International Journal of Computer Science and Artificial Intelligence Sept. 2012, Vol. 2 Iss. 3, PP. 11-23 11 DOI: 10.5963/IJCSAI0203002 Multi-Representation Ontology for Requirements Specification Achraf Mtibaa 1 , Faïez Gargouri 2 1 Higher Institute of Electronics and Communication, Computer Science Department, University of Sfax /MIRACL Laboratory, Tunis Road KM 10 B. P. 242 Sakiet Ezziet Sfax, Tunisia 2 Higher Institute of Computing and Multimedia, Computer Science Department, University of Sfax /MIRACL Laboratory, Tunis Road KM 10 B. P. 242 Sakiet Ezziet Sfax, Tunisia 1 achrafmtibaa@gmail.com; 2 faiez.gargouri@isimsf.rnu.tn Abstract- The requirements specification step is considered as a crucial step involved during the requirements analysis in the life cycle of an information system. This step is considered as a contract between future users and designers. It concerns the expected characteristics: functional and non-functional requirements. However, many problems arise in this step such as the difficulty of gathering information, misunderstanding and incomplete requirements, lack of opportunities and constraints of the proposed systems, etc. In addition, requirements risk is unclear. This materializes in particular by conflict profiles, points of view and contexts among different users admitting different techniques to specify their requirements. For this reason, we propose a multi- representation ontology (MRO) for requirements specification (RS) to solve the multi-context and the multi-representation problems. This paper proposes a MRO to enhance the effectiveness of RS. It presents the complementarities between context and ontology. It exposes an approach to establish the MRO providing the formalization and the visualization of this ontology. The proposed ontology is operationally defined in ContextOntoMR prototype. Keywords- Ontology; Requirements Specification; Context; Multi-Representation I. INTRODUCTION The variation of the environment and the user context of the information system (IS) can cause the change of users’ requirements or even their views and attitudes towards a given situation (a decision). The user’s reaction and his decision may be influenced by different aspects, namely skills, personal characteristics (profile) and the situation in which it is located (the context of use when decision- making). The profile itself can be influenced by the user’s context. This multitude of contexts results different requirements expression, even contradictory. A good design of an IS must take into account certain essential aspects for the project success, such as the requirements specification, taking into account the multitude of contexts and heterogeneity of techniques used to the specification of requirements. The designer, in this case, is facing various problems including inconsistency, semantic ambiguity and the difficulty of requirements modelling. As a solution, we propose the use of ontologies known by their incontestable contributions to the semantic level. They are typically used to address the semantic problems. For the problems of multi-context, we proceed to a requirements multi-contextual modelling. To address these problems and assist future users to express their requirements, we combine the ontology with the multitude of contexts. In this paper, we propose an approach to establish ontology for the multi-context requirements. Our goal is to assist the users to specify their requirements in different contexts specified with several techniques. We aim to solve some of these problems. For that, we plan to cover the requirements specification step engaging users to express their requirements and analysts to specify these requirements. The remaining of this paper is structured as follows: Section 2 presents RS problems. Section 3 shows the contextual aspect in ontology. In Section 4, we propose a MRO for RS to solve the multi-context and multi- representation problems. Section 5 shows a comparative study of related research works. In Section 6, we present an approach to establish the MRO. We suggest, in Section 7, formalization and visualization of MRO. Section 8 shows ContextOntoMR prototype. In Section 9, we enumerate the MRO contributions via ContextOntoMR. Section 10 concludes the paper. II. REQUIREMENTS SPECIFICATION PROBLEMS The RS is a very important step to ensure a consistent and durable system. However, it can cause some problems against the user. Among them, we mention: - users do not know what they want; - users do not want to write their requirements; - users insist on new requirements after the cost and calendar have been set; - communication with users is time-consuming; - users lack technical competence; - users do not understand the development process. These problems can make some conflicts like: - Omission: one or more requirements that should be specified are omitted; - Inconsistency: the requirements specification is in disagreement with the expressed requirement; - Ambiguity: the requirements specification is not clear, and could cause a misinterpretation or misunderstanding of requirements meaning; - High cost and time-consuming spent on this step; - Requirements collection misunderstands;