As the technology associated to the ?Web Services? trend gains significant adoption, the need for a corresponding design approach becomes increasingly important. This paper introduces a foundational model for designing (composite) services. The innovation of this model lies in the identification of four interrelated viewpoints (interface behaviour, provider behaviour, choreography, and orchestration) and their formalization from a control-flow perspective in terms of Petri nets. By formally capturing the interrelationships between these viewpoints, the proposal enables the static verification of the consistency of composite services designed in a cooperative and incremental manner. A proof-of-concept simulation and verification tool has been developed to test the possibilities of the proposed model.

Service-oriented Design : A Multi-viewpoint Approach

Enterprises depend on business-critical systems that have been developed over the last three decades or more, also known as legacy systems. They have several well-known disadvantages (e.g., inflexible, domain unspecific, and hard to maintain), and this is recognized by both the vendors and customers of these software systems. Both vendors and customers of these systems are well aware that better and cheaper customer specific solutions can be created following the service-oriented paradigm. Hence, momentum is growing within enterprises to evolve legacy systems towards Service-Oriented Architecture (SOA). The evolution to SOA is favored because of various advantages including well established sets of open standards, platform and language independent interfaces, clear separation of service interface and implementation, and loose-coupling among services. Over a decade there have been significant developments in legacy to SOA evolution and that has resulted in a large research body of which there exists no comprehensive overview. This chapter provides an historic overview, focusing on the methods and techniques used in a legacy to SOA evolution. We conducted a systematic literature review to collect legacy to SOA evolution approaches reported from 2000 to August 2011. To this end, 121 primary studies were collected and evaluated using an evaluation framework, which was developed from three evolution and modernization methods widely used in software re-engineering domain. The resulting evaluation constitutes the inventory of current research approaches, methods and techniques used in legacy to SOA evolution and identification of several research directions for future research.

Legacy to SOA Evolution: A Systematic Literature Review

Legacy to SOA Evolution.

This thesis proposes a concept and transformations for designing interactions in a service composition at related abstraction levels. The concept and transformations are aimed at helping designers to bridge the conceptual gap between the business and software domains. In this way, the complexity of an interaction design can be managed adequately.
A service composition is specified as one or more interactions between application components. Interaction design is therefore the central activity in the design of a service composition. Interaction design at related abstraction level requires an interaction concept that can model interactions at a higher abstraction level (called abstract interactions) and interactions at a lower abstraction level (called concrete interactions), in order to avoid any conceptual gap between abstraction levels.
An interaction is defined as a unit of activity that is performed by multiple entities or participants in cooperation to establish a common result. Different participants can have different views on the established result. Two design transformations are defined, namely interaction refinement and interaction abstraction. Interaction refinement replaces an abstract interaction with a concrete interaction structure. Interaction abstraction replaces a concrete interaction structure with an abstract interaction. A set of conformance requirements and a conformance assessment method are defined to check the conformance between an abstract interaction and concrete interaction structure.
To facilitate the development process of a service composition, this thesis also provides (i) patterns for interaction refinement; (ii) abstract representations of interaction mechanisms; and (iii) a transformation tool to transform an interaction design at an implementation level to an executable implementation.
The use of the interaction concept and design transformations are illustrated with two case studies. In the first case study, we design a travel reservation application as a service composition. In the second case study, we design enterprise application integration for an order management by using our interaction concept in an integration approach. The obtained integration solution is then transformed to an executable implementation using our transformation tool.

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Interaction design in service compositions

Handbook of Research on E-Learning Standards and Interoperability: Frameworks and Issues promotes the discussion of specific solutions for increasing the interoperability of standalone and Web-based educational tools. This book investigates issues arising from the deployment of learning standards and provides relevant theoretical frameworks and leading empirical research findings. Chapters presented in this work are suitable for practitioners and researchers in the area of educational technology with a focus on content reusability and interoperability.

Handbook of Research on E-Learning Standards and Interoperability: Frameworks and Issues

IMS QTI is a popular and important standard for e-learning assessment. The second version of the standard (QTIv2) works alongside other IMS standards, but take-up has been slow, with problematic implementations and no definitive reference software. The R2Q2 project aims to produce a set of loosely coupled web services that will provide definitive reference software for QTIv2. In this paper we describe how we have learnt from previous development efforts in order to produce a first architecture and initial implementation, we also describe the results of our interviews with the wider QTI community to identify what is believed to be important for our planned final reference implementation.

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R2Q2: Rendering and Reponses Processing for QTIv2 Question Types

Web Services are increasingly being used to create a wide range of distributed systems, many of which involve legacy software. Developing service interfaces for these legacy systems can be difficult, as for interoperability reasons it is advantageous to use a common service interface that is independent of the particular legacy system behind it. This enables other services to interoperate with like legacy systems regardless of their implementation. Unfortunately, similar legacy systems can offer subtly different functionality from each other, making agreeing on a common interface difficult. This paper introduces three design patterns for managing this problem: Lowest Common Denominator, Most Popular and Negotiated Interfaces. It formally presents these patterns and reflects on how they have been used within the domain of e-learning to wrap legacy systems that function as databases of objective questions.

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Design Patterns for Wrapping Similar Legacy Systems with Common Service Interfaces

Service-Oriented Architectures (SOAs) are increasingly deployed to achieve distributed systems that are modular, flexible and extensible. Designing for a SOA can be difficult, however. There are issues involving the granularity of the cooperating services, and there are no currently accepted conventions for describing a service or its interactions at an abstract level. This paper presents the Service Responsibility and Interaction Design Method (SRI-DM), a light-weight agile method for engineering a Web service design, based on capturing a scenario as a use-case, factoring this into a set of Service Responsibility and Collaboration Cards (SRCs), and constructing a Sequence diagram illustrating their interactions in fulfilling the scenario. The paper presents the notation for each step and describes with the aid of an example how this process is being used to create a service design within the domain of e- assessment.

Ehtesham-Rasheed Jam

Papers

R2Q2: Rendering and Reponses Processing for QTIv2 Question Types

Design Patterns for Wrapping Similar Legacy Systems with Common Service Interfaces

FREMA method for describing Web Services in a Service Oriented Architecture.