Recently, researchers and practitioners pay attentions to the topics on architecture-based approache for software reliability modeling, because they utilize actively design tools such as a UML (unified modeling language) in model-driven software development. In this tutorial paper, we introduce the architecture-based software reliability models using the source codes diagrams and/or UML diagrams. First, we give the definition of software architecture, and, particularly, mention the dynamic architecture-based software reliability models, which can be represented by software user's operational profiles. Moreover, we summarize the recent researche results and refer to the future works.

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The N-version programming (NVP) approach is a kind of fault tolerant techniques and is a software system employing functionally equivalent, yet independently developed software components. It relies on the application of design diversity, i.e., program versions are independently designed to meet the same system requirements. A consistent set of inputs is supplied to all versions and all N versions are executed in parallel. A decision mechanism must gather the available results from N versions and determine the result to be delivered to the user. When constructing a large size software system with extreme high reliability, we must use much higher reliable components, however, it needs very much expense. But, such a large, highly reliable software system should be designed with as low cost as possible. Genetic algorithm (GA) is known as one of the most powerful optimizers or near-optimizers of combinatorial optimization problems. We introduce two genetic algorithms, one employs the Random-key representation, and the other employs the Binary representation for solving the N-version program design problem formulated as a 0-1 non-linear integer programming problem, respectively. Further, the efficiency of the proposed GAs will be ensured through some numerical experiments. Then the characteristics of each representation scheme are investigated and evaluated.

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Computerized railway interlocking systems have seen significant evolution and improvement since their introduction in 1985 and have demonstrated a high level of safety and reliability in safety-critical systems. However, it is costly and troublesome to develop current interlocking systems to ensure safety. In this paper, we present a new approach which aims to significantly improve interlocking system safety and reliability and to curtail system costs by developing a component-based railway interlocking system (CBRIS). We illustrate a method of modeling CBRIS using deterministic and stochastic Petri nets (DSPNs). Based on this modeling method, we also discuss a method of analyzing the safety and reliability of the presented CBRIS.

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Traditional file sharing systems are constructed as the server-client model. In these systems, a shared file is stored in a server storage and is referred by clients. In this model, traffic is concentrated near the server and user management is complicated. On the other hand, Peer-to-Peer(P2P) protocol is used on the internet for sharing files between unspecified large number of users. But on P2P network, all users can access every file and user access is uncontrollable. This paper presents a P2P style distributed storage system for bunch of unused storage which are distributed on the network. A file is divided into many segments and these segments are distributed considering load balance of the network and reliability of stored data.

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