Martin Hitz

Chidamber and Kemerer's metrics suite: a measurement theory perspective

The metrics suite for object-oriented design put forward by Chidamber and Kemerer (1994) is partly evaluated by applying principles of measurement theory. Using the object coupling measure (CBO) as an example, it is shown that failing to establish a sound empirical relation system can lead to deficiencies of software metrics. Similarly, for the object-oriented cohesion measure (LCOM) it is pointed out that the issue of empirically testing the representation condition must not be ignored, even if other validation principles are carefully obeyed. As a by-product, an alternative formulation for LCOM is proposed.

An integrated simulation and optimization modelling environment for decision support

Abstract A general framework and a specific implementation of a software environment for model prototyping, simulation and optimization are presented. The integration of simulation and optimization, and the possibility of comparing experimental results under complete user control represent the central parts of the proposed approach. Optimization is performed by repetitive simulation runs under the control of an optimization method. The integration of simulation and optimization as well as the post processing facilities offer an effective support to the classical phases of the decision process: intelligence, design, and choice. The software is based on an object-oriented structure and encourages the user to develop his own hierarchy of model classes and experiments.

Measuring Product Attributes of Object-Oriented Systems

The role of internal product attributes for software measures is analyzed. Attributes are classified as “fundamental”, “auxiliary” and “useless” with respect to their relevance for controlling software quality. The impact of inappropriate attributes on the usefulness of resulting metrics is discussed with emphasis on the object-oriented paradigm. We demonstrate that some of the obvious shortcomings of proposed metrics are caused by inconsiderate attribute selections. In the course of this discussion which recurs to commonly accepted frameworks in measure theory, both, well-known attributes and new proposals are treated.

Developing with UML - Some Pitfalls and Workarounds

The object-oriented modeling language UML offers various notations for all phases of application development. The user is left alone, however, when applying UML in up-to-date application development involving distribution, data management, and component-oriented mechanisms. Moreover, various shortcomings have been encountered, most notably w.r.t. refinement of model elements throughout the development life cycle and employment of interaction diagrams to formalize use cases. The paper will shed some light on how these issues may be handled with UML

Business-oriented component-based software development and evolution

The huge size and high complexity of legacy software are the main sources of todays software evolution problems. While we can ease software evolution with re-engineering tools, in the long term we should look for a more fundamental and effective solution. Component-based software development (CBSD) technology makes it possible to build software systems as collections of cooperating autonomous application components. This new paradigm has the potential to ease software evolution problems, as modification or replacement of components is deemed to be much easier than modification of todays huge monolithic legacy programs. For CBSD to bring its promised benefits, we must identify the right components in a given business domain. The claim of this paper is that, while CBSD is an important enabling technology, the decomposition of a software system into components must be driven by business considerations. If we let logical models of business processes drive the planning and design of software systems, we can avoid creating huge legacy software. Similar approaches may apply to software evolution in non-business domains too.

Modula-2 versus C++ as a first programming language—some empirical results

The success of an experiment of using C++ as a first programming language for students of a specific type of computer science is presented. The paper motivates the shift from Modula-2 to C++ in the curriculum, shortly describes the course and discusses the statistical evaluation of the results of the last Modula-2 course and the first C++ course, respectively. The main findings of the study are the fact that in contrast to most expectations, the shift from a typical “educational” language to a much “dirtier” language had no significant effect to the performance of the students taking the course.

An intelligent simulation model generator

The conceptual design and a prototype implementation of a knowledge based interactive genera tor of simulation models is pre sented. The system administrates several components, among them a model base, a knowledge-base, and a data base. Emphasis is laid on the integration of the model and the knowledge base. This connection of numeric and knowledge representa tion components is one of the main advantages of the system. A frame based approach has been chosen for the semantic representation of the simulated models. The prototype has been implemented on a XEROX 1186 workstation and takes advan tage of the presence of two proces sors : a LISP processor managing the logical description, selection, and maintenance of models as well as the overall control of the system, and an 8088 processor to run the simulation programs that are written in classical programming languages like FORTRAN. The system is designed to free the scien tific expert from details about computer science and to let him concentrate on the actual simulation problems.

Employing databases for large scale reuse of simulation models

To enhance reusability in the field of simulation, model bases must be equipped with powerful tools for retrieval, modification and aggregation of simulation models. In this paper, the role of database management systems supporting a modeling environment is discussed and reuse oriented query interfaces are presented. Specifically, we advocate a graph browser operating on a semantic network of reusable components.

Requirements for a repository-based simulation environment

Simulation tools and environments can provide several types of computer assistance. It is envisaged that this functionality is going to increase. Even though this increase of functionality is highly desirable, it is anticipated that there will bean interface problem between the simulation tools and environments, similar to the interface problems in computer-aided software engineering (CASE) tools and environments. The problem is diagnosed and a solution is proposed.

Measuring Reuse Attributes In Object-Oriented Systems

We demonstrate that measuring reuse in object-oriented systems is not as straight-forward as it might seem. On the basis of a small example application, we show that object-oriented reuse metrics tend to overestimate the “real” reuse in an application and that this problem can partly be overcome by carefully selecting an appropriate definition of the “size” attribute used in many proposed metrics. We also emphasize that it is necessary to distinguish between different flavors of “reuse” in order to achieve consistent measurements.