriodicalId":133514,"journal":{"name":"2011 31st International Conference on Distributed Computing Systems Workshops","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131407491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving Fairness of Quantized Congestion Notification for Data Center Ethernet Networks","authors":"Yuki Hayashi, H. Itsumi, M. Yamamoto","doi":"10.1109/ICDCSW.2011.15","DOIUrl":"https://doi.org/10.1109/ICDCSW.2011.15","url":null,"abstract":"In large-scale data centers, two types of network are implemented: local area networks (LANs) and storage area networks (SANs). To achieve simple network management, integration of these two networks by Ethernet technology is of great interest. A SAN requires a significantly low frame loss rate. To integrate LANs and SANs, a multi-hop Ethernet configuration is generally used, and congestion may occur in traffic hot spots. Therefore, layer-2 congestion control that prevents frame loss in multi-hop Ethernet, Quantized Congestion Notification (QCN), is now discussed in IEEE 802.1Qau. In this paper, we evaluate QCN's throughput performance and reveal a technical problem with fairness among active flows. We also propose an enhancement of QCN's rate increase principle and demonstrate that it improves fairness.","PeriodicalId":133514,"journal":{"name":"2011 31st International Conference on Distributed Computing Systems Workshops","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132876229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding Social Networks Properties for Trustworthy Computing","authors":"Aziz Mohaisen, Huy Tran, Nicholas Hopper, Yongdae Kim","doi":"10.1109/ICDCSW.2011.48","DOIUrl":"https://doi.org/10.1109/ICDCSW.2011.48","url":null,"abstract":"The ever-increasing popularity of social networks opens new directions for leveraging social networks to build primitives for security and communication, in many contexts. Such primitives utilize the trust in these social networks to ensure collaboration and algorithmic properties exhibited in such networks to argue for the effectiveness of such primitives. Despite the importance of such properties and their quality to the operation of these primitives, less effort is made to measure these properties and understand the relationship among them and to other characteristics of social networks. We extend our earlier results measuring the mixing time, to investigate a new property used for building Sybil defenses, namely the expansion of social graphs. We measure the expansion of social graphs, and show quantitatively that, with a few exceptions, it is sufficient to support Sybil defense mechanisms based on expansion. We relate the mixing time of social graphs to graph degeneracy, which captures cohesiveness of the graph. We experimentally show that fast-mixing graphs tend to have a larger single core whereas slow mixing graphs tend to have smaller multiple cores. While this study provides quantitative evidence relating the mixing time to coreness of the graph, it also agrees with our previous observations about the tight-knit community structure in slow mixing social graphs.","PeriodicalId":133514,"journal":{"name":"2011 31st International Conference on Distributed Computing Systems Workshops","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132013041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}