A short description is given of software process models and the issues they address. An outline is given of the process steps involved in the spiral model, an evolving risk-driven approach that provides a framework for guiding the software process, and its application to a software project is shown. A summary is given of the primary advantages and implications involved in using the spiral model and the primary difficulties in using it at its current incomplete level of elaboration. >

A spiral model of software development and enhancement

A discussion is presented of the two primary ways of understanding software costs. The black-box or influence-function approach provides useful experimental and observational insights on the relative software productivity and quality leverage of various management, technical, environmental, and personnel options. The glass-box or cost distribution approach helps identify strategies for integrated software productivity and quality improvement programs using such structures as the value chain and the software productivity opportunity tree. The individual strategies for improving software productivity are identified. Issues related to software costs and controlling them are examined and discussed. It is pointed out that a good framework of techniques exists for controlling software budgets, schedules, and work completed, but that a great deal of further progress is needed to provide an overall set of planning and control techniques covering software product qualities and end-user system objectives. >

/pdf/understanding-and-controlling-software-costs-4qntwpm1yk.pdf

Understanding and controlling software costs

Publisher Summary This chapter describes a spiral model of software development and enhancement. The spiral model of the software process has been evolving for several years, based on experience with various refinements of the waterfall model as applied to large government software projects. The spiral model can accommodate most previous models as special cases and further provides guidance as to which combination of previous models best fits a given software situation. Development of the TRW Software Productivity System (TRW-SPS) is its most complete application to date. The chapter illustrates the radial dimension that represents the cumulative cost incurred in accomplishing the steps to date and the angular dimension that represents the progress made in completing each cycle of the spiral.

/pdf/a-spiral-model-of-software-development-and-enhancement-4h9aj1nnyh.pdf

Design Space Analysis is an approach to representing design rationale. It uses a semiformal notation, called QOC (Questions, Options, and Criteria), to represent the design space around an artifact. The main constituents of QOC are Questions identifying key design issues, Options providing possible answers to the Questions, and Criteria for assessing and comparing the Options. Design Space Analysis also takes account of justifications for the design (and possible alternative designs) that reflect considerations such as consistency, models and analogies, and relevant data and theory. A Design Space Analysis does not produce a record of the design process but is instead a coproduct of design and has to be constructed alongside the artifact itself. Our work is motivated by the notion that a Design Space Analysis will repay the investment in its creation by supporting both the original process of design and subsequent work on redesign and reuse by (a) providing an explicit representation to aid reasoning about the design and about the consequences of changes to it and (b) serving as a vehicle for communication, for example, among members of the design team or among the original designers and later maintainers of a system. Our work to date emphasises the nature of the QOC representation over processes for creating it, so these claims serve as goals rather than objectives we have achieved. This article describes the elements of Design Space Analysis and illustrates them by reference to analyses of existing designs and to studies of the concepts and arguments used by designers during design discussions.

Questions, options, and criteria: elements of design space analysis

Software productivity has been steadily increasing over the past 30 years, but not enough to close the gap between the demands placed on the software industry and what the state of the practice can deliver; nothing short of an order of magnitude increase in productivity will extricate the software industry from its perennial crisis. Several decades of intensive research in software engineering and artificial intelligence left few alternatives but software reuse as the (only) realistic approach to bring about the gains of productivity and quality that the software industry needs. In this paper, we discuss the implications of reuse on the production, with an emphasis on the technical challenges. Software reuse involves building software that is reusable by design and building with reusable software. Software reuse includes reusing both the products of previous software projects and the processes deployed to produce them, leading to a wide spectrum of reuse approaches, from the building blocks (reusing products) approach, on one hand, to the generative or reusable processor (reusing processes), on the other. We discuss the implication of such approaches on the organization, control, and method of software development and discuss proposed models for their economic analysis. Software reuse benefits from methodologies and tools to: (1) build more readily reusable software and (2) locate, evaluate, and tailor reusable software, the last being critical for the building blocks approach. Both sets of issues are discussed in this paper, with a focus on application generators and OO development for the first and a thorough discussion of retrieval techniques for software components, component composition (or bottom-up design), and transformational systems for the second. We conclude by highlighting areas that, in our opinion, are worthy of further investigation. >

Cheatham

Papers

Software Technology in the 1990's: Using a New Paradigm