Towards Interoperability of Information Sources within a Hospital Intranet

Transcription

1 Towards Interoperability of Information Sources within a Hospital Intranet Sylvain Aymard a, Dominique Fieschi a, Michel Joubert a,b, Marius Fieschi a,b a LERTIM, Faculté de Médecine, Université de la Méditerranée, Marseille, France b Service de l'information Médicale, Hôpital de la Timone, Marseille, France Information is usually available in heterogeneous data format and various legacy sources. Interoperability appears to be a major approach for applications to access information. The project ARIANE is devoted to provide end-users with an easy to use and natural access to information datbases. In this frame we defined actors able to operate the mediation between end-users and information servers: a "broker" which selects appropriate resources and "mediators" which access data suppliers. We have implemented a Web-oriented stand-alone application accessing three type of information sources: a bibliographical server, a SQL database server and a hypertext server. Both broker and mediators exploit the Unified Medical Language Sysytem knowledge sources, especially the Information Sources Map which allows a way to identify information servers. INTRODUCTION As information systems grow, they depend increasingly on various heterogeneous resources, such as databases, knowledge bases, bibliographic files, Web-based information, and so on. Accessing relevant information requires users to be familiar with different communication protocols as well as various database software. Interoperability appears to be a major approach for the design of applications dedicated to access information [1]. The aim of the project ARIANE is to provide end-users with easy-to-use and natural means to query and access heterogeneous information sources [2]. Objectives of this research work consist in building a conceptual interface by means of the Internet technology inside an enterprise Intranet, and to propose a method to operate information access. Thus, we were faced to the challenge of defining what is an information source, what it contains and how to access it. Authors who experiment integration of information sources for decision support, literature searching or Web exploration conclude to the necessity to develop an external and shareable representation of information and metadata requirements [3-7]. They suggest to design intelligent agents, as a mediation layer, which execute specific tasks and may be reused then reducing development, deployment time, and cost. In this objective we define two kinds of actors: a "broker" which selects appropriate resources and "mediators" which access data suppliers. Each of them needs knowledge to perform its task. In this frame, we try to extract a preliminary model of these agents involved in the mediation with their needed knowledge. We present a prototype that accesses three servers : PubMed [8], a currently free of charge server of Medline at the NLM site, Thériaque [9] a French drug database available in our University Intranet Hospital, and HepGen [10], a gastroenterology and nutrition Web site located in the Faculty of Medicine of Nice (France). Each of them is different with regard to the type of information it contains and to the technology used to represent and query it. METHODS ARIANE architecture is organized around different components as illustrated by the drawing of Figure 1. A first component is a conceptual interface allowing end-users to formulate a query. The development of this conceptual interface needed an ontology which describes a representational vocabulary and semantic links between objects of the biomedical domain. The Unified Medical Language System (UMLS) project of the U.S. National Library of Medicine [11] includes in its knowledge sources a part of the medical knowledge [12] and almost all of the biomedical vocabularies. The UMLS can be considered today as an operational and suitable ontology for the biomedical domain. In previous research works, we have shown how to use the UMLS knowledge sources with the intent to query information databases in an easy to use way [2]. The second component, a broker, has in charge to select appropriate information sources with regard to a user's request. According to the

2 information a source contains the broker realizes a semantic choice and determines a list of target servers able to respond the query. For the broker works it needs a precise qualification of the current query, and the knowledge of the available information sources. To achieve selection each data source is characterized by semantic information about its content (nature and utilization context). Some sources properties are described in the Information Sources Map (ISM) [13] of the UMLS. Moreover, the broker must be able to qualify precisely the concepts occuring in a query with properties necessary to realize its matching. Each term involved in the expression of a query can t always match exactly those terms used for qualify information servers. So, we defined a matching process based on the hierarchy of MeSH terms included in the UMLS Metathesaurus [14]. After the matching, the broker return a list of servers able to deliver information. When an end-user selects one of these target information servers, the broker activates a mediator identified in the server s definitions. This operation needs that the broker analyzes the user request and eventually split it into sub-requests in order to choose the right mediators able to communicate with the declared information suppliers. The third component, the mediators, is activated to initiate communication with suppliers. A mediator translates the transmitted query into the syntax of the server query language depending on the ontology of the source and the syntax of server search engine. To achieve its task it needs to know the correct syntax for writing a query according to servers access language. Each mediator addresses a type of suppliers. A mediator requires two different kinds of knowledge. First, is the list of parameters used to control the answer built by the server, (the number of answers by screen, a selection of fields needed by end-users or a period used to extract data, etc). This information may be optional. These parameters give to a target server some information style that will be used to display information and how users can make changes. Second, a mediator has definitions to translate end-users queries into a language compliant with servers search engines. In order to do that, a mediator can, in some cases, have to use a knowledge for vocabulary translation (for example to translate a code from one classification to another, or a concept name in another language...). Servers query string formalism must be defined by the use of a grammar. This grammar is the guideline to translate end-users queries into the server query language. A mediator is then able to create the connection with server according to the right network protocol defined in the server specifications. Semantic Network + Metathesaurus Metathesaurus + Information Sources Map PubMed (NLM) Biblio. INTRANET Conceptual Interface Broker SQL Thériaque (Intranet) Hypertext INTERNET / INTRANET Gastroenterology (Web Site) Figure 1 - General architecture of the project ARIANE The last components are various information servers whose connection protocols are declared at the system level. According to the above principles, each server has to declare the relevant knowledge to select and query it (parameters, grammar, and so on). RESULTS In order to illustrate the above principles, we developed a web-oriented stand-alone application that implements access to the three mentioned types of information servers. A particular interface has been implemented for the prototype; a more integrated would be implemented in a next future. Interface is realized by means of HTML pages using Microsoft Active Server Page (ASP) technology [15]. With ASP-based applications, we are able to maintain application and session objects. We already describe the conceptual interface implemented in the frame of the project ARIANE and how it processes users queries on the base of the UMLS Semantic Network and Metathesaurus [2]. Let us suppose a user interested in the treatment of gastric ulcer by ranitidine. In this case, the query is represented

3 by the conceptual graph: [Pharmacological substance: ranitidine] (treats) [Disease or syndrome: gastric ulcer] where the two involved concepts ("ranitidine" and "gastric ulcer") are attached to their respective types ("pharmacological substance" and "disease or syndrome") and are linked by means of the semantic relationship "treats". The broker takes into account a request to search relevant available resources to route queries towards appropriate information servers. In order to achieve its aim it uses information contained in two knowledge sources: an information source based on the ISM data structure to define our site. In the ISM every server object is defined with different fields, such as name, language, brief description, protocol of communication and so on. Semantics links using the UMLS ontology are added to each server definition, using MeSH keywords and subheadings, to indicate the nature and context of information it delivers. Additional knowledge describe associated mediators, source access type and syntax of their query languages. a declarative knowledge used to translate a semantic relationship between concepts into MeSH subheadings. Translation depends on the types of the associated concepts. A given relationship may associate different subheadings to a same concept according to the type it is connected to. Selection of subheadings is thus processed regarding not only the involved relationship but also the two types and related concepts it links. So, the initial conceptual query is translated into a formula expressed in the MeSH vocabulary where semantic relationships are replaced by subheadings. In our example, the initial graph becomes: Gastric Ulcer\Drug Therapy AND (Ranitidine\Therapeutic Use OR Ranitidine\Pharmacokinetics OR Ranitidine\Administration & Dosage OR Ranitidine\Pharmacology) A matching process is operated according to the MeSH structure between the query representation and the servers semantic descriptions. Then the broker provide the user with a list of information servers able to possibly deliver response to the query. Each server is shortly presented by a textual description issued from ISM and pointed by a hypertext link. A mouse click on one of these links activate a mediator which acts as an interface between the user and a data source. With the knowledge on concerned data source and related search engine, the mediator translates a query into the syntax of the server query language, possibly realizing a matching between ontology concepts with source terms, adding, if necessary semantics and operators of the source native language. We experimented three kinds of information servers as illustrated in Figure 2. PubMed Access: PubMed, is a NLM' search service to access bibliographic information like Medline database. PubMed accesses database using a specific query language comparable to HTML. Queries are given as logical expressions of MeSH terms and subheadings. Options may be added to restrict a search period, fields to take into account, and so on. Using the concepts saved during the session, subheadings extracted by the broker and the query syntax of the search engine, the mediator builds its query. Thériaque Access: Thériaque is a drug database implemented in our hospital Intranet. It can be accessed by several entry points: active substance, indications, and so on. Scripts have been implemented with the database which realize these accesses. Integrated accesses are associated with concepts types, data properties or relations present in the database. A dedicated mediator processes a matching between the concepts involved in a query and information source terms. Then, the result of a successfull matching is to activate scripts associated with the corresponding terms. The server Thériaque displays results in dynamic Web pages. HyperText : At simplest level a Hypertext is like a database which associate pages by means of links. Today, as the Internet technology evolves, it can't be thinking without a search tool able to localize information inside a Web site. It is the case of HepGen a documentary site which contains a compilation of Internet resources about hepato-gastroenterology and nutrition. HepGen web pages are static pages indexed according the World-Wide- Web Consortium recommendations. Keywords have been chosen in MeSH and have been placed in the HTML pages between Meta-tags. In order to query these pages, an index server is used to index the full text and properties of documents (for instance, the meta-tag "Keywords"). The related mediator has to translate the query transmitted by the broker into a logical operation following the index server syntax.

4 The broker processes a user s request to route the query towards appropriate information servers. Each server is presented by a short textual description and pointed by a hypertext link. A mediator devoted to access relational databases realizes a matching between the query and APIs entries into the database (here: the pharmacological classes of «ranitidine») An indexed page of the HepGen Web site devoted to gastroenterology and nutrition is directly accessed by a mediator conceived to hypertext. From this page a user may navigate to other referenced sites according to his/her current focus. A mediator accesses bibliographical databases. The PubMed server returns references retrieved by means of MeSH keywords and subheadings. Figure 2. Example of the broker and mediators process

5 CONCLUSION Our implementation shows that it is possible to integrate and access various heterogeneous information sources within a hospital Intranet on the base of the ARIANE architecture and the UMLS ontology. This prototype demonstrates the interest of this common ontology when associated with the ISM which provides with a catalog of existing servers. We had to specify some additional properties about these sources to access directly relevant information. For future works we have to integrate other types of information sources to finalize their definitions and extract a more general representation. This would allow to express criteria a new information source must satisfy to plug in according to interoperability aspects at semantic and syntactic levels. Many interrogations are remaining, such as : to consider when and how merging results returned by information servers. Presently, mediators, give access to Internet or Intranet servers, and then a user is connected to a Web site from which (s)he can navigate. Depending the target sources, results wrapping may be necessary before answering a user. a server may be selected by the broker according to its definition, and correctly queried by a mediator according to the syntax of its search engine, but it is possible that it gives no answer. A possible solution could be to give access the home page of the site Even if pages can be accessed directly, it could be not pertinent to access them when information gathered by readers along the paths to reach them have been judged significant by the authors. This later point is particularly important when a site is devoted to education. Web users need today even more powerful information retrieval tools. An ontology for the biomedical domain constitute an approach adapted to express complex queries. These capabilities and the design of client-server applications in the frame of middleware developments should constitute a step toward the interoperability of information sources within a hospital Intranet. Acknowledgments This work has been partially founded by the French Ministry of Education and Research. The authors thank the U.S. National Library of Medicine which gracefully provided them with the results of the UMLS project. This work has been achieved with the 1997 release. Many thanks to Microsoft France for its helpful assistance. References 1. Degoulet P, Fieschi M. Interopérabilité des Systèmes d'information de Santé - Aspects Syntactiques et Sémantiques. Paris: CIHS, Joubert M, Fieschi M, Robert JJ et al. UMLSbased Conceptual Queries to Biomedical Information Databases. JAMIA 1998; 5 (1): Bayardo RJ, Bohrer W, Brice R, and al. InfoSleuth: Agent-Based Semantic Integration of Information in Open and Dynamic Environments. Proc. ACM SIGMOD'97, 1997: Detmer WM, Barnett GO, Hersh WR. MedWeaver: Integrating Decision Support, Literature Searching, and Web Exploration using the UMLS Metathesaurus. In: Masys D, ed. JAMIA Symposium Suppl. 1997: Baldonado M, Chang C, Gravano L, Paepcke A. Metadata for Digital Librairies. Architecture and Design Rationale. Technical Report SIDL-WP , Stanford University, October Gravano L, Chang C, Garcia-Molina H. STARTS: Stanford Proposal for Internet Meta- Searching. Proc. ACM SIGMOD'97, 1997: Wiederhold G. Mediation in Information Systems. ACM Computing Surveys 1995; 27 (2): PubMed François M, Joubert M, Fieschi D, Fieschi M. Implementation of a Database on Drugs into a University Hospital Intranet. Proc. MEDINFO'98. To appear. 10. HepGen Lindberg DAB, Humphreys BL, McCray AT. The Unified Medical Language System. Meth Inform Med 1993; 32: McCray AT, Nelson SJ. The Representation of Maening in the UMLS. Meth Inform Med 1995; 34: Masys DR, Humphreys BL. Structure and Function of the UMLS Information Sources Map. In: Lun KC, Degoulet P, Piemme TE et al, eds. Proc. MEDINFO 92. North-Holland 1992: Nelson SJ, Fuller LF, Erlbaum MS et al. The Semantic Structure of the UMLS Metathesaurus. In: Safran C, ed. Proc. SCAMC 1993: ASP. toc.asp#asp