Moa and the multi-model architecture: a new perspective on XNF2

Advanced non-traditional application domains such as geographic information systems and digital library systems demand advanced data management support. In an effort to cope with this demand, we present the concept of a novel multi-model DBMS architecture which provides evaluation of queries on complexly structured data without sacrificing efficiency. A vital role in this architecture is played by the Moa language featuring a nested relational data model based on XNF2, in which we placed renewed interest. Furthermore, extensibility in Moa avoids optimization obstacles due to black-box treatment of ADTs. The combination of a mapping of queries on complexly structured data to an efficient physical algebra expression via a nested relational algebra, extensibility open to optimization, and the consequently better integration of domain-specific algorithms, makes that the Moa system can efficiently and effectively handle complex queries from non-traditional application domains

A DESIGN OF AN OBJECT-ORIENTED DATABASE FOR EFFECTIVE DATA MINING

This paper focuses on the design of an object-oriented database (OODB), through incorporation of object-oriented programming (OOP) concepts into existing relational databases. The proposed approach makes use of the OOP concepts namely, inheritance, encapsulation and polymorphism to design an OODB and perform classification in it respectively. Usually, database is a collection of tables with common fields. In this study, those common fields are grouped together to form a single generalized table. The newly created table resembles the base class in the inheritance hierarchy. Polymorphism allows different classes to have methods of the same name and structure, performing different operations based on the calling object. The polymorphism is specifically employed to achieve classification in a simple and effective manner while Encapsulation ensures the hiding of the data and behavior of an object behind a limited and well-described interface. In Java terms, the limited and well-described interface is the set of public methods and attributes. The use of these object oriented concepts for the design of OODB ensures that even complex queries can be answered more efficiently. Particularly, data mining task and classification can be achieved in an effective manner.Â

The advantages and cost effectiveness of database improvement methods

Relational databases have proved inadequate for supporting new classes of applications, and as a consequence, a number of new approaches have been taken (Blaha 1998), (Harrington 2000). The most salient alternatives are denormalisation and conversion to an object-oriented database (Douglas 1997). Denormalisation can provide better performance but has deficiencies with respect to data modelling. Object-oriented databases can provide increased performance efficiency but without the deficiencies in data modelling (Blaha 2000). Although there have been various benchmark tests reported, none of these tests have compared normalised, object oriented and de-normalised databases. This research shows that a non-normalised database for data containing type code complexity would be normalised in the process of conversion to an objectoriented database. This helps to correct badly organised data and so gives the performance benefits of de-normalisation while improving data modelling. The costs of conversion from relational databases to object oriented databases were also examined. Costs were based on published benchmark tests, a benchmark carried out during this study and case studies. The benchmark tests were based on an engineering database benchmark. Engineering problems such as computer-aided design and manufacturing have much to gain from conversion to object-oriented databases. Costs were calculated for coding and development, and also for operation. It was found that conversion to an object-oriented database was not usually cost effective as many of the performance benefits could be achieved by the far cheaper process of de-normalisation, or by using the performance improving facilities provided by many relational database systems such as indexing or partitioning or by simply upgrading the system hardware. It is concluded therefore that while object oriented databases are a better alternative for databases built from scratch, the conversion of a legacy relational database to an object oriented database is not necessarily cost effective

Migrating relational databases into object-based and XML databases

Rapid changes in information technology, the emergence of object-based and WWW applications, and the interest of organisations in securing benefits from new technologies have made information systems re-engineering in general and database migration in particular an active research area. In order to improve the functionality and performance of existing systems, the re-engineering process requires identifying and understanding all of the components of such systems. An underlying database is one of the most important component of information systems. A considerable body of data is stored in relational databases (RDBs), yet they have limitations to support complex structures and user-defined data types provided by relatively recent databases such as object-based and XML databases. Instead of throwing away the large amount of data stored in RDBs, it is more appropriate to enrich and convert such data to be used by new systems. Most researchers into the migration of RDBs into object-based/XML databases have concentrated on schema translation, accessing and publishing RDB data using newer technology, while few have paid attention to the conversion of data, and the preservation of data semantics, e.g., inheritance and integrity constraints. In addition, existing work does not appear to provide a solution for more than one target database. Thus, research on the migration of RDBs is not fully developed. We propose a solution that offers automatic migration of an RDB as a source into the recent database technologies as targets based on available standards such as ODMG 3.0, SQL4 and XML Schema. A canonical data model (CDM) is proposed to bridge the semantic gap between an RDB and the target databases. The CDM preserves and enhances the metadata of existing RDBs to fit in with the essential characteristics of the target databases. The adoption of standards is essential for increased portability, flexibility and constraints preservation. This thesis contributes a solution for migrating RDBs into object-based and XML databases. The solution takes an existing RDB as input, enriches its metadata representation with the required explicit semantics, and constructs an enhanced relational schema representation (RSR). Based on the RSR, a CDM is generated which is enriched with the RDB's constraints and data semantics that may not have been explicitly expressed in the RDB metadata. The CDM so obtained facilitates both schema translation and data conversion. We design sets of rules for translating the CDM into each of the three target schemas, and provide algorithms for converting RDB data into the target formats based on the CDM. A prototype of the solution has been implemented, which generates the three target databases. Experimental study has been conducted to evaluate the prototype. The experimental results show that the target schemas resulting from the prototype and those generated by existing manual mapping techniques were comparable. We have also shown that the source and target databases were equivalent, and demonstrated that the solution, conceptually and practically, is feasible, efficient and correct

An Approach to Transformational Reengineering of SSADM Application Specifications to Object-Oriented Specifications

Many organizations are planning for transition to object-oriented software development for savings in development and maintenance costs. Appropriate tools and techniques to support this process of transition will help such organizations in overcoming many problems associated with the transition process. This paper outlines an approach to transformational reengineering of SSADM application specifications to Object-Oriented specifications

Cross: an OWL wrapper for teasoning on relational databases

One of the challenges of the Semantic Web is to integrate the huge amount of information already available on the standard Web, usually stored in relational databases. In this paper, we propose a formalization of a logic model of relational databases, and a transformation of that model into OWL, a Semantic Web language. This transformation is implemented in Cross, as an open-source prototype. We prove a relation between the notion of legal database state and the consistency of the corresponding OWL knowledge base. We then show how that transformation can prove useful to enhance databases, and integrate them in the Semantic Web

Conceptual and application issues in the implementation of object-oriented GIS

The adoption of object-oriented technology for spatial data modeling is becoming a significant trend in GIS. This research explores the concepts of Object-Oriented GIS (OOGIS) and illustrates its versatility in two case studies. OOGIS provides a feature-based, intuitive representation of real world features. The study emphasizes the fundamental concepts of inheritance, polymorphism, and encapsulation in OOGIS and explores schema design, long transactions, and versioning. Further, the study discusses the advantages of OOGIS in the management and analysis of geospatial data. The case studies demonstrate both the conceptual basis of OOGIS and specific functionality including behavior, methods, versioning, long transactions and data locking. OOGIS demonstrates many advantages over the traditional entity-relationship model in database maintenance and functionality

An object-oriented view of backend databases in a mobile environment for navy and marine corps applications

A Database Management System (DBMS) is system software for managing a large amount of data in secondary memory. The standard DBMS used today in both industry and the military is the Relational DBMS (RDBMS). The RDBMS is based upon the relational paradigm, whereas modern software development technologies that interact with the RDBMS are based upon the object-oriented paradigm. This difference in paradigms presents a conceptual mismatch which greatly reduces programmer and developer productivity. Additionally, wireless handheld devices have become ubiquitous both in the military and in the community at large. These handheld devices provide a convenient means of information access. To date, the military has failed to capitalize on the use of handheld devices as a convenient means of information access with respect to the large amounts of information stored in its databases. This thesis investigates various database application architectures and proposes an architecture that will not only overcome the conceptual mismatch between the relational and object-oriented paradigms, but also allows handheld device access to the database. A proof-of-concept prototype database application that provides handheld device access to a military personnel database is built to show the viability of the proposed architecture.http://archive.org/details/anobjectoriented109452577Approved for public release; distribution is unlimited

Exploiting a perdurantist foundational ontology and graph database for semantic data integration

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University London.The view of reality that is inherent to perdurantist philosophical ontologies, often termed four dimensional (4D) ontologies, has not been widely adopted within the mainstream of information system design practice. However, as the closed world of enterprise systems is opened to Internet scale Semantic Web and Open Data information sources, there is a need to better understand the semantics of both internal and external data and how they can be integrated. Philosophical foundational ontologies can help establish this understanding and there is, therefore, an emerging need to research how they can be applied to the problem of semantic data integration. Therefore, a prime objective of this research was to develop a framework through which to apply a 4D foundational ontology and a graph database to the problem of semantic data integration, and to assess the effectiveness of the approach. The research employed design science, a methodology which is applicable to undertaking research within information systems as it encompasses methods through which the research can be undertaken and the resultant artefacts evaluated. This methodology has a number of discrete stages: problem awareness; a core design-build-evaluate iterative cycle through which the research is conducted; and a conclusion stage. The design science research was conducted through the development of a number of artefacts, the prime being the 4D-Semantic Extract Load (4D-SETL) framework. The effectiveness of the framework was assessed by applying it to semantically interpret and integrate a number of large scale datasets and to instantiate a prototype graph database warehouse to persist the resultant ontology. A series of technical experiments confirmed that directly reflecting the model patterns of 4D ontology within a prototype data warehouse proved an effective means of both structuring and semantically integrating complex datasets and that the artefacts produced by 4D-SETL could function at scale. Through illustrative scenario, the effectiveness of the approach is described in relation to the ability of the framework to address a number of weaknesses in current approaches. Furthermore the major advantages of the 4D-SETL are elaborated; which include ability of the framework is to combine foundational, domain and instance level ontological models in a single coherent system that dispensed with much of the translation normally undertaken between conceptual, logical and physical data models. Additionally, adopting a perdurantist realist foundational ontology provided a clear means of establishing and maintaining the identity of physical objects as their constituent temporal and spatial parts unfold over the course of tim