Pre/post conditioned slicing

Th paper shows how analysis of programs in terms of pre- and postconditions can be improved using a generalisation of conditioned program slicing called pre/post conditioned slicing. Such conditions play an important role in program comprehension, reuse, verification and reengineering. Fully automated analysis is impossible because of the inherent undecidability of pre- and post- conditions. The method presented reformulates the problem to circumvent this. The reformulation is constructed so that programs which respect the pre- and post-conditions applied to them have empty slices. For those which do not respect the conditions, the slice contains statements which could potentially break the conditions. This separates the automatable part of the analysis from the human analysis

VADA: A transformation-based system for variable dependence analysis

Variable dependence is an analysis problem in which the aim is to determine the set of input variables that can affect the values stored in a chosen set of intermediate program variables. This paper shows the relationship between the variable dependence analysis problem and slicing and describes VADA, a system that implements variable dependence analysis. In order to cover the full range of C constructs and features, a transformation to a core language is employed Thus, the full analysis is required only for the core language, which is relatively simple. This reduces the overall effort required for dependency analysis. The transformations used need preserve only the variable dependence relation, and therefore need not be meaning preserving in the traditional sense. The paper describes how this relaxed meaning further simplifies the transformation phase of the approach. Finally, the results of an empirical study into the performance of the system are presented

A post-placement side-effect removal algorithm

Side-effects are widely believed to impede program comprehension and have a detrimental effect upon software maintenance. This paper introduces an algorithm for side-effect removal which splits the side-effects into their pure expression meaning and their state-changing meaning. Symbolic execution is used to determine the expression meaning, while transformation is used to place the state-changing part in a suitable location in a transformed version of the program. This creates a program which is semantically equivalent to the original but guaranteed to be free from side-effects. The paper also reports the results of an empirical study which demonstrates that the application of the algorithm causes a significant improvement in program comprehension

FORTEST: Formal methods and testing

Formal methods have traditionally been used for specification and development of software. However there are potential benefits for the testing stage as well. The panel session associated with this paper explores the usefulness or otherwise of formal methods in various contexts for improving software testing. A number of different possibilities for the use of formal methods are explored and questions raised. The contributors are all members of the UK FORTEST Network on formal methods and testing. Although the authors generally believe that formal methods are useful in aiding the testing process, this paper is intended to provoke discussion. Dissenters are encouraged to put their views to the panel or individually to the authors

Branch-coverage testability transformation for unstructured programs

Test data generation by hand is a tedious, expensive and error-prone activity, yet testing is a vital part of the development process. Several techniques have been proposed to automate the generation of test data, but all of these are hindered by the presence of unstructured control flow. This paper addresses the problem using testability transformation. Testability transformation does not preserve the traditional meaning of the program, rather it deals with preserving test-adequate sets of input data. This requires new equivalence relations which, in turn, entail novel proof obligations. The paper illustrates this using the branch coverage adequacy criterion and develops a branch adequacy equivalence relation and a testability transformation for restructuring. It then presents a proof that the transformation preserves branch adequacy

A Query Language for Software Architecture Information (Extended version)

Software maintenance is an important part of a software system's life cycle. Maintenance tasks of existing software systems suffer from architecture information that is diverging over time (architectural drift). The Digital Architecture Twin (DArT) can support software maintenance by providing up-to-date architecture information. For this, the DArT gathers such information and co-evolves with a software system, enabling continuous reverse engineering. But the crucial link for stakeholders to retrieve this information is missing. To fill this gap, we contribute the Architecture Information Query Language (AIQL), which enables stakeholders to access up-to-date and tailored architecture information. We derived four application scenarios in the context of continuous reverse engineering. We showed that the AIQL provides the required functionality to formulate queries for the application scenarios and that the language scales for use with real-world software systems. In a user study, stakeholders agreed that the language is easy to understand and assessed its value to the specific stakeholder for the application scenarios

Bridging Technical Spaces: Model Translation from TA to XMI and Back Again

There are many different techniques and notations for extracting architecturally interesting information from the source code of existing software systems. This process is known as reverse engineering. One current problem with reverse engineering techniques is that models of software systems cannot easily be transferred from one notation and storage format to another. We refer to this as the problem of bridging technical spaces. In this work, we approach the issue of bridging between the SWAG technical space and the UML technical space. The SWAG technical space, named after the Software Architecture Group at the University of Waterloo, consists of fact extractors, fact manipulators, schemas, and a fact storage language - the Tuple-Attribute language (TA). The UML technical space consists of the UML metamodel, the XML Metadata Interchange (XMI) format for encoding UML models, and various UML modeling tools. We have designed and implemented a plugin for MagicDraw UML, which will import, export, and merge between XMI-encoded UML models and TA-encoded Function-Level Schema models. We document evidence of what is referred to as a Bridge Domain - a technical space which exists between two encodable spaces. The metamodels of the two notation languages that we have focused on are very rich and flexible, but neither technical space is capable of fully expressing an accurate architectural model of any given software system; however, each technical space is capable of maintaining certain semantic information relevant to that technical space through multiple merge operations

Visual representation of a customizable software maintenance process model

Managing the evolution of complex and large software systems involves many different types of resources and knowledge such as software artefacts, user expertise, tools and techniques, etc. Variations and interrelationships among these types of resources and knowledge create well-known challenges for maintainers. Current research mainly focuses on establishing comprehension model, and developing tools to tackle a specific aspect of maintenance problems. Little research has been conducted to study how resources and knowledge work collaboratively together to provide guidance to maintainers to complete specific maintenance tasks in a given context. In this research, we introduce a customizable maintenance process model, which extends an existing IEEE standard process model, to allow visually link various resources (e.g. tools, artifacts, maintainers etc.) and knowledge to relevant maintenance process elements. A visual metaphor has been created to graphically represent the process model. Finally, a tool environment has been developed to provide utilities for maintainers to create, customize and apply our maintenance process to provide guidance for maintainers for their maintenance tasks