A Tutorial Proposal for ICWE 2004
Providing Interoperability of
Medical Information Systems through Semantically Enriched Web Services
- Semantic Web Services PART-1,
Christoph
Bussler
,
pdf
- Semantic Web Services PART-2,
Asuman Dogac
,
pdf
- Semantic Web Services PART-2,
Asuman Dogac
,
ppt
Asuman Dogac (Primary contact)
Director
06531,
Web site: http://www.srdc.metu.edu.tr/~asuman/
Fax: +90 312
2101004, +90 312 2101259
Phone: +90 312
2105598, +90 312 2102076
Email:
Christoph Bussler
Science
Foundation
Executive
Director
Digital
Enterprise Research Institute (DERI)
National
Web site: http://hometown.aol.com/chbussler
Phone
+353-91-512460
E-Mail Chris.Bussler@DERI.ie
Abstract:
Most of the health information systems today are
proprietary and often only serve one specific department within a healthcare
institute. To complicate the matters worse, a patient's health information may
be spread out over a number of different institutes which do not interoperate.
This makes it very difficult for clinicians to capture a complete clinical
history of a patient.
On
the other hand, the Web services model provides the healthcare industry with an
ideal platform to achieve the difficult interoperability problems. Web services
are designed to wrap and expose existing resources and provide interoperability
among diverse applications. To be able to exploit Web services to their full
potential, it is necessary to describe their semantic. This will provide
interoperability at the semantic level as well as helping the discovery,
composition and monitoring of Web services.
Semantics
is domain dependent; in other words in order to describe the semantics of Web
services in a given domain, domain knowledge is essential. Medicine is one of
the few domains to have extensive domain knowledge exposed through standards
such as HL7 for exchanging messages and CEN TC251, ISO TC215 and Good
Electronic Health Record (GEHR) for describing electronic healthcare records.
These standards offer significant value in terms of expressing the semantic of
Web services in the healthcare domain.
The
aim of the tutorial is to describe the state-of-the-art in all the involved topics
such as Web services, Web service registries, Semantic of Web services,
Semantic mediation, Conceptual architecture of semantically enriched Web
services, and how healthcare standards can contribute to defining the semantics
for Web services in the healthcare domain. The ultimate aims are to increase
the research and development efforts in semantic Web services in general and in
healthcare domain in particular and to encourage the take up of Web services by
the healthcare organizations.
Table of contents
I.
We
services, SOAP and WSDL: Web service technology is an emerging Internet-based distributed computing paradigm to
address interoperability in heterogeneous distributed systems. In fact, Web services have been described as the
third phase of the Internet. In the first phase communications over the
Internet were mainly through static content. In the second phase there was a
degree of dynamic content creation. In the third, Web services phase, Internet
is becoming a global common platform where organizations and individuals
communicate among each other to carry out various commercial activities and to
provide value-added services. Considerable progress has been made in the area
of Web service description and invocation: There are two almost universally accepted
standards for these purposes: SOAP (Simple Object Access Protocol) for invoking
services and WSDL (Web Services Description Language) for describing the
technical specifications of the services. There are also two well-known service
registries, UDDI by Microsoft and IBM and ebXML by
UN/CEFACT.
a.
The Simple Object Access Protocol (SOAP) provides a
means of messaging between a service provider and a service requestor. SOAP is a
simple enveloping mechanism for XML payloads that defines a remote procedure
call (RPC) convention and a messaging convention.
b.
The Web Services Description Language (WSDL) is an XML
document for describing Web services as a set of endpoints operating on
messages containing either document-oriented (messaging) or RPC payloads.
Service interfaces are defined abstractly in terms of message structures and
sequences of simple message exchanges (or operations, in WSDL terminology) and
then bound to a concrete network protocol and data-encoding format to define an
endpoint.
II.
Web
service Registries:
Interactions among Web services involve three types of participants: service
provider, service registry and service consumer. Service registries are
searchable repositories of service descriptions. There are two well-known
service registry specifications, UDDI by Microsoft and IBM, and ebXML by UN/CEFACT.
a. UDDI: UDDI is a service registry architecture that presents
a standard way for businesses to build a registry, discover each other, and
describe how to interact over the Internet. Currently IBM and Microsoft are
running public registries. UDDI defines a programmatic interface for publishing
(publication API) and discovering (inquiry API) Web services. Conceptually, the
information provided in a UDDI registry consists of white pages (contact information), yellow pages (industrial categorization) and green pages (technical information about services). There are a
number of implementations of UDDI registries such as IBM UDDI. The
infrastructures for Web services are also readily available through
well-established application servers like IBM WebSphere,
Microsoft .NET Framework or BEA WebLogic. These
application servers allow creating SOAP messages, initiating SOAP invocations,
and receiving SOAP invocations. These application servers also provide WSDL
generation and interpretation functionality and UDDI connectivity.
a. ebXML: Electronic Business XML is an initiative from OASIS
and United Nations Centre for Trade Facilitation and Electronic Business. ebXML aims to provide the exchange of electronic business
data in Business-to-Business and Business-to-Customer environments. The ebXML specifications provide a framework in which EDI's
substantial investments in Business Processes can be preserved in an
architecture that exploits XML's technical capabilities. An ebXML
registry is a mechanism where business documents and relevant metadata can be
registered, and can be retrieved as a result of a query. A registry can be
established by an industry group or standards organization. A service in ebXML is represented with a “Service” class in ebXML Registry. The technical specification files (i.e.,
WSDL descriptions of the service instance) are stored in ebXML
registry together with “Service” class as extrinsic objects. The relationship
between the description files and the “Service” class is established through
the “ServiceBinding” Class of ebXML.
A “Service” class may have a collection of “ServiceBinding”
classes each of which represents technical information on how to access a
specific interface offered by a “Service” instance. Also, a “ServiceBinding” instance has several “SpecificationLink”s
each of which provides the linkage between a ServiceBinding
and one of its specifications describing how to use the Service. There are a
number of implementations of these registries such as OASIS ebXML
Registry/Repository implementation.
III.
How
semantic is defined in current Web service registries
a. UDDI: In UDDI, services use category bags
for semantic information. An item in a category bag contains a tModel key and an associated OverviewDoc
element. tModels provide the ability to describe
compliance with a specification, a concept, or a shared design. When a
particular specification is registered with the UDDI as a tModel,
it is assigned a unique key, which is then used in the description of service
instances to indicate compliance with the specification. The specification is
not included in the tModel itself. The “OverviewDoc” and “OverviewURL”
elements of tModels are used to point at the actual
source of a specification. To invoke a
service in an UDDI registry, it is necessary to know either its key or the
business the service belongs. If the service key is not known, the service is
located through its business in the UDDI registry using the APIs provided by
the registry (e.g. IBM's UDDI4J API), and the corresponding WSDL description is
accessed. After gathering all the information about the service to be invoked,
the necessary SOAP calls are made as specified in the WSDL description. The
current mechanism to associate some semantics with Web services is to use a
number of industrial taxonomies. The most widely used taxonomies are North
American Industrial Classification Scheme (NAICS) for associating services with
industry semantics, that is, which industry domain they belong;
Universal Standard Products and Services Classification (UNSPSC) for
classifying product/services and ISO 3166 for locale.
b. Taxonomies vs. Ontologies:
A taxonomy is a hierarchy and a unique code is usually assigned to each node of
the hierarchy. This code also encodes its path. For example, UNSPSC code for
“Medical Equipment and Accessories and Supplies” is [42.00.00.00].
One of the leaf classes under this root class is “Dental laboratory curing
units” whose code is [42.15.17.05]. By relating a service
with the codes in such taxonomies, it is possible to give the service a certain
amount of semantics. For example, when a Web service uses the code
[42.15.17.05] to describe its semantics, we understand that the service is
about “Dental laboratory curing units”. Therefore, a user looking for a service
related with such items can search the UDDI service registries with the
corresponding UNSPSC code to obtain all services that have been declared to be
related with this UNSPSC code. However there is no way to narrow down the
search space by declaring further properties. Hence the user has to go through
the services found to manually pick the service that satisfies her
requirements. In short, taxonomies provide very restricted help in describing
Web service semantics. It follows that to exploit the Web services to their
full potential we need more powerful tools, that is, ontologies
to describe their semantics.
c. ebXML: An ebXML
compliant registry allows metadata to be stored in the registry. This is
achieved through a “classification" mechanism, called ClassificationScheme which helps to classify the objects in
the registry. ClassificationScheme
defines a hierarchy of ClassificationNodes. Furthermore, it is possible to
define the properties of registry entries through “slots” which gives way to
define the properties of Web services.
IV.
Describing
semantics: Semantic Web Initiative
a. Semantic Web: Currently, describing the semantic of Web in general,
and semantic of Web services in particular are very active research areas.
World Wide Web Consortium has started the initiative to develop Semantic Web
and a semantic markup language for publishing and sharing ontologies,
namely Web Ontology Language (OWL), is being developed for this purpose. OWL is
derived from DAML+OIL by incorporating learnings from
the design and application use of DAML+OIL. It builds upon the Resource
Description Framework.
b. Web Ontology Language: OWL divides the universe into two disjoint
parts. One part consists of the values that belong to XML Schema datatypes. This part is called the datatype
domain. The other part consists of (individual) objects that are considered to
be members of classes described within OWL (or RDF). This part is called the
object domain. OWL describes the structure of a domain in terms of classes
and properties. Classes can be names (URIs) or
expressions and the following set of constructors are provided for building
class expressions: owl:intersectionOf,
owl:unionOf, owl:complementOf,
owl:oneOf, owl:allValuesFrom,
owl:someValuesFrom, owl:hasValue.
In OWL, properties can have multiple domains and multiple ranges. Multiple
domain (range) expressions restrict the domain (range) of a property to the
intersection of the class expressions. Another aspect of the language is the
axioms supported. These axioms make it possible to assert subsumption
or equivalence with respect to classes or properties. The following are the set
of OWL axioms: rdfs:subClassOf,
owl:sameClassAs, rdfs:subPropertyOf,
owl:samePropertyAs, owl:disjointWith,
owl:sameIndividualAs, owl:differentIndividualFrom,
owl:inverseOf, owl:transitiveProperty,
owl:functionalProperty, owl:inverseFunctionalProperty.
c. Web Service Ontology Language (OWL-S): OWL-S (previously DAML-S) defines an upper
ontology for defining the semantics of Web services. It is based on DAML+OIL
and aims to enable the automation of the following functionalities: Web service discovery, Web service invocation, Web service composition and interoperation,
Web service execution monitoring. The
top level class in DAML-S service taxonomy is the “Service" class. Service class has the following three
properties: presents: The range of
this property is ServiceProfile class. That is,
the class Service presents a ServiceProfile to
specify what the service provides for its users as well as what the service
requires from its users. describedBy:
The range of this property is ServiceModel
class. That is, the class Service is describedBy a ServiceModel to specify how it works. supports: The range of this property is ServiceGrounding. That is, the class Service supports a ServiceGrounding to specify how
it is used.
V.
An
Brief Introduction to Healthcare Standards
a. HL7: The primary goal of HL7 is to provide
standards for the exchange of data among healthcare computer applications. The
standard is developed with the assumption that an event in the healthcare
world, called the trigger event, causes exchange of messages between a
pair of applications. When an event occurs in an HL7 compliant system, an HL7
message is prepared by collecting the necessary data from the underlying
systems and it is passed to the requestor, usually as an EDI message. For
example, the trigger event can occur when a patient is admitted and this may
cause the data about that patient to be collected and sent to a number of other
systems.
b. CEN ENV 13606-2: The
CEN ENV 13606-2 information models provide a
means to represent the original organizational structure of one or more nested
electronic healthcare record entries, to be conveyed in a standardized form to
a recipient system for incorporation into that local EHR. This standard
proposes sub-categorization of the EHR into four specializations:
·
Folder: High-level subdivisions of the entire EHR for a patient, usually
grouping entries over long time-spans within one organization or department, or
for a particular health problem.
·
Composition: A set of record entries relating to one time and place of care
delivery; grouped contributions to an aspect of health care activity; composed
reports and overviews of clinical progress.
·
Headed Section: Sub-divisions used to group entries with a common theme or
derived through a common healthcare process.
·
Cluster: Low-level aggregations of elementary entries (Record Items) to
represent a compound clinical concept.
c.
Good
Electronic Health Record (GEHR): The GEHR approach
uses a formal semantic model, known as the GEHR Object Model (GOM). Rather than
try to model a myriad of possible clinical concepts, the GOM provides concepts
at a number of levels:
·
EHR and Transaction level
·
Navigation level
·
Content (e.g. observation, subjective, instruction) level
·
Data types (e.g. quantity, multimedia) level
·
Clinical models are expressed outside the GOM in the form of archetypes.
These archetypes act as constraint definitions and define how to create
clinically valid structures out of the GOM primitives.
VI.
What
the semantically enriched Web services offer in terms of the interoperability
of Medical Information Systems and How this can be achieved
a. HL7: Since HL7 defines message based
events, one might think that these events can directly be mapped into Web services.
However, this may result in several inefficiencies. The input and output
messages defined for HL7 events are usually very complex containing innumerous
segments of different types and optionality.
Furthermore, all the semantics about the business logic and the document
structure are hard coded in the message. This implies that, the party invoking
the Web service must be HL7 compliant to make any sense of the content of the
output parameter(s) returned by the service.
On the other hand, Since HL7 has already
been through an effort of categorizing the events in healthcare domain
considering service functionality, this classification can be used as a basis
for a Web service functionality ontology.
b. EHR based standards: Electronic healthcare
record (EHR) based standards like HL7 CDA (Clinical Document Architecture), GOM
(GEHR Object Model) and CEN's ENV 13606 aim to
facilitate the interoperability between Medical Information Systems. However,
they do not aim direct machine-to-machine interoperability. They only define
the metadata about patients' clinical information. In other words, these
standards do not prescribe a monolithic EHR architecture, rather they provide
conceptual building blocks or meaningful components by which any
clinical model can be represented within the standardized framework. This
provides flexibility by allowing the same building block to be composed
differently by two different institutes, which in turn results in different
message structures. This necessitates structural and semantic mappings between
the message components in order to automate their interoperation. By developing
ontologies based on existing healthcare standards and
by providing the semantic mapping of these ontologies,
it is possible to map these standards one into another. When the Web services
are annotated with these ontologies, it becomes
possible for healthcare organizations conforming to different standards to
invoke each others Web services by making use of the semantic mediation
component.
VII.
Semantic
Mediation
Mediators are developed to process data
from possibly several data sources and to prepare them for the effective use by
applications. However with WWW becoming the global communication medium and
with the Semantic Web initiative, ontologies are
becoming the primary part of the mediation process. Ontology Mapping is the
process whereby two ontologies are semantically
related at conceptual level, and the source ontology instances are transformed
into the target ontology entities according to those semantic relations. There
are a number of ontology mapping tools which will be covered in the tutorial.
Target
audience
The tutorial will address the topics mentioned above
in a concrete way through simple but comprehensive examples. The aim is to make
these topics easily digestible to the audience so that they can judge for
themselves the possible benefits of these technologies.
Two different types of audience are targeted:
- Researchers
in the Semantic of Web services area:
Semantics of Web services is an active research area. However since
the semantics is domain dependent, the researchers need to consider a
domain while working on the semantics.
- Health
Informatics professionals: It is time for the healthcare domain with very
serious interoperability problems, to consider taking up the semantically
enriched Web service technology.
Specify
assumed background knowledge needed, if any.
No background is needed except for a familiarity with
XML. The tutorial will start with the very basic concepts like SOAP and WSDL
and will gradually build on top of the preliminary concepts. The aim is to make
the concepts easily understandable through simple but meaningful examples.
Facilities,
equipments, equipment and materials required.
A beamer is
necessary to project the power point slides from the notebook to the screen.
Biography of
Asuman Dogac
Asuman Dogac (http://www.srdc.metu.edu.tr/~asuman/) is a full professor of Department of
Computer Engineering at the
Prof. Dogac
is the recipient of 1991 Mustafa Parlar Research
Award, 1994 Husamettin Tugac
Research Award, 1999 METU Achievement Award, 2000 METU Tarik
Somer Superior Achievement award, 2000 Mustafa Parlar Science award and 2001 Tarik
Somer award. She is an editor of Journal of
Distributed and Parallel Databases (Kluwer), editor
of Journal of Very Large Databases (Springer), editor of Information Systems Management and
e-Business Management (ISeB, Springer-Verlag) and Associate Editor of
ACM Special Interest Group on e-commerce (ACM SIGecom)
Newsletter. She has served on the program committee of several international
conferences (including SIGMOD, VLDB, ICDE, EDBT, CIKM, CoopIS,
ER, NGITS and ICWE) and as a reviewer to IEEE Transactions on Knowledge and
Data Engineering, Data & Knowledge Engineering, IEEE Transactions on
Software Engineering, IEEE Computer, ACM TODS and Communications of the ACM. She has guest edited special issues
of three journals on Electronic Commerce, namely, ACM Sigmod
Record, Vol. 27, No. 4, December 1998, Journal of Parallel and Distributed
Databases, Vol. 7, No. 2, April 1999, ACM Sigmod
Record, Special Section on Data Management Issues in e-commerce, Vol. 31, No.
1, March 2002. She has been actively involved in European Commission’s IST
projects and currently, she is the coordinator of an FP6 project, called
Artemis for deploying semantically enriched Web services to the healthcare
domain.
Biography of
Christoph Bussler
Christoph Bussler (http://hometown.aol.com/chbussler)
is Science Foundation
Before taking
this position he was Member of Oracle's Integration PlatformArchitecture
Group based in
He has a Ph.D. in
computer science from the University of Erlangen,
Germany and a Master in computer science from the Technical University of
Munich, Germany. Chris published a new book titled 'B2B Integration' (Springer Verlag, Berlin 2003, ISBN 3-540-43487-9), two books in
workflow management, over 60 research papers in journals and academic conferences,
gave tutorials on several topics including B2B integration and workflow
management and was keynote speaker at many conferences and workshops.
His tutorials
were accepted for presentation at DAIS 2003, CAiSE
2003, Net.ObjectDays 2002, at the federated conferences
(CoopIS, DOA, ODBASE) 2002, SIGMOD '02, International
Semantic Web Conference 2002, the International Semantic Web Working Symposium
2001, SIGMOD '01, IFIP Conference on Database Semantics 2001 (DS-9), ECSCW '99,
CAISE '99, CSCW '98 and EuroPDS '98 conferences.
He serves as
program committee member as well as reviewer at many international conferences.
In addition, he is professionally active as member of many organizations
including the Semantic Web Services Initiative and Semantic Web Science Association.
He is frequently invited to present keynotes and serves as panel member.
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