Abstract-Massive Open Online Courses (MOOCs) have recently gained high popularity among various universities and even in global societies. A critical factor for their success in teaching and learning effectiveness is assignment grading. Traditional ways of assignment grading are not scalable and do not give timely or interactive feedback to students. To address these issues, we present an interactive-gaming-based teaching and learning platform called Pex4Fun. Pex4Fun is a browser-based teaching and learning environment targeting teachers and students for introductory to advanced programming or software engineering courses. At the core of the platform is an automated grading engine based on symbolic execution. In Pex4Fun, teachers can create virtual classrooms, customize existing courses, and publish new learning material including learning games. Pex4Fun was released to the public in June 2010 and since then the number of attempts made by users to solve games has reached over one million. Our work on Pex4Fun illustrates that a sophisticated software engineering technique -automated test generation -can be successfully used to underpin automatic grading in an online programming system that can scale to hundreds of thousands of users.
Abstract. Web services are becoming progressively popular in the building of both inter-and intra-enterprise business processes. These processes are composed from existing Web services based on defined requirements. In collecting together the services for such a composition, developers can employ languages and standards for the Web that facilitate the automation of Web service discovery, execution, composition and interoperation. However, there is no guarantee that a composition of even very good services will always work. Mechanisms are being developed to monitor a composition and to detect and recover from faults automatically. A key factor in such self-healing is to know what faults to look for. If the nature of a fault is known, the system can suggest a suitable recovery mechanism sooner. This paper proposes a novel taxonomy that captures the possible failures that can arise in Web service composition, and classifies the faults that might cause them. The taxonomy covers physical, development and interaction faults that can cause a variety of observable failures in a system's normal operation. An important use of the taxonomy is identifying the faults that can be excluded when a failure occurs. Examples of using the taxonomy are presented.
Groupware allows many concurrent users to work on the same project. Whereas a single user system focuses on the individual, Groupware focuses on the group. We take a look at what makes a CSCW application, the categories of CSCW applications, and the differences between CSCW and Groupware. We compare a number of academic and commercial systems against a number of criteria. We conclude by comparing each of these systems against all criteria. We notice the similarities and differences between each of these systems and our Groupware system, Nomad.
Mastering a complex skill like programming takes many hours. In order to encourage students to put in these hours, we built Code Hunt, a game that enables players to program against the computer with clues provided as unit tests. The game has become very popular and we are now running worldwide contests where students have a fixed amount of time to solve a set of puzzles. This paper describes Code Hunt and the contest experience it offers. We then show some early results that demonstrate how Code Hunt can accurately discriminate between good and bad coders. The challenges of creating and selecting puzzles for contests are covered. We end up with a short description of our course experience, and some figures that show that Code Hunt is enjoyed by women and men alike.
Short Message Service is usually used to transport unclassified information, but with the rise of mobile commerce it has become an integral tool for conducting business. However SMS does not guarantee confidentiality and integrity of the message content. This paper proposes a protocol called SMSSec that can be used to secure a SMS communication sent by Java's Wireless Messaging API. The physical limitations of the intended devices such as mobile phones, made it necessary to develop a protocol which would make minimal use of computing resources. SMSSec has a two-phase protocol with the first handshake using asymmetric cryptography which occurs only once, and a more efficient symmetric nth handshake which is used more dominantly. What distinguishes this work from conventional protocols is the ability to perform the secure transmission with limited size messages.Performance analysis showed that the encryption speed on the mobile device is faster than the duration of the transmission. To achieve security in the mobile enterprise environment, this is deemed a very acceptable overhead. Furthermore, a simple mechanism handles fault tolerance without additional overhead is proposed.
The original purpose of addresses was to enable the correct and unambiguous delivery of postal mail. The advent of computers and more specifically geographic information systems (GIS) opened up a whole new range of possibilities for the use of addresses, such as routing and vehicle navigation, spatial demographic analysis, geo-marketing, and service placement and delivery. Such functionality requires a database which can store and access spatial data effectively. In this paper we present address databases and justify the need for national address databases. We describe models used for national address databases, and present our evaluation framework for an address database at a national level within the context of a spatial data infrastructure (SDI). The models of data harvesting, federated databases and data grids are analyzed and evaluated according to our novel framework, and we show that the data grid model has some unique features that make it attractive for a national address database in an environment where centralized control and/or coordination is difficult or undesirable.
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