Summary Performance problems in a cloud service are difficult to diagnose because they may be caused by various system components. This study proposes an automatic cloud service testing and bottleneck detection system that is applicable to different types of services. With the proposed test module, the user can customize test scenarios to automatically test and collect the corresponding metrics of the target service. Afterward, the proposed bottleneck detection algorithm analyzes the collected metrics and determines whether a bottleneck is presented in the target system. The bottleneck detection module also provides a scaling recommendation for the service provider to facilitate the service system reconfiguration. The experimental results reveal that the proposed system could detect a potential bottleneck in a service system accurately. In accordance with the scaling recommendation, the performance of the target cloud service can be improved efficiently after reconfiguration. Therefore, usage of the proposed system can ensure a high quality of service, and the service level objective could be fulfilled.

Recent years the prevalence of fraudulent websites has become more severe than before. Fraudulent ecommerce websites that sell counterfeit goods not only cost financial damage to consumers but also have a great impact on Internet industry. Nowadays, there is not an effective way to confront these websites. In this paper, we look forward to achieving three goals: find the characteristics of counterfeit websites, train models for classifying ecommerce websites and provide a service to help consumers distinguish counterfeit websites from legitimate ones.

This paper presents a blind dual watermarking mechanism for digital color images in which invisible robust watermarks are embedded for copyright protection and fragile watermarks are embedded for image authentication. For the purpose of copyright protection, the first watermark is embedded using the discrete wavelet transform in YCbCr color space, and it can be extracted blindly without access to the host image. However, fragile watermarking is based on an improved least significant bits' replacement approach in RGB components for image authentication. The authenticity and integrity of a suspicious image can be verified blindly without the host image and the original watermark. The combination of robust and fragile watermarking makes the proposed mechanism suitable for protecting valuable original images. The experimental results indicated that the proposed watermarking mechanism can withstand various processing attacks and accurately locate the tampered area of an image.

Advertising is a form of delivering commercial messages. It contributes people to get more acknowledge of a product and persuades the potential consumers to take some action, such as buying, sharing, and registering as a member. With the popularity of Internet technology growing up, there are more and more advertising methods using the Internets to deliver promotional messages. Since the benefits of advertising are good for enterprises, enterprises almost spending a large amount of money engaging the advertisement companies to advertise for a new product. Due to the lack of money, microenterprises usually use other suitable methods to promote their products or activities. The common media are the poster, advertising board, and social network. However, not all methods are suitable for these microenterprises. For example, online stores have no appropriate places to post their advertisement. Entity stores have no Internet-related knowledge to manage the fan club on the social platform. And these methods can only deliver messages to the fixed consumer groups. In this paper, we proposed a reciprocal model in order to solve the problem of cost and the fixed consumer groups. The participants obtain the Contribution Point (CP) in the system by helping the other participants to advertise something. They can ask for the other participants to help them by using the CP. When advertisers ask for the other participants to help them, they will consume the CP. When publishers help the advertisers, they will obtain the CP. This method gives an advertising service for free. It can solve the problem of cost. Because participants encounter the different consumer groups compared with each other, this method will make an advertising message reach the different consumer groups. Therefore, this method can solve the problem of the fixed consumer groups.

In this paper, we have shown that a regular Toeplitz matrix-vector product (TMVP) can be transformed into a Toeplitz block TMVP (TBTMVP) using a suitable permutation matrix. Based on the TBTMVP representation, we have proposed a new (a,b)-way TBTMVP decomposition algorithm for implementing a digit-serial multiplication. Moreover, it is shown that, based on iterative block recombination, we can improve the space complexity of the proposed TBTMVP decomposition. From the synthesis results, we have shown that the proposed TBTMVP-based multiplier involves less area, less area-delay product, and higher throughput compared with the existing digit-serial multipliers.

The bandwidth of the network is precious. As cloud computing provides powerful computation power and more and more devices are connected to the Internet there is a need to seek for methods to reduce the traffic. Fog computing was proposed to adding the computation and storage ability to the edge devices. The requests from the end device can be pre-processed or even responded at the edge device. In this work, the ability of Web Resource Caching is added to the edge device to serve as a caching proxy server. In order to obtain more caching storage, the end devices are also exploits to provide some caching space. As the whole caching storage is enlarged, large resource like media files are able to be cached near to the end devices once any of the end devices in the same network just recently requested it. The result shows that the proposed architecture has better downloading latency compares to the single caching proxy approach.

Guiding young learners' attention improves their self-directed learning skills, and that attention can be analyzed via the learners' eye movements. Thus, we propose a self-directed learning system integrating eye trackers with a web based interface to provide an attention guiding function that aims at notifying the learners about the ignored or the skipped parts from the learning material as well as providing hints about the confusing sections. We aim at implementing a cost-effective system that can be used by learners not only at school, but also at home. In conclusion, we believe that the proposed system can be considered as effective tool to enhance the learners' self-directed learning skills.

To guarantee quality of the service, services need to be tested to ensure the service quality. But most of existing testing service can't provide multi-type testing and deploy testing clients concurrently in different regions. To overcome these problems, in this paper, a cloud testing service combine cloud computing and multi-testing tools is proposed. Using the proposed service user can deploy the testing clients in different countries to access the testing targets, when the testing is finish user can easily get both of detail and summarized test results. To show the capabilities of proposed service, an experiment is performed. The results shows that the proposed service can guarantee testing quality, automatically deploy testing clients concurrently in different region, get latency from different countries, and perform press testing.

In this paper, we present a novel in-domain neighborhood approach to clarify the dynamic load balancing problem on a heterogeneous network and to solve many practical problems. The distributed system consists of a network of workstations with different domains, speeds and capacities. Since the number of workstations and the diameter of the network affect the convergences rate, our approach introduces the in-domain relation that classifies the entire network into sub-networks called domains. The algorithm runs in each workstation in order to reach the fairness state in-domain and in entire network rapidly. In this paper, our approach is applied to a cafeteria system as a case study, each workstation is viewed as a cafeteria where the maximum number of orders that can be submitted to one cafeteria corresponds to the capacity of that cafeteria workstation, the communication channels are modeled between the in-domain cafeterias, and the workload is represented as orders. An algorithm is presented to simulate the migration of the orders between in-domain cafeterias and to distribute a proportion of the excessive workload of heavily loaded node to lightly loaded node by considering the capacity of each node such that when the algorithm terminates, the effective-load in all cafeterias is the same. Therefore, each workstation receives an amount of workload proportional to its total capacity. This framework is analyzed mathematically, and it is proved that the proposed algorithm converges and achieves the fairness state.

One of the most challenging problems of cloud service solicitation is to persuade users to trust the security of cloud service and upload their sensitive data. Although cloud service providers can claim that their services are well‐protected by elaborate encryption mechanisms, traditional cloud systems still cannot persuade the users that even if the cloud servers are compromised, the data are still securely protected. This study proposes uCloud, a user‐centric key management scheme for cloud data protection, to solve this problem. uCloud utilises RSA and indirectly encrypts users’ data by users’ public keys, but stores the users’ private keys on neither servers nor users’ PCs; instead, the private keys are stored on users’ mobile devices and presented via two‐dimensional (2D) barcode images when they are utilised to decrypt users’ sensitive data. In this manner, users’ data are safely protected even if the cloud servers are compromised. Also, uCloud provides users with the experience of managing visible private keys by storing the keys into mobile phones and displaying them via 2D barcodes. Moreover, three scenarios: personal storage, home surveillance and enterprise storage scenarios are proposed to present the practicability of uCloud. In addition, a hierarchical structure is designed for basic key backup and data sharing in the proposed scheme.

The development in social network services changes our traditional social structure. Nowadays, people can easily communicate with their old friends or even make new ones. The "Small World Theory" [5] states that the median path length equal to 6 when posting letters through intermediaries, but researchers have not prove this theory completely until now. Because of social networks our world becomes smaller and smaller. In this paper, we propose new ideas about the "Small World Theory". We performed our experiment on Facebook platform to collect social data. Additionally, the graph database is used to conduct further analyses. To re-verify the "Small World Theory" and to extend this theory, we focused on the degree of separation and control the size of the dataset. The experimental results show that our dataset is "Four Degrees of Separation", and this conclusion can be extended to the whole world by further experiments.

This study presents efficient vision-based finger detection, tracking, and event identification techniques, as well as a low-cost hardware framework for multi-touch sensing and display applications. A fast bright-blob segmentation process based on automatic multilevel histogram thresholding is performed to extract pixels of touch blobs from the captured image sequences obtained from the scattered infrared lights by the video camera. Given the touch blobs extracted from each of the captured frames, a blob tracking and event recognition process is then conducted to analyze the spatial and temporal information of these touch blobs from consecutive frames and determine the possible touch events issued by users. This process also refines the detection results and corrects for errors and occlusions caused by noise and errors during the blob extraction processes. Our proposed blob tracking and touch event recognition process includes two phases. First, the phase of blob tracking associates the motion correspondence of blobs in succeeding frames by analyzing their spatial and temporal features. Then the phase of touch event recognition process can identify meaningful touch events activated by users from the motion information of touch blobs. Experimental results demonstrate that the proposed vision-based finger detection, tracking, and event identification system is feasible and effective for multi-touch sensing applications in various operational environments and conditions.

In the tide called Cloud Computing, people move their applications previously running on on-premise servers to the Cloud. However, this migration is not a comfortable trip. Compatibility is a critical issue of the new environment. It is reasonable for the enterprises to decide to move certain portions of their IT infrastructure to the Cloud. And database is one important piece that may be migrated. In this article, a database model backed by cloud data-store which can be consumed by on-premise application is introduced. This works addresses several issues to provide the on-premise applications access to data-store in the cloud while guarantees efficiency and compatibility.

Classification is an important issue both in Machine Learning and Data Mining. Decision tree is one of the famous classification models. In the reality case, the dimension of data is high and the data size is huge. Building a decision in large data base cost much time in computation. It is a computationally expensive problem.

With the growing capability of mobile devices, platforms, and wireless communication technologies, Web browsing on mobile devices is made possible and receives more and more attentions. However, environment of mobile device varies; traditionally, Web pages cannot be browsed if mobile user enters an environment where there is no connection to Internet, such as in a basement or countryside. Although Google Gears had been proposed to support offline Web browsing, there are still a lot of Web servers providing their services without support Google Gears. In this paper, we propose a middleware for mobile devices with properties including (1) enabling users to access the predefined Web information without network connection, (2) offline data stored on mobile device should be long-term storage, and (3) even a Web server doesn't support Google Gears, its Web pages still can be browsed offline.

Blog service has become popular in recently years. Web users can post their articles on their blog sites. However, users do not have full control of their articles after these articles have been posted while blog service is built with client/server model. Therefore, peer-to-peer (P2P) technology has been proposed to establish blog services. However, compare those P2P systems with traditional blog systems, the user experiences of using blog systems in those P2P systems are still far from the ones in traditional systems. For example, only a part of multimedia content types are supported. This paper proposes a new platform, named Pebble2P, which combines traditional blog system and P2P blog system. Thus, users can have user experience similar to the one in traditional blog while the benefits of P2P blog system remain preserved.

Since the term “Web 2.0” appears, a new generation of Web is coming. There are many technical articles referring to how to design a Web 2.0 website. However, the traditional Web 1.0 websites are still multitudinous currently. The developers of the traditional Web 1.0 website may not have adequate techniques to reconstruct the websites into Web 2.0 timely. Rebuilding a website often takes tremendous efforts. A simple and effective strategy to upgrade the websites is essential. The paper attempts to provide a flexible framework, Web 2.0 Toolbar, to upgrade websites from Web 1.0 to Web 2.0. The Web 2.0 Toolbar combines the original Web 1.0 web page and additional Web 2.0 information together on the fly. Therefore, the website developers need not to rewrite their websites, and the users will be able to experience additional Web 2.0 functions. In the paper, we have implemented tag, and comment functionalities of Web 2.0.

Certificates play a critical role in mobile applications. By exploiting certificates, mobile applications are capable of accessing the trading or other m-commerce services (mobile commerce) on mobile environments. WTLS (Wireless Transport Layer Security) [1], WPKI (Wireless Public-Key Infrastructure) [3], WIM (Wireless Identity Module) [5], and WMLScript Crypto Library [6] are defined in WAP [15]. Though the formats of certificates seem abundant, they are not compatible with the existing Internet X.509 certificates [7]. Therefore, we design and implement a WAP Certificate Converter Toolkit to provide the convenient interfaces. By using this toolkit, X.509 certificates can be converted into WAP compatible form, and then deployed in WAP-enabled mobile devices. The functions designed can let the Internet CA's (Certification Authority) dynamically and easily transform their issued certificates into WAP certificates. Besides, we consider some issues including mechanism enhancement and processing cost reducing. In brief, the toolkit can provide a userfriendly development environment to accelerate commerce application on mobile environments.

Wearable, handheld, and embedded or standalone intelligent devices are becoming quite common and can support a diverse range of applications. In order to simplify development of applications which can adapt to a variety of mobile devices, we propose an adaptation framework which includes three techniques: follow-me, context-aware adaptation, and remote control scheme. For the first, we construct a personal agent capable of carrying its owner's applications. Second, we design a personal agent capable of carrying applications with an adaptable hierarchical structure. Then, applications can be adapted approximately to the context of evices by using an attribute-based component decision algorithm. Finally, to achieve a remote control scheme, we distribute the computational load of applications on the resource-restricted mobile devices. An application is divided into two parts that can be executed on a user device and a server separately. In short, this framework facilitates the development of widespread applications for ubiquitous computing environments. Furthermore, it enables the applications to follow their owners and automatically adapt to different devices. Copyright © 2005 John Wiley & Sons, Ltd.

Portfolio is a process which systematically and purposefully collects artifacts or works created by students. These works and artifacts not only can be treated as a reference to improve students' learning process, but also as a learning outcome when passing into next learning stage or seeking a job. Assessment in such a way is called authentic assessment, since it assesses students' real learning performance. Portfolio process requires administrative staffs, students, and teachers to put effort on. To keep this process working, teachers take most of burden. In this paper, we present a Web-based system which will let teachers take burden as low as possible while provide most beneficial to students. This system has been installed at an Institute of Technology in Taiwan, the result shows positive and most of students appreciate functionality of this system.

In this paper, we presented an IP-multicast-based Java message service implementation called FJM (fast Java messaging) library. We discussed its architecture, protocols, and implementation issues. For achieving better performance, we revised the original design of the FJM. The details of the refinement were also described in this paper. Then, we compared the performance of both versions of the FJM with the performance of other JMS implementations. After our careful design and tuning, in most cases, the revised version of the FJM can offer the highest throughput among the well known industrial or open source JMS implementations. Therefore, FJM can be used in many innovative or mission critical cluster applications, such as massively multiplayer virtual worlds or military simulator.

This study applied NetPeas (networked peer assessment system) in peer assessment activities of graduate level of thesis writing course. Authors wish to discover the students' attitudes toward and desired system requirements of NetPeas in writing course. This study involved 100 electrical engineering graduates from two research-oriented universities at northern Taiwan. Those students were required to attend a weekly thesis writing course and submit eight assignments through four rounds of networked peer assessment, and then authors survey their attitudes and opinions toward NetPeas. In the last, quantitative and qualitative surveys indicated that significantly more students willing to join the networked peer assessment activities via NetPeas in the near future and stand for using NetPeas. Authors also have dug several desirable requirements for NetPeas.

Despite their increasing availability on the Internet, networked peer assessment systems lack feasible automatic dispatching algorithm of student's assignments and ultimately inhibit the effectiveness of peer assessment. Therefore, this study presents a reviewer dispatching algorithm capable of supporting networked peer assessment system in order to automatically dispatch student's assignments to their peer reviewers.

Abstract The thread synchronization mechanism of Java is derived from Hoare's monitor concept. In the authors' view, however, it is over simplified and suffers the following four drawbacks. First, it belongs to a category of no‐priority monitor, the design of which, as reported in the literature on concurrent programming, is not well rated. Second, it offers only one condition queue. Where more than one long‐term synchronization event is required, this restriction both degrades performance and further complicates the ordering problems that a no‐priority monitor presents. Third, it lacks the support for building more elaborate scheduling programs. Fourth, during nested monitor invocations, deadlock may occur. In this paper, we first analyze these drawbacks in depth before proceeding to present our own proposal, which is a new monitor‐based thread synchronization mechanism that we term EMonitor. This mechanism is implemented solely by Java, thus avoiding the need for any modification to the underlying Java Virtual Machine. A preprocessor is employed to translate the EMonitor syntax into the pure Java codes that invoke the EMonitor class libraries. We conclude with a comparison of the performance of the two monitors and allow the experimental results to demonstrate that, in most cases, replacing the Java version with the EMonitor version for developing concurrent Java objects is perfectly feasible. Copyright © 2001 John Wiley & Sons, Ltd.

Object oriented database system (OODB) supports an object oriented data model with the functionality of persistency and transaction semantics. In order to facilitate the use of OODB, the Object Database Management Group (ODMG) defined a standard for object database management systems. On the other hand, the Object Management Group (OMG) defined the Common Object Request Broker Architecture (CORBA), which is an emerging standard of distributed object technology providing the interconnection network between distributed objects. For the sake of matching these two object models, taking the advantages of merging both of them, and building a more sophisticated infrastructure, the integration of CORBA and OODB is currently an urgent and important issue in distributed object systems. Instead of using Object Database Adapter (ODA) suggested by the ODMG, we provide a novel way of reusing the Object Transaction Service (OTS) and wrapping techniques to introduce OODB into CORBA automatically. Through our design, CORBA clients or OODB object implementers do not need to learn any knowledge of each other. In addition, error recovery is also provided to guarantee the consistency of object states. The whole task for integrating CORBA and OODB is done transparently by our proposed preprocessor, which plays an important role in solving problems encountered by ORB and OODB vendors easily.

The distributed object oriented computing model is the next logical step to develop distributed applications. In recent years, several object models have been proposed, such as COM/DCOM, CORBA, and JAVA Bean etc. In CORBA, which was announced by OMG, object request broker is a software bus to connect applications and object components. In addition, multi threaded programming is a well known technique to improve the performance of applications. In a CORBA environment, clients can invoke the remote objects that are shared. If those objects are single threaded it will affect system performance in large distributed applications. We describe in detail the design and implementation of multi threaded object request broker based on CORBA. Our ORB was implemented atop Windows NT and underlying TCP protocol. Finally, we compare our system's performance with IONA's Orbix, which is a well known commercial product, in both one-way and two-way request.

The concept of transactions is not only indispensable in database applications, but also useful in building robust software for mission critical applications. The paper presents an implementation of the Object Transaction Service (OTS) based on CORBA 2.0 specification. Transactional applications developed with the support of our OTS implementation are able to assure the ACID properties even in the presence of node crashes, software system failures and process hangs. The preliminary results obtained from the experiments on Sun workstations with Orbix 1.3 show that the overhead due to the OTS service is satisfactory for most applications.

Many problems frustrate WWW users, who suffer limited accessibility to WWW resources, and so the authors propose a two-level agent architecture to try to solve them. The agent consists of two parts: the local agent interacts directly with end-users, while the remote agent interacts primarily with the public Internet. Together they learn user preferences, and help users find and filter information more efficiently, economically, and enjoyably. The paper introduces the concept of the two-level agent, and investigates practical issues involved in further design.

There are more and more COSS (Common Object Service Specifications) on CORBA (Common Object Request Broker Architecture) announced by the OMG (Object Management Group), but no common specification about fault-tolerance exists. We propose a "warm stand-by" replication approach. When an object (primary object) is invoked, it will invoke a secondary object, and the primary object will log the messages and checkpoint the state to the secondary object periodically. If the primary object fails, the secondary object can take over by way of a client executing a few operations to change the secondary object's mode to primary. Following the style of COSS, we define four interfaces and provide class implementations that can help programmers write programs with fault-tolerant capability. The whole model has been implemented on Orbix, which is a full implementation of CORBA specification.

The tree quorum algorithm, which logically organizes the sites in a system to a tree structure, is an efficient and fault-tolerant solution for distributed mutual exclusion. In this paper, the performance characteristics of the tree quorum algorithm is analyzed. A refinement algorithm is proposed to refine a logical tree structure by eliminating nodes or subtrees which do not improve the performance. Thus the refined tree performs better than the original.>

The tree quorum algorithm (TQA) uses a tree structure to generate intersecting (tree) quorums for distributed mutual exclusion. This paper analyzes the number of messages required to acquire a quorum in TQA. Let i be the depth of the complete binary tree used in TQA, and let M/sub i/ be the number of messages required to acquire a quorum or to determine that no quorum is accessible. We discuss M/sub i/ as a function of i and p, where p ( 1/2>

The tree quorum algorithm (TQA), which logically organizes the sites in a system into a tree, is an efficient and fault-tolerant solution for distributed mutual exclusion. Quorum size can be reduced to log N in the best case of TQA. In this paper, message complexity of TQA is analyzed. Moreover, it is shown that the ratio of message complexity to quorum size converges to 1/p, where p is the probability that a site is operational.>

We present a decentralized, symmetric mutual exclusion algorithm in a computer network. The proposed algorithm has the same message complexity as that of the Maekawa's O(/spl radic/(N)) mutual exclusion algorithm ( Maekawa, 1985) and can be applied to arbitrary sizes of distributed systems. It is more suitable than Maekawa's when the symmetry of a system is a criticism. In addition, our algorithm has smaller request set size than that of Gupta, Bruell and Ghosh's (1987) mutual exclusion algorithm on a system of size 2/sup n/ for some integer n.

H. Kakugawa et al. (1993) proposed the k-majority coterie for the distributed k-mutual exclusion problem (k-mutex). It was claimed that the k-majority coterie is a k-coterie, which is a general solution for k-mutex. In this comment, we show that the k-majority coterie is not necessary a k-coterie.>

Two different schemes are presented to make commit protocols fault-tolerant. The first scheme ensures that a failed site can directly recover to a state which is consistent with all other sites, using only its local information. This scheme can only make commit protocols resilient to a single site failure. The second scheme ensures that failed sites can recover to a state consistent with all others with as few information exchanges as possible. This scheme can make commit protocols resilient to any type of site failure.>

The message complexity of decentralized commit protocols is studied. It is shown that O(kNN/sup 1/k/) messages are necessary if only k rounds of message interchanges are allowed. It is also shown that O(Nln N) is a message lower bound for any decentralized commit protocol. A class of decentralized commit protocols that need O(kNN/sup 1/k/) messages and use k rounds of message interchanges is proposed. If k=ln N, then a decentralized commit protocol that needs O(Nln N) messages only is obtained. The communication scheme is also used to derive some decentralized consensus protocols.>