Introduction

1.1 Background

The Resource Description Framework (RDF) is a model developed by the W3C for representing information about resources in the World Wide Web. Topic Maps is a standard for knowledge integration developed by the ISO. The two specifications were developed in parallel during the late 1990's within their separate organizations for what at first appeared to be very different purposes. The results, however, turned out to have a lot in common and this has led to calls for their unification.

While unification has to date not been possible (for a variety of technical and political reasons), a number of attempts have been made to uncover the synergies between RDF and Topic Maps and to find ways of achieving interoperability at the data level. There is now widespread recognition within the respective user communities that achieving such interoperability is a matter of some urgency. This document is the result of the work done by the Semantic Web Best Practices and Deployment Working Group of the W3C with the support of the ISO Topic Maps committee to address this issue. It provides a set of Guidelines for users who want to combine usage of the W3C's RDF/OWL family of specifications and the ISO's family of Topic Maps standards.

1.2 Purpose and target audience

The purpose of this document is to present a solution to the problem of RDF/Topic Maps interoperability at the data level. It consists of guidelines that describe how to author topic maps and RDF documents in order to ensure maximum interoperability, and a set of rules for performing automated translation between RDF and Topic Maps.

As the word guidelines might suggest, this document contains a possible way to perform the translation between RFD and Topic Maps and it is advised as best practice. It is the result of the analysis of different possible approaches which are in part described in [Survey].

The goal is to be able to translate data from one form to the other without unacceptable loss of information or corruption of the semantics. Furthermore, it must be possible to query the results of a translation in terms of the target model and it must be possible to share vocabularies across the two paradigms.

[RDF-Schema] and [OWL] are considered relevant to this work to the extent that the classes and properties they define are supportive of its goals.

However, the followings are explicity not goals of the current work:

• to enable the general use of RDF Schema and OWL with Topic Maps, although this issue may be addressed later;
• to provide the mapping between the RDF and Topic Maps models.

This document is aimed at anyone with an interest in the problem of RDF/Topic Maps interoperability and a willingness to acquire the necessary understanding of both formalisms. In particular it targets authors of Topic Maps and RDF documents; creators of tools for translating between RDF and Topic Maps; and those who seek reassurance that data can be easily reused across the two paradigms. The reader is expected to be familiar with both RDF and Topic Maps to a level that at least corresponds to the tutorial material in [Pepper 00] and [RDF-Primer]. To fully understand Chapter 5, the reader must in addition be familiar with the models described in [TMDM] and [RDF-Semantics], and the syntaxes described in [LTM] and [N3].

Comments and reviews

Fabio

Two very fast reflections on the overall process of developing the guidelines:

1. They are guidelines: that is to say, suggestions. They are not meant to provide the mapping between RDF and TM, which does not exist. Rather, they are meant to identify, among the thousand possible ways to convert one language to the other, the one that we are willing to endorse. Other will still be possible, but we choose one, and only one, and provide reasons for the choice. Summary: choose the best, but choose one.
2. The overall objective is to provide interchangeably query-able document sets, not identity of models. That is to say, if we manage to obtain good queries by converting the underlying model, that's fine. If, otherwise, it is necessary to stretch things a little bit, or not to convert parts of the data that are not relevant to the queries anyway, I say we should not bother. Summary: never give up queryability for completeness.

• Set IMMEDIATENOTIFY = FabioVitali, ValentinaPresutti, NicolaGessa, LarsMarius, StevePepper

LarsMarius

This looks fine for now. I don't think we should be working on the introduction now. Let's work out how we want to approach this, and what the solution to each of the problems is first. Then we can return to the introduction and polish it, but wordsmithing is not what we should be doing now.

Nicola

Fine for now; anyway, we have to bear in mind the set of requirements that we have listed in the previous document: we have eight MUST and six SHOULD that concern the aim and the scope of RDFTM. Do they need to be reorder with new priorities to clarify our work and answer to the objections, or not (or do we need new requirements)? Otherwise we can use them as they are. Perhaps it is not so clear that we not want to provide an unified semantic model for RDF and TM.
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