Satish Subramanian

Software maintenance—an industrial experience

This paper gives an overview of the software maintenance process of Hitachi Software Engineering (HSK) Co., Ltd in Japan-including its success and failure cases. It discusses HSKs software processes, issues, use of specific tools and techniques such as IMOZU diagrams, and approaches in solving problems. These include the requirement capturing process, reverse-engineering techniques, environmental changes, change management, and project management. By discussing actual project experiences, we point to certain lessons and their implications for research in software maintenance. We also present the latest re-engineering CASE tools, such as RE-ENGINEERING and SEWB3, used at HSK.

A framework for designing safe software systems

The paper describes a framework for designing safety-critical software systems, in the context of a software safety analysis process that is based on fault tree analysis. This software design process has four steps: 1) software design fault tree generation, 2) fault tree verification, 3) safe software design, and 4) design safety verification. Approaches to safe software design, and verification of the safe design against the safety requirements have also been presented.

Fault mitigation in safety-critical software systems

Software hazard analysis involves identifying safety faults in software and mitigating their causes. Designing safe systems is a creative process and there are no systematic guidelines for generating safe designs. Here, the authors present some patterns of safety fault mitigation in medical devices, which were identified from a case study at the Guidant Corporation. These patterns prescribe appropriate fault mitigation processes and techniques for different safely situations. The patterns are classified into two major categories. Process Patterns and Technique Patterns. The process patterns are the patterns found in the process and decisions taken by engineers during safety analysis. The technique patterns are patterns found in the various mitigation techniques used to mitigate faults. The factors affecting the usage of these patterns and the process of mitigation are also discussed here.

Flow analysis for concurrent, reactive, real-time systems

One of the widely used techniques in software safety analysis is fault tree analysis. The paper discusses the use of flow analysis techniques for supporting fault tree generation from software specifications. Earlier work on flow analysis techniques has focused on sequential systems. We discuss how system characteristics such as concurrency and real time reactive features impact the flow analysis techniques. The paper discusses concepts and algorithms that can be used in performing flow analysis for concurrent reactive real time systems.

Monitoring Interval Properties in Real-Time Systems

Abstract In this paper, techniques for designing run-time monitorS for a class of real-time constraints have been presented. The constraints express relationships between different event occurrence rates over intervals of time and are useful in many safety-aitical applications. Monitor algorithms that focus on reporting any changes with minimum delay, while keeping the monitor overhead also low have been presented The algorithms aim at reporting not only constraint violations, but also check if the corrective actions are working by detecting changes from a violated to a not-violated state.

Run-time assertion schemes for safety-critical systems [pacemakers/defibrillators application]

The authors discuss issues in designing run-time mechanisms for enhancing the dependability of safely-critical systems. Such mechanisms are aimed at failure avoidance and failure detection and can complement the other design methods in achieving higher dependability. The authors introduce a safety-constraint centered transformation methodology that is based on a systems safety constraint specification and the development of techniques for analyzing the constraints to derive the run-time checking schemes. The authors also discuss other issues that are important in designing run-time checks, such as the types of safety constraints that can arise, features that specification languages must have to specify such constraints, how such safety constraints can be violated, and run-time support required for the mechanisms.

Opusdei-integrated environment for software development and maintenance

This paper discusses an integrated software development and maintenance environment, Opusdei, built and used for the past seven years at Hitachi Software Engineering (HSK) for its various projects. Industrial software is usually large, has many versions, undergoes frequent changes, and is developed concurrently by multiple programmers. Opusdei was developed by HSK to handle the various problems that arise in such an industrial environment. In Opusdei, all information needed for development is stored using an uniform representation in a central repository, and the various documentation and views of the software artifacts can be generated automatically using the tool repository. The innovative capabilities of this tool are: (1) Uniform software artifacts representation; (2) Inter-relation and traceability maintenance among software artifacts; (3) Tools repository and integration using tool composition scenarios; (4) Automatic documentation and versioning control. Opusdei was used in various software engineering projects and was found to improve productivity to a great extent.

AN OBJECT-BASED ENVIRONMENT (OPUSDEI) FOR SOFTWARE DEVELOPMENT AND MAINTENANCE

This paper discusses an object-based software development and maintenance environment, Opusdei, built and used for several years at Hitachi Software Engineering (HSK - Since 1994, University of Minnesota has been involved in the Opusdei project.) Industrial software is usually large, has many versions, undergoes frequent changes, and is developed concurrently by multiple programmers. Opusdei was designed to handle various problems inherent in such industrial environments. In Opusdei, all information needed for development is stored using an uniform representation in a central repository, and the various documentation and views of the software artifacts can be generated automatically using the tool repository. Opusdeis’ innovative capabilities are 1) uniform software artifacts representation 2) inter-relation and traceability maintenance among software artifacts 3) tools coordination and tool integration using tool composition scenarios 4) automatic documentation and versioning control. Tool coordination and composition has been discussed in the literature as a possible way to make software development environments more intelligent. Opusdei provides a uniform representation of software artifacts and tools which is an essential first step in addressing the issues of tool coordination and composition. Opusdei has been operational for several years and has been used in many large software development projects. The productivity gain reported for some of these projects, by using Opusdei ranged from 50–90%.