International Journal of Software Engineering and Knowledge Engineering

Changes and adaptations are always necessary after the deployment of a multi-agent system (MAS), as well as of any other type of software systems. Some of these changes may be simply perfective and have local impact only. However, adaptive changes to meet new situations in the operational environment of the MAS may impact globally on the overall design. More specifically, those changes usually affect the organizational structure of the MAS. In this paper we analyze the issue of design change/adaptation in a MAS organization, and the specific problem of how to properly model/design a MAS so as to make it ready for adaptation. Special attention is paid to the Gaia methodology, whose suitability in dealing with adaptable MAS organizations is also discussed with the help of an illustrative application example.

A great deal of data on the Web lies in the hidden databases, or the deep Web. Most of the deep Web data is not directly available and can only be accessed through the query interfaces. Current research on deep Web search has focused on crawling the deep Web data via Web interfaces with keywords queries. However, these keywords-based methods have inherent limitations because of the multi-attributes and top-k features of the deep Web. In this paper we propose a novel approach for siphoning structured data with structured queries. Firstly, in order to retrieve all the data non-repeatedly in hidden databases, we model the hidden database as a hierarchy tree. Under this theoretical framework, data retrieving is transformed into the traversing problem in a tree. We also propose techniques to narrow the query space by using heuristic rule, based on mutual information, to guide the traversal process. We conduct extensive experiments over real deep Web sites and controlled databases to illustrate the coverage and efficiency of our techniques.

Extraction-Transformation-Loading (ETL) tools are pieces of software responsible for the extraction of data from several sources, their cleaning, customization and insertion into Data Warehouses (DWs). Complexity, usability and maintainability are the primary problems concerning ETL processes. To deal with these problems, in this paper we provide a dynamic approach for designing, modeling and realizing ETL processes. We propose a new architecture based on Unified Views Model (UVM) for ETL processes, in which Unified view layer is added between source data level and DWs level. The unified views model serves as the means to conform the structure and semantics of the source data to the ones of the data warehouses, and help designers understand and analyze the meaning, relationships and lineage of information. In order to guarantee the transparency access and the usability, two mapping methods are adopted between Unified view level and source data level as well as between DWs level and Unified view level. Based on this architecture, the method of constructing UVM and ETL operations among three levels is given. Then, we describe how to build the conceptual modeling for ETL processes based on UVM by using an extension of the Unified Modeling Language (UML). Finally, we present an ETL tool based on UVM (UVETL) with the goal of facilitating the design, modeling and realization of ETL processes, and give a case study to exemplify the benefits of our proposal.

Software evolution is inevitable. When a system evolves, there are certain relationships among software artifacts that must be maintained. Requirement traceability is one of the important factors in facilitating software evolution since it maintains the artifacts relationship before and after a change is performed. Requirement traceability can be expensive activities. Many researchers have addressed the problem of requirement traceability, especially to support software evolution activities. Yet, the evaluation results of these approaches show that most of them typically provide only limited support to software evolution. Based on the problems of requirement traceability, we have identified three directions that are important for traceability to support software evolution, i.e. process automation, procedure simplicity, and best results achievement. Those three directions are addressed in our multifaceted approach of requirement traceability. This approach utilizes three facets to generate links between artifacts, i.e. syntactical similarity matching, link prioritization, and heuristic-list based processes. This paper proposes the utilization of multifaceted approach to traceability generation and recovery in facilitating software evolution process. The complete experiment has been applied in a real case study. The results show that utilization of these three facets in generating the traceability among artifacts is better than the existing approach, especially in terms of its accuracy.

An object invariant consisting of a set of properties that must hold for all instances of a class at any time is usually used in object-oriented design. However, verifying object invariants at runtime is always a challenging task in software verification. This paper proposes a method for verifying invariants of Java objects at runtime using AOP. Suppose that a software application is designed using UML models and its constraints are specified in OCL expressions, the software is then implemented, by default, using the UML design. They propose to construct verifiable aspects which are automatically generated from OCL constraints. These aspects can be woven into Java code to check whether object invariants are violated at runtime. Benefiting from AOP in separation of crosscutting concerns and weaving mechanisms, generated aspects can do the verification task whenever values of objects' attributes are changed. A Verification Aspect Generator (VAG) tool has been developed allowing the automatic generation of verifying aspects from the UML/OCL constraints.