Mobile Ad-hoc NETworks (MANETs) are wireless networks designed for communications among nomadic hosts in absence of fixed infrastructure. Different reactive protocols for MANETs, in which routes are established only when needed, provide different network topology awareness (NTA) to each host, depending on their algorithmic features. NACK-based AODV (N-AODV) is a variant of the well-known Ad-hoc On-demand Distance Vector (AODV) reactive protocol for MANETs we proposed with the aim of improving NTA of the original protocol. In this paper, a performance comparison between AODV and N-AODV is conducted in order to investigate whether N-AODV effectively improves NTA with respect to AODV, and how this improvement affects both its effectiveness and efficiency. The experiment is executed within a simulation environment. The obtained results show that a MANET adopting N-AODV exploits higher NTA than a MANET adopting AODV. Moreover, the improved awareness impacts effectiveness and efficiency of routing activities because, in the long-run, it results in a lower need to activate the route discovery process for establishing new communications sessions.

Mobile Ad-hoc NETwork (MANET) is an emerging approach for communication among hosts, which does not need any fixed infrastructure. Several tools are available for simulating the behavior of MANETs: the main disadvantages of most of them concern the difficulties in managing the synchronization among the components involved in the simulation. Our research is aimed at building a tool, which is able to both modeling and simulating MANETs, so that synchronization and concurrency can be properly managed. In our research the tool DEMONE has been developed with the aim to build an environment for both modeling and simulating MANETs, and in which synchronization is established by the internal behavior of the hosts. In this paper the tool DEMONE is presented, and it is empirically validated through simulations. The results obtained in 3000 simulations are analogous to the findings reported in literature, but obtained with other simulators. This experience is an evidence of the ability of DEMONE in measuring performance of MANETs.

Software reuse can become a key factor for improving and guaranteeing software quality, when adopted systematically all along the software process. The main characteristic of reuse-oriented processes is that they require a common repository for storing, searching and retrieving software modules. Moreover, reuse occurs systematically and is an integrated part of the process. Previous works of the same authors have empirically shown that the full reuse maintenance model (FRM) slows down quality degradation following to maintenance interventions on a software system. This work is a further step in the investigation towards demonstrating how reuse oriented development (ROD) impacts on software quality; how it favors FRM model; and finally, whether reuse-oriented development influences productivity, and as so, is more efficient. This has been done through a case study carried out on two ongoing industrial projects. Results are positive and support our research hypotheses.

During its life, a legacy system is subjected to many maintenance activities, which cause degradation of the quality of the system: When this degradation exceeds a critical threshold, the legacy system needs to be reengineered. In order to preserve the asset represented by the legacy system, the familiarity with it gained by the system's maintainers and users, and the continuity of execution of current operations during the reengineering process, the system needs to be reengineered gradually. Moreover, each program needs to be reengineered within a short period of time. The paper proposes a reengineering process model, which is applied to an in-use legacy system to confirm that the process satisfies previous requirements and to measure its effectiveness. The reengineered system replaced the legacy one to the satisfaction of all the stakeholders; the reengineering process also had a satisfactory impact on the quality of the system. Finally, this paper contributes to validate the cause-effect relationship between the reengineering process and overcoming the aging symptoms of a software system.

A transferable quality model must be general. This implies that only the high level characteristics can be transferred into different settings and that the refinement of the characteristics into metrics must be operated according to the context peculiarities. In spite of the amount of quality models and approaches to quality models definition presented in literature, there are no experiences reported showing the same quality model reused in different environments. This statement needs further investigation. The aim of this work is to present an experience on the field that involves two industrial projects in which the same quality model was used. The study confirms the need to modify the quality model, not only in the metrics but also in the measurement processes and in the interpretation of the resulting measures as side effects.

A large software project may be distributed over multiple sites when the organization believes that there are not enough people to staff a single collocated team. However, previous empirical research in the context of telecommunication organizations has shown that distance may increase cycle time and costs. We report on a large software massive maintenance project in the information systems domain, which in part has been carried out on a single site and in part across multiple sites of the same organization. We performed a comparative postmortem analysis of the two parts. Our results show that, with respect to cycle time and cost no significant differences exist among the distributed and collocated work. Indeed there is a significant difference in communication during the project. This implies that for massive maintenance activities the distribution over multiple sites can be really helpful.

This paper describes a process of gradual reengineering of the procedural components of a legacy system. The process is integrated and completed by the data reengineering process analyzed in a previous paper by the same authors. The proposed method enables the legacy system to be gradually emptied into the reengineered system, without needing to either duplicate the legacy system or freeze it. The process consists of evolving the legacy system components toward firstly a restored system and then toward the reengineered system. Meanwhile, the legacy system can coexist with both the restored and the reengineered parts. By the end of the process, a single system will be in existence: the reengineered one. The method has been applied to reengineer a real system and demonstrated its ability to: support gradual reengineering, maintain the system at work during the process, minimize the need to freeze maintenance requests, renew the operative environment of the reengineered system with respect to the legacy system and, finally, eliminate all the system's aging symptoms.