Alvin T. S. Chan

Singapore Institute of Technology (SIT) | SIT

An important part of software maintenance is bug report analysis during bug-fixing, especially for large-scale software projects. Since bugs reported to the bug repository need to be fixed, triagers are responsible to identify appropriate developers to execute the fix. Previous research focused on optimizing this process, such as by duplicate detec...

Due to the increasing scale and complexity of software products, software maintenance especially on bug resolution has become a challenging task. Generally in large-scale software programs, developers depend on software artifacts (e.g., bug report, source code and change history) in bug repositories to complete the bug resolution task. However, a m...

The Radio Frequency IDentification (RFID) technology is greatly revolutionizing applications such as warehouse management and inventory control in retail industry. In large RFID systems, an important and practical issue is tag searching: Given a particular set of tags called wanted tags, tag searching aims to determine which of them are currently p...

In wireless sensor networks (WSNs), congestion may lead to a plethora of malfunctions such as packet loss, lower throughput and energy inefficiency, potentially resulting in reduced deployment lifetimes and underperforming applications. In this paper, we comprehensively investigate the drawbacks to the CTP protocol in congestion control and propose...

Adaptivity is the capacity of software to adjust itself to changes in its environment. A common approach to achieving adaptivity is to introduce dedicated code during software development stage. However, since those code fragments are designed a priori, self-adaptive software cannot handle situations adequately when the contextual changes go beyond...

Recently, for large scale software projects, developers rely on bug reports for corrective software maintenance. The severity of a reported bug is an important feature to decide how fast it needs to be fixed. Therefore, to arrange a new submitted bug to an appropriate fixer, it is necessary to recognize the severity of each bug report. Unfortunatel...

Lecture-based learning (LBL) as a teaching method has been assessed. Survey has been conducted to evaluate its effectiveness for international service-learning projects. Uncertainties and limitations associated with LBL are discussed. Results indicate that LBL is not a suitable teaching method for students to be used in service-learning settings. I...

As computer and interaction technologies mature, a much broader range of media is now used for input and output, each of which has its own rich repertoire of techniques, instruments, and cultural heritage. The combination of multiple media can produce novel multimedia human-computer interaction approaches which are more efficient and interesting th...

Android provides native development kit through JNI for developing high-performance applications (or simply apps). Although recent years have witnessed a considerable increase in the number of apps employing native libraries, only a few systems can examine them. However, none of them scrutinizes the interactions through JNI in them. In this paper,...

Combinatorial interaction testing is a widely used approach. In testing, it is often assumed that all combinatorial test cases have equal fault detection capability, however it has been shown that the execution order of an interaction test suite's test cases may be critical, especially when the testing resources are limited. To improve testing cost...

Most sensor networks require application-specific network-wide performance guarantees, suggesting the need for adaptive parameters and flexible network optimization. Since sleep scheduling degrades the end-to-end delay performance in asynchronous duty-cycle wireless sensor networks, we propose a Cross-Layer Adaptive Duty Cycle (CLA-DC) control by d...

Due to the difficulties and importance of multi-hop broadcasts in low duty-cycled wireless sensor networks, we propose a novel Delay-Constrained and Energy-Balanced (DCEB) broadcast protocol. DCEB neither assumes time synchronization for sleep scheduling, which requires all neighboring nodes to wake up at the same time, nor assumes duty-cycled awar...

Caching is an important technique for improving the data retrieval performance of mobile clients who store frequently needed data items in their local cache, often of a limited size. With the concept of cooperative data dissemination (CDD), the mobile clients not only retrieve data items from mobile support stations, but also from the cache in thei...

The proliferation of Web 2.0 technology, coupled with the advancements in social networking, have unraveled a new Internet information exchanging paradigm where every individual user involved is capable of publishing information at will and at any time, while also being able to filter and selectively receive any information they are interested in a...

Existing distributed XML-based pub-sub systems normally targeted on filtering precision, while lacked scalability and fault-tolerance concern. In a large-scale dynamic network, nodes may join/leave/fail at times, hence a scalable yet fault-tolerant architecture is crucial. In this paper, we proposed HOPE: a hypercube overlay based pub-sub architect...

We present i*Chameleon, a configurable and extensible multimodal platform for developing highly interactive applications. The platform leverages a principled and comprehensive development cycle to systematically capture the multimodal interaction artifact. Importantly, by introducing MVC architectural pattern, it enforces the concept of separation-...

Combinatorial testing (CT) aims at detecting interaction failures between parameters in a system. Identifying the failure-inducing combinations of a failing test configuration can help developers find the cause of this failure. However, most studies in CT focus on detecting the failures rather than identifying failure-inducing combinations. In this...

At present, in most context-aware systems, decisions on when and how to adapt an application are made a priori by developers during the compile time. While such approaches empower developers with sufficient flexibility to specify what they want in terms of adaptation rules, they inevitably place an immense load on developers, especially in an extre...

Wireless sensor networks (WSNs) are set to form a significant part of the new pervasive Internet, often referred to as the Internet of Things. WSNs have traditionally been powered by limited energy sources, viz. batteries, limiting their operational lifetime. To ensure the sustainability of WSNs, researchers have turned to alternative energy source...

The contribution of cloud computing and mobile computing technologies lead to the newly emerging mobile cloud computing paradigm. Three major approaches have been proposed for mobile cloud applications: 1) extending the access to cloud services to mobile devices; 2) enabling mobile devices to work collaboratively as cloud resource providers; 3) aug...

The explosion in the volume of information and drastic increase in the number of users involved in mobile computing applications have brought radical challenges to data management and dissemination. Traditional request- reply style searching techniques no longer suffice. Instead, pub/sub-based selective dissemination has emerged as a better solutio...

The virtual programming lab (VPL) project described in this paper is designed to facilitate Internet access to application software. It emulates a real computing laboratory environment that promotes group learning and project management. The laboratory resources are situated at the university and are centrally controlled. Users of the virtual progr...

Multimodality inputs are becoming increasingly popular in supporting pervasive applications, due to the demand for highly responsive and intuitive human control interfaces beyond the traditional keyboard and mouse. However, the heterogeneous nature of novel multimodal input devices and the tight coupling between input devices and applications compl...

Existing XML filtering approaches suffer from excessive overheads incurred in matching time and the storage/memory space needed during the matching process. This makes them unsuitable in mobile computing environment, where computing resources are extremely scarce. Hence there is a need to formulate a filtering mechanism that optimizes the computati...

i*Chameleon is a multimodal interaction framework that enables programmers to readily prototype and test new interactive devices or interaction modes. It allows users to customize their own desktop environment for interaction beyond the usual KVM devices, which would be particularly useful for users with difficulty using the keyboard and mouse, or...

Wireless sensor networks (WSNs) should handle multiple sensing tasks for various applications. How to improve the quality of the data acquired in such resource constrained environment is a challenging issue. In this paper, we propose a sensor-channel co-allocation model for scheduling the sensing tasks. The proposed model considers the capability,...

This paper studies the problem of adaptation decisions for context-aware mobile computing. In most context-aware systems to date, context-aware adaptation decisions are made by developers during the design-time or compile-time. Such approaches inevitably place an immense load on developers, especially in an extremely dynamic environment like mobile...

User interaction is an essential feature in the design of an interactive game. Most existing games receive inputs from users via conventional devices such as keyboard, mouse, joystick and paddle. More recent games make use of infrared beams from user's devices, the stylus from touch screen, or pressure-sensing pads to provide rich contextual sensin...

Computation and networking resources in mobile operating environments are much scarcer and more dynamic than in desktop operating environments. Mobile applications can leverage on the benefits of adaptive computing to optimize the QoS delivery based on contextual situations. Fuzzy control models have been successfully applied to various distributed...

The need for a middleware layer to facilitate context-aware adaptation for applications has been widely reported and acknowledged in the research community. However, the majority of existing efforts employs an application-driven compile-time approach to supporting context-aware adaptation decisions. Such approach places a heavy burden on applicatio...

Purpose Context‐aware mobile computing extends the horizons of the conventional computing model to a ubiquitous computing environment that serves users at anytime, anywhere. To achieve this, mobile applications need to adapt their behaviors to the changing context. The purpose of this paper is to present a generalized adaptive middleware infrastruc...

Riding on the success of the previous Mobile Computing and Applications Track in 2003 to 2007, we are delighted to present the 2008 Mobile Computing and Applications Track that features research papers drawn from a highly diversified spectrum of mobile computing. We have been receiving an increasing number of submissions, hitting again a record hig...

One way to improve the throughput of a wireless ad hoc network at the media access (MAC) layer is to allow as much as possible concurrent transmissions among neighboring nodes. In this paper, we present a novel high-throughput MAC protocol, called Concurrent Transmission MAC(CTMAC), which supports concurrent transmission while allowing the network...

Future ubiquitous computing has accelerated the need of context-awareness that leverages information about surrounding situation so as to adapt applications. There is considerable interest in context-awareness, and many prototypes have been proposed, which have demonstrated the potential of context-aware applications. That notwithstanding, these ki...

Minimizing the communication overhead is always a hot topic in wireless sensor networks. In a multirate query system, data sources disseminate the data streams to users at the frequency they request. However, sending data in different frequencies to individual users is very costly. We address this problem by broadcasting a single consolidated data...

Wireless sensor networks (WSN) are a fundamental part of the networking infrastructure for pervasive computing. WSN can be easily deployed to various environments to monitor target objects and various conditions, and to collect information. In this paper, we survey the various forms of sensors and wireless sensor networks with different application...

In a mobile cooperative caching environment, we observe the need for cooperating peers to cache useful data items together, so as to improve cache hit from peers. This could be achieved by capturing the data requirement of individual peers in conjunction with their mobility pattern, for which we realized via a GROup-based COoperative CAching scheme...

An infrastructure-based mobile environment is formed with a wireless network connecting mobile hosts (MHs) and mobile support stations (MSSs). MHs are clients equipped with portable devices, such as laptops, personal digital assistants, cellular phones, and so on, while MSSs are stationary servers providing information access for the MHs residing i...

Mobile computing devices vary in terms of display, memory, and battery life, and current network protocols aren’t necessarily suited to the mobile computing environment. As computer networks' complexity increases, communication-related software must be able to adapt to mobile computing’s constraints. This study aims to develop a software system tha...

The use of middleware is one important approach in facilitating adaptation across wireless and mobile environments, where augmented service entities are composed and deployed to shield mobile clients from the effects of dynamic network characteristics. The MobiGate Coordination Language (MCL) system provides a language-based approach to the buildin...

In a mobile environment, it is desirable for mobile applications to adapt their behaviors to the changing context. However, adaptation mechanism may emphasize more on overall system performance, while neglecting the needs of individual. We present a generalized Adaptive Middleware Infrastructure (AMI) to cater for individual needs in a fair manner,...

Application scheduling plays an important role in high-performance cluster computing. Application scheduling can be classified as job scheduling and task scheduling. This paper presents a survey on the software tools for the graph- based scheduling on cluster systems with the focus on task scheduling. The tasks of a parallel or distributed applicat...

In wireless sensor networks, energy is the most crucial resource. In-network data processing is a common technique in which an intermediate proxy node is chosen to house a possibly complicated data transformation function to consolidate the sensor data streams from the source nodes, en route to the sink node. We investigate into the placement probl...

In wireless ad hoc networks, the performance of the media access control (MAC) protocol has significant impact on the overall network performance. Although the popular IEEE 802.11 DCF mechanism still works under multi-hop scenarios, its efficiency is unacceptable. Many efforts have been made to enhance the mechanism in various aspects. In this pape...

The monitor concept provides a structured and flexible high-level programming construct to control concurrent accesses to shared resources. It has been widely used in a concurrent programming environment for implicitly ensuring mutual exclusion and explicitly achieving process synchronization. This paper proposes an extension to the monitor constru...

The use of gateway proxies is one important approach to facilitating adaptation across wireless and mobile environments. Importantly, augmented service entities deployed within the gateway proxy residing on the wired network can be composed and deployed to shield mobile clients from the effects of poor network characteristics. The usual approach to...

Riding on the success of the 2003 and 2004 Mobile Computing and Applications Track, we are pleased to present the 2005 Mobile Computing and Applications Track that features research papers drawn from a highly diversified spectrum of mobile computing. We have continued to receive a significant number of submissions this year. The papers collected in...

The use of middleware is one important approach to facilitating adaptation across wireless and mobile environments, where augmented service entities are composed and deployed to shield mobile clients from the effects of dynamic network characteristics. The MCL system provides a language-based approach to the building of mobile applications running...

Computation and networking resources in mobile operating environments are much scarcer and more dynamic than in desktop operating environments. Mobile applications require the benefits of adaptive computing to optimize the QoS management of dynamic contextual situations. Fuzzy control models have been successfully applied to various distributed net...

Many general range query schemes for DHT-based peer-to-peer (P2P) systems have been proposed, which do not need to modify the underlying DHTs, However, most existing works have the query delay depending on both the scale of the system and the size of the query space or the specific query, and thus cannot guarantee to return the query results in a b...

SUMMARY GOP is a graph-oriented programming model which aims at providing high-level abstractions for configuring and programming cooperative parallel processes. With GOP, the programmer can configure the logical structure of a parallel/distributed program by constructing a logical graph to represent the communication and synchronization between th...

WEBGOP is a programming architecture for collaborative Web services using graph-oriented programming. The motivation for the project comes from the realization that the integration of collaborative Web services lacks support. The aim of WEBGOP is to extend the Web from a client-server system to a structured multipoint system. A graph abstraction of...

The design and implementation of the prototype CookiesCard demonstrates the benefits of managing cookies on a smartcard. Cookies are small bits of textual information a Web site might send to Web browsers to be stored within the client machine and returned unchanged in subsequent visits to the site. The ability to store cookies on the machine enabl...

Context-aware mobile computing middleware is designed to automatically adapt its behavior to changing environment. To achieve this, an important issue to be addressed is how to effectively select services for adaptation according to the user's current context. Existing work does not adequately address this issue. In this paper, we propose a fuzzy-b...

The infiltration of the Web as the preferred choice for online e-commerce and IT applications has motivated the need to introduce innovative mechanisms to enforce strong security monitoring and control on transactions conducted over a distributed environment. The smart card technology presents an attractive solution for providing strong security an...

This paper describes a dynamic service reconfiguration model where the proxy is composed of a chain of service objects called mobilets (pronounced as mo-be-lets), which can be actively deployed onto a network. This model offers flexibility because the chain of mobilets can be dynamically reconfigured to adapt to dynamic changes in the wireless envi...

Caching is a key technique for improving data retrieval performance of mobile clients. The emergence of state-of-the-art peer-to-peer communication technologies now brings to reality what we call "cooperative caching" in which mobile clients not only can retrieve data items from mobile support stations, but also from the cache in their peers, there...

In this paper, we propose a reliable multicast protocol for mobile agent communications, which is a multicast extension to our previous adaptive and reliable protocol (ARP). ARP uses the mailbox-based scheme, where each mobile agent is associated with a mailbox for message delivery. The mailbox can be decoupled from the mobile agent and migrate wit...

The advances of parallel and distributed computing demand high-level programming models that support efficient software development and execution. Graphs can effectively represent the logical structures of distributed systems and applications so as to facilitate the programming of distributed applications and support efficient mapping of programs t...

XML (extensible Markup Language) has been developed and deployed by domain-specific standardization bodies and commercial companies. Studies have been conducted on a wide variety of issues encompassing XML. In the use of XML for wireless computing, the focus has been on investigating ways to efficiently represent XML data for transmission over a wi...

Using gateway proxies is one important approach to facilitating adaptation across wireless and mobile environments. Importantly, augmented service entities deployed within the gateway proxy residing on the wired network can be composed and deployed to shield mobile clients from the effects of poor network characteristics. The usual approach to the...

Mobile agents (MAs) can support mobile computing by carrying out tasks autonomously for a mobile user temporarily disconnected from the network. We describe PDAgent, a lightweight and highly portable platform for developing and deploying mobile agent-enabled applications on wireless handheld devices. Our approach offers the following advantages: (i...

Using gateway proxies is one important approach to facilitating adaptation across wireless and mobile environments. Importantly, augmented service entities deployed within the gateway proxy residing on the wired network can be composed and deployed to shield mobile clients from the effects of poor network characteristics. The usual approach to the...

Caching is a key technique for improving data retrieval performance of mobile clients. The emergence of robust and reliable peer-to-peer (P2P) communication technologies now brings to reality what we call "cooperating caching" in which mobile clients not only can retrieve data items from mobile support stations, but also can access them from the ca...

Many parallel applications involve different independent tasks with their own data. Using the MPMD model, programmers can have a modular view and simplified structure of the parallel programs. Although MPI supports both SPMD and MPMD models for programming, MPI libraries do not provide an efficient way for task communication for the MPMD model. We...

In a conventional mobile environment, mobile clients retrieve data items from database servers via mobile support stations, by downloading the items over scalable broadcast channels (push-based), requesting them over shared point-to-point channels (pull-based), or making use of both types of channels to retrieve them (hybrid). Caching is a key tech...

In this paper, we present a framework, called OrbGOP, to support the architecting and high-level programming of CORBA-based distributed applications. OrbGOP makes two contributions to the development of CORBA applications: (1) it provides higher-level abstractions for programming CORBA applications and frees the programmer from the underlying irrel...

Caching is a key technique for improving the data retrieval performance of mobile clients in mobile environments. The emergence of robust and reliable peer-to-peer (P2P) technologies now brings to reality what we call "cooperative caching " in which mobile clients can access data items from the cache in their neighboring peers. We discuss cooperati...

The proliferation of mobile devices in wireless environments has put special requirements on the ability to access the Web seamlessly. To address the impact of varying contextual characteristics on mobile access, the authors developed the WebPADS framework, which can actively deploy new mobile services. Moreover, WebPADS can dynamically reconfigure...

In this paper we investigated the issues pertaining to streaming generalized XML documents over the wireless environment. We highlight the disadvantages of employing existing approach to fragment and manage the transfer of XML contents across a wireless environment. In particular, existing approach of fragmenting data takes no consideration of the...

Despite the widespread use and adoption of cookies as the basis for web applications to keep state information, cookies present some design issues that are yet to be fully addressed. The fact that cookies are stored on client-side's memory means that they are tightly coupled to the machine that is interacting with the web server. Yet often, these c...

The formulation of a context-aware middleware requires researchers to devise suitable control mechanisms that allow applications to directly participate in resource adaptation in response to dynamic operating environments. This paper describes the design and implementation of an event model for a highly adaptive mobile middleware, Web Proxy for Act...

Caching is a key technique for improving data retrieval performance of mobile clients in mobile environments. The emergence of robust and reliable peer-to-peer (P2P) technologies now brings to reality what we call "cooperative caching" in which mobile clients can access data items from the cache in their neighboring peers. This paper considers a CO...

This paper introduces an XML-based generic Context Request Language (CRL), whose construction is part of a web services framework in the domain of mobile context sensing. The paper describes an implementation of the technique that is in accordance with the formal mathematical representational model, using first-order temporal language [6]. The lang...

Traditionally, middleware technologies, such as CORBA, Java RMI, and Microsoft's DCOM, have provided a set of distributed computing services that essentially abstract the underlying network services to a monolithic "black box." In a mobile operating environment, the fundamental assumption of middleware abstracting a unified distributed service for...

XML (eXtensible Markup Language) has been developed and deployed by domain-specific standardization bodies and commercial companies. We investigate the possibilities and issues encompassing the use of generalized XML in a wireless computing environment. Current approaches of fragmenting data do not take into account of the semantics and structure o...

Based on business processes, composite Web services combine the offerings of two or more Web services to achieve the desired business goals. Several candidate standards have been proposed, providing a foundation for composite Web service specifications. However, at a higher level, there is no framework that supports composite Web service constructi...

Dynamic con#guration is a desirablepsirabl of a distributed system where dynamic modi #cation and extension to the system and theap7T;q1/K7k are required. It allows the system con#guration to besp;IT;7 and changed while the system is executing. This pis/ describes a software ptware/ that facilitates a novelapel/7x to the dynamically con#gurable pn#...

A grid service is a Web service that provides a set of well-defined interfaces and that follows specific conventions. Composition of grid services combines the offerings of two or more grid services to achieve the desired computing goals. Candidate standards have been proposed, providing a foundation for service composition specifications. However,...

The virtual programming lab (VPL) project described in this paper offers is designed to facilitate Internet access to application software. It emulates a real computing laboratory environment that promotes group learning and project management. The laboratory resources are situated at the university and are centrally controlled. Users of the virtua...

This paper presents a graph-oriented framework, called WebGOP, for architecture modeling and programming of Web-based distributed applications. WebGOP is based on the graph-oriented programming (GOP) model, under which the components of a distributed program are configured as a logical graph and implemented using a set of operations defined over th...

Dynamic configuration is a desirable property of a distributed system where dynamic modification and extension to the system and the applications are required. It allows the system configuration to be specified and changed while the system is executing. This paper describes a software platform that facilitates a novel approach to the dynamically co...

This paper examines the application of smart cards in the development of distributed medical information systems. The pocket mobility and security features of smart cards make them an ideal medium for storing the critical medical records of individual. However, the lack of interoperability and support for distributed operation has limited the devel...

Mobile computing has induced a class of killer applications recently by extending the paradigm of parallel and distributed computing across a mobile environment. A very important class of applications involves the location-awareness of a mobile user. Two major issues must be addressed to deliver appropriate services to mobile users. One is the avai...

This paper presents a novel architectural approach to support fault tolerance in component-based distributed software (CBDS) through dynamic reconfiguration. Using the graph-oriented programming (GOP) model, the software architecture of CBDS is specified by a logical graph which is reified as an explicit object distributed over the network. Dynamic...