Conference Papers

Museums and the Web: An International Conference
Los Angeles, CA, March 16 - 19, 1997

Martin Doerr, Irene Fundulaki and Vassilis Christophidis

The specialist seeks expert views: Managing digital folders in the AQUARELLE project

September, 1996
Institute of Computer Science
Foundation for Research and Technology - Hellas


The AQUARELLE project will connect researchers and museum specialists in order to enable access to information describing and documenting the European cultural heritage such as painting, sculptures, historical sites and monuments, musical instruments and furniture. One of the main objectives of AQUARELLE is to facilitate the creation and dissemination of information folders and detailed catalogues. The management of cultural information, related to a given theme or activity, in structured collections, so-called folders, play a central role in the AQUARELLE project.

In this paper we present the folder server and editing environment which will support scholars, administrators and conservators to maintain secondary SGML documents, that describe, comment and refer the primary material (image or text bases etc.) across the European borders. The technical challenge of this undertaking is to cater for the diversity in specialization, organizational and cultural context, the data integrity and the adequate high precision in reference and retrieval through the Internet. On the other side, the organization of agreement on shared contents and resources at all levels raises also interesting questions. The project so far provides first solutions and serves moreover as a forum to obtain valid requirements for future extensions.

1. Introduction

The WWW attracts more and more the interest of museums and cultural organizations as a means to project cultural contents, but as well as to exchange information on an international level, addressing not only the typical museum visitor but also the professional curator, documentalist or scientist of any related discipline. The fact, that cultural spaces of the past cross our modern borders, but even more the scattering of cultural material objects all over the world, makes the possibility of cost-efficient international data-exchange very attractive to the professional community. See for instance the various locations of "haystacks" by Monet or of the medieval bronze from Benin, Africa (e.g.

Current WWW technology provides the necessary standardization and global communication structure, but existing tools are somehow limited to manage documents in a professional framework (poor data structures, dangling links, ad-hoc search engines, etc.). The AQUARELLE project (TELEMATICS Application Program of the European Commission, Project IE-2005 1996), relies on the fundamental concept of the Web and intends to provide a reliable and precise access to heterogeneous cultural data sources within an open federation of organizations for mutual benefit. According to the AQUARELLE vision each author of a given information component should be able to link directly a part of his own creation to another information asset created and updated by another author in the Web. The organization of cultural data into structured collections of primary material, called "folders" (a translation of the French term "dossiers"), will bring much more than a simple access to the existing information: linking and commenting relevant pieces of information belonging to different owners will add value to the information content itself. The overall AQUARELLE architecture is designed to guarantee referential integrity as well as to support the adequate high precision in reference and retrieval.

The AQUARELLE project has identified in an initial feasibility study several examples of such folders: sets of pictures collected by a publisher to edit a city guide; supporting documentation for exhibition preparation by museum curators; collections of information elements on monuments and sites at the "Inventaire General" of the French Ministry of Culture ( Depending on the purpose, these collections may need considerable structuring in order to be useful. Relations between collected or referred data and opinions, meanings, domain knowledge, intended or actual use can be rather complex and will be supported by the tools developed in the project. Folders themselves will be a subject of data exchange, giving raise to a cooperative environment the potential of which yet has to be explored.

The strong involvement of user groups in the project helped to identify in a very early stage a series of important requirements specific to the professional aspect of the systems to be developed. It was required to provide high precision semantic indexing in fine granularity under the control of high quality terminology, preferably multilingual, whereas access by uncontrolled terms and data-mining aspects were regarded to be of secondary importance. Rather than using a fixed data structure, specific user groups need the possibility to customize their own data structures in the running system on demand. Finally, it was ranked high to have reliable metadata, especially on database contents.

AQUARELLE has finished the first design phase and it expects to present the first prototype implementation in early spring this year. Being a Technical Integration Project, it is going to solve with first priority the questions of interoperability and reliability of service, based on SGML ( and Z39.50 ( as key standards. This is a major subject of the close cooperation with the Consortium for Interchange of Museum Information (CIMI, which has so far concentrated its implementation efforts (the CHIO project) more on the support of the non-professional user. There is also a cooperation with the Getty Information Institute ( on thesaurus use and multilinguality.

Isolated components of the first prototype exist, and the overall component integration begins in March 1997. Very good progress has been made, which allows us to present here a realistic view of the system to be, but moreover to discuss aspects of its use.

The current paper concentrates on the folder management and indexing, which comes right now into its first prototype stage. Besides the description of the technical choices, we address consequences and open questions of user procedures and organization, which emerged so far or are expected to be outcome of the practical experiences with the system.

2. The Notion of Folders

A folder in the sense of AQUARELLE is a container gathering a structured collection of specific information (text, image, etc.) and links to other documents which relates to a certain theme or an activity. This is typically the first step for most scientific work or planning of cultural programs.

Obvious themes could be cultural objects or monuments, seen under the aspect of construction, material and state, style and artistic expression, function and social or political context. More complex themes could be historical persons, artist schools or any other organization, places at certain periods, or any kind of performance as theater, music, crafts and social events. As folders are seen close to the primary material (called archives), wide-spreading themes as "Impressionism" or "Ming Dynasty" are rather out of scope. The focus is clearly on setting archive material in a context and on the visual aspects of items of the present and the past, i.e. we talk about multimedia documents. Opposite to multimedia authoring, aesthetic aspects of representation will only be regarded to the degree they serve the comprehensiveness of the display. The folders are seen as an auxiliary means for the research, documentation, didactic presentation etc, and not as the presentation itself.

Folders may also be created or used to support characteristic activities of the cultural professional. It may be a documentary service for general use, but more typically the preparation of any kind of documentation and publication, as exhibitions, traditional books, guides etc. or the planning of conservation or restoration activities at a political or technical level. Characteristic is the multitude of reasons, why data are referred and for which purpose they may be regarded as useful (e.g. as in Principia Cybernetica, They may support or contradict an opinion, show various stages of a process, sides or phases of a building, be unique or of high quality, prototypical or unusual. Such hypermedia networks of semantically typed links will provide a real added value to data collections, and relieve the user from the cumbersome manual maintaining of cross references. We need for this purpose flexible structures with an extensible variety of link types, enriched by free-text comments.

Besides that, rigid data structures are needed for documentation of cultural material for statistical purposes. Statistical analysis needs complete data on few data fields from many objects. Metadata about handling of cultural material and the folders themselves such as authors, working groups, tasks, subtasks, phases and versions require fixed structures as well. We see, that neither a pure hypertext approach, nor a conventional database schema is appropriate, but a combination of fixed schema for the necessary information and extensible structures of explanatory character for the optional information.

A question that arises is, who will create all these data structures and at which cost. Fortunately, there are some prototypes or examples in the field, beginning from the CIDOC Relational Data Model ( and other CIDOC documents, work of the CIMI Consortium, the MDA (, until data forms internally in use at various organizations. It can be expected, that there will be similarities and common "cores" between the needed structures, allowing experts or service providers to rapidly customize new ones from suitable prototypes. Such procedures are explicitly foreseen by the TEI (Text Encoding Initiative), as detailed below. Prototypes also help to maintain semantic consistency between the products. Nevertheless, a more formal agreement between the users on "core structures", fixed or "official" schemata, as well as guidelines for variable structures, will be helpful to support interoperability at retrieval and data interchange. Obviously such structures will be more purpose-specific than even domain specific.

"Core" data structures are not easily or never found, if the domain is initially taken too wide, as e.g. with the CIDOC efforts to create a minimal data model. The CIDOC Relational Data Model work shows clearly on the other side, that a set of relevant interrelated data and a convention on their formal representation can be achieved for a multitude of more separate purposes.

Primary and secondary data are in general not public, and quite often represent a considerable capital of their owners. Besides data, that will be published in the proper sense, we expect that an important part of folders and primary data will be shared exclusively between smaller or larger working groups and consortia. In particular, folders can refer to folders allowing collaborating teams to create composite documents, where each partner is owner of his part only. We must note that the target of authors' interest may be not a whole folder, but a detail within it. AQUARELLE currently discusses to allow for interdocument links directly to document parts.

This mutual interlinkage provides the data layer for cooperative work. Questions to be clarified in practice are the conditions under which folder parts are regarded to be suitable to be referred by others, and which changes should be possible, once a reference was made. There may be stages of proposals for discussion, drafts, personal official opinions and opinions of an organization. References may be to a document only as it was at the time the reference was made. They may be tolerant to minor (e.g. spelling) corrections or to changes of references therein. Or just the opposite, they may refer to a document with the explicit wish that it should always be updated to the latest state of knowledge.

Besides the widely discussed and open questions of intellectual rights, economic models of data sharing would be useful, which allow to make the mutual benefit of those putting much effort in providing data to those exploiting data more explicit. Many good IT solutions may not find their way from research prototypes to real use just because of that, which is clearly a question out of the scope of technology providers and technology funding.

In an interlinked network of documents, there is no clear semantic boundary between the interior and exterior of a document. We adopted a definition of the unit "folder" motivated by the creatorship - the unit someone signs responsible for, an administrative view. Hence ownership and access rights are at folder level, as well as spiritual rights.

The state-of-the-art standard to implement the appropriate data structures for the above requirements is SGML. Rather than one Document Type Definition (DTD), the system is designed to support an open number of DTDs. In order to bootstrap the first evaluation phase, and for reasons of interoperability from the very beginning, the project starts with the CIMIs CHIO (Cultural Heritage Information On-Line) DTD and that of the French Ministry of Culture CI ("Classer d'Inventaire"). We briefly comment the two different approaches with respect to information structuring and handling.

The CHIO DTD takes Text Encoding Initiative (TEI as its starting point. One of the most important aspect of TEI is that it provides a core of well-established SGML techniques for representing hypermedia documents for humanities, in a system-independent manner. People can then modify and extent the set of basic element definitions (e.g., sections, subsections, lists, footnotes, illustrations, bibliographies, etc.) so a specific version of the TEI DTD can be designed for a specific domain such as Art descriptions (e.g., personal names, dates, places, etc.). In order to indicate the "museum" interest to specific parts of documents, two mechanisms are identified in the CHIO DTD: primary or secondary access points used for the description of documents profiles to give a scope for (Z39.50) queries.

Primary access points indicating that a given part of the work is "about" a particular concept (i.e., a element) or a particular "museum point of view" (i.e., a element). The corresponding tags gain their expressive power from SGML attributes, indicating the type of information they hold as well as their values. The element is a general way to qualify a part of text as for instance "his is about that person ... event, etc" The element gives more precise museum context to elements as for instance "this is bout that creator ... historical context".

Secondary access points dealing with mentioning of people, places, etc which are of interest, but do not form the main topic of discourse. They are represented by "ordinary" SGML elements either inherited directly by the TEI DTD or invented specially for the CIMI DTD.

The French Ministry of Culture CI DTD is dedicated to territory inventory making. It consists of folders that are classified in Content and Filling folders. Content folders are used to describe single objects (i.e., artifacts like paintings), individuals (i.e. monuments like churches), sets (i.e, cities like Cognac) and collections of objects (i.e., places-hotels-farms). Filling folders are used to classify the content folders and they are organized on a geographical area (e.g., a specific commune) or a thematic topic. The approach used in the CI DTD is very structural: filling folders can contain each other based on their topological relationships and content folders are constructed recursively. We must note that opposite to the CIMI DTD quite all elements are caring a part of the cultural information described in the documents.

There is on-going work to compare these projects with the AQUARELLE specifications. First, it remains open how to map the proposed structures to the existing Cultural Databases i.e. the archive servers of the AQUARELLE partners. Second, the mapping between information encoded according to these DTDs, and Access Points in the AQUARELLE (Z39.50) query profile will also be defined. Clearly, the two DTDs have a different approach in marking cultural interest of information: a) using a pair of specific tag to mark all Access Points (CIMI); b) using an SGML element for each Access Point (CI). Finally, SGML folders' modularity and internal and external links are subjects that needs further formalization and experimentation.

3. Folder Management Functionality

Contract to the primary archive servers, folder servers are rare or do not exist at all. They are however central to the objectives and exploitation of AQUARELLE since they provide indirectly a sophisticated user interface tool for discovering and digesting archive information. In order to encourage users to switch from classic to digital authoring, the folder environment will be provide flexible tools for creating and managing folders as well as for searching information and browsing within the network of inter-connected folder servers. More precisely the AQUARELLE folder server supports the basic functions of: folders authoring and publishing to the intended audience, "republishing" updates, withdrawing a folder in an "unpublishing" action, classification, indexing and retrieval.

We can imagine a typical scenario of folder creation as follows.

he user starts to retrieve via the reader user interface (not described in more detail here) data, texts, images, folders, or other objects related to her study or research. She may browse through folders and identify other objects of interest within them.

She denotes the objects found in a list like the Netscape bookmarks.

She opens the AQUARELLE folder editor. It is a full SGML structured editor, working as WYSIWYG (What You See is What You Get) relieving the user from the obstacle to learn unintelligible codes spread out over the text she writes. She may start with an empty screen, a special template containing her usual header information, or a former folder as template. The SGML structure guides the user to provide necessary and useful information in a defined way.

The user inserts references of the data objects she has marked before in the folder. Copies of these data objects will be hold locally as appropriate during the editing process to reduce network traffic and the dependency from an open connection. When the folder is stored, references and not the copies are saved for reasons of space economy, copyrights and to allow for updates in the referred object. If permitted, the user may request a copy to be inserted instead.

The folder can be saved at any time and brought back to the editor, being accessible only by the author. Saving the folder implies its registration on the server.

AQUARELLE will use SGML attributes to denote the wish, that the respective tag has to contain words of a controlled vocabulary. For that sake, a thesaurus browser is available to assist the user. Terms will be "cut and paste" to the folder editor to avoid spelling errors. In case the appropriate term cannot be found on the system, the user has the possibility to define its own local term. It will be mandatory however to link the new term with the next controlled broader term. This link allows the query processors to access all information through controlled terms. Thesaurus maintainers can use these links to embed local terms into the authorities at an appropriate later stage.

The possibility to use controlled and local terms was an important requirement of the AQUARELLE user community, expressed as well by other working groups (MDA Workshop on Terminology, 11-14 Sept. '96, Only the linkage to controlled terms we implement here provides the means to handle consistently controlled and local terms. It furthermore facilitates a more efficient gathering of term proposals for the authorities in use (see M. Doerr: "Authority Services in Global Information Spaces", TechnicalReports.html). Current systems do not foresee such a functionality.

The user will "cycle" between editing and retrieval until she achieves a satisfactory form. In general, more than one editor is foreseen, however only one instance can be downloaded for editing at a time, synchronizing cooperative editing that way.

Finally, the keyword indexing facility is invoked and the folder is submitted for publishing. The keyword indexing proposes to the user words in the text as indices for retrieval. The user can accept, reject or alter the proposed words. She may further classify the whole folder or parts of it by more controlled indexing terms. For publishing, she defines the user group, for which the folder will be accessible, and a narrower group, which has editing permission - per default the author herself. The precise permission scheme is still under discussion.

Once published, the system regards any changes to the folder as a new version. A new version can be edited as above, and finally it will be exchanged with the previous version. This "republishing" act may eventually invalidate references, that other people have already made to this folder. Necessarily in this case, a communication will be initiated by the system which requests the other user to withdraw her reference. Only after the situation is settled, the new version can be installed. This dependency from external conditions is also the reason, why after the publishing a new version must be introduced in any case. The same happens if the folder is withdrawn as a whole in an "unpublishing" act. The precise communication procedure on links going to be invalid will be subject to experimentation. In any case, it will be a combination of human interaction and system enforcement - in case the previous fails.

Besides the folder environment, a separate environment will be setup to develop and maintain multilingual thesauri. It will be based on a monolingual prototype developed by ICS-FORTH in cooperation with the Getty Information Institute. It became absolutely clear in extensive discussions with the AQUARELLE users, that multiple thesauri will be in use, that they need to be semantically interlinked in order to simultaneously process queries sent to servers indexed in different languages or thesauri, and that user groups without thesauri in their native language will start with translating foreign thesauri.

This system is capable to maintain simultaneously several thesauri, links between them and term translations in various languages. Within AQUARELLE it will be further developed to support specific AQUARELLE user needs for editing, a simple versioning mechanism, and display and access to all subthesauri and versions separately and in combination. Even though these are novel features, the users need definitely more. The ideal functionality will furthermore comprise distant communication between users on the concepts and linkage to be done, utilities for term matching, translations, quality control, reconfigurations and data exchange. This exceeds the framework of AQUARELLE, and partners of the consortium wish to use the experience in AQUARELLE for further focused projects on this issue.

Another important aspect, that may be partially clarified in AQUARELLE, are the organization and human procedures to achieve thousands of small agreements on bunches of terms and links in a reasonable time in international teams. It seems, that enabling techniques of electronic communication and Computer Supported Cooperative Work (CSCW) will play a key role, as well as tools to assess logical consistency of the inner structure of thesauri and proposed changes them.

4. Technical Choices

One of the basic choices is to follow standard technology at the data and communication level, in order to facilitate open access by existing systems and future service providers, to guarantee a long life-time of the data created in the AQUARELLE environment, and to cater for use by low and high-end systems and services. These standards are the WWW (e.g. HTML) for access by low-cost systems, SGML for high-quality structuring of information and Z39.50 for reliable access among heterogeneous data sources. This motivates the architecture chosen as a modular system, with a set of inner interfaces, that are standard and open to non-AQUARELLE data and systems.

figure 1 :1 block diagram of the AQUARELLE architecture

A block diagram of the AQUARELLE architecture is shown in figure 1. Its central module is the access server, which mediates between archive databases, folder servers, thesaurus servers and user clients. It is responsible for resource discovery, query handling, result management, folder publication and one-to-one connection with servers. It also supports handling of metadata of documents and guarantees the referential integrity of links between folders.

The user client module of the AQUARELLE user interface, consists of the reader system and the authoring editor system. The reader system allows the AQUARELLE end user to access any published folder or folder part. It supports folder retrieval through queries as well as browsing through the folder hyperlinks. The reader system is implemented with a WWW client solution. Either usual HTML clients can be used , or full SGML clients (GRIF symposia, etc). Thus, the retrieved SGML folders are presented to the user either in units of SGML subdocuments, if the client has the respective capability, or as simple HTML pages by transcoding display behavior from the original DTD format.

The authoring editor system is an environment suitable for creating and modifying structured folders. The GRIF SGML editor ( was selected as tool for folder editing according to the selected specific DTDs (CIMI, CI see section 2). During folder editing, the user can add content descriptors (semantic information) to folders under the discipline of the DTD. This is supported by on-line queries on the thesaurus (Authority Service).

The main components of the folder server are the Local Folder Catalogue,and the FTR (Full Text Retrieval System). A dedicated front-end coordinates the cooperation of the Local Folder Catalogue and the Full Text Retrieval System with the rest of the AQUARELLE architecture. More precisely, it maintains communication with the Access Server, accepts the queries, interprets them and routes them to Local Folder Catalogue and the FTR. It manages storage and retrieval of folder instances.

The Local Folder Catalogue is based on the Semantic Index System developed by ICS-FORTH (, a tool for describing and documenting large evolving varieties of highly interrelated data, concepts and complex relationships. It consists of a persistent storage mechanism based on an object oriented semantic network model. The Local Folder Catalogue also provides a navigation interface and a stateful Z39.50 compatible query protocol.

In the Local Folder Catalogue a local copy (of a part) of the thesaurus subject hierarchy, the SGML DTDs and the folder instances are maintained. The thesaurus servers in the access server as well as the Local Folder Catalogue are based on the SIS and share identical structures but eventually different data. The thesaurus servers are designed to support query formulation and mediation. As such, they may provide for query purposes other thesauri and links between them than those installed on a local folder server. The Local Folder Catalogue can be accessed however as thesaurus server by itself. The backbone of the Local Folder Catalogue is a conceptual model (see figure 2) which describes the basic SGML constructs (document logical elements), the basic notions of a thesaurus (Subject Hierarchy) as well as the different categories of annotation links associating SGML elements with thesaurus terms.

The left part of figure 2 illustrates the SGML metamodel, instances of which can be any SGML DTD (such as CIMI or CI). The right part of the figure illustrates the thesaurus model which has been developed following the standards ISO 2788 (for monolingual thesauri) and the standard ISO 5964 (for multilingual thesauri). This model can support any thesaurus which have been developed according to the above standards (such as AAT or MERIMEE). The relations defined in this model are ``inter-thesaurus-relations'' and ``intra-thesaurus-relations''. The former denote all the relations among terms existing in a specific thesaurus (i.e. broader term relation BT) while the latter denote the relations between terms residing in different thesauri (i.e. equals relation EQ).

figure 2 : Logical Structure of the Local Folder Catalogue

In the middle of figure 2 the link talks_about represents the association of SGML elements with the thesaurus Subject Hierarchy notions. Thus, it is possible to index (at fine granularity) any DTD element using related thesaurus terms. For example, the folder_1 and folder_2 in figure 2 are respectively instances of the CI and CIMI DTD. As we can see, a component of folder_1 is indexed by the ``Terme`ABBAYE'' existing in the MERIMEE thesaurus. Components of the folder_2 are indexed by ``Term`factory sites'' and ``Term`abbeys'' from the AAT thesaurus. The representation of the inter thesaurus relations (i.e. EQ relation) allows the association of terms (i.e. the english term ``Term`abbeys'' is equal to the french one (``Terme`ABBAYE''). In this way, the Local Folder Catalogue can offer automatic indexing facilities on folders (i.e. under the subject hierarchy) by using the semantic information that the folder contains. The folder creator can also index the folder using non-controlled terms which must be associated to a broader controlled term of the thesaurus.

The FTR provided by INRIA ( ), offers mechanisms for automatic indexing of folders based on textual analysis. It provides indexing and searching interfaces to the Authoring Environment and the folder server front-end respectively. FTR indices can be keyword extraction or relevance weighted. In addition, keywords can be associated to thesaurus terms (i.e. controlled vocabulary) or not. The FTR system will use the same contents identifications as the Local Folder Catalogue uses for analyzing folders. It will not store any contents by itself, but will refer to the Local Folder Catalogue contents in its results. The AQUARELLE user community made clear, that it sees a priority in extracting names and use of controlled or local terms over typical FTR access by weighted occurrences of accidental words in a text. Actually, the non-weighted indexing by names of persons, places, objects and events was ranked very high.

A still open question is, to which degree the rich information structure of the folders should be only exploited by Z39.50 queries and browsing. The current AQUARELLE architecture focus on queries only to Z39.50 access points. Then the retrieved folder identifiers are used for browsing to locate specific parts of interest. It may be more useful to provide a query interface to retrieve folders by combined conditions on content and structure and this at any granularity of SGML tags according to the user needs. To which degree such features could be "encoded" in "abstract" Z39.50 access points needs further study. Finally to which degree DTDs and Z39.50 profiles have to be harmonized for AQUARELLE purposes, and what may be the consequences of working with multiple profiles has to be investigated in the later phases of the project.

5. Summary and Conclusions

The AQUARELLE folders provide appropriate structures rich enough for the demands of a support system for professional work in the cultural domain. The elaboration of these structures and questions of how and to which degree domain knowledge (as authorities or semantic SGML tags) can or has to be embedded will be an interesting task from now on for users and system providers.

The classification system and the resulting retrieval capabilities deliver the technical means for the precision required by the expert. The population of the thesauri to fully exploit this potential is however a long term task for the cultural community, which will require considerable organization.

The access services as directory service, metadata management, referential integrity and access permission control are expected to provide the mandatory reliability and transparency for the professional environment so far not available on the Web.

AQUARELLE is going to provide kinds of services the user community typically has no experience with. For that reason, many details for an ideal implementation can only be worked out with hands-on experience on prototypes. The project foresees therefore a redesign phase in the middle of the project.

In order to become an efficient groupware however, the user community must develop and clarify certain practices. Those will be modes of sharing information under respect of intellectual rights, liability for contents, and economic or other means to balance mutual benefit. They will in turn give raise to modifications and enhancements of the system.

We hope, that the activities of AQUARELLE, CIMI and all others in the field will give raise to a long and efficient cooperation of information science and arts.

Copyright Archives & Museum Informatics, 1997

Archives & Museum Informatics Museums and the Web Register Exhibit Sponsor Program

Last modified: February 28, 1997
This file can be found below

Send questions and comments to