Students learn about design principles and "best practices" in many courses. However, small scale assignments do not give enough opportunity for students to appreciate the value of software design principles or even to learn how to apply principles in practice. To fill the gap between theoretical and experiential knowledge, we introduced a team-based project course focused on design and implementation phases of the software development lifecycle. We teach design principles and team work in problem-based way, through architectural concepts and iterative development process. The product students build must meet stated quality requirements in terms of reliability, reusability and documentation. We trust this kind of the course is essential in curricula as it allows students better absorb knowledge learned in other software engineering courses. Such course also plays a role in better preparing students for industrial work. We describe a teaching method, course infrastructure and lessons learned over three years of teaching of our course. Based on experiences, we postulate and motivate the need for teaching at least two project courses in undergraduate curricula, one dealing with design and process issues, and the other focused on unstable requirements

Many decision support applications are characterized by several features: (1) the query is typically based on multiple criteria; (2) there is no single optimal answer (or answer set); (3) because of (2), users typically look for satisfying answers; (4) for the same query, different users, dictated by their personal preferences, may find different answers meeting their needs. As such, it is important for the DBMS to present all interesting answers that may fulfill a user's need. In this article, we focus on the set of interesting answers called the skyline. Given a set of points, the skyline comprises the points that are not dominated by other points. A point dominates another point if it is as good or better in all dimensions and better in at least one dimension. We address the novel and important problem of evaluating skyline queries involving partially-ordered attribute domains.

In this paper, we study the evaluation of skyline queries with partially-ordered attributes. Because such attributes lack a total ordering, traditional index-based evaluation algorithms (e.g., NN and BBS) that are designed for totally-ordered attributes can no longer prune the space as effectively. Our solution is to transform each partially-ordered attribute into a two-integer domain that allows us to exploit index-based algorithms to compute skyline queries on the transformed space. Based on this framework, we propose three novel algorithms: BBS+ is a straightforward adaptation of BBS using the framework, and SDC (Stratification by Dominance Classification) and SDC+ are optimized to handle false positives and support progressive evaluation. Both SDC and SDC+ exploit a dominance relationship to organize the data into strata. While SDC generates its strata at run time, SDC+ partitions the data into strata offline. We also design two dominance classification strategies (MinPC and MaxPC) to further optimize the performance of SDC and SDC+. We implemented the proposed schemes and evaluated their efficiency. Our results show that our proposed techniques outperform existing approaches by a wide margin, with SDC+-MinPC giving the best performance in terms of both response time as well as progressiveness. To the best of our knowledge, this is the first paper to address the problem of skyline query evaluation involving partially-ordered attribute domains.

We propose a partition-based framework for evaluating preference queries. The framework is independent of how partitions are generated, and returns answers progressively as the query is being evaluated. We evaluated the framework using partitions obtained from the leaf nodes of R-trees. Our study shows that our approach can shorten the initial response time.

In this paper, we reexamine the issue of selective tuning using the flexible indexing scheme by T. Imielinski et al. (1994) in the context of unreliable wireless channels. We propose a mechanism that can be applied to uniform and nonuniform broadcast to enable a client using the scheme to recover from errors.