Applying Description Logics with Concrete Domains to Solve the Problems of Semantic Web Services Discovery and Composition

This research is one of the branches of a general scientific and applied problem, namely, the problem of using and developing ontological approaches with descriptive logics (DL) apparatus to obtain the effective automated solution of complex business task based on service-oriented architecture. The base idea of the proposed method is the maximal ontologization, that is, all aspects of the task are determined by means of DL ontologies. The proposed ontology system is based on five basic types of ontologies, namely: (1) an ontology of general entities for defining the characteristics of the service’s context, (2) an ontology of the application domain to formalize and unify semantical descriptions of web services, (3) the top-level ontology of web services for the DL formalization of the definition of the web services in general, (4) the ontologies of the web services tasks, which provide a formal representation of the tasks on all stages of web services life cycle, and (5) the ontologies of specific web services. All listed ontologies are related. Such, ontologies of the last type include links to all other above-mentioned ontologies and, together with them, provide a unified formally defined semantic resource, which enables the automatic solution of web service tasks. The focus of this study is the applying descriptive logics with concrete domains to the formalization of such basic semantic web services tasks as the web services discovery and composition. In this article, the ontologies of the web services tasks are defined as an extension of the general top-level web service ontology with special complex concepts. Their elements are pairs of “web service-goal (request)”/”web service-web service”, which are compared according to the task being solved. Also, on their basis, special complex concepts are determined, which specify a set of found similarities between existing services and a goal in the discovery task, or «predecessor-follower» type responsibilities of web services to build a composite service. The proposed TBox statements are constructed using descriptive logic with concrete domains 𝓐𝓛𝓒(𝓓). For this purpose, a concrete domain is defined as a pair of sets: (1) the union of sets of possible subsets of the set of individuals of the Parameter concept and possible subsets of the set of individuals of the Context concept, and (2) a set of predicates defined on it. Such definition of the concrete domain provides possibility of using only functional roles to construct the DL statements of complex concepts DiscoveryServices and CompositionObject for determining corresponding web services tasks. Note, the defined tasks and web services ontologies cover only simplified model of the representation of web services, in particular, functional Input/Output model extended by contexts descriptions. They provide the basis for further improvement by expanding this model and involving additional characteristics of both functional and process models of representation to the specified task ontologies. This will certainly increase the accuracy of the obtained result, but is the subject of further research.