Business Process Model and Notation (BPMN) provides organizations with a standard that facilitates further compression of the business process. BPMN focuses on the functional processes, leaving the development of interfaces to one side. Thereby, interface design usually depends on the subjective experience of the analyst. This article aims to propose a new method to generate user interfaces from BPMN models and Class Diagrams. The proposed method is based on the identification of different rules and makes use of stereotypes to extend BPMN notation. The rules have been extracted from seven existing projects on the Bizagi repository. Specifically, the proposal is based on the extraction of rules for generating user interfaces based on three widely used patterns: sequence pattern, exclusive decision pattern and synchronization pattern. As a result of our proposal, eleven new stereotypes have been added to BPMN notation. These stereotypes allow generating interfaces based on business process models. For a better understanding, the proposed stereotypes have been applied to an illustrative example. The results show that this work is a “step forward to” the automatic code generation from models.

Last years have witnessed the widespread use of online terrain visualization applications. However, the significant improvements achieved in sensing technologies have allowed an increasing size of the terrain databases. These increasing sizes represent a serious drawback when terrain data must be transmitted and rendered at interactive rates. In this paper, we propose a novel wavelet-tiled pyramid for compressing terrain data that replaces the traditional multiresolution pyramid usually used in wavelet compression schemes. The new wavelet-tiled pyramid modifies the wavelet analysis and synthesis processes, allowing an efficient transmission and reconstruction of terrain data in those applications based on multiresolution tiled pyramids. A comparative performance evaluation with the currently existing techniques shows that the proposed scheme obtains a better compression ratio of the terrain data, reducing the storage space and transmission bandwidth required, and achieving a better visual quality of the virtual terrain reconstructed after data decompression.

Abstract The increasing popularity of multi‐player online games is leading to the widespread use of large‐scale Distributed Virtual Environments (DVEs) nowadays. In these systems, peer‐to‐peer (P2P) architectures have been proposed as an efficient and scalable solution for supporting massively multi‐player applications. However, the main challenge for P2P architectures consists of providing each avatar with updated information about which other avatars are its neighbors. This problem is known as the awareness problem. In this paper, we propose a comparative study of the performance provided by those awareness methods that are supposed to fully solve the awareness problem. This study is performed using well‐known performance metrics in distributed systems. Moreover, while the evaluations shown in the literature are performed by executing P2P simulations on a single (sequential) computer, this paper evaluates the performance of the considered methods on actually distributed systems. The evaluation results show that only a single method actually provides full awareness to avatars. This method also provides the best performance results. Copyright © 2008 John Wiley & Sons, Ltd.

The current expansion of multi-player online games has promoted the growth of large scale distributed virtual environments (DVEs). In these systems, peer-to-peer architectures have been proved as the most scalable scheme for supporting massively multi-player applications. Nevertheless, the interactions among clients that can take place in this type of systems can lead to the temporal saturation of some of the clients. Since a client saturation has an effect on other clients, these situations limit the performance of peer-topeer DVEs. In this paper, we propose an adaptive technique for avoiding the saturation of the client computers in DVE systems based on peer-to-peer architectures. This technique is based on monitoring the client state and discarding some of the messages received from other clients when the client is close to saturation. The evaluation results show that the proposed method improves the system performance without having an effect on the awareness rate, regardless of the movement pattern that avatars can follow. As a result, both the performance and the scalability of peer-to-peer DVEs are significantly improved.

The current expansion of multi-player online games has promoted the growth of large scale distributed virtual environments (DVEs). In these systems, peer-to-peer architectures have been proved as an efficient scheme for supporting massively multi-player applications. In order to research on this type of architecture, stand-alone simulators do not take into account inconsistencies due to network latency, and it is necessary to develop a distributed tool that allows to simulate large-scale DVEs in an efficient way. In this paper, we propose a distributed platform for simulating the behavior of peer-to-peer DVEs. This simulator is implemented following a modular architecture. It is capable of providing the main performance metrics in distributed systems, and it contains all the elements involved in real DVE simulations like the awareness method and the graphic interface. As a result, this tool can be used in real simulations of peer-to-peer DVEs, becoming an invaluable tool for capturing the behavior of this kind of systems.

Large scale distributed virtual environments (DVEs) have become a major trend in distributed applications, mainly due to the enormous popularity of multi-player online games in the entertainment industry. Since architectures based on networked servers seem to be not scalable enough to support massively multi-player applications, peer-to-peer (P2P) architectures have been proposed as an efficient and truly scalable solution for this kind of systems. However, in order to design efficient DVEs based on peer-to-peer architectures these systems must be characterized, measuring the impact of different client behaviors on system performance. This paper presents the experimental characterization of peer-to-peer distributed virtual environments in regard to well-known performance metrics in distributed systems. Characterization results show that system saturation is inherently avoided due to the peer-to-peer scheme, as it could be expected. Also, these results show that the saturation of a given client exclusively has an effect on the surrounding clients in the virtual world, having no noticeable effect at all on the rest of avatars. Finally, the characterization results show that the response time offered to client computers greatly depends on the number of new connections that these clients have to make when new neighbors appear in the virtual world. These results can be used as the basis for an efficient design of peer-to-peer DVE systems.

Distributed virtual environment (DVE) systems allow multiple users working on different client computer's interconnected through different networks to interact in a shared virtual world. In these systems, latency is crucial for providing an acceptable quality of service (QoS), since it determines how fast client computers are reported about changes in the shared virtual scene produced by other client computers. This paper presents in a unified manner a partitioning approach for providing a latency below a threshold to the maximum number of users as possible in DVE systems. This partitioning approach searches the assignment of avatars, which represents the best trade-off among system latency, system throughput, and partitioning efficiency when solving the partitioning problem. Evaluation results show that the proposed approach not only maximizes system throughput, but also allows the system to satisfy, if possible, any specific latency requirement needed for providing QoS. This improvement is achieved without decreasing either image resolution or quality of animation, and it can be used together with other techniques already proposed. Therefore, it can contribute to provide QoS in DVEs.