Innovations in Software Engineering for Defense Systems (2003) / Chapter Skim
Currently Skimming:
2 Requirements and Software Architectural Analysis
2 Requirements and Software Architectural Analysis
Pages 12-19
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 12... ...
It is believed that roughly half of software defects are introduced during the requirements and functional analysis stage, 1 and some well-known software development projects have had a large percentage of serious software defects introduced during the specification of requirements. Therefore, utilization of techniques that improve the software requirements can save substantial time and money in software development and will often result in higher-quality software.
|
From page 13... ...
A critical step in constructing an SCR software requirements document is to identify all outputs that the software must produce and to express the value of each output as a mathematical function of the state and history of the environment. To represent these functions accurately, unambiguously, and concisely, the A-7 document introduced a special tabular notation that facilitates writing and understanding the functions and also aids in detecting specification errors, such as missing cases
|
From page 14... ...
Not only can such tools find specification errors that manual inspections miss, they can do so more cheaply. To establish a formal foundation for tools supporting the development of an SCR requirements specification, Heitmeyer and her research group formulated a formal model to rigorously define the implicit state machine model that underlies an SCR requirements specification.
|
From page 15... ...
To construct these auxiliary properties, the user may invoke the SCR invariant generator Jeffords and Heitmeyer, 1998) , a tool that automatically constructs state invariants (properties true of every reachable state)
|
From page 16... ...
In under five person-weeks, the contractor specification was translated into SCR, and the SCR tools were used to analyze the specification for errors and to develop a realistic simulator for demonstrating and validating the required behavior of the TTCP. Analysis with the SCR tools and the SPIN model checker identified a serious safety violation in the SCR specification.
|
From page 17... ...
(This state box is an excellent starting point for the model underlying Markov chain usage testing, discussed in the following section.) Sequence-based specification provides a constructive process for defining the state machine in a manner that ensures complete, consistent, and correct requirements, whereas SCR, in attaining the same goals, relies on intuition assisted by graphical tools to develop the state machine.
|
From page 18... ...
In 2The semantics of Statemate is being applied to the definition of formal behavioral semantics for the graphical state diagram notation employed by the Unified Modeling Language standard. This modeling and domain analysis notation for system specifications is supported by many vendor tools.
|
From page 19... ...
REQUIREMENTS AND SOFTWAREARCHITECTURAL ANALYSIS 19 addition, other related approaches have similar advantages. The workshop participants generally agreed on the potential benefit of applying these methods widely to defense software systems in development, and therefore the value of continued testing and analysis of the applicability of such methods to defense systems.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.