Utilization of data access and manipulation in conceptual schema definitions

The basic idea of this approach is to use data access and manipulation functions in data definition, such that testing a given individual data object on its conformance to data definition is done by running a (finally boolean) procedure against it. In essence, schema entries (i.e. definitions, declarations, etc.) are viewed as expressions of predicate logic where the individuals are obtained by the execution of data manipulation operations which include a rather general information selection technique or conceptual access method.Selection of information constructs in databases usually adopts a technique closely tailored to the specific “data model”. It is one of the intentions of this paper to demonstrate the common principles behind the variety of selection techniques by a uniform approach which comprises the selection features of most of the database management systems and makes them comparable.At the level of information structure a kind of “geography” is introduced into a database, which allows to distinguish the same information construct (record, file, segment, item, coset, tuple,…) in distinct information contexts or at distinct conceptual locations called “spots”. By definition, every spot (“construct in/with context”) exists only once in a given database. In combination with some basic operators a logical addressing mechanism has been designed, which follows the context of a construct to identify it within this very context. This algorithm turns out to be a general vehicle to locate a construct at a spot, independently of whether the database has a relational, network, hierarchical or any other appearance.The method of context directed addressing along with pertinent operators allows in a very general way—i.e. neither biased nor restricted to a “data model”—to define types of information constructs and of construct transitions as is required in a conceptual community schema. This is demonstrated through examples of schema entries with rather complex cross-consistency conditions and additional transition rules called persistency conditions. The examples also intend to give an idea of the minimum support to be expected from any future conceptual schema language.     

基于路径无关语言的等价模式演化策略

面向对象数据库的许多应用环境需要频繁的模式演以化,但模式演化以后,基于先前模式的应用程序因此而不得不修改或重编,这就造成了巨大的软件浪费.提出了基于路径无关语言的等价模式演化方案来解决这个问题.首先,路径无关语言是一种面向对象数据库的编程语言,它能使程序脱离对细节数据模式的导航,对模式演化具有较强的适应性.而等价模式演化是一种新的模式演化方案,它能保证用路径无关语言编写的应用程序在模式演化以后无须修改而完全重用.此外,在实现等价模式演化的系统中,为了减少演化开销以及不增加用户的额外编程负担,提出了虚拟关系机制和对象演化技术.     

A conceptual schema-based temporal meta database schemas generation technique for 3D objects

In this paper, a temporal meta database for three-dimensional (3D) objects whose properties and relationships are supported by valid time is introduced. Based on our proposed temporal object-oriented conceptual schema model, a conceptual schema of the temporal meta database can be generated from a 3D graphical data source and other particular application requirements. Based on our proposed temporal object relational data model with attribute timestamping, logical schemas of the temporal meta database can be systematically and automatically generated from the conceptual schema. From the temporal meta database, non-temporal/temporal metadata about temporal 3D objects are available for temporal information system users. Convenient access using database languages such as SQL can be performed. Queries over 3D objects using a temporal object relational SQL are demonstrated.     

Database application evolution: A transformational approach

While recent data management technologies, such as object oriented techniques, address the problem of database schema evolution, standard information systems currently in use raise challenging evolution problems. This paper examines database evolution from the developer point of view. It shows how requirements changes are propagated to database schemas, to data and to programs through a general strategy. This strategy requires the documentation of database design. When absent, such documentation has to be rebuilt through reverse engineering techniques. Our approach, called DB-MAIN, relies on a generic database model and on transformational paradigm that states that database engineering processes can be modeled by schema transformations. Indeed, a transformation provides both structural and instance mappings that formally define how to modify database structures and contents. We describe both the complete and a simplified approaches, and compare their merits and drawbacks. We then analyze the problem of program modification and describe a CASE tool that can assist developers in their task of system evolution. We illustrate our approach with Biomaze, a biochemical knowledge-based the database of which is rapidly evolving.     

Schema versioning and database conversion techniques for bi-temporal databases

Schema evolution and schema versioning are two techniques used for managing database evolution. Schema evolution keeps only the current version of a schema and database after applying schema changes. Schema versioning creates new schema versions and converts the corresponding data while preserving the old schema versions and data. To provide the most generality, bi-temporal databases can be used to realize schema versioning, since they allow both retroactive and proactive updates to the schema and database. In this paper we first study two proposed database conversion approaches for supporting schema evolution and schema versioning: single table version approach and multiple table version approach. We then propose the partial table version approach to solve the problems encountered in these approaches when applied to bi-temporal databases. This revised version was published online in June 2006 with corrections to the Cover Date.     

Treating data privacy in distributed systems

This papers describes and is primarily concerned with the security data definition and management in a distributed data base of aggregated type, although the approach described may be applied to any distributed system architecture. A multi-level logical security architecture is presented reflecting the logical architecture of the distributed system. In particular, three security logical schemata are proposed: the network security schema, the external security schemata, and the intermediate security schemata. For each schema data models are introduced, allowing the definition and the management of security information. Mapping rules between the logical levels are discussed. Finally security mechanisms are analyzed.     

一种解决联邦数据库系统查询处理的模式转换方法

本文在分析联邦数据库系统成员异构的特点后，论述了一种基于输入／输出模式和概念模式的转换方法，通过该转换处理可以有效地解决模式异构的问题，这种方法已在ＳＵ－ＦＤＢＳ原型中实现。     

Managing schema evolution in a container‐based persistent system

Managing schema evolution is a problem every persistent system has to cope with to be useful in practice. Schema evolution consists basically of supporting class modification and dealing with data objects created and stored under the old class definitions. Several proposals have been made to handle this problem in systems that follow a full orthogonally persistent approach, but, until now, there has not been any proposal to support it in container‐based persistent systems. In this paper we describe a schema evolution management system designed for Barbados. Barbados is a complete programming environment which is based on an architecture of containers to provide persistent storage. Barbados does not provide full orthogonal persistence, but, as will be described in this paper, its architecture has several other advantages. Among them is the fact that this model is especially suitable for solving the schema evolution problem. Copyright © 2002 John Wiley & Sons, Ltd.     

Translating relational schema into XML schema definition with data semantic preservation and XSD graph

Many legacy systems have been created by using relational database operating not for the Internet expression. Since the relational database is not an efficient way for data explosion, electronic transfer of data, and electronic business on the Web, we introduce a methodology in which a relational schema will be translated to an Extensible Markup Language (XML) schema definition for creating an XML database that is a simple and efficient format on the Web. We apply the Indirect Schema Translation Method that is a semantic-based methodology in this project. The mechanism is that the Relational Schema will be translated into the conceptual model, an Extended Entity Relationship (EER) Model using Reverse Engineering. Afterward, the EER model will be mapped to an XML Schema Definition Language (XSD) Graph as an XML conceptual schema using Semantic Transformation. Finally, the XSD Graph will be mapped into the XSD as an XML logical schema in the process of Forward Engineering, and the data semantics of participation, cardinality, generalization, aggregation, categorization, N-ary and U-ary relationship are preserved in the translated XML schema definition.     

Modeling and Management of Fuzzy Information in Multimedia Database Applications

In this paper, we firstly present a conceptual data model for multimedia database applications based on ExIFO₂ model. The ExIFO₂ data model is chosen as the conceptual model since it handles complex objects along with their uncertain and imprecise properties. We enhanced this conceptual model in order to meet the multimedia data requirements. In addition to uncertain and imprecise information, we present a way of handling relationships among objects of multimedia database applications. Events that might be extracted from video or audio are also considered in this study. Secondly, the conceptual model is mapped to a logical model, which the fuzzy object-oriented data (FOOD) model is chosen, for storing and manipulating the multimedia objects. This mapping is done in a way that it preserves most of the information represented at the conceptual level. Finally, in this study videos of football (soccer) games is selected as the multimedia database application to show how we handle crisp and fuzzy querying and retrieval of fuzzy and crisp data from the database. A program has been developed to draw ExIFO₂ schemas and to map the schema to FOOD code automatically.     

Domain-knowledge-guided schema evolution for accounting database systems

The static meta-data view of accounting database management is that the schema of a database is designed before the database is populated and remains relatively fixed over the life cycle of the system. However, the need to support accounting database evolution is clear: a static meta-data view of an accounting database cannot support next generation dynamic environment where system migration, organization reengineering, and heterogeneous system interoperation are essential. This paper presents a knowledge-based approach and mechanism to support dynamic accounting database schema evolution in an object-based data modeling context. When an accounting database schema does not meet the requirements of a firm, the schema must be changed. Such schema evolution can be realized via a sequence of evolution operators. As a result, this paper considers the question: what heuristics and knowledge are necessary to guide a system to choose a sequence of operators to complete a given evolution task for an accounting database? In particular, we first define a set of basic evolution schema operators, employing heuristics to guide the evolution process. Second, we explore how domain-specific knowledge can be used to guide the use of the operators to complete the evolution task. A well-known accounting data model, REA model, is used here to guide the schema evolution process. Third, we discuss a prototype system, REAtool, to demonstrate and test our approach.     

Four-schema approach: An extended model for database architecture

This paper presents an integrative approach for database design. A four-schema architecture, extending the work of the ANSI/X3/SPARC Committee, is proposed as an overall design framework. The concept of the conceptual schema is analyzed, and its two rather independent components are separated. A database design project is briefly discussed as an example of the proposed four-schema approach.     

Landscaping the information space of large multi-database networks

The promises of network-accessible information are increasingly difficult to achieve. These difficulties are due to a variety of causes, such as, the rapid growth in the volume of network-available information and the increasing complexity, diversity and terminological fluctuations of the different information sources available. This paper presents a conceptual architecture for the organization information space across collections of component systems in a multi-database network that provides serendipity, exploration and contextualisation support so that users can achieve logical connections between concepts they are familiar with and schema terms employed in multi-database systems. Large-scale searching for multi-database schema information is guided by a combination of lexical, structural and semantic aspects of schema terms in order to reveal more meaning both about the contents of an information term and about its placement within the distributed information space.     

Evolution of XML schemas and documents from stereotyped UML class models: A traceable approach

Context

UML and XML are two of the most commonly used languages in software engineering processes. One of the most critical of these processes is that of model evolution and maintenance. More specifically, when an XML schema is modified, the changes should be propagated to the corresponding XML documents, which must conform with the new, modified schema.

Objective

The goal of this paper is to provide an evolution framework by which the XML schema and documents are incrementally updated according to the changes in the conceptual model (expressed as a UML class model). In this framework, we include the transformation and evolution of UML profiles specified in UML class models because they are widely used to capture domain specific semantics.

Method

We have followed a metamodeling approach which allowed us to achieve a language independent framework, not tied to the specific case of UML-XML. Besides, our proposal considers a traceability setting as a key aspect of the transformation process which allows changes to be propagated from UML class models to both XML schemas and documents.

Results

As a general framework, we propose a Generic Evolution Architecture (GEA) for the model-driven engineering context. Within this architecture and for the particular case of the UML-to-XML setting, our contribution is a UML-to-XML framework that, to our knowledge, is the only approach that incorporates the following four characteristics. Firstly, the evolution tasks are carried out in a conceptual model. Secondly, our approach includes the transformation to XML of UML profiles. Thirdly, the proposal allows stereotyped UML class models to be evolved, propagating changes to XML schemas and documents in such a way that the different elements are kept in synch. Finally, we propose a traceability setting that enables evolution tasks to be performed seamlessly.

Conclusions

Generic frameworks such as that proposed in this paper help to reduce the work overload experienced by software engineers in keeping different software artifacts synchronized.     

The Piazza peer data management system

Intuitively, data management and data integration tools are well-suited for exchanging information in a semantically meaningful way. Unfortunately, they suffer from two significant problems: They typically require a comprehensive schema design before they can be used to store or share information and they are difficult to extend because schema evolution is heavyweight and may break backward compatibility. As a result, many small-scale data sharing tasks are more easily facilitated by nondatabase-oriented tools that have little support for semantics. The goal of the peer data management system (PDMS) is to address this need: We propose the use of a decentralized, easily extensible data management architecture in which any user can contribute new data, schema information, or even mappings between other peers' schemes. PDMSs represent a natural step beyond data integration systems, replacing their single logical schema with an interlinked collection of semantic mappings between peers' individual schemas. This paper describes-several aspects of the Piazza PDMS, including the schema mediation formalism, query answering and optimization algorithms, and the relevance of PDMSs to the semantic Web.     

Conceptual design of object-oriented database schemas using the binary-relationship model

We describe an algorithmic method for transforming a binary-relationship (BR) conceptual schema to an object-oriented (OO) database schema. The BR schema is a semantically rich diagram that represents the reality being modeled in terms of objects, relationships and constraints. It is easy to understand and serves as a communication tool between users and designers. Therefore it can be created in the early stages of system development, and later on be transformed into a specific OO database schema. The transformation method employs a multi-stage algorithm, which first identifies the essential objects in the BR schema, together with their relationships and constraints. These are then mapped to object classes, attributes, and constraints, maintaining the semantics and all types of constraints present in the conceptual schema.     

分布式多媒体数据库系统的分层体系结构

本文研究分布式多媒体数据库系统的分层体系结构，分析了多媒体数据的表现特征，强调分离出独立的多媒体数据表现模式层的必要性，给出了多媒体数据对象的概念描述，提出了在多媒体计算机概念体系结构基础之上的我媒体数据库系统的分层体系结构框架，并进行了分析，最后给出了灵活的目录制导的分布式多媒体数据库系统结构。     

Towards a new approach to secure database design

The problem of designing and managing a secure database system is considered in this paper. The approach which is proposed is primarily concerned with the security information definition and management in a database environment. A multiphase design methodology is presented reflecting current proposals of database design methodology. In particular four design phases are proposed: requirements analysis of the security system, conceptual, logical and physical design of security information. The content and the solution techniques of each phase are examined. A database management system architecture is also presented which is suitable to control access rights to the database.