Jorge Lloret

Evolving XML schemas and documents using UML class diagrams

The widespread use of XML brings new challenges for its integration into general software development processes. In particular, it is necessary to keep the consistency between different software artifacts and XML documents when evolution tasks are carried out. In this paper we present an approach to evolve XML schemas and documents conceptually modeled by means of UML class diagrams. Evolution primitives are issued on the UML class diagram and are automatically propagated down to the XML schema. The XML documents are also automatically modified to conform to the new XML schema. In this way, the consistency between the different artifacts involved is kept. This goal is achieved by using an intermediate component which reflects how the UML diagrams are translated into the XML schemas.

MeDEA: A database evolution architecture with traceability

One of the most important challenges that software engineers (designers, developers) still have to face in their everyday work is the evolution of working database systems. As a step for the solution of this problem in this paper we propose MeDEA, which stands for Metamodel-based Database Evolution Architecture. MeDEA is a generic evolution architecture that allows us to maintain the traceability between the different artifacts involved in any database development process. MeDEA is generic in the sense that it is independent of the particular modeling techniques being used. In order to achieve this, a metamodeling approach has been followed for the development of MeDEA. The other basic characteristic of the architecture is the inclusion of a specific component devoted to storing the translation of conceptual schemas to logical ones. This component, which is one of the most noteworthy contributions of our approach, enables any modification (evolution) realized on a conceptual schema to be traced to the corresponding logical schema, without having to regenerate this schema from scratch, and furthermore to be propagated to the physical and extensional levels.

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.

A survey of UML models to XML schemas transformations

UML is being increasing used for the analysis and design of Web Information Systems. At the same time, many XML-based languages are cornerstones in the development of this kind of system. As a consequence of the predominance of these languages, there are many works in the literature devoted to exploring the relationships between UML and XML. In this paper we present a survey of current approaches to the transformation of UML models into XML schemas. The study is focused on the case of transformation of UML class diagrams to XML schemas, since we have not found any proposal regarding other kinds of UML diagrams.

An Architecture for Managing Database Evolution

This paper presents an architecture for managing database evolution when all the components of the database (conceptual schema, logical schema and extension) are available. The strategy of evolution in which our architecture is based is that of ‘forward database maintenance’, that is, changes are applied to the conceptual schema and propagated automatically down to the logical schema and to the extension. In order to put into practice this strategy, each component of a database is seen under this architecture as the information base of an information system. Furthermore, a translation information system is considered in order to manage the translation of conceptual elements into logical schema elements. A current Oracle implementation of this architecture is also presented.

Model---Driven, View---Based Evolution of Relational Databases

Among other issues, database evolution includes the necessity of propagating the changes inside and between abstraction levels. There exist several mechanisms in order to carry out propagations from one level to another, that are distinguished on the basis of when and how the changes are performed. The strict mechanism, which implies the immediate realization of modifications, is a time---consuming process. In this paper we propose a solution that is closer to the lazy and logical mechanisms, in which changes are delayed or not finally realized, respectively. This solution makes use of the notion of view. The use of views allows the data not to be changed if it is not necessary and facilitates carrying out changes when required.

Model-driven development based transformation of stereotyped class diagrams to XML schemas in a healthcare context

The health sector uses clinical guidelines as instruments for helping decision making. We are interested in the development of a ubiquitous decision support system (UDSS) for clinical guidelines in order to help the medical staff in their decisions and in order to record a trace of the application of the guidelines. For the development of such a system in a Model-Driven Development (MDD) setting, we propose the use of class diagrams of the Unified Modeling Language (UML) with stereotypes and eXtensible Markup Language (XML) schemas. When both languages, UML and XML, have to share a common modelling space, the necessity of transforming UML models into XML schemas arises. However, to our knowledge, previous transformation proposals do not consider the case in which some profiles have been applied to the UML model. For this reason, in this paper we propose a set of rules for translating stereotyped UML class diagrams into XML schemas, storing a trace of the application of the guideline.

Validation of XML documents: from UML models to XML schemas and XSLT stylesheets

The widespread use of XML brings out the need of ensuring the validity of XML data. The use of languages such as XML Schema makes easier the process of verification of XML documents, but the problem is that there are many constraints that can not be expressed by means of XML Schema. Besides, several works in the literature defend the consideration of a conceptual level in order to save XML designers from dealing with low level implementation issues. The approach of this paper is based on the inclusion of such a conceptual level, using UML as a conceptual modeling language. Starting from a UML class diagram annotated with conceptual constraints, our framework automatically generates an XML Schema together with a set of XSLT stylesheets to check those integrity constraints that can not be expressed in XML Schema.

Elementary Translations: The Seesaws for Achieving Traceability Between Database Schemata

There exist several recent approaches that leverages the use of model transformations during software development. The existence of different kinds of models, at different levels of abstraction, involves the necessity of transferring knowledge from one model to another. This framework can also be applied in the context of metadata management for database evolution, in which transformations are needed both to translate schemata from one level to another and to modify existing schemata. In this paper we introduce the notions of translation rule and elementary translation which are used within a forward database maintenance strategy.

Integrity Constraint Enforcement by Means of Trigger Templates

The specification of data integrity controls in DBMS, and particularly support for triggers, is one of the most important features for database developers and administrators. However, it is recognized that the specification of a correct set of triggers is a difficult and error-prone task. Our proposal aims to facilitate such a task by suggesting a different method for determining constraints and triggers that check constraints when database updates take place. Specifically, the method proposes to define trigger templates in order to enforce constraints imposed in a schema pattern and to store them in a database. When the analyst specifies a particular conceptual schema (which matches the schema pattern) the associated triggers are automatically generated from the information stored in the trigger template database.