A design-for-change approach: developing distributed applications from enterprise models

This paper presents a novel approach to distributed applications design. The proposed approach considers both the enterprise viewpoint and the computational\ud viewpoint of distributed applications during the design process. Two important benefits are thus accomplished: (1) the resulting distributed applications will better match the enterprise’s needs, and (2) changes in the enterprise can easily be translated to changes in the distributed application. The approach comes with a formal notation that makes it possible to define a precise relation between enterprise models and models of the distributed applications

Model-driven design of distributed applications

The design process is structured into a preparation and an execution phase. In the preparation phase, designers identify (and, when necessary, define) the required levels of models, their abstract platforms and the modelling language(s) to be used. In addition, a designer may also identify or define transformations between related levels of models. The results of the preparation phase are used in the execution phase, which entails the creation of models of an application using specific modelling languages and abstract platforms.\ud The main aspects of the approach are illustrated with a case study involving the design of context-aware mobile services. We define three levels of models: a platform-independent service specification level, a platformindependent service design level and a platform-specific service design level. Particular attention is given to the representation and transformation of behavioural aspects of service designs

Stable Structures for Distributed Applications

For distributed applications, we define the linear, tree and graph structure types with different variants and modalities to aggregate them. The distributed applications have assigned structures that through their characteristics influence the costs of stages for developing cycle and the costs for exploitation, transferred to each user. We also present the quality characteristics of a structure for a stable application, which is focused on stability characteristic. For that characteristic we define the estimated measure indicators for a level. The influence of the factors of stability and the ways for increasing it are thus identified, and at the same time the costs of development stages, the costs of usage and the costs of maintenance to be keep on between limits that assure the global efficiency of application. It is presented the base aspects for distributed applications: definition, peculiarities and importance. The aspects for the development cycle of distributed application are detailed. In this article, we alongside give the mechanisms for building the defined structures and analyze the complexity of the defined structures for a distributed application of a virtual store.distributed applications, data structures, costs, software quality

Distributed Information Management with Mobile Agents

With more users taking advantage of publicly accessible networks, such as corporate intranets and the Internet, larger amounts of information is becoming electronically distributed and disseminated. Distributed information management is an emerging technology for dealing with the problems of managing information that is spread across networks, users and applications. We present four categories that we consider being necessary to developing tools to undertake distributed information management tasks. To help model the dynamic and heterogeneous nature of a user's distributed information, we advocate the use of agents and agent technologies when building distributed information management applications. We present an agent-oriented architecture which is based around a concept of mobile agents, since they provide a convenient abstraction for modelling distributed applications

Reliability in Distributed Software Applications

Reliability is of vital importance for distributed software application and should be ensured in all stages of the development cycle. Ensuring a high level of reliability for distributed software applications leads to competitive applications which increase the level of user satisfaction. The aim of this paper is to present techniques and methods which ensure high level of reliability. A model for estimating the reliability through risk assessment is presented. Distributed software applications are composed of multiple components spread across multiple heterogeneous platforms and partial failures are inherent. To ensure high reliability is very important that the input data for distributed application components are correct and complete.Distributed Applications, Reliability Model, Risk Assessment, Data Acquisition

Platform-independent Dynamic Reconfiguration of Distributed Applications

The aim of dynamic reconfiguration is to allow a system to evolve incrementally from one configuration to another at run-time, without restarting it or taking it offline. In recent years, support for transparent dynamic reconfiguration has been added to middleware platforms, shifting the complexity required to enable dynamic reconfiguration to the supporting infrastructure. These approaches to dynamic reconfiguration are mostly platform-specific and depend on particular implementation approaches suitable for particular platforms. In this paper, we propose an approach to dynamic reconfiguration of distributed applications that is suitable for application implemented on top of different platforms. This approach supports a platform-independent view of an application that profits from reconfiguration transparency. In this view, requirements on the ability to reconfigure components are expressed in an abstract manner. These requirements are then satisfied by platform-specific realizations

Tools for monitoring and controlling distributed applications

The Meta system is a UNIX-based toolkit that assists in the construction of reliable reactive systems, such as distributed monitoring and debugging systems, tool integration systems and reliable distributed applications. Meta provides mechanisms for instrumenting a distributed application and the environment in which it executes, and Meta supplies a service that can be used to monitor and control such an instrumented application. The Meta toolkit is built on top of the ISIS toolkit; they can be used together in order to build fault-tolerant and adaptive, distributed applications