15968114
An Efficient Explicit-time Description Method for Timed Model Checking
Timed modelchecking,the methodtoformallyverifyreal-timesystems, is attractingincreasingatten-tion from both the model checking community and the real-time community. Explicit-time descrip-tion methods verify real-time systems using general model constructs found in standard un-timedmodel checkers. Lamport proposed an explicit-time description method [17] using a clock-tickingprocess (Tick) to simulate the passage of time together with a group of global variables to model timerequirements. Two methods, the Sync-based Explicit-time Description Methodusing rendezvoussynchronization steps and the Semaphore-based Explicit-time Description Methodusing only oneglobal variable were proposed [27, 26]; they both achieve better modularity than Lamport’s methodin modelingthe real-time systems. In contrast to timed automatabased model checkerslike UPPAAL[7], explicit-time description methods can access and store the current time instant for future calcula-tions necessary for many real-time systems, especially those with pre-emptive scheduling. However,the Tick process in the above three methods increments the time by one unit in each tick; the statespaces therefore grow relatively fast as the time parameters increase, a problem when the system’stime period is relatively long. In this paper, we propose a more efﬁcient method which enables theTick process to leap multiple time units in one tick. Preliminary experimentalresults in a high perfor-mance computing environment show that this new method signiﬁcantly reduces the state space andimproves both the time and memory efﬁciency.
7625765
Solving QoS-driven Web service dynamic composition as fuzzy constraint satisfaction
The creation of value-added composite web service raises an opportunity to the formation of online B2B collaborations. However, web services are usually overlapping in functionality. How to make a choice based on non-functional factors becomes a problem that needs to be solved. In this paper, it argues that the selection of component services should be considered in a global manner and the user's QoS preferences is more appropriate to be expressed in a fuzzy way. It advocates using fuzzy set to express the user's QoS preference on a specific QoS criteria and using fuzzy expression to express the user's trade-off among QoS criteria's. The service selection problem is formalized as a fuzzy constraint satisfaction problem and deep-first branch-and-bound method is chosen to search for a solution with some adjustments to web service composition. It also develops an uncritical fuzzy consistency checking algorithm as an aid to faster search. Experiments are conducted to prove the effectiveness of the approach.
10472791
Certified Email Delivery with Offline TTP
Email has become a standard communication method nowadays. But when it comes to important correspondences containing sensitive governmental, commercial or medical information, certified delivery is required. We present in this paper a new certified email protocol which assures fair delivery, non-repudiability, confidentiality and timeliness. To achieve definite fairness, an offline TTP is employed which will be involved only if there is a dispute.
1947084
Fair Payment Protocols for E-Commerce
It has been widely accepted that fairness is a critical property for electronic commerce. Fair payment protocol is designed to guarantee fairness in a payment process over asynchronous network. Fairness means that when the protocol terminates, either both parties get their expected items, or neither does. In this paper we first present a new generic offline fair payment protocol with fairness, timeliness and invisibility of TTP. Then we introduce the property of abuse-freeness into electronic payment and implement a fair abuse-free payment protocol.
4594972
New Fair Payment Protocols
Fair payment protocol is designed to guarantee fairness in electronic purchasing, that is, no party can falsely deny involvement in the transaction or having sent/received the specific items/payment. In this paper we first present an efficient fair payment protocol providing invisibility of TTP, timeliness, and standard RSA signatures as the final non-repudiation evidences. Then we present a second payment protocol which is the first one to provide abuse-freeness. Our protocols can be easily integrated into the existing electronic payment systems.
38699742
Dependable Transaction for Electronic Commerce
Electronic transaction becomes common practice in real world business. This paper focuses on the issue of dependability in critical transactions like electronic payment, electronic contract signing. Recent fair protocols can recover transactions from network crashes, but cannot survive local system crashes. A two-party dependable transaction protocol is proposed. During the protocol, both parties can recover the transaction from network and local system failures in a transparent way, which means that after the recovery, outcome messages would be just the same as those from a successful run of the transaction.
16326025
Research on Positioning Technology of Xinjiang Mobile GIS
In this paper, the characteristics of Xinjiang mobile communication network are analyzed, the results show that for a reliable mobile communication network, BS (base station) and base station control BSC (base station controller) monitoring system, cable and fiber optic cable monitoring system and mobile communications troubleshooting and dispatching system should be built. Combined with GIS, GPS, GSM and geographic database technology, positioning technology for different targets and detection on fault point are studied, the results indicate that precise positioning of static target can accurately locate the failure telecom equipment in the electronic map and provide data source for the realization of real-time monitoring and management system for telecom equipment based on GIS & wireless sensor network technology. GSM-based wireless messaging communications and real-time fast positioning of dynamic target is the key to the emergency repair vehicles monitoring and dispatch system. The proposed fault determination and fault point location method can provide fast accurately fault devices location with detailed geography information and prompt the efficiency of fault management and improve the reliability of telecom network services. The above research results are important basis on the design and implementation of the system.
15067408
Adapting LDA Model to Discover Author-Topic Relations for Email Analysis
Analyzing the author and topic relations in email corpus is an important issue in both social network analysis and text mining. The Author-Topic model is a statistical model that identifies the author-topic relations. However, in its inference process, it ignores the information at the document level, i.e., the co-occurrence of words within documents are not taken into account in deriving topics. This may not be suitable for email analysis. We propose to adapt the Latent Dirichlet Allocation model for analyzing email corpus. This method takes into account both the author-document relations and the document-topic relations. We use the Author-Topic model as the baseline method and propose measures to compare our method against the Author-Topic model. We did empirical analysis based on experimental results on both simulated data sets and the real Enron email data set to show that our method obtains better performance than the Author-Topic model.
14899060
Automatic model-based service hosting environment migration
The proper operation of Service-Oriented Architecture (SOA) depends on underlying system services of operating systems, so efficient and effective migration of Service Hosting Environment is critical to cope with intrinsic-changed nature of SOA. However, due to the large amount of configuration items, complicated mapping and complex dependency relationship among system services, migrating into a new Service Hosting Environment satisfying the operation requirement of SOA becomes an error-prone and time-consuming task. The SCM project in IBM develops a novel approach to migrate Service Hosting Environment shaped in Unix-like systems. Firstly, this approach builds a set of configuration models to describe various system services. Then based on models, it presents knowledge based mapping to translate system service configurations between Service Hosting Environments. Finally, it designs a dependency hierarchy deducting algorithm to compute the dependency relationship among system services for migration traceability and error determination. A SCM prototype has performed well on largely reducing time, labor and errors in real migration cases.
14490221
Exploiting Request Characteristics to Improve Performance of Web Services Based Business Applications
Web Services and workflow have been widely adopted in building complicated business systems. In these systems, high security concern is claimed. But frequent authentication and computing-intensive encoding and decoding operation bring extra workload to the systems and greatly impact the performance of Web Services and workflow engine, especially under heavy load. In this paper, we propose Requests Automated Binding Mechanism, RABM, to automatically pack the requests from multiple clients but to a common target service in a short time period into one SOAP message, then sent by the workflow engine at runtime. Extra security operation costs are reduced without modifying of application programs. We use the Travel Service provided by W3C to evaluate RABM. As the experiment result shows, we can achieve up to 130% improvement of throughput and lower the average response time to 41%1.
5494803
Wireless Network Dynamic Topology Routing Protocol Based on Aggregation Tree Model
As the scale of the network increases, especially wireless and mobile networks comes into fashion, the problem of network dynamic topology management turns into a focus topic in the network world. When network information changes, frequent route computing and network state updates can cause computing and traffic overhead, respectively. Therefore, minimum of influence to network structure has been identified as one of the key issues in designing dynamic network routing protocols. A novel protocol, which is based on Aggregation Tree Routing Model (ATRM) as well as an effective ball-and-string algorithm, is introduced in this paper which aims to minimize the alteration of network topology and to speed up the minimum cost route computation. This routing protocol is applicable to all kinds of networks, including Internet, ad hoc and wireless sensor networks. The simulations show that our protocol not only results in significantly lower overhead, but also gives high levels of dynamic network topology management performance while keeping practical.