An approach to impact analysis in software maintenance

Impact analysis is a software maintenance activity, which consists of determining the scope of a requested change, as a basis for planning and implementing it. After a change request has been specified (change understanding) and the initial part of the system to be changed has been identified (change localization), impact analysis helps to understand consequences of the change on other parts of the system. Induced changes, also named ripple effects, among software components are detected. Most existing approaches perform impact analysis for changes occurring at the code level. In this thesis, concepts developed to perform impact analysis at the code level are applied to trace changes occurring at the design level. The method consists of proposing an activity model addressing the different steps of impact analysis and a data model on which propagations of changes can be traced. The method is validated with a case study applied to a system from the aerospace field. The tools we developed on PCTE help for consistency checks in HOOD based designs during editing. Our data-model based on an Entity Relationship notation describes a way to model HOOD diagrams in PCTE and further on to propagate changes on the repository. Examples chosen address the design phase of a simple engine system. We show that addressing modifications at a higher level of abstraction than the code eases understanding and localization of changes. It also limits the propagation of ripple effects (i.e., unexpected behaviour of the system) by detecting secondary changes at an earlier stage

MATrA: meta-modelling approach to traceability for avionics

PhD ThesisTraceability is the common term for mechanisms to record and navigate relationships between artifacts produced by development and assessment processes. Effective management of these relationships is critical to the success of projects involving the development of complex aerospace products. Practitioners use a range of notations to model aerospace products (often as part of a defined technique or methodology). Those appropriate to electrical and electronic systems (avionics) include Use Cases for requirements, Ada for development and Fault Trees for assessment (others such as PERT networks support product management). Most notations used within the industry have tool support, although a lack of well-defined approaches to integration leads to inconsistencies and limits traceability between their respective data sets (internal models). Conceptually, the artifacts produced using such notations populate four traceability dimensions. Of these, three record links between project artifacts (describing the same product), while the fourth relates artifacts across different projects (and hence products), and across product families within the same project. The scope of this thesis is to define a meta-framework that characterises traceability dimensions for aerospace projects, and then to propose a concrete framework capturing the syntax and semantics of notations used in developing avionics for such projects which enables traceability across the four dimensions. The concrete framework is achieved by exporting information from the internal models of tools supporting these notations to an integrated environment consisting of. i) a Workspace comprising a set of structures or meta-models (models describing models) expressed in a common modelling language representing selected notations (including appropriate extensions reflecting the application domain); ii) well-formedness constraints over these structures capturing properties of the notations (and again, reflecting the domain); and iii) associations between the structures. To maintain consistency and identify conflicts, elements of the structures are verified against a system model that defines common building blocks underlying the various notations. The approach is evaluated by (partial) tool implementation of the structures which are populated using case study material derived from actual commercial specifications and industry standards