Mapping Rules to Convert from ODL to XML-SCHEMA Artur Afonso de Sousa 1 , José Luís Pereira 2 and João Álvaro Carvalho 2 1 Escola Superior de Tecnologia de Viseu, Departamento de Informática, Portugal ajas@di.estv.ipv.pt 2 Universidade do Minho, Departamento de Sistemas de Informação, Guimarães, Portugal {jlmp, jac}@dsi.uminho.pt Abstract As new standards for technology specifications related to XML are unveiled, and stable tools to implement them become available, the widespread usage of XML as an universal format for data exchange between heterogeneous systems (using the Internet), will increasingly become a reality. Therefore, in order to deal efficiently with the large amounts of XML data that will be generated in the near future it is imperative to find efficient alternatives for the storage and management of this special kind of data. For that matter, object-oriented databases seem to be a good alternative. In this paper, we begin with an analysis of the different alternatives available to store and manage XML data. After that, we concentrate our attention on the Object-Oriented (OO) database approach and, in that context, we present a first set of rules that allow the translation from a simple database schema specified in ODL (Object Definition Language) into a schema specified in XML-SCHEMA. In the near future we intend not only to expand this set with new rules that will handle other, more complex, OO modeling constructs, but also to create another set of transformation rules to work the other way round (i. e. from XML-SCHEMA to ODL). Our aim is to cover all the possible modeling situations one may come across in OO database schemas specified in ODL. 1. Introduction Everyone agrees that, despite its infancy, XML promises to revolutionize the future of the WWW. Due to its flexibility and extensibility, some even consider that XML has all the qualities to become the “lingua franca” of the Internet. Indeed, the expectations around XML are increasingly high, particularly in the area of data interchange between heterogeneous systems connected to the Internet. Therefore, in order to deal efficiently with the large amounts of XML data that, certainly, will be generated and exchanged between systems in the near future, it is essential to analyze the different options available regarding the storage and management of this special kind of data. In the database community there are different opinions about the merits of each database model in dealing with XML data. There are those who claim that the relational (and object-relational) model is still the best available option, due to its maturity and widespread use in organizations. There are others who argue against the relational model, because of its over simplicity and limited semantic power, and rather prefer the object- oriented model. An increasing number of people are embracing the very recent semi-structured data models and the native systems as the best alternative regarding this matter. So, the point is, everybody claims that “their” model is the right one to store and manage XML data. With this paper we hope to contribute to this discussion, clarifying a little bit more what is involved with the storage and management of XML data using object-oriented databases. With this purpose in mind, we present a first set of nine rules that allow the translation from a simple database schema specified in ODL (Object Definition Language) into a schema specified in XML- SCHEMA [11, 26, 5], which, from a conceptual point of view, seems to be a particularly adequate option. Regarding the structure of this paper: the second section deals with the storage and management of XML data; in the third section we present a set of transformation rules to convert an ODL schema to a XML-SCHEMA schema; finally, the fourth section concludes the paper. 2. Storage and management of XML data Nowadays, there are several alternatives to the storage and management of XML data, namely relational (and object-relational) databases, object-oriented databases, semi-structured databases, native XML databases, and even the file system. XML is quickly becoming the standard for data interchange in the WWW. Therefore, if we take into account that today a large amount of electronic data is stored in relational and object-relational databases, it Proceedings of the XXII International Conference of the Chilean Computer Science Society (SCCC’02) 1522-4902/02 $17.00 © 2002 IEEE