Distributed system software design paradigm with application tocomputer networks

A paradigm for the system and software design of distributed systems is presented with application to an actual large-scale computer network involving both local area networks and a wide area network. A number of design principles are offered with particular reference to how they can be applied to the design of distributed systems. The author's major point is an explanation of how to make design decisions about distributed systems in a way which will enhance maintainability and understandability of the software and, at the same time, result in good system performance. The aim is to recognize the implications for software quality of various decisions which must be made in the process of specifying a distributed system     

Software metrics validation: Space Shuttle flight software example

Software quality metrics have potential for helping to ensure the quality of software on large projects such as theSpace Shuttle flight software. It is feasible to validate metrics for the purpose of controlling and predicting software quality during design by validating metrics against a quality factor. Quality factors, like reliability, are of more interest to customers than metrics, like complexity. However, quality factors cannot be collected until late in a project. Therefore, the need arises to validate metrics, which developers can collect early in a project, against a quality factor. We investigate the feasibility of validating metrics for controlling and predicting quality on theSpace Shuttle. The key to the approach is the use of validated metrics for early identification and resolution of quality problems.     

Measuring and evaluating maintenance process using reliability,risk, and test metrics

In analyzing the stability of a software maintenance process, it is important that it is not treated in isolation from the reliability and risk of deploying the software that result from applying the process. Furthermore, we need to consider the efficiency of the test effort that is a part of the process and a determinate of reliability and risk of deployment. The relationship between product quality and process capability and maturity has been recognized as a major issue in software engineering based on the premise that improvements in the process will lead to higher-quality products. To this end, we have been investigating an important facet of process capability-stability-as defined and evaluated by trend, change and shape metrics, across releases and within a release. Our integration of product and process measurement serves the dual purpose of using metrics to assess and predict reliability and risk and to evaluate process stability. We use the NASA Space Shuttle flight software to illustrate our approach     

Controlling and predicting the quality of space shuttle software using metrics

Software quality metrics have potential for helping to assure the quality of software on large projects such as the Space Shuttle flight software. It is feasible to validate metrics for controlling and predicting software quality during design by validating metrics against a quality factor. Quality factors, like reliability, are of more interest to customers than metrics, like complexity. However quality factors cannot be collected until late in a project. Therefore the need arises to validate metrics, which developers can collect early in a project, against a quality factor. We investigate the feasibility of validating metrics for controlling and predicting quality on the Space Shuttle. The key to the approach is the use of validated metrics for early identification and resolution of quality problems.     

Software maintenance: The need for standardization

Hardware and software maintenance are contrasted. The key difference between the two-the ease with which software can be changed-leads to the need for managing software change. Standardization of software maintenance is proposed as a method for managing software change. A model of software maintenance is advanced as the foundation for standardizing software maintenance     

How to evaluate legacy system maintenance

Drawing on extensive data from the NASA Space Shuttle's guidance software, the author proposes a method for evaluating the effectiveness of legacy software maintenance efforts. He provides several formulas for tracking maintenance stability, defined as increasing functionality with decreasing failures over time, and offers data that supports their validity. He also provides tips for applying his formulas to different projects     

Representativeness models of systems: smart grid example

Given the great emphasis being placed on energy efficiency in contemporary society, in which the smart grid plays a prominent role, this is an opportune time to explore methodologies for appropriately representing system attributes. We suggest this is important for effective system development because the primary factor in correctly mapping between requirements and implementation is how representative the system design is of requirements. Since representativeness is an abstract term, it is imperative to identify ways to quantify it. We use several metrics. Among these is the priority of system elements (e.g., electric generator) in the set of elements, based on importance to system success. Secondly, fault tree analysis is employed to identify elements that operate in an unsafe state and the probabilities of reaching these unsafe states. Thirdly, state transition analysis provides traces of which elements are on the routes to unsafe states. These analyses provide the information needed to reduce element faults and failures on a priority basis.