A CASE tool for conceptual database design

The paper describes a Computer Aided Software Engineering (CASE) tool to support conceptual database modelling. One popular approach for conceptual database modelling is use of the Entity-Relationship (ER) model. The paper proposes the use of an Enhanced Entity-Relationship (EER) model for conceptual database modelling. This Enhanced Entity-Relationship model extends the Entity-Relationship model by incorporating the generalization/specialization, aggregation and categorization abstractions. The CASE tool, which is based on the Enhanced Entity-Relationship model, is known as the Enhanced Entity-Relationship Diagrammer (EERD). In addition, the CASE tool supports direct visual query and update based on the EERM.     

面向对象的数据模型设计方法的研究与实现

应用程序处理的数据大部分来源于数据库,数据库中的数据与应用程序交互的数据模型接口存在差异,如何利用更适合应用的＂概念模型＂来处理数据库中的数据,简化应用程序的设计和调用,是软件设计师和数据架构师必须合作解决的问题。利用概念模型的方法将数据在存储和调用过程中的复杂问题简易化,从而为大型应用程序的数据处理提供一种方法。     

Performance evaluation of the object-relational transformation methodology

The emergence of the object-oriented (OO) methodology has shown its capabilities in modelling the real world better than the earlier relational methodology. However, object-oriented databases (OODBs) are still considered immature in comparison with relational databases (RDBs) which have existed for many years. RDBs still continue to dominate the implementation of databases constituting more than 90% of all database implementations [28]. It was felt worthwhile to exploit the great modelling power of OO methodology, while still facilitating relational implementations. These reasons have led us to develop an object-relational transformation methodology [20, 21, 22, 23, 24 and 25] which allows us to use the OO methodology for data modelling and to transform it into a relational logical model for implementation in relational database management systems (RDBMSs). The main purpose of this paper is to present a performance evaluation of the transformation methodology. The evaluation covers I/O cost models of different types of queries. The type of evaluation is basically comparison-based, in which the performance of SQL operations upon a set of tables derived from the relational data model is compared with the tables derived from the OO data model using the transformation methodology. The results of the evaluation show that the performance of the RDB implementation transferred from an OO conceptual model using our object-relational transformation methodology is better than the relational implementation using a conventional relational modelling. Moreover, in many cases, the relational modelling is not applicable since it cannot capture the design semantics particularly relating to collection types. Our object-relational methodology solves this problem.     

SEAM: A state-entity-activity-model for a well-defined workflowdevelopment methodology

Current conceptual workflow models use either informally defined conceptual models or several formally defined conceptual models that capture different aspects of the workflow, e.g., the data, process, and organizational aspects of the workflow. To the best of our knowledge, there are no algorithms that can amalgamate these models to yield a single view of reality. A fragmented conceptual view is useful for systems analysis and documentation. However, it fails to realize the potential of conceptual models to provide a convenient interface to automate the design and management of workflows. First, as a step toward accomplishing this objective, we propose SEAM (State-Entity-Activity-Model), a conceptual workflow model defined in terms of set theory. Second, no attempt has been made, to the best of our knowledge, to incorporate time into a conceptual workflow model. SEAM incorporates the temporal aspect of workflows. Third, we apply SEAM to a real-life organizational unit's workflows. In this work, we show a subset of the workflows modeled for this organization using SEAM. We also demonstrate, via a prototype application, how the SEAM schema can be implemented on a relational database management system. We present the lessons we learned about the advantages obtained for the organization and, for developers who choose to use SEAM, we also present potential pitfalls in using the SEAM methodology to build workflow systems on relational platforms. The information contained in this work is sufficient enough to allow application developers to utilize SEAM as a methodology to analyze, design, and construct workflow applications on current relational database management systems. The definition of SEAM as a context-free grammar, definition of its semantics, and its mapping to relational platforms should be sufficient also, to allow the construction of an automated workflow design and construction tool with SEAM as the user interface     

一种通用聚合算法在统计工作中的应用研究

目前政府统计部门正在积极建设统计数据库,统计数据库具有典型的多维特征。同时,统计业务人员经常要对各种级别的统计数据尤其是汇总级的数据进行所谓的即席查询(Ad-hoc query)。为了实现这一点,大多数统计查询和分析系统依赖于关系数据库平台本身提供的OLAP功能和接口,造成应用系统与数据库系统紧耦合反而降低了应用系统的可移植性。文中根据统计数据库多维特征和OLAP聚合操作的原理提出一种跨数据库系统平台的通用聚合算法,并成功应用于统计工作中,有效地解决了上述问题。     

Evaluating the quality of entity relationship models

Entity Relationship (E-R) models are at the core of logical database design. This paper describes the development of a model, associated metrics and methodology for assessing the quality of an E-R model. The model was developed by investigating into the causal relationships between ontological and behavioural factors influencing data quality. The methodology describes aggregation of the scores on various metrics to calculate an overall quality score for an E-R model, and use of the model to identify problem areas if the individual quality scores on different factors do not meet organizational standards. Further possible improvement of the model and future research issues are also discussed.     

Developing secure data warehouses with a UML extension

Data Warehouses (DWs), Multidimensional (MD) Databases, and On-Line Analytical Processing Applications are used as a very powerful mechanism for discovering crucial business information. Considering the extreme importance of the information managed by these kinds of applications, it is essential to specify security measures from the early stages of the DW design in the MD modeling process, and enforce them. In the past years, some proposals for representing main MD modeling properties at the conceptual level have been stated. Nevertheless, none of these proposals considers security issues as an important element in its model, so they do not allow us to specify confidentiality constraints to be enforced by the applications that will use these MD models. In this paper, we will discuss the specific confidentiality problems regarding DWs as well as present an extension of the Unified Modeling Language for specifying security constraints in the conceptual MD modeling, thereby allowing us to design secure DWs. One key advantage of our approach is that we accomplish the conceptual modeling of secure DWs independently of the target platform where the DW has to be implemented, allowing the implementation of the corresponding DWs on any secure commercial database management system. Finally, we will present a case study to show how a conceptual model designed with our approach can be directly implemented on top of Oracle 10g.     

Fact-oriented modelling for data analysis

Abstract. Although entity-relationship modelling is the most popular means of specifying the conceptual schema for the data perspective of an information system, an alternative design approach known as fact-oriented modelling appears to offer advantages. This paper provides an overview of fact-oriented modelling, including some recent revisions and an evaluation of how the method has coped with large-scale practical applications. One distinguishing feature of the approach is its emphasis on natural verbalization of information examples in terms of elementary facts. This notion of elementarity is clarified to cater for a problematic case involving compositely identified object types. Finally, the algorithm for mapping a conceptual to a relational schema is revised to cater for lazy object types.     

Database design with user-definable modelling concepts

Modelling is an integral part of engineering processes. Consequently, database design for engineering applications should take into account the modelling concepts used by engineers. On the other hand, these applications exhibit a wide diversity of modelling concepts. Rather than consolidating these into one single semantic data model one should aim for correspondingly specialized semantic models. This paper takes a constructive approach to developing such specialized models by proposing an Extensible Semantic Model (ESM) as the basis for declaring specialized semantic data models. The paper introduces a computerized environment for database design based on an ESM, and discusses the consequences of the ESM for a number of design tools: the need for a formal definition of the notion of modelling concept in order to have reliable and precise foundation for the extensions, declarative techniques for quickly introducing graphical representations for new concepts and for using them during schema design, conceptual-level test data generation for a designer-oriented evaluation of designs, and optimization techniques to control the wide latitude in mapping a conceptual schema to a logical schema. First experiences seem to point to considerable productivity gains during database design.     

面向机械产品概念设计的知识库设计研究

针对机械产品概念设计中设计知识功能语义定义模糊和隐形知识重用率低的问题, 研究了基于领域本体表示的知识库设计方法,支持设计知识的自助发布管理和语义信息检索等 功能。提出设计知识表示的本体模式和建模方法,建立领域本体;从概念设计方案需求粒度、 功能目标及企业知识自管理等方面考虑,建立多维设计知识分类体系;设计JSON 文件到OWL 文件的映射规则,实现设计知识的发布、维护、存储和检索。最终实现面向机械产品概念设计 的知识管理,为企业设计人员提供知识共享和重用,支持产品概念设计的方案创新。     

Bridging Ontologies and Conceptual Schemas in Geographic Information Integration

Integration of geographic information has increased in importance because of new possibilities arising from the interconnected world and the increasing availability of geographic information. Ontologies support the creation of conceptual models and help with information integration. In this paper, we propose a way to link the formal representation of semantics (i.e., ontologies) to conceptual schemas describing information stored in databases. The main result is a formal framework that explains a mapping between a spatial ontology and a geographic conceptual schema. The mapping of ontologies to conceptual schemas is made using three different levels of abstraction: formal, domain, and application levels. At the formal level, highly abstract concepts are used to express the schema and the ontologies. At the domain level, the schema is regarded as an instance of a generic data model. At the application level, we focus on the particular case of geographic applications. We also discuss the influence of ontologies in both the traditional and geographic systems development methodologies, with an emphasis on the conceptual design phase.     

Object-relational complex structures for XML storage

XML data can be stored in various database repositories, including Object-Relational Database (ORDB). Using an ORDB, we get the benefit of the relational maturity and the richness of Object-Oriented modeling, including various complex data types. These data types resemble the true nature of XML data and therefore, the conceptual semantic of XML data can be preserved. However, very often when the data is stored in an ORDB repository, they are treated as purely flat tables. Not only do we not fully utilize the facilities in current ORDB, but also we do not preserve the conceptual semantic of the XML data.In this paper, we propose novel methodologies to store XML data into new ORDB data structures, such as user-defined type, row type and collection type. Our methodology has preserved the conceptual relationship structure in the XML data, including aggregation, composition and association. For XML data retrieval, we also propose query classification based on the current SQL.Compared to the existing techniques, this work has several contributions. Firstly, it utilizes the newest features of ORDB for storing XML data. Secondly, it covers a full database design process, from the conceptual to the implementation phase. Finally, the proposed transformation methodologies maintain the conceptual semantics of the XML data by keeping the structure of the data in different ORDB complex structures.     

B2B集成技术的体系结构

介绍了B2B集成技术的体系结构和概念上的模型，用来支持统一概念集成模型中并发的A2A和B2B集成。概念集成模型通过设计时仓库完成，集成模型作为元数据存储在设计时仓库。B2B集成技术的执行时范例完成实际的应用和贸易伙伴商务交易遵循编译的方法，根据存储在设计时仓库中的集成模型，执行器完成实际的集成实例。     

Implementation design for databases: the `forgotten' step

Most methodologies for database analysis and design specify conceptual, logical, and physical design as the three major design steps. However, although this three-step approach is popular, there is no consensus on when to use implementation design techniques, such as table partitioning and denormalization. Consequently, these techniques are treated as substeps in one of the three main design steps. This inconsistent treatment may be why many designers frequently rely on their intuition in applying implementation design techniques. Clearly, this ad hoc practice shouldn't continue. Ad hoc anything is not a good idea when designing a complex system. To resolve this problem, the author proposes that we extend the three-step methodology to include a fourth major step: implementation design. In this methodology, implementation design is the process of modifying an “ideal” logical data model (relational or object-oriented) to produce a more machine-efficient, “pragmatic” model: the implementation model. The implementation model, in turn, serves as input to the physical design step. This four-step method will encourage practitioners to resist the ad hoc approach and simplify the other design steps. It will also help in addressing the additional complexity associated with advanced database architectures, such as distributed and parallel databases and data warehouses     

A conceptual database design approach based on rules and heuristics

Conceptual and logical database design are complex tasks for non-expert designers. Currently, the popular data models for conceptual and logical database design are the entity–relationship (ER) and the relational model, respectively. Logical design methodologies for relational databases have relied on mathematically rigorous approaches which are impractical, or textbook approaches which do not provide the rich constructs to capture real applications. Consequently, designers have to use their intuition to develop their own rules and heuristics. There is a need, therefore, to develop practical rules and heuristics that can be used to handle the complexity of design in real applications. This paper proposes a realistic and detailed approach for conceptual design using the ER model for relational databases. The approach is based on four rules that specify the order in which various types of relationships must be modelled, three rules that pertain to detection of derived relationships, and three heuristics based on observation of constructs in real applications. The approach is illustrated by many examples.     

一种基于UML的双时态概念模型

随着数据库技术的发展,信息系统对时鸯信息的处理需求越来越强烈。尽管出现了一些时态数据库管理系统,如TimeDB,但这些时态数据模型仍存在着一些不足。该文参考双时态概念数据模型BCDM,对UML类图进行扩展,提出了一种支持时态信息概念建模的概念模型UTCM,UTCM能够支持对时态信息的概念建模,并易于在成熟的DBMS产品上进行实现;     

Mapping Considerations in the Design of Schemas for the Relational Model

The typical design process for the relational database model develops the conceptual schema and each of the external schemas separately and independently from each other. This paper proposes a new design methodology that constructs the conceptual schema in such a way that overlappings among external schemas are reflected. If the overlappings of external schemas do not produce transitivity at the conceptual level, then with our design method, the relations in the external schemas can be realized as a join over independent components. Thus, a one-to-one function can be defined for the mapping between tuples in the external schemas to tuples in the conceptual schema. If transitivity is produced, then we show that no such function is possible and a new technique is introduced to handle this special case.