Albert L. Baker

Preliminary design of JML: a behavioral interface specification language for java

JML is a behavioral interface specification language tailored to Java(TM). Besides pre- and postconditions, it also allows assertions to be intermixed with Java code; these aid verification and debugging. JML is designed to be used by working software engineers; to do this it follows Eiffel in using Java expressions in assertions. JML combines this idea from Eiffel with the model-based approach to specifications, typified by VDM and Larch, which results in greater expressiveness. Other expressiveness advantages over Eiffel include quantifiers, specification-only variables, and frame conditions.This paper discusses the goals of JML, the overall approach, and describes the basic features of the language through examples. It is intended for readers who have some familiarity with both Java and behavioral specification using pre- and postconditions.

JML: A Notation for Detailed Design

JML is a behavioral interface specification language tailored to Java. It is designed to be written and read by working software engineers, and should require only modest mathematical training. It uses Eiffel-style syntax combined with model-based semantics, as in VDM and Larch. JML supports quantifiers, specification-only variables, and other enhancements that make it more expressive for specification than Eiffel and easier to use than VDM and Larch.

VR Juggler: a virtual platform for virtual reality application development

Today, scientists and engineers are exploring advanced applications and uses of immersive systems that can be cost-effectively applied in their fields. However, one of the impediments to the widespread use of these technologies is the extensive technical expertise required of application developers. A software environment that provides abstractions from specific details of hardware configurations and low-level software tools is needed to provide a common base for the prototyping, development, testing and debugging of applications. This paper describes VR Juggler, a virtual platform for the creation and execution of immersive applications, that provides a virtual reality system-independent operating environment. We focus on the approach taken to specify, design and implement VR Juggler and the benefits derived from our approach.

A philosophy for software measurement

Abstract We as a group—called the Grubstake Group—are convinced that software measures are essential for “controlling” software. Thus, we are dedicated to producing an environment in which software measures can be confidently used by software managers and programmers. However, we are also convinced that such an environment can only be created if there exists a formal and rigorous foundation for software measurement. This foundation will not have to be understood by the users of the software measures, but it will have to be understood by those who define, validate, and provide tool support for the measures. It is this foundation that we are introducing in this article.

Rigorous definition and analysis of program complexity measures: an example using nesting

Abstract Two deficiencies persist in program complexity measures research: a lack of formalism in defining complexity measures and a lack of analytical tools for evaluating these measures. The lack of formalism significantly hinders independent empirical evaluations of proposed measures. The lack of analytical tools and techniques for evaluating measures makes comparisons between independent research efforts difficult. As an example of one attempt to avoid these deficiencies, we formally define “nesting” for arbitrary (not necessarily well-structured) programs and use this definition to redefine four existing measures of nesting that have appeared in the literature. We then define one simple tool that can be used to evaluate nesting measures. Application of this tool to the redefined measures reveals in one case that the proposed measure does not adequately quantify the nesting represented by the simple tool. In the other three cases the measures are demonstrably similar. Analogous analytical evaluations of proposed measures prior to the requisite empirical studies are encouraged.

A standard representation of imperative language programs for data collection and software measures specification

Abstract Software measures and software tools are often defined in terms of a particular, limited programming language. For example, a number of software measures are defined only for structured programs. Several approaches to program testing and debugging are defined using a specific simple language. As a result, implementing tools and measures so that they can be applied to “real” programs in “real” programming languages is difficult. Further, independent evaluation and comparison of measures and tools is difficult. We propose a standard representation of imperative language programs that is independent of the syntax of any particular programming language, and that supports the definition of a wide range of tools and measures. Additionally, the standard representation masks the actual program semantics. Thus the standard representation provides a vehicle by which large volumes of industrial software can be made available to researchers while protecting the proprietary nature of the programs.

Executing Formal Specifications with Concurrent Constraint Programming

We have implemented a technique for execution of formal, model-based specifications. The specifications we can execute are written at a level of abstraction that is close to that used in nonexecutable specifications. The specification abstractions supported by our execution technique include using quantified assertions to directly construct post-state values, and indirect definitions of post-state values (definitions that do not use equality). Our approach is based on translating specifications to the concurrent constraint programming language AKL. While there are, of course, expressible assertions that are not executable, our technique is amenable to any formal specification language based on a finite number of intrinsic types and pre- and postcondition assertions.

VjControl: an advanced configuration management tool for VR Juggler applications

Virtual reality (VR) installations are often unique; every one is a complex blend of hardware devices, displays and computing resources. The configuration of VR software is therefore a difficult and time-consuming process. VR Juggler, our toolkit for VR application development, addresses these problems with a number of innovations. VR Juggler provides a unique system for organizing the configuration information for a system and minimizing the proliferation of configuration files that many systems suffer. It provides a graphical tool, called VjControl, for editing configurations, which can protect users from many common mistakes. VR Juggler also has advanced capabilities for monitoring and altering the configuration of a running immersive application.

Formal semantics for SA style data flow diagram specification languages

Using operational semantic techniques, we present a formal semantics for an extended variant of structured analysis style data flow diagrams. This semantics is intended to serve as a semantic foundation for many different specification languages that specify concurrent systems using a graphical notation similar to data flow diagrams. Besides allowing one to specify how information is processed, it allows one to specify the dynamic behavior of a concurrent system. We discuss various semantic issues, including the need for a twostep firing rule and how the semantics supports the notion of refinement.

The software process model

The authors define a software process model (SPM). The SPM is a model of evolution of the full set of documents produced in a software project. It is a general model for software development using any development approach, providing a framework for measuring, analyzing, and understanding the software development process. The authors use the model to characterize formally research in software measures and metrics. Data obtained from two software projects are presented in the SPM format.<<ETX>>