11540730
Vectorizing and querying large XML repositories
Vertical partitioning is a well-known technique for optimizing query performance in relational databases. An extreme form of this technique, which we call vectorization, is to store each column separately. We use a generalization of vectorization as the basis for a native XML store. The idea is to decompose an XML document into a set of vectors that contain the data values and a compressed skeleton that describes the structure. In order to query this representation and produce results in the same vectorized format, we consider a practical fragment of XQuery and introduce the notion of query graphs and a novel graph reduction algorithm that allows us to leverage relational optimization techniques as well as to reduce the unnecessary loading of data vectors and decompression of skeletons. A preliminary experimental study based on some scientific and synthetic XML data repositories in the order of gigabytes supports the claim that these techniques are scalable and have the potential to provide performance comparable with established relational database technology.
15301775
Implementing Xquery 1.0: The Galax Experience
Galax is a light-weight, portable, open-source implementation of XQuery 1.0. Started in December 2000 as a small prototype designed to test the XQuery static type system, Galax has now become a solid implementation, aiming at full conformance with the family of XQuery 1.0 specifications. Because of its completeness and open architecture, Galax also turns out to be a very convenient platform for researchers interested in experimenting with XQuery optimization. 
 
We demonstrate the Galax system as well as its most advanced features, including support for XPath 2.0, XML Schema and static type-checking. We also present some of our first experiments with optimization. Notably, we demonstrate query rewriting capabilities in the Galax compiler, and the ability to run queries on documents up to a Gigabyte without the need for preindexing. Although early versions of Galax have been shown in industrial conferences over the last two years, this is the first time it is demonstrated in the database community.
3203090
What are real DTDs like?
DTDs have proved important in a variety of areas: transformations between XML and databases, XML storage, XML publishing, consistency analysis of XML specifications, typechecking, and optimization of XML queries. Much of this work depends on certain assumptions about DTDs, e.g., the absence of recursion and non-determinism. With this comes the need to justify these assumptions against DTDs in the real world. This paper surveys a number of DTDs collected from the Web, and provides statistics with respect to a variety of criteria commonly discussed in XML resesarch.
2642886
Cache-Conscious Automata for XML Filtering
Hardware cache behavior is an important factor in the performance of memory-resident, data-intensive systems such as XML filtering engines. A key data structure in several recent XML filters is the automaton, which is used to represent the long-running XML queries in the main memory. In this paper, we study the cache performance of automaton-based XML filtering through analytical modeling and system measurement. Furthermore, we propose a cache-conscious automaton organization technique, called the hot buffer, to improve the locality of automaton state transitions. Our results show that 1) our cache performance model for XML filtering automata is highly accurate and 2) the hot buffer improves the cache performance as well as the overall performance of automaton-based XML filtering
17095732
Incremental evaluation of schema-directed XML publishing
When large XML documents published from a database are maintained externally, it is inefficient to repeatedly recompute them when the database is updated. Vastly preferable is incremental update, as common for views stored in a data warehouse. However, to support schema-directed publishing, there may be no simple query that defines the mapping from the database to the external document. To meet the need for efficient incremental update, this paper studies two approaches for incremental evaluation of ATGs [4], a formalism for schema-directed XML publishing. The reduction approach seeks to push as much work as possible to the underlying DBMS. It is based on a relational encoding of XML trees and a nontrivial translation of ATGs to SQL 99 queries with recursion. However, a weakness of this approach is that it relies on high-end DBMS features rather than the lowest common denominator. In contrast, the bud-cut approach pushes only simple queries to the DBNS and performs the bulk of the work in middleware. It capitalizes on the tree-structure of XML views to minimize unnecessary recomputations and leverages optimization techniques developed for XML publishing. While implementation of the reduction approach is not yet in the reach of commercial DBMS, we have implemented the bud-cut approach and experimentally evaluated its performance compared to recomputation.
10441527
Efficient Support for Ordered XPath Processing in Tree-Unaware Commercial Relational Databases
In this paper, we present a novel ordered XPATH evaluation in treeunaware RDBMS. The novelties of our approach lies in the followings. (a) We propose a novel XML storage scheme which comprises only leaf nodes, their corresponding data values, order encodings and their root-to-leaf paths. (b) We propose an algorithm for mapping ordered XPATH queries into SQL queries over the storage scheme. (c) We propose an optimization technique that enforces all mapped SQL queries to be evaluated in a "left-to-right" join order. By employing these techniques, we show, through a comprehensive experiment, that our approach not only scales well but also performs better than some representative tree-unaware approaches on more than 65% of our benchmark queries with the highest observed gain factor being 1939. In addition, our approach reduces significantly the performance gap between tree-aware and tree-unaware approaches and even outperforms a state-of-the-art tree-aware approach for certain benchmark queries.
30747196
Addressing a standards creation process: a focus on ebXML
Current trends in e-business are creating opportunities for automation of business processes across business boundaries. However, lack of standards has caused difficulties for industry players in exploiting resources and coordinating activities in the context of e-business. ebXML--an emerging e-business standard framework to unite competing factions under a banner of international trade--has been developed within an industry consortium using an open, collaborative process with no barriers to entry, whose approach is very different from traditional approach to create standards. Drawing on socio-technological perspective, this paper attempts to gain deeper understanding of such phenomenon by using a case study methodology. This paper uses data drawn mostly from email discussions and minutes of teleconference and face-to-face meeting. Our exploration of the ebXML standardization process generates specific propositions. In summary, our analysis found that the 'openness' of standardization process helps to create a more comprehensive standard than proprietary standards--effectively leading to convergence of technologies, and that the unfolding dynamics of standardization process varies depending on the characteristics of standards to be developed. We also discuss user participation as an important factor that influences the dynamics of standardization process in such an open, collaborative standardization process. Surprisingly, user participation seems to be more effective in creating technical infrastructure oriented standards rather than business process oriented standards.
6267168
A qualitative cross-national study of cultural influences on mobile data service design
As the use of mobile data services has spread across the globe, the effect of cultural differences on user requirements has become important issue. To date, however, little research has been conducted on the role cultural factors play in the design of mobile data services. This paper proposes a set of critical design attributes for mobile data services that takes cross-cultural differences into account. To determine these attributes, we devised a qualitative method and conducted in-depth long interviews in Korea, Japan, and Finland. We found 52 attributes considered important by mobile data service users, and 11 critical attributes that showed a clear correlation with characteristics of the user's culture. The paper concludes with a discussion of limitations and of implications for developers of mobile data services.
9581771
Scalable QoS guaranteed communication services for real-time applications
We propose an approach to flow-unaware admission control which is a combination with an aggregate packet forwarding scheme, improving scalability of networks while guaranteeing end-to-end deadlines for real-time applications. We achieve this by using an off-line delay computation and verification step, which allows to reduce the overhead at admission control while keeping admission probability and resource utilization high. Our evaluation data show that our system's admission probabilities are very close to those of significantly more expensive flow-aware approaches. At the same time, the admission control overhead during flow establishment is very low. Our results therefore support the claim from the DS architecture literature that scalability can be achieved through flow aggregation without sacrificing resource utilization and with significant reduction in run time overhead.
11364385
An organizational memory for facilitating knowledge: an application to e-business architecture
Abstract Our economy is increasingly dependent on knowledge. Organizational memory (OM) contains knowledge that companies need to manage. This paper proposes a knowledge facilitating organizational memory (KFOM) to decipher a harmony mechanism of OM from the Oriental Yin and Yang perspective. KFOM clarifies an architecture to catapult the OM to organizational effectiveness. This architecture is made up of two layers: storage layer and facilitation layer. Storage layer represents task and domain knowledge. Facilitation layer identifies the harmony mechanism for utilizing knowledge. This harmony mechanism leverages the knowledge chain with agent, collaborator, transactor, object and registry facilitators. In order to demonstrate its practical usefulness, we explore how KFOM can sharpen an international e-business technical standard. Furthermore, an extension to a real-life B2B collaboration project for Korean steel and automotive companies confirms that KFOM can lead to business practices which most knowledge-oriented companies can adopt.
7584097
An Adaptive Web Cache Access Predictor Using Neural Network
This paper presents a novel approach to successfully predict Web pages that are most likely to be re-accessed in a given period of time. We present the design of an intelligent predictor that can be implemented on a Web server to guide caching strategies. Our approach is adaptive and learns the changing access patterns of pages in a Web site. The core of our predictor is a neural network that uses a backpropagation learning rule. We present results of the application of this predictor on static data using log files; it can be extended to learn the distribution of live Web page access patterns. Our simulations show fast learning, uniformly good prediction, and up to 82% correct prediction for the following six months based on a one-day training data. This long-range prediction accuracy is attributed to the static structure of the test Web site.