Sinuhé Arroyo

Choreography frameworks for business integration: Addressing heterogeneous semantics

Choreography is an essential element of business integration that allows the modeling of the external behavior of services for a specific interchange or collaboration. Existing service-oriented technologies attempt to model such external visible behavior. However, they lack the decoupling and consistent semantic support required in heterogeneous B2B environments. This paper describes the practical application of SOPHIE, a semantic web service-based choreography framework, to generic Request for Quote (RFQ) and quote processes based on the OAGIS canonical model. In doing so, the paper has the objective of showing how existing limitations are overcome, by means of the intermediate structures that conciliate the heterogeneities between services from the semantic descriptions of the message exchange patterns (MEPs) they follow. The essential elements of the framework are briefly presented, describing compatibility in terms of ontology mapping, so the basis for understanding the applicability of the SOPHIE philosophy to general business integration is clear.

SOPHIE: Use case and evaluation

Services communicate with each other by exchanging self-contained messages. Depending on the specific requirements of the business model they serve and the application domain for which services were deployed, a number of mismatches (i.e. sequence and cardinality of messages exchanges, structure and format of messages and content semantics), can occur which prevent interoperation among a priori compatible services. This paper presents the evaluation of SOPHIE, a conceptual framework for supporting the conceptualization of ontology-based services choreographies. In doing so a three fold approach is taken that considers formal, epistemological and technical aspects. The formal evaluation tries to prove the consistency, completeness and conciseness of ontological model used. The epistemological evaluation enumerates the improvements and differentiating aspect of SOPHIE with respect to existing related work and reviews a number of application areas where the work was successfully applied. Finally, the technical feasibility evaluation tries to demonstrate the viability of the approach from the point of view of the engineering process required to allow the interaction of heterogeneous Semantic Services.

A model-driven choreography conceptual framework

A number of languages exist that try to model the external visible behavior of services. However, they constitute incomplete solutions, either because, they do not include proper support for semantics, they have a lack of technological independence, they mix internal and external aspects and finally, they do not provide consistent approaches or present ad-hoc ones to solve behavioral and structural heterogeneities, or worse, they mix both aspects resulting in confusing specifications. This paper describes SOPHIE, a conceptual framework that attempts to overcome these limitations. It allows the production of the intermediate structures that allow overcoming the heterogeneities between services from the semantic descriptions of the Message Exchange Patterns (MEPs) they follow.

Patterns of message interchange in decoupled hypermedia systems

Open hypermedia systems provide a decoupled approach to structural computing. This entails that the architecture of the systems are made up of user agents that communicate with distributed link servers. This in turn raises the consideration of the different message exchange patterns that may be implemented in such interaction, which determines the behaviour of systems according to them. The definition of such exchange patterns is critical if interoperability and flexibility are design objectives. This paper describes a structural model for such kind of message patterns, and provides a list of possible courses of interaction. Then, the influence of such heterogeneity of communication patterns is analyzed from the perspective of composing structure in hypermedia, and a framework for their integration is sketched. This represents a first attempt to advance current Service-Oriented specifications for decoupled hypermedia to cover the heterogeneity of potentially diverging system behaviours.

A unified Semantic Web services architecture based on WSMF and UPML

Current semantic web services lack reusability and conceptual separation between services and goals. We propose a unified architecture based on the principles of WSMF and UPML. We introduce goal- and domain-independent web services. Reuse is achieved through the use of bridges and refiners for goal, web service and domain descriptions.

Describing web services with semantic metadata

Web services are self-describing, self-contained applications that can be published, located, and invoked through common web protocols. Self-descriptions are in fact a form of metadata that provide details on the services offered. Semantic web services are, thus, an extension of such metadata-based descriptions to richer ontology-based description semantics. This paper provides an account on the main usage scenarios of semantic web services, as a roadmap for metadata research on the topic.

Design by Contract-Based Selection and Composition of Learning Objects

Selection and composition of learning objects are two essential activities in automated approaches to Web-based learning. Such activities require high-quality metadata records that are not only conforming to current specifications and standards, but that provide clear system-oriented run-time semantics that support automated decision processes. In this paper, the Design by Contract paradigm is described as a method to formally specify and drive selection and composition of contents aimed at concrete learning requirements. In addition, an architectural mapping for such approach to Web Service technology is described, which provides a flexible integration mechanism in a context of heterogeneous and dynamic learning content-providers.

PSM approach to Web service composition

In this paper we describe a PSM based initiative towards the dynamic composition of Web services, which is achieved by assembling independently deployed components, pluggable in any context that requires its functionality. The ideas used in our approach based on the Unified-Solving Method development Language (UPML), and CBSE research, adapting and extending them to meet the requirements of component composition. The PSM-based composition count with three main features that distinguish our approach from other works in the field. First, it uses a zero-modification composition policy, which enables the construction of application systems out of existing components independently developed in various domains, without any modification of components. Second, it uses a composition mechanism based on mediators and pipe structures. Mediators allow overcoming compositional mismatches without modifying the code of components, preserving its black box and reusability features. Pipes supply a unified pathway that communicates components or mediators with each other transporting the effects of services. Finally, it makes use of a simple Composition Description Language (CDL), which is intended as a mechanism to depict the internal connection between components representing its physical links. The main functionalities of PSM-based composition are illustrated by means of a scenario involving a book price currency conversion

Dynamic Generation of Agent Communities from Distributed Production and Content-Driven Delivery of Knowledge

In an agent-mediated distributed knowledge management system, knowledge is firstly produced and then delivered to a person or community of users that is interested in it. A common issue to this aim is the setting-up of communities that can drive the delivery of contents. In our study, knowledge-producing agents are arranged into separate interaction domains and a distributed interaction protocol is used to consolidate knowledge that is generated therein. Knowledge produced in this way can be used as the source data to dynamically build user communities that drive the delivery of knowledge amongst users. The multi-agent architecture presented here can be applied to the shared creation of various electronic resources, like learning objects, e-books or software artifacts.

Architecture and algorithms of the SOPHIE choreography framework

Services communicate with each other by exchanging self-contained messages, enabling them to make or to respond to requests. Depending on the specific application requirements a number of mismatches affecting the semantics, sequence, cardinality and structure of messages can occur, which prevent interoperation among a prior compatible services. Current technologies present an “ad-hoc” approach for overcoming mismatches. Initiatives to overcome mismatches based on semantic descriptions and mediators, i.e. choreography service, are envisioned as promising in solving these problems. The SOPHIE framework tackles precisely these objectives. It supports the conceptualization and mediation of ontology-based choreographies among interacting services, as a realization of a fully fledged Service Oriented Architecture (SOA). This paper provides an overview of the architecture and algorithms behind SOPHIE. In detail, the service topologies that define the different ways in which parties can be linked and the structure they define are depicted. The operational algorithms that model the mechanisms to generate mediators for overcoming heterogeneity among the Message Exchange Patterns (MEP) of interacting parties are presented. Finally, the correlation algorithms that put in place the required logic to link the messages sent by one party to the ones expected by another are described.