A formal approach to perfective software maintenance: System integration using a basis of formal object-oriented components

We investigate how a formalism known as a basis and common to many areas of applied mathematics and engineering can be applied to perfective maintenance and the integration of application systems in software engineering, using an object-oriented approach. It is concluded that this formalism serves as a mathematical model for perfective software maintenance and software systems integration activities under object-oriented development. Theorems and properties about the model are reported as guides to software maintenance. The model and formal maintenance techniques have been applied to a software system in the management information systems area to demonstrate this approach to perfective maintenance and to assist in validating the model.     

A formal approach to object-oriented databases

Object-oriented database systems are the focus of current research and development efforts. Yet, there is no commonly accepted object model, nor is it clear whether such a model can be developed. This paper reports on efforts to develop a formal framework that contains most features found in current object oriented database systems. The framework contains two parts. The first is a structural object model, including concepts such as structured objects, identity, and some form of inheritance. For this model, we explain the distinction between values and (abstract) objects, describe a system as a directed graph, and discuss declarative languages. The second part deals with higher-order concepts, such as classes and functions as data, methods, and inheritance. This part is a sketch, and leaves many issues unresolved. Throughout the paper, the emphasis is on logic-oriented modeling.     

A formal approach to lock escalation

Since database management systems(DBMSs) have limited lock resources, transactions requesting locks beyond the limit must be aborted, degrading the performance abruptly. Lock escalation is considered a solution to this problem. However, existing lock escalation methods have been designed in an ad hoc manner. So, they do not provide a complete solution. In this paper, we propose a formal model of lock escalation. Using the model, we analyze the roles of lock escalation formally and solve the problems of the existing methods systematically. In particular, we introduce the concept of the unescalatable lock that cannot be escalated due to conflicts. We identify that the unescalatable lock is the major cause of exhausting lock resources. We then analyze the reasons why unescalatable locks are generated and propose a new lock escalation method, adaptive lock escalation, which controls lock escalation based on the number of unescalatable locks. Through extensive simulation, we show that adaptive lock escalation significantly outperforms existing methods reducing the number of aborts and the average response time and increasing the throughput to a great extent. Adaptive lock escalation drastically reduces (more than 10 fold) the number of lock resources required to maintain the same level of throughput and average response time. At the same time, the throughput and average response time when using adaptive lock escalation are rather insensitive to the number of lock resources. Existing methods rely on users to estimate this number accurately at system initialization time. Adaptive lock escalation greatly alleviates this burden.     

A formal approach to fuzzy modeling

A formalism for coding fuzzy models of dynamical systems is presented. It is shown that the formalism is rich enough to capture the performance of arbitrary conventional discrete time dynamical systems whose transition maps are polynomials with rational coefficients. The proof of this fact provides a constructive algorithm for generating fuzzy models to arbitrarily closely approximate an arbitrary map on a compact set. Our modeling formalism highlights the similarities between fuzzy systems and hybrid control systems. We hope to be able to exploit these similarities by extending results from the area of hybrid systems to the fuzzy domain and vice versa     

A formal approach to negotiating agents development

This paper presents a formal and executable approach to capture the behaviour of parties involved in a negotiation. A party is modeled as a negotiating agent composed of a communication module, a control module, a reasoning module, and a knowledge base. The control module is expressed as a statechart, and the reasoning module as a defeasible logic program. A strategy specification therefore consists of a statechart, a set of defeasible rules, and a set of initial facts. Such a specification can be dynamically plugged into an agent shell incorporating a statechart interpreter and a defeasible logic inference engine, in order to yield an agent capable of participating in a given type of negotiations. The choice of statecharts and defeasible logic with respect to other formalisms is justified against a set of desirable criteria, and their suitability is illustrated through concrete examples of bidding and multi-lateral bargaining scenarios.     

A Formal Approach to Protocol Interoperability Testing

Porotocol Interoperability testing is an important means to ensure the interconnection and interoperation between protocol products.In this paper,we proposed a formal approach to protocol interoperability testing based on the operational semantics of Concurrent TTCN.We define Concurrent TTCN‘s operational semantics by using Labeled Transition System,and describe the interoperability test execution and test verdict based on Concurrent TTCN.This approach is very helpful for the formation of formal interoperability testing theory and construction of general interoperability testing system.     

A formal approach to software error removal

There is a dichotomy of opinion on the use of software testing versus formal verification in software development. Testing has been the accepted method for detecting and removing errors and has played a significant error removal role. Formal verification has only recently matured into accepted practice but shows the potential for playing an even more significant error prevention role. The Cleanroom software development process which has been developed by the IBM Federal Systems Division combines both ideas into an effective development tool. Software engineering methods based on functional verification support the production of software with sufficient quality to forego traditional unit or structural testing. Statistical methods are introduced that define objective and formal strategies for product or functional testing. The synergism between the two ideas results in software with fewer errors which are both easier to find and to fix and in products with exceptional operating characteristics. Error prevention, not removal, is the key and the only viable approach to any sustained software quality growth. The Cleanroom development method and its impact on the error prevention and removal processes are covered in this paper. The results from its use for software development are also discussed.     

A formal approach to designing delay-insensitive circuits

Summary A method for designing delay-insensitive circuits is presented based on a simple formalism. The communication behavior of a circuit with its environment is specified by a regular expression-like program. Based on formal manipulations this program is then transformed into a delay-insensitive network of basic elements realizing the specified circuit. The notion of delay-insensitivity is concisely formalized. Jo C. Ebergen received his Master's degree in Mathematics from Eindhoven University of Technology in 1983. From 1983 until 1987 he has been working as a researcher at the Centre for Mathematics and Computer Science in Amsterdam in the area of VLSI design. In 1987, he received his Ph.D. degree from Eindhoven University of Technology. Currently, he is assistant professor at the University of Waterloo. His main research interests are programming methodology, parallel computations, and delay-insensitive circuit design. Dr. Ebergen is a member of ACM and EATCS.The research reported in this article was carried out while the author was working at CWI (Centre for Mathematics and Computer Science) in Amsterdam     

A formal approach to managing design processes

To capture market opportunities, competition within the microelectronics industry demands ever-faster product development, which means ever-shorter design cycles. Shorter design cycles can be achieved by carefully managing the design process during rapid prototyping. Careful management is important because the design process must be (1) adjusted to accommodate constraints such as product performance and design time, and (2) frequently updated to take advantage of new design tools and methodologies. Traditionally, designers have used whatever tools seemed convenient to them at the time, which has made it virtually impossible to determine what methodology was used to produce a given design. These problems can be avoided through design methodology management, which ensures that appropriate tools are selected and executed in the appropriate sequence. Effective design management requires an environment equipped with a formal representation of supported design processes and tools, and an execution environment that helps designers select and execute an appropriate design process. We propose a methodology management system that provides this functionality     

A formal approach to MpSoC performance verification

Multiprocessor system on chip designs use complex on-chip networks to integrate different programmable processor cores, specialized memories, and other components on a single chip. MpSoC have been become the architecture of choice in many industries. Their heterogeneity inevitably increases with intellectual-property integration and component specialization. System integration is becoming a major challenge in their design. Simulation is state of the art in MpSoC performance verification, but it has conceptual disadvantages that become disabling as complexity increases. Formal approaches offer a systematic alternative. The article presents a technology that uses event model interfaces and a novel event flow mechanism that extends formal analysis approaches from real-time system design into the multiprocessor system on chip domain.     

A formal approach to protocol performance testing

This paper proposes a formal approach to protocol performance testing based on the extended concurrent TTCN,To meet the needs of protocol performance testing,concurrent TTCN is extended,and the extended concurrent TTCN‘s operational semantics is defined in terms of Input-Output Labeled Transition System.An architecture design of protocol performance test system is described,and an example of test cases and its test result are given.     

A formal methods approach to medical device review

With software playing an increasingly important role in medical devices, regulatory agencies such as the US Food and Drug Administration need effective means for assuring that this software is safe and reliable. The FDA has been striving for a more rigorous engineering-based review strategy to provide this assurance. The use of mathematics-based techniques in the development of software might help accomplish this. However, the lack of standard architectures for medical device software and integrated engineering-tool support for software analysis make a science-based software review process more difficult. The research presented here applies formal modeling methods and static analysis techniques to improve the review process. Regulation of medical device software encompasses reviews of device designs (premarket review) and device performance (postmarket surveillance). The FDA's Center for Devices and Radiological Health performs the premarket review on a device to evaluate its safety and effectiveness. As part of this process, the agency reviews software development life-cycle artifacts for appropriate quality-assurance attributes, which tend to reveal little about the device software integrity.     

A formal approach to AADL model-based software engineering

International Journal on Software Tools for Technology Transfer - Formal methods have become a recommended practice in safety-critical software engineering. To be formally verified, a system should...     

A formal approach to modeling office information systems

This paper formally specifies a document model for office information systems, including formal definitions of document types (frame templates), a document type hierarchy, folders, and folder organizations. Folder Organizations are defined using predicates and directed graphs. AReconstruction Problem for folder organizations is then formulated; viz., under what circumstances it is possible to reconstruct a folder organization from its folder level predicates. The Reconstruction Problem is solved in terms of such graph-theoretic concepts as Associated Digraphs, transitive closure, and redundant/nonredundant filing paths. A Transitive Closure Inversion algorithm is then presented which efficiently recovers a Folder Organization digraph from its Associated Digraph.This work was supported in part by the National Science Foundation under Grant No. IRI-9224602, by the New Jersey Institute of Technology undre Grant No. 421280 and by a grant from AT&T Foundation.     

Formal approach to scenario analysis

Scenarios offer promise as a way to tame requirements analysis, but progress has been impeded by the lack of a systematic way to analyze, generate, and validate them. The authors propose such a method and apply it to a simple PBX system. Their method has a formal mathematical base, generates precise scenarios, accommodates change, and keeps users involved in the process     

A relationship-based approach to model integration

A key problem in model-based development is integrating a collection of models into a single, larger, specification as a way to construct a functional system, to develop a unified understanding, or to enable automated reasoning about properties of the resulting system. In this article, we suggest that the choice of a particular model integration operator depends on the inter-model relationships that hold between individual models. Based on this observation, we distinguish three key integration operators studied in the literature—merge, composition and weaving—and describe each operator along with the notion of relationship that underlies it. We then focus on the merge activity and provide a detailed look at the factors that one must consider in defining a merge operator, particularly the way in which the relationships should be captured during merge. We illustrate these factors using two merge operators that we have developed in our earlier work for combining models that originate from distributed teams.     

A formal approach to finding inconsistencies in a metamodel

Software and Systems Modeling - Checking the consistency of a metamodel involves finding a valid metamodel instance that provably meets the set of constraints that are defined over the metamodel....