Schema Transformation Research Articles

Sequencing material handling equipment in production facilities

AbstractIn this article we consider the problem of sequencing material handling equipment in manufacturing systems, subject to constraints that restrict the start and end time of each production activity, according to pre‐specified daily resource operational schedules and process planning information. The underlying decision problem is modeled using an integer programming formulation similar to vehicle routing with time windows (VRPTW). To take advantage of standard approaches for the VRPTW, we develop a transformation schema that allows a one‐to‐one mapping between the manufacturing problem and VRPTW. An efficient heuristic to solve the resulting transformed problem is proposed. The method, which is a penalty‐based sequential insertion heuristic, allows routes to be constructed by exploiting the tradeoff between material handling and resource starvation costs. The steps of the method are illustrated via a comprehensive example and results on benchmark problems are reported.

An XML-Based Middleware for Information Integration of Enterprise Heterogeneous Systems

Nowadays, most data in enterprise systems is still stored in relational databases, which brings the majority of difficulties to achieve information interoperation between enterprise-level heterogeneous systems. In this context, we propose a middleware to integrate information from heterogeneous enterprise system based on XML standard. The proposed integration architecture aims at providing a coherent and meaningful view of the integrated heterogeneous information systems by leverage the back-end relational data sources. The architecture of the middleware relies on the well-known mediator/wrapper architecture and satisfies the semantic integration features by several main functions including data descriptions, schema transformations and integrations based on the XML-Schema standard.

Semantic Integration of Manufacturing Data Sources

In order to gain insight into business processes, multiple autonomous data sources residing in the manufacture enterprise need to integrate not only on storage and access methods but also capturing the meaning of data to get a coherent and meaningful data views for different applications requirements. This paper presents a semantic-based architecture for the integration of heterogeneous manufacturing data sources. The integration is realized on a semantic level by the explicit presentation of data semantics with ontology and relationships between ontologies. During applications usage, heterogeneous data sources which represent relations of relevance are dynamically organized in terms of their semantics. The paper discusses some major problems in the architecture: unified schema transformation, semi-automatic ontology generation and mediation.

Reverse engineering relational databases to identify and specify basic Web services with respect to service oriented computing

Service-oriented computing (SOC) is the computing paradigm that utilizes services as a fundamental building block. Services are self-describing, open components intended to support composition of distributed applications. Currently, Web services provide a standard-based realization of SOC due to: (1) the machine-readable format (XML) of their functional and nonfunctional specifications, and (2) their messaging protocols built on top of the Internet. However, how to methodologically identify, specify, design, deploy and manage a sound and complete set of Web services to move to a service-oriented architecture (SOA) is still an issue. This paper describes a process for reverse engineering relational database applications architecture into SOA architecture, where SQL statements are insulated from the applications, factored, implemented, and registered as Web services to be discovered, selected, and reused in composing e-business solutions. The process is based on two types of design patterns: schema transformation pattern and CRUD operations pattern. First, the schema transformation pattern allows an identification of the services. Then the CRUD operations pattern allows a specification of the abstract part of the identified services, namely their port types. This process is implemented as a CASE tool, which assists analysts specifying services that implement common, reusable, basic business logic and data manipulation.

Automated Derivation of Translators From Annotated Grammars

In this paper we propose a technique to automate the process of building translators between operations languages, a family of DSLs used to program satellite operations procedures. We exploit the similarities between those languages to semi-automatically build a transformation schema between them, through the use of annotated grammars. To improve the overall translation process even more, reducing its complexity, we also propose an intermediate representation common to all operations languages. We validate our approach by semi-automatically deriving translators between some operations languages, using a prototype tool which we implemented for that purpose.

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.

AN INTERACTIVE TOOL BASED ON XML TECHNOLOGY FOR DATA EXCHANGE BETWEEN HETEROGENEOUS ERP SYSTEMS

ABSTRACT Data exchange between enterprise resource planning (ERP) systems in a supply chain system needs to fulfill requirements of both schema integration and message translation. Since ERP systems with relational database systems are developed independently, schema conflicts between databases is a common problem for schema integration. Thus, supply chain partners need to preserve the data integrity of transacting messages with respect to the ERP database systems. The core technique of this kind of data exchange is matching XML documents and relational database schemas. An interactive tool is proposed here to simplify the integration and implementation efforts of data exchange between heterogeneous database systems in the supply chain system. The interactive tool is Web-enabled and it applies XML and XSL to translate trading messages. In order to store XML documents into the relational database, the structure and content of the XML document should be matched with the database schemas and verified by the users. The data contents of the XML document need to be matched not only with data types of the database but also with relational constraints to preserve the data integrity. XML schema and XSL transformation are applied to translate data and solve schema conflicts between XML documents and the database system. Using this interactive tool, the matching methods provide mapping suggestions, and it relies on users with specific schema knowledge to provide final verification of the matching results. This tool provides an environment for administrators and designers of heterogeneous database systems to communicate data requirements, to resolve semantic conflicts, and to preserve data integrity.

Fusing Cooperative Technical-Specification Knowledge Components

In this paper, the problem of fusing various logic-based technical specification knowledge components about a same physical device or process is investigated. It is shown that most standard logic approaches to beliefs and knowledge fusion are not relevant in this context since some rules should be merged even in the case of mutually consistent knowledge components. Accordingly, we discuss the various types of formulas that should be merged during a fusion process, in order to avoid necessary conditions for the absence of failure to become sufficient conditions. This transformation is then described formally. It can be performed as an efficient preprocessing step on the knowledge components to be fused. The properties of this transformation schema are then investigated from a semantical point of view. Finally, a series of subsumption tests are proposed, preventing conditions for the absence of failure from being overridden by subsumption.

공통 문서 구조 추출을 통한 XML DTD의 관계형 데이터 베이스 스키마 변환 기법

XML은 W3C에 제안된 마크업 언어고 HTML의 단순함과 SGML의 복잡함을 극복하여, 웹 상에서 데이터를 표현하고 교환하기 위한 표준으로 등장하고 있다. XML 문서를 질의 처리하기 위한 방법으로 XML 문서 전용 질의 언어가 개발되고 있지만, 데이터의 양이 증가한다면 결국 막대한 양의 데이터를 처리 할 데이터베이스 시스템을 필요하게 된다. 본 논문에서는 XML DTD를 관계형 데이터베이스 시스템 스키마로 변환하는 기법을 제안한다. 제안된 기법은 XML 데이터의 스키마 역할을 하는 DTD의 트리 구조를 생성하여, XML 데이터들의 공통구조와 비공통구조를 추출한 후 관계형 데이터베이스 스키마를 추출하는 기법이다. 추출된 관계형 데이터베이스 스키마는 기존의 방법들에 비해 생성 테이블 수가 적으며, 널(NULL)값의 출현을 감소시킨다. 또한, 제안기법은 XML 데이터를 보다 적은 테이블로 맵핑(mapping)시킴으로써 데이터 검색 시 참조 테이블 수를 감소시킬 수 있으며 질의 처리 시에도 성능 면에서 우수함을 보인다. XML is emerging as a standard data format to exchange and to present data on the Web. There are increasing needs to efficiently store and to query XML data. In this paper. we propose a new schema transformation algorithm based on a common structure extracting technique from XML documents. The common structure is shared by all XML documents referenced by DTD and the uncommon structure is ununiformly appeared on all XML documents referenced by DTD. Based on the extracted common and uncommon structures, we transform XML DTD into relational database schema. We conduct a performance evaluation based on the number of the generated tables, the size of the record, query processing time and the number of joins on the query. The performance of our algorithm is compared with the existing algorithms, then in most cates, our algorithm is better than the existing ones with respect to the number of the generated tables and appearance of NULL values in the tables.

Representing and Reasoning on Database Conceptual Schemas

In this paper we address the problem of reasoning about database conceptual schemas by exploiting the possibility of using a description logic. We develop an approach by using as a foundation an entity-relationship model that displays features such as ISA, disjointness and cardinality constraints. We propose an equivalence-preserving transformation of entity relationship schemas into terminologies in a description logic. This equivalence, based on the measure of information capacity, ensures that the semantics of entity-relationship schemas is accurately captured by the corresponding terminologies. As a consequence, reasoning on entity-relationship schemas is appropriately reduced to reasoning on terminologies in a description logic.

Evolving object-oriented designs with refactorings

Refactorings are behaviour-preserving program transformations that automate design-level changes in object-oriented applications. Our previous research established that many schema transformations, design patterns and hot-spot meta-patterns are automatable. This research evaluates whether refactoring technology can be transferred to the mainstream by restructuring non-trivial C++ applications. The applications that we examine were evolved manually by software engineers. We show that an equivalent evolution could be reproduced significantly faster and cheaper by applying a handful of general-purpose refactorings. In one application, over 14 K lines of code, that otherwise would have been coded by hand, were transformed automatically. Our experiments identify the benefits, limitations and topics of further research related to the transfer of refactoring technology to a production environment.

An extendible language for database schema refinement transformations

The paper presents a formal language for specifying database schema transformations. This language consists of a set of primitive operators and a composition operator. Each of the primitive operators has associated the conditions under which it can be applied. A rule is given for generating the applicability conditions of a composed transformations from those of the component transformations. The paper shows how this language can be exploited for supporting a flexible and correct database schema design also when other transformational frameworks are used. © 2001 John Wiley & Sons, Inc.

A hybrid approach to convert relational schema to object-oriented schema

In the paradigm of DataBase Re-Engineering (DBRE), reverse-engineering data semantics by schema translation from lower level of abstraction such as relational schema to a higher level of abstraction such as Extended Entity Relational (EER) model has been, in the past, extensively studied with due to its relative simplicity in matching. However, schema transformation from EER model to Object-Oriented DataBase (OODB) schema is not straightforward due to its missing of dynamic semantic representation, since an Object-Oriented (OO) schema should contain both the structure and operations of the data objects. In this paper, we describe a hybrid approach which applies both heuristic learning techniques in discovering the behavioural semantics from relational schema and knowledge-based approach in recovering static and structural semantics, to reach a complete conversion. A practical case is applied through an implemented prototype to validate the effectiveness of our methodology.

Equivalence of Keyed Relational Schemas by Conjunctive Queries

The concept of two schemas being equivalent is fundamental to database design, schema integration, and data model translation. An important notion of schema equivalence, query equivalence, was introduced by Atzeni et al., and used to evaluate the correctness of schema transformations. The logically equivalent notion of calculous equivalence, as well as three progressively more general notions of schema equivalence were introduced in 1984 by Hull, who showed that two schemas with no dependencies are equivalent (under all four notions of equivalence) if and only if they are identical (up to renaming and re-ordering of attributes and relations). Hull also conjectured that the same result holds for schemas with primary keys. In this work, we resolve the conjecture in the affirmative for the case of query equivalence based on mappings using conjunctive relational queries with equality selections.

A general formal framework for schema transformation

Several methodologies for integrating database schemas have been proposed in the literature, using various common data models (CDMs). As part of these methodologies, transformations have been defined that map between schemas which are in some sense equivalent. This paper describes a general framework for formally underpinning the schema transformation process. Our formalism clearly identifies which transformations apply for any instance of the schema and which only for certain instances. We will illustrate the applicability of the framework by showing how to define a set of primitive transformations for an extended ER model and by defining some of the common schema transformations as sequences of these primitive transformations. The same approach could be used to formally define transformations on other CDMs.

Migrating to an object-oriented database using semantic clustering and transformation rules

This paper presents a methodology for handling an important step of database migration. The methodology is based on a set of techniques: (i) semantic clustering, (ii) metamodeling, and (iii) knowledge-based schema transformation. Semantic clustering (i.e., grouping based on semantic cohesion) is mainly used to facilitate the process of translating an extended entity relationship schema into a schema of complex objects. Meta modeling is used to define the data models involved in the process of schema transformation. Finally, transformation rules are defined and used for mapping a schema from a source model into a schema expressed in a target model. In this paper, we limit ourselves to the mapping of an extended entity relationship diagram into an object-oriented database schema using the object model supported by the ODMG standard.

Aesthetics and the Environment

This article presents a framework for understanding aesthetic experience, with special reference to the natural environment. The framework entails 2 broad perspectives. First, from a functional perspective, aesthetic experiences are analyzed in terms of biological, sociocultural, and psychological systems of behavior; succinctly stated, objects are experienced aesthetically if they activate cognitive representations of response patterns that do or did contribute to the survival or enhancement of the species, society, or the self. Second, from the perspective of mediating mechanisms, the cognitive processes that enable aesthetic experiences are examined. The mechanisms discussed range from simple sensory processes to the activation and transformation of complex schemas. To the extent that cognitive representations of behavioral systems are flexible and subject to elaboration and refinement, aesthetic experience is a creative, skillful act.

Semantic schema refinements for multilevel schema integration

Within the database field, schema refinements have been proved useful for documentation and maintenance purposes; moreover, schemata describing the reality of interest at different levels of abstraction are extensively used in Computer Aided Software Engineering tools and visual query languages. So, much effort has been spent in analyzing schema transformations and schema refinements. Till now, however, while the syntaxof schema transformations has been deeply investigated, the semantics has been very often neglected. In this paper we present a full formal framework, supporting both the syntax and the semantics of schema refinements. Such a formal framework is used to support a methodology able to merge a set of schemata and the top-down chains of refinement planes produced during their design. The result of this kind of integration, that we call multilevel integration, is an integrated schema plus an associated top-down chain of schemata. The integrated schema and the chain are related to the input schemata by interesting properties, giving rise to a two-dimensional structure useful for exploring the data content of complex information systems.

Verification and Transformation of Complex and Uncertain Conceptual Schemas

In database environment, it is necessary to represent complex and uncertain information at conceptual level and then transform the conceptual schema into the logical one for ultimate implementation. It is also important to verify the conceptual schema with respect to the constraints imposed on the schema definition. In this paper we primarily focus on the verification and transformation of the conceptual schema. For the purpose of verification of the conceptual schema represented by the ExIFO data model (the extension of the IFO data model), we introduce a number of invariants. We also describe the transformation algorithm for mapping the conceptual specification into a logical database schema represented with the extended NF 2 database model. The system that we describe in this paper is implemented and it can test whether the given ExIFO specification is valid and transforms the conceptual specification into the logical schema. The transformation algorithm is computationally efficient and preserves the knowledge represented with verified conceptual schema.

Applications of a categorical framework for conceptual data modeling

For successful information systems development, conceptual data modeling is essential. Nowadays a plethora of techniques for conceptual data modeling exist. Many of these techniques lack a formal foundation and a lot of theory, e.g. concerning updates or schema transformations, is highly data model specific. As such there is a need for a unifying formal framework providing a sufficiently high level of abstraction. In this paper, focus is on the applications of such a framework defined in category theory. Well-known conceptual data modeling concepts, such as relationship types, generalization, specialization, and collection types are defined from a categorical point of view in this framework and an essential advantage is its “configurable semantics”. Features such as null values, uncertainty, and temporal behavior can be added by selecting appropriate instance categories. The addition of these features usually requires a complete redesign of the formalization in traditional set-based approaches to semantics. Applications of the framework in the context of schema transformations and improved automated modeling support are discussed.