Anthony Chiu Wa Lo

Synchronization of mobile XML databases by utilizing deferred views

In today fast pace, technologically based world, people need access to information on the go, anywhere at anytime. Because of this, mobile databases are greatly increasing in popularity. Using mobile devices, users can access and modify information without a network connection, and can then synchronize any updates when they get connected. This synchronization process must not only be able to perform updates on data from multiple users, but must also be able to detect and resolve conflicts. This process can sometimes be expensive and the synchronization algorithm must not only be robust, but also efficient. Motivated by this, we present DeferredSync as a new efficient XML based synchronization technique. DeferredSync converts relational data into XML tree structure and then makes use of deferred views in order to minimize bandwidth and storage space for the client. Finally, a conflict detection and resolution algorithm using priority selection to synchronize the data is outlined.

VIREX: visual relational to XML conversion tool

Developing user-friendly transformation tools for converting all or part of a given relational database into XML has not received enough consideration. This paper presents a flexible user interface called VIREX (VIsual RElational to XML), which facilitates converting a selected portion of a given underlying relational database into XML. VIREX works even when the catalogue of the underlying relational database is missing. For the latter case, VIREX extracts the required catalogue information by analyzing the underlying database content. From the catalogue information, whether available or extracted, VIREX derives and displays on the screen a graph similar to the entity-relationship diagram. VIREX provides a user-friendly interface to specify on the graph certain factors to be considered while converting relational data into XML. Such factors include: (1) selecting the relations/attributes to be converted into XML; (2) specifying a predicate to be satisfied by the information to be converted into XML; (3) deciding on the order of nesting between the relations to be converted into XML. All of these are specified by a sequence of mouse clicks with minimum keyboard input. As a result, VIREX displays on the screen the XML schema that satisfies the specified characteristics and generates the XML document from the underlying relational database. Finally, VIREX is essential to optimize the amount of information to be transferred over a network by giving the user the flexibility to specify the amount of relational data to be converted into XML. Also, VIREX can be used to teach XML to beginners.

Flexible User Interface for Converting Relational Data into XML

This paper presents VIREX (VIsual RElational to XML) as a flexible user interface for converting a selected portion of a given relational database into XML. VIREX works even when the catalogue of the relational database is missing; it extracts the required catalogue information by analyzing the database content. From the catalogue information, whether available or extracted, VIREX derives and displays on the screen a graph similar to the entity-relationship diagram. VIREX provides a user-friendly interface to specify on the graph certain factors to be considered while converting relational data into XML. Such factors include: 1) selecting the relations/attributes to be converted into XML; 2) specifying a predicate to be satisfied by the information to be converted into XML; 3) deciding on the order of nesting between the relations to be converted into XML. All of these are specified by a sequence of mouse clicks with minimum keyboard input. As a result, VIREX displays on the screen the XML schema that satisfies the specified characteristics and generates the XML documents from the relational database. Finally, VIREX helps in optimizing the amount of information to be transferred over a network. Also, it can be used to teach XML to beginners.

Cluster validity analysis using subsampling

Cluster validity investigates whether generated clusters are true clusters or due to chance. This is usually done based on subsampling stability analysis. Related to this problem is estimating true number of clusters in a given dataset. There are a number of methods described in the literature to handle both purposes. In this paper, we propose three methods for estimating confidence in the validity of clustering result. The first method validates clustering result by employing supervised classifiers. The dataset is divided into training and test sets and the accuracy of the classifier is evaluated on the test set. This method computes confidence in the generalization capability of clustering. The second method is based on the fact that if a clustering is valid then each of its subsets should be valid as well. The third method is similar to second method; it takes the dual approach, i.e., each cluster is expected to be stable and compact. Confidence is estimated by repeating the process a number of times on subsamples. Experimental results illustrate effectiveness of the proposed methods.

Novel Approach for Reengineering Relational Databases into XML

In this paper, we present COCALEREX (converting relational to XML) which can address both catalog-based and legacy relational databases. It handles the latter category by first applying the reverse engineering approach described in [2] to extract the ER (Extended Entity Relationship) model from legacy relational databases. This reverse engineering approach is emplyed also not to extract from catalog-based databases meta-data not available in the catalog. Then, COCALEREX converts the ER to XML schema. Deriving the ER model empowers the proposed approach to smoothly consider many-to-many and nary relationships during the mapping into XML schema. COCALEREX provides a user-friendly interface that displays the result of each phase of the conversion process. Experimental results are encouraging, demonstrating the applicability and effectiveness of the proposed approach.

VIREX: Interactive Approach for Database Querying and Integration by Re-engineering Relational Data into XML

VIREX is a user-oriented novel approach for visual-querying of relational databases and converting the result into XML. VIREX works even when the catalogue of the relational database is missing; it extracts the required catalogue information by analyzing the database content. Further, VIREX allows the user to define views by specifying on the interactive diagram certain factors to be considered while converting relational data into XML. As a result, VIREX displays on the screen the XML schema that satisfies the specified characteristics and generates colored (easy to read) XML document(s)

XML materialized views and schema evolution in VIREX

Web-based databases are gaining increased popularity. This has positively influenced the availability of structured and semi-structured databases for access by a variety of users ranging from professionals to naive users. The number of users accessing online databases will continue to increase if the visual tools connected to web-based databases are flexible and user-friendly enough to meet the expectations of naive users and professionals. Further, XML is accepted as the standard for platform independent data exchange. This motivated for the development of the conversion tools between structured databases and XML. Realizing that such a need has not been well handled by the available tools, including Clio from IBM, we developed VIREX as a visual tool for converting relational databases into XML, and since then has been empowered with further capabilities to manipulate the produced XML schema including the maintenance of materialized views and schema evolution functions. VIREX provides an interactive approach for querying and integrating relational databases to produce XML documents and the corresponding XML schema(s). VIREX supports VRXQuery as a visual naive users-oriented query language that allows users to specify queries and define views directly on the interactive diagram as a sequence of mouse clicks with minimum keyboard input. As the query result, VIREX displays on the screen the XML schema that satisfies the specified characteristics and generates colored (easy to read) XML document(s). The main contribution described in this paper is the novel approach for turning query results into materialized views which are maintained to remain consistent with the underlying database. VIREX supports deferred update of XML views by keeping an ordered summary of the necessary and sufficient information required for the process. Each view has a corresponding marker in the ordered summary to indicate the start of the information to be reflected onto the view when it is accessed. When a view is accessed, its marker moves to the head of the list to mark for the next update. In addition, VIREX supports some basic schema evolution functions include renaming, adding and dropping of elements and attributes, among others. The supported schema evolution functions add flexibility to the view maintenance and materialization process.

Wrapping VRXQuery with Self-Adaptive Fuzzy Capabilities

This paper addresses the development of a plug and run wrapper to incorporate fuzziness into VRXQuery, the querying facility of VIREX which is a user-friendly system for transforming and querying relational data as XML. Our basic argument is not to force the underlying XML data to incorporate fuzziness. Rather, fuzziness is smoothly supported in a novel plug and run manner via a wrapper. Either the user specifies the membership functions for the elements/attributes to be queried as fuzzy, or multi-objective genetic algorithm is used to automatically decide on and optimize the membership functions. The interface of VIREX has been expanded to allow specifying queries with fuzziness. Then, queries expressed in VRXQuery empowered with fuzziness are translated into corresponding XQuery code, which is run on the underlying XML and the returned result is translated into a fuzzy representation; translation into SQL is also possible. The user is given the choice to display the result either as colored- text or in graphical format.

Human Centric Data Representation: From Fuzzy Relational Databases into Fuzzy XML

The Extensible Markup Language (XML) is emerging as the dominant data format for data exchange between applications. Many translation techniques have been devised to publish large amounts of existing conventional relational data in XML format. There also exists a need to be able to represent imprecise data in both relational databases and XML. This paper describes a fuzzy XML schema model for representing a fuzzy relational database in XML format. It also outlines a translation algorithm to include fuzzy relations and similarity matrices with their associated conventional relations. We also describe how the proposed fuzzy XML schema and the conversion process from fuzzy relational data into fuzzy XML have been integrated into VIREX, which is a prototype with powerful visual tool for transforming relational data into XML.

XML views based approach for Web services

This paper describes the necessity of converting relational databases to XML documents for Web services. One approach for this ultimate goal is to define a virtual XML document (XML view) over the given database schema. This allows the other applications over the Web service to exchange data without knowing the relational database structure, and more important, all these applications can be accessed using different operations and database systems. We present architecture that uses XML schema to define XML views, and uses Java API called JAXB for binding this schema into Java objects. All data exchange is to be done between objects. Thus, this is an object-oriented approach that uses matured Java technology to avoid complicated relational to XML mapping.