Project-based learning is among the most common learning approaches aimed at conveying professional standards and best practices to students in programming courses. However, team projects commonly impose problems related to responsibility sharing, such as low effort or inequality in contributions. This paper presents a collaborative programming assessment system featuring a code quality assessment function with specific metrics to measure individual contributions. Student engagement data is used to detect nonconformities in collaboration using a learning analytical approach. Latent profile analysis was used to detect four theoretical team profiles differentiated by team effort (2 levels) and within-team collaboration (2 levels). We demonstrated the efficacy of assessing code to evaluate team dynamics and student behaviour, wherein efforts to resolve coding style failures can be used as a proxy by which to estimate the taskwork awareness of team members. Submission data from 146 students in 41 web-programming projects revealed four behavioural patterns that could potentially hinder the effective functioning of programming teams: free-riding, social loafing, the bystander effect, and lone wolves. We also demonstrated the applicability of automated programming assessment systems to the monitoring of learning progress, thereby facilitating timely interventions to correct difficulties at the team level.

Recently, as more and more mobile devices embedded with intelligent software become part of our daily lives, Open Services Gateway initiative (OSGi) has gained increasing attention in the development of services for such devices. However, services residing in OSGi platforms are devised specifically for the platforms' local bundles. Although several works have enhanced OSGi with various communication mechanisms that enable remote service invocations, two crucial issues pertaining to mobile computing remain to be addressed: One is limited resources of mobile devices, and the other is unstable links experienced with mobile devices. To address these two issues, we propose an itinerary-based mobile agent approach with four major features: To implement mobile agents as OSGi bundles to deliver distributed OSGi services with lower resource consumption; to extend WSDL and WS-BPEL to help developers design mobile agent itineraries; to provide an opportunistic service matchmaking mechanism allowing mobile agents to adapt to context changes at runtime; and to devise asynchronous communication mechanism to enable reliable mobile agent transmissions among mobile devices with dynamic IP addresses and intermittent connection to the Internet. Through experimental evaluations, we demonstrate that both network traffic and turnaround time of our approach are better than those of client-server ones.

In this paper, we present the design and implementation of a negotiation-based resource management system called Mercury. As the number of resources in Grids is increasing rapidly, selecting appropriate resources to execute tasks has become a crucial issue. The proposed system implements the Extended Contract Net Protocol (ECNP), which improves the standard bidding model by integrating a matchmaking technique. Our model addresses the issues of matchmaker overload and the lack of up-to-date resource state information in the original matchmaking model. To ensure that the system is user-friendly, we provide a web interface. By using the provided job templates, users can describe their jobs more easily, and service providers can deploy their services in the system in a simple manner. Furthermore, to improve the interoperability of the system, we adopt open standards, such as the WS-Agreement and JSDL protocols. Our experimental results demonstrate the scalability and efficiency of the system.

In recent years, Data Grid becomes a promising technology to collect geographically distributed storage resources and provide a large amount of storage capacity. Such resources include personal computers, clusters or high-end servers managed by different administrative domains. Although many production Data Grids have been developed for various usages, there remain no approaches to integrating them together. To solve the problem, we propose a federation middleware, called FedMi, to integrate heterogeneous Data Grids as a single Data Grid and provide users with a uniform access interface. In this paper, four issues, including interoperability among Data Grids, single sign-on, secure communication and high performance data transfer, are addressed. We also present the evaluation results of the approaches proposed to improve the performance of data transfer across Data Grids.

Delivering distributed telematics services has gained increasing attention in mobile computing and advanced traveler information fields. In this paper, to design and implement telematics applications, OSGi technology is exploited to support interoperability of various telematics services. Moreover, we propose a mobile agent approach to enabling the delivery of distributed OSGi services, which can gain better performance when applying it to mobile devices with limited resources and unstable connections. An application of telematics services, which assists drivers in reporting accident events when accident occurs and warns them of traffic accidents or jams on their planned routes is developed. In this application, OSGi is adopted as a service platform to manage services provided by diverse devices, while mobile agents are employed to migrate across multiple devices to access required services.

As mobile agents reside on on-board units or mobile devices and act on behalf of drivers, it imposes a strong demand to devise mechanisms for protecting the algorithms that are exclusively coded in mobile agents for different drivers. Although contactless smart cards are widely used as a means to protecting personal information, it is still a challenge to protect the whole code of a mobile agent in a limited storage. In this paper, we propose a tool, called jExtractor, by which the private or sensitive data coded in a Java-based mobile agent can be extracted and moved to a contactless smart card, and can further be read from the card and merged to be the original mobile agent. Moreover, we use 30,000 Java classes as samples to validate jExtractor. In the experimental result, 79.4% of the sample classes can successfully be extracted and moved to Mifare Standard S50 (1K) smart card with our strictest configuration level.

In the last decade, the evolution of distributed computing has shifted from cluster computing to Grid computing. Although bidding provides a useful means of resource allocation for this novel computing paradigm, there exist two challenges to scheduling metatasks in bidding-based Grid systems. (1) The scheduling algorithm has to avert collisions between the jobs of a metatask, as well as prevent contention between the metatasks submitted by different requesters. (2) There is no global information system to facilitate optimum decision-making; hence, requesters are only aware of partial information released by resource providers. To address these challenges, we propose a set of scheduling heuristics to minimize the makespan of each metatask, while simultaneously considering the level of information about competing metatasks revealed by providers. We also present the results of experiments conducted to evaluate the performance of the proposed heuristics.

In this paper, we propose a resource management model that extends the Contract Net Protocol by integrating the advantages of the matchmaking technique. Our model addresses the issues of matchmaker overload and the lack of up-to-date resource state information suffered by the original matchmaking model. It also enables resource requesters to obtain a list of qualified resources with which they can narrow down the selection of resources and reduce the number of ineffective communication messages. In addition, we present five strategies to facilitate resource selection on our model from the perspective of turnaround time and reporton experiments to evaluate their performance. The experiment results show that, in the presence of resource contention, the probabilistic strategies outperform random and the deterministic ones, and the performance of the presented strategies executed on our model is superior to their performance on the original matchmaking model.

As open multi-agents systems are getting increasing attentions in building large-scale software systems, the study on agent organizations - a building block of multi-agents systems, becomes a promising research track. Roles as a first class citizen in agent organizations impose an imperious demand for dealing with the major challenge: how agents bind roles in the formation of agent organizations in which agents can dynamically enter or leave the organizations. This challenge can be further decomposed into four issues: how to discover agents distributed over various organizations, how to select reliable agents to bind roles, how to enable agents to cooperate in roles binding, and how to unbind roles as agents leave an organization. The focus of this paper is on an extension to Contract Net protocol with reputation model to address these four issues related to the life cycle of dynamic role binding, called Agent-centric Contract Net Protocol (ACNP), as a negotiation mechanism that agents can adopt to establish agent organizations at run time through roles binding.

A dynamic aspect-oriented system weaves aspects into applications at run time. As a result, a static model can be dynamically modified to include the codes needed to fulfill non-functional requirements without having to shut down the running program. Although this provides a high degree of flexibility, it may lead to a conformance problem. In this paper, we study the conformance issues of aspect-oriented programs and propose a scheme to check the conformance of running programs with the original software specification in dynamic aspect-oriented systems. First, we propose extensions of the UML model to express the specification of aspect-oriented applications, after which we study and classify typical mistakes made in deploying aspects. Then, we design a scheme to check if the current state conforms to the software specification. We take JAsCo as the target system to implement the proposed scheme. When the program starts running or aspects in the registry are changed, the system informs the developers if the current state violates the software specification.

As the number of data-intensive applications increases in various domains, scientists need to save, retrieve, and analyze increasingly large datasets. The huge volume of data and the long latency of data transfer on the Internet make it very difficult to ensure high-performance access to data grids. Thus, data replication techniques have been widely adopted to solve the latency problem. In this paper, we propose an efficient data replication algorithm for multi-source data transfer, whereby a data replica can be assembled in parallel from multiple distributed data sources and adapted to the variability of network bandwidths. The experimental results show that the proposed algorithm can obtain more aggregated bandwidth, reduce connection overheads, and achieve superior load balance.

As the number of agents increases rapidly on the Internet, discovering appropriate service agents with required capabilities for request agents becomes a crucial issue in multi-agent systems. Two major discovering approaches have been developed: centralized matchmaking approaches and distributed bidding approaches. However, the former approaches may suffer the problem of middle agent overload and can not reflect the dynamic characteristic of agent capabilities, while the later has the problems of the overhead for maintaining contact lists of service agents in each request agent and sending ineffective CFP messages to non-qualified service agents. To address the above problems, in this paper, we propose a CNP-based bidding mechanism based on Possibilistic Petri Nets that facilitates request agents to find preferred service agents. Moreover, our mechanism provides more flexible match that not only supports exact match but also takes the degree of satisfaction into account.

The persistence problem of collaborative applications is an essential issue in the research of computer-supported collaborative work. A collaborative computing environment requires a simple and transparent persistence middleware to deal with complex data accesses. Therefore, in this paper, we propose a data persistence mechanism and implement a persistence server, called tree-structured persistence server (TSPS), to support the data management for collaborative applications. The TSPS allows states of collaborative applications to be stored in a tree fashion beside tables. By introducing TSPS, the problems of collaborative applications, such as persistence data access, asynchronous collaboration, latecomer, version control, etc., can be solved easily. The TSPS was originally developed to serve as a persistence layer to support a project of computer-supported collaborative work. We intend to develop our persistence mechanism for universal use so that it can be applied in more application areas.

Computer-supported cooperative work (CSCW) supports groups with communication and coordination during the execution of their activities. It allows physically dispersed teams to engage in a common task by providing an interface to a shared workspace. A variety of synchronous applications are playing a major role in distance education, joint program development, cooperative publishing, etc. These applications are usually platform-dependent, groupware programmers have to develop new applications for each groupware platform. In this paper, we present a developing environment called CollabRunJava. Users can collaborate to design and process their job and can also develop groupware only concentrate on application-specific details on our system. CollabRunJava supports 2 modes for developing applications. In the instant-develop mode, user can immediately execute and test the classes. In the runtime-evolution mode, user can observe application behavior, debug applications and change the running applications codes without re-execution. Our system can be further enhanced by using plug-in components with the above mechanisms. For example, with the aid of visualization components, our system can help users explore program behavior. In addition, all these activities can be performed in a collaborative way. This makes it also helpful for distant learning and program testing.