Y. Cao, Z. Shao, M. Wang, C. Xue, Youdong Chen, Hongxing Wei, Tianmiao Wang
As a distributed computing system, a CNC system needs to be operated reliably, dependably and safely. How to design reliable and dependable software and perform effective verification for CNC systems becomes an important research problem. In this paper, we propose a new modeling method called TTM/ATRTTL (Timed Transition Models/All-Time Real-Time Temporal Logics) for specifying CNCsystems. TTM/ATRTTL provides full supports for specifying hard real-time and feedback that are needed for modeling CNC systems. We also propose a verification framework with verification rules and theorems and implement it with STeP and SF2STeP. The proposed verification framework can check reliability, dependability and safety of systems specified by our TTM/ATRTTL method. We apply our modeling and verification techniques on an open architecture CNC (OAC) system and conduct comprehensive studies on modeling and verifying a logical controller that is the key part of OAC. The results show that our method can effectively model and verify CNC systems and generate CNC software that can satisfy system requirements in reliability, dependability and safety.
{"title":"A Formal Specification and Verification Framework for Designing and Verifying Reliable and Dependable Software for Computerized Numerical Control (CNC) Systems","authors":"Y. Cao, Z. Shao, M. Wang, C. Xue, Youdong Chen, Hongxing Wei, Tianmiao Wang","doi":"10.1109/ICDCS.2008.21","DOIUrl":"https://doi.org/10.1109/ICDCS.2008.21","url":null,"abstract":"As a distributed computing system, a CNC system needs to be operated reliably, dependably and safely. How to design reliable and dependable software and perform effective verification for CNC systems becomes an important research problem. In this paper, we propose a new modeling method called TTM/ATRTTL (Timed Transition Models/All-Time Real-Time Temporal Logics) for specifying CNCsystems. TTM/ATRTTL provides full supports for specifying hard real-time and feedback that are needed for modeling CNC systems. We also propose a verification framework with verification rules and theorems and implement it with STeP and SF2STeP. The proposed verification framework can check reliability, dependability and safety of systems specified by our TTM/ATRTTL method. We apply our modeling and verification techniques on an open architecture CNC (OAC) system and conduct comprehensive studies on modeling and verifying a logical controller that is the key part of OAC. The results show that our method can effectively model and verify CNC systems and generate CNC software that can satisfy system requirements in reliability, dependability and safety.","PeriodicalId":240205,"journal":{"name":"2008 The 28th International Conference on Distributed Computing Systems","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130011112","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}
DHT is a widely-used building block in P2P systems, and complex queries are gaining popularity in P2P applications. To support efficient query processing over DHTs, effective indexing structures are essential. Recently, a number of indexing schemes have been proposed. However, these schemes have focused on improving query efficiency, and as a trade-off, sacrificed maintenance efficiency - an important performance measure in the P2P context, where frequent data updating and high peer dynamism are typically incurred. In this paper, we propose LHT, a Low maintenance Hash Tree, for efficient data indexing over DHTs. LHT employs a novel naming function and a tree summarization strategy to gracefully distribute its index structure. It is adaptable to any DHT substrates, and is easy to be implemented and deployed. Experiments show that in comparison with the state-of-the-art indexing technique, LHT saves up to 75% (at least 50%) maintenance cost, and achieves better performance for exact-match queries and range queries.
{"title":"LHT: A Low-Maintenance Indexing Scheme over DHTs","authors":"Y. Tang, Shuigeng Zhou","doi":"10.1109/ICDCS.2008.61","DOIUrl":"https://doi.org/10.1109/ICDCS.2008.61","url":null,"abstract":"DHT is a widely-used building block in P2P systems, and complex queries are gaining popularity in P2P applications. To support efficient query processing over DHTs, effective indexing structures are essential. Recently, a number of indexing schemes have been proposed. However, these schemes have focused on improving query efficiency, and as a trade-off, sacrificed maintenance efficiency - an important performance measure in the P2P context, where frequent data updating and high peer dynamism are typically incurred. In this paper, we propose LHT, a Low maintenance Hash Tree, for efficient data indexing over DHTs. LHT employs a novel naming function and a tree summarization strategy to gracefully distribute its index structure. It is adaptable to any DHT substrates, and is easy to be implemented and deployed. Experiments show that in comparison with the state-of-the-art indexing technique, LHT saves up to 75% (at least 50%) maintenance cost, and achieves better performance for exact-match queries and range queries.","PeriodicalId":240205,"journal":{"name":"2008 The 28th International Conference on Distributed Computing Systems","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130263225","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}
In a realistic sensor network, in particular with a non-uniform deployment, sensor nodes inevitably have varying workloads. This causes a natural problem that some sensor nodes are subject to excessive power consumption and thus become hot. These hot nodes deplete much earlier resulting in system performance degradation. This paper proposes a systematic approach to design a hotness-aware sensor network where each node is able to obtain its own hotness information. Based on these vital information, the system is able to provide various technologies to protect the critical set of hot nodes. More specifically, we design a centralized optimal algorithm to derive the precise hotness of each node. In addition, we develop a completely distributed algorithm to estimate hotness with high accuracy. An effective hotness-aware MAC is developed to offer medium access priority to the nodes with higher hotness to protect and prolong their lifetimes. It is demonstrated, through both theoretical analysis and comprehensive simulations, that our approach is valuable to improving system performance of practical sensor networks.
{"title":"Hotness-Aware Sensor Networks","authors":"Dong Li, Yanmin Zhu, Li Cui, L. Ni","doi":"10.1109/ICDCS.2008.50","DOIUrl":"https://doi.org/10.1109/ICDCS.2008.50","url":null,"abstract":"In a realistic sensor network, in particular with a non-uniform deployment, sensor nodes inevitably have varying workloads. This causes a natural problem that some sensor nodes are subject to excessive power consumption and thus become hot. These hot nodes deplete much earlier resulting in system performance degradation. This paper proposes a systematic approach to design a hotness-aware sensor network where each node is able to obtain its own hotness information. Based on these vital information, the system is able to provide various technologies to protect the critical set of hot nodes. More specifically, we design a centralized optimal algorithm to derive the precise hotness of each node. In addition, we develop a completely distributed algorithm to estimate hotness with high accuracy. An effective hotness-aware MAC is developed to offer medium access priority to the nodes with higher hotness to protect and prolong their lifetimes. It is demonstrated, through both theoretical analysis and comprehensive simulations, that our approach is valuable to improving system performance of practical sensor networks.","PeriodicalId":240205,"journal":{"name":"2008 The 28th International Conference on Distributed Computing Systems","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121185923","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}
Pub Date : 2007-11-22DOI: 10.1142/S0129054115500173
Stéphane Devismes, S. Tixeuil, M. Yamashita
Self-stabilization is a strong property which guarantees that a network always resume a correct behavior starting from an arbitrary initial state. Weaker guarantees have later been introduced to cope with impossibility results: probabilistic stabilization only gives probabilistic convergence to a correct behavior. Also, weak-stabilization only gives the possibility of convergence. In this paper, we investigate the relative power of weak, self, and probabilistic stabilization, with respect to the set of problems that can be solved. We formally prove that in that sense, weak stabilization is strictly stronger that self-stabilization. Also, we refine previous results on weak stabilization to prove that, for practical schedule instances, a deterministic weak-stabilizing protocol can be turned into a probabilistic self-stabilizing one. This latter result hints at more practical use of weak-stabilization, as such algorithms are easier to design and prove than their (probabilistic) self-stabilizing counterparts.
{"title":"Weak vs. Self vs. Probabilistic Stabilization","authors":"Stéphane Devismes, S. Tixeuil, M. Yamashita","doi":"10.1142/S0129054115500173","DOIUrl":"https://doi.org/10.1142/S0129054115500173","url":null,"abstract":"Self-stabilization is a strong property which guarantees that a network always resume a correct behavior starting from an arbitrary initial state. Weaker guarantees have later been introduced to cope with impossibility results: probabilistic stabilization only gives probabilistic convergence to a correct behavior. Also, weak-stabilization only gives the possibility of convergence. In this paper, we investigate the relative power of weak, self, and probabilistic stabilization, with respect to the set of problems that can be solved. We formally prove that in that sense, weak stabilization is strictly stronger that self-stabilization. Also, we refine previous results on weak stabilization to prove that, for practical schedule instances, a deterministic weak-stabilizing protocol can be turned into a probabilistic self-stabilizing one. This latter result hints at more practical use of weak-stabilization, as such algorithms are easier to design and prove than their (probabilistic) self-stabilizing counterparts.","PeriodicalId":240205,"journal":{"name":"2008 The 28th International Conference on Distributed Computing Systems","volume":"281 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131485819","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}
Wanmin Wu, Zhenyu Yang, K. Nahrstedt, G. Kurillo, R. Bajcsy
3D tele-immersion (3DTI) has recently emerged as a new way of video-mediated collaboration across the Internet. Unlike conventional 2D video-conferencing systems, it can immerse remote users into a shared 3D virtual space so that they can interact or collaborate "virtually". However, most existing 3DTI systems can support only two sites of collaboration, due to the huge demand of networking resources and the lack of a simple yet efficient data dissemination model. In this paper, we propose to use a general publish-subscribe model for multi-site 3DTI systems, which efficiently utilizes limited network resources by leveraging user interest. We focus on the overlay construction problem in the publish-subscribe model by exploring a spectrum of heuristic algorithms for data dissemination. With extensive simulation, we identify the advantages of a simple randomized algorithm. We present optimization to further improve the randomized algorithm by exploiting semantic correlation. Experimental results demonstrate that we can achieve an improvement by a factor of five.
{"title":"Towards Multi-Site Collaboration in 3D Tele-Immersive Environments","authors":"Wanmin Wu, Zhenyu Yang, K. Nahrstedt, G. Kurillo, R. Bajcsy","doi":"10.1145/1291233.1291406","DOIUrl":"https://doi.org/10.1145/1291233.1291406","url":null,"abstract":"3D tele-immersion (3DTI) has recently emerged as a new way of video-mediated collaboration across the Internet. Unlike conventional 2D video-conferencing systems, it can immerse remote users into a shared 3D virtual space so that they can interact or collaborate \"virtually\". However, most existing 3DTI systems can support only two sites of collaboration, due to the huge demand of networking resources and the lack of a simple yet efficient data dissemination model. In this paper, we propose to use a general publish-subscribe model for multi-site 3DTI systems, which efficiently utilizes limited network resources by leveraging user interest. We focus on the overlay construction problem in the publish-subscribe model by exploring a spectrum of heuristic algorithms for data dissemination. With extensive simulation, we identify the advantages of a simple randomized algorithm. We present optimization to further improve the randomized algorithm by exploiting semantic correlation. Experimental results demonstrate that we can achieve an improvement by a factor of five.","PeriodicalId":240205,"journal":{"name":"2008 The 28th International Conference on Distributed Computing Systems","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123711735","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}
S. Al-Kiswany, M. Ripeanu, Sudharshan S. Vazhkudai, Abdullah Gharaibeh
Checkpointing is an indispensable technique to provide fault tolerance for long-running high-throughput applications like those running on desktop grids. This article argues that a checkpoint storage system, optimized to operate in these environments, can offer multiple benefits: reduce the load on a traditional file system, offer high-performance through specialization, and, finally, optimize data management by taking into account checkpoint application semantics. Such a storage system can present a unifying abstraction to checkpoint operations, while hiding the fact that there are no dedicated resources to store the checkpoint data. We prototype stdchk, a checkpoint storage system that uses scavenged disk space from participating desktops to build a low-cost storage system, offering a traditional file system interface for easy integration with applications. This article presents the stdchk architecture, key performance optimizations, and its support for incremental checkpointing and increased data availability. Our evaluation confirms that the stdchk approach is viable in a desktop grid setting and offers a low cost storage system with desirable performance characteristics: high write throughput as well as reduced storage space and network effort to save checkpoint images.
{"title":"stdchk: A Checkpoint Storage System for Desktop Grid Computing","authors":"S. Al-Kiswany, M. Ripeanu, Sudharshan S. Vazhkudai, Abdullah Gharaibeh","doi":"10.1109/ICDCS.2008.19","DOIUrl":"https://doi.org/10.1109/ICDCS.2008.19","url":null,"abstract":"Checkpointing is an indispensable technique to provide fault tolerance for long-running high-throughput applications like those running on desktop grids. This article argues that a checkpoint storage system, optimized to operate in these environments, can offer multiple benefits: reduce the load on a traditional file system, offer high-performance through specialization, and, finally, optimize data management by taking into account checkpoint application semantics. Such a storage system can present a unifying abstraction to checkpoint operations, while hiding the fact that there are no dedicated resources to store the checkpoint data. We prototype stdchk, a checkpoint storage system that uses scavenged disk space from participating desktops to build a low-cost storage system, offering a traditional file system interface for easy integration with applications. This article presents the stdchk architecture, key performance optimizations, and its support for incremental checkpointing and increased data availability. Our evaluation confirms that the stdchk approach is viable in a desktop grid setting and offers a low cost storage system with desirable performance characteristics: high write throughput as well as reduced storage space and network effort to save checkpoint images.","PeriodicalId":240205,"journal":{"name":"2008 The 28th International Conference on Distributed Computing Systems","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124903504","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}
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