| The semantic web concept proposed in 2000 by Tim Berners-Lee, it isthe expansion and extendsion of current web. The information on thesemantic web has full and complete semantic definition, and it can establishunderstanding and cooperation between the human and the computer insemantic level. Ontology has the extremely important status in Semantic Web.It is the foundation of solving sharing and exchanging of Web information insemantic level, and can provide the tool for the knowledge sharing andreusing in the knowledge level. The utilization of the ontology causes thestarting and prosperity of the ontology engineering. Research on ontologydescription, the ontology modelling method and tool are several importantdirections.Ontologies are often captured in knowledge representation languages thatcame out of the AI community. These languages are often structured afterlogic formalisms, such as predicate logic, and have a grounding in them,which supports machine reasoning. This structure, however, has led tolanguage syntax that is unfamiliar and awkward for domain experts, whichhas been a major hindrance to the development of ontologies.One recentexception is OWL, the W3C Web Ontology Language. After absorb themerits of many kinds of ontology describling language, W3C has releasedWeb ontology language (OWL). OWL uses familiar constructs such asclasses, properties, and individuals for defining ontologies and uses XML asthe syntax for documenting and exchanging ontologies. OWL is a keycomponent of the W3C Semantic Web initiative and is likely to gain widesupport in the industry.The huge success of UML in the software engineering, purticularly therapid development of the Model Driven Architecture (MDA) in recently,urges the researcher think how to combine ontology modeling with UMLtechnology.The Unified Modeling Language (UML) is a graphical modelinglanguage that is often used for conceptual and information modeling. TheUML has been the industry standard for visualizing, specifying, constructing,and documenting the artifacts of a software-intensive system. As the de factostandard modeling language, the UML facilitates communication and reducesconfusion among project stakeholders. OCL is the supplement of UML, alsois a part of UML2.0 standard. The Object Constraint Language (OCL) is atext language for writing navigation expressions, Boolean expressions, andother queries. It may be used to construct expressions for constraints, guardconditions, actions, preconditions and postconditions, assertions, and otherkinds of UML expressions. XML Metadata Interchange (XMI) is an externalformat for serializing and exchanging models across platforms and systems.It is the standard interchange format for UML. It is based on the XMLlanguage. The similarities of UML constructs to constructs used in definingontologies suggest that UML could be a means towards rapid development ofontologies.UML is well established in many communities with extensive toolsupport from both commercial and open source vendors. Many domainexperts are familiar with UML and many domain models in UML havesimilarity to ontologies.There are many similarity between UML and OWL.An ontology descripted in OWL is similar to the UML package whichrepresent a specific model;OWL and UML all have the concept of class,individual, inherit, cardinal number and so on;the OWL Property is similar tothe UML relationship between classes or the attribute of classe. Reseach onhow to use UML visualize ontology model and how to use UML for ontologymodelling become hot spot. In the mass, current researches were mainlyabout the discussion and supposition of theory, lack of available method andthe tool. On the other hand, even if some implementations were introduced,because of lacking of the theoretical foundation it is difficulty to be broadlyacknowledged as standard methods.In 2003, OMG released the Ontology Definition Metamodel Request ForProposal (ODM RFP). The goal of this proposal is to specify technologiesthat enable using UML for rapid development of ontologies. The OntologyDefinition Metamodel (ODM) is a MOF2 compliant metamodel that allows auser to define ontology models using the same terminology and concepts asthose defined in OWL. IBM Corporation has submitted his own proposal,which content including ODM, mapping between ODM and OWL, the UMLontology Pofile (UOP) as well as mapping between ODM and UOP. TheODM Metamodel uses packages to control complexity, promoteunderstanding, and support reuse. The model elements are contained in thefollowing packages: Kernel package Contains classes and associations thatform the kernel of the ODM metamodel, which are used by all other ODMpackages;Ontology package Contains classes and associations that can beused to define an ontology;Classes package Contains classes andassociations that can be used to define ODM classes for use in defining anontology;Properties package Contains classes and associations that can beused to define ODM properties for use in defining an ontology;Individualspackage Contains classes and associations that can be used to describe factsabout individuals in an ontology;Datatypes package Contains classes andassociations that can used to create data types and data values for use indefining an ontology. This submission proposal six UML Profiles: AnnotationProfile defined all the stereotypies used to annotate the ontology, Class,Property and Individual;Ontology Profile defined all the stereotypies used indefined the ontology package and relation between the ontology;ClassProfile defined all the stereotypies used in the definition Class, relationbetween Classes as well as Restricition;Property Profile defined all thestereotypies used in defining the Property (including object Property and dataProperty) and relationship between them;Individual Profile defined all thestereotypies used in defining individuals and the relationship between them;Datatype Profile defined all the stereotypies used in defining the data typesand theirs usage. The IBM ODM proposal submission solved two premises ofontology modelling in UML. The definition of ODM and UOP causemodeling of ontology in UML stayed no longer on the discussion stage butbecame practical method which has strict theory foundation.My research is based on IBM submission. This paper putt forward fiveprinciples: accuracy, completeness, similarity, simplicity and usability, thenmodify UOP of IBM submission according these principles and implementedit in specific UML modelling tool -Sparx Enterprise Architecture (EA). AfterUOP created and deployed in EA, it becomes a visual modeling enviromentfor ontology. In UOP part of IBM's submission, there are lists of stereotypesmerely and the explanations and restraints of these stereotypes were omitted.In order to enhancement the accuracy of UOP, it is necessary to add certainOCL restraint for UOP. The stereotype applied to Association is mostpossible misused in modeling process, therefore constraint on thesestereotypes is mainly considered. The method is forcing the source and targetof the instance of these stereotypes to be the proper instance of stereotypesapplied to Class acording to OWL semantics. The advantage of adding OCLrestricton for UOP Lies on improving the accuracy of UOP, providing abilityto the early validation of model and reducing complexity of the software toolfor mapping XMI to OWL.This paper also introduced how to implemente the mapping tool whichused in conversion XMI file of UML model of ontology into OWLdocuments. The major function of this tool is file conversion, and it has someother funcitons, for instance, optional output format (RDF/XML or XMLPresentation), model validation and error reporting. The software wasimplemented in Java languages, and mainly uses DOM API. The DocumentObject Model (DOM) is a platform-and language-neutral interface that willallow programs and scripts to dynamically access and update the content,structure and style of documents. The document can be further processed andthe results of that processing can be incorporated back into the presentedpage.This research has the important theoretical and practical significance.From the theoretical point of view, it not only expands the UML applicationscope, but also has established the relation between the ontology engineeringand the software engineering in a way. From the practical point of view, thecombind of UOP deployed and the mapping tool become a kind of visualontology development enviroment, which provided the standard method forrepresentation of ontology model in UML diagram.Future work will be developing the perfect Ontology IntegratedDevelopment Environment (OIDE). This tool must possess several crucialcharacters, namely the ability to processing large-scale ontology, perfectcooperation mechanism and distributed processing mechanism. |
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