AN INDUCTIVE METHOD FOR DISCOVERING DESIGN PATTERNS FROM OBJECT-ORIENTED SOFTWARE SYSTEMS

Object-Oriented Design Patterns (OODPs) have been proposed as a technique to encapsulate design experience and aid in design reuse. However, so far, there is very little empirical evidence about what we can expect from this emergent technology. For instance, to date little research has focused on the development of techniques for discovering workable patterns that can be captured, formalized, packaged, and quantitatively evaluated. Our work is a step in this direction. In this paper we present an inductive method aimed at helping us discover OODPs in existing OO software systems. It encompasses a set of procedures rigorously defined in order to be repeatable and usable by practitioners who are not acquainted with reverse architecting processes. Guidelines are provided and a case study is shown that demonstrates the usefulness of the approach. (Also cross-referenced as UMIACS-TR-96-10

A Validation of Object-Oriented Design Metrics as Quality Indicators

This paper presents the results of a study conducted at the University of Maryland in which we experimentally investigated the suite of Object-Oriented (OO) design metrics introduced by [Chidamber&Kemerer, 1994]. In order to do this, we assessed these metrics as predictors of fault-prone classes. This study is complementary to [Li&Henry, 1993] where the same suite of metrics had been used to assess frequencies of maintenance changes to classes. To perform our validation accurately, we collected data on the development of eight medium-sized information management systems based on identical requirements. All eight projects were developed using a sequential life cycle model, a well-known OO analysis/design method and the C++ programming language. Based on experimental results, the advantages and drawbacks of these OO metrics are discussed. Several of Chidamber&Kemerer's OO metrics appear to be useful to predict class fault-proneness during the early phases of the life-cycle. We also showed that they are, on our data set, better predictors than "traditional" code metrics, which can only be collected at a later phase of the software development processes. (Also cross-referenced as UMIACS-TR-95-40

Measuring the Impact of Reuse on Quality and Productivity in Object-Oriented Systems

This paper presents the results of a study conducted at the University of Maryland in which we assessed the impact of reuse on quality and productivity in OO systems. Reuse is assumed to be a very effective strategy for software industry to build high-quality software. However, there is currently very little empirical information about what we can expect from reuse in terms of productivity and quality gains. This also applies to OO development which is supposed to facilitate reuse. Our experiment is one step towards a better understanding of the benefits of reuse in an OO framework, considering currently available technology. Data was collected, for four months, on the development of eight medium-size management information systems with equivalent requirements. All eight projects were developed using the Waterfall Software Engineering Life Cycle Model, an Object-Oriented (OO) design method and the C++ programming language. This study indicates significant benefits from reuse in terms of reduced defect density and rework as well as increased productivity. (Also cross-referenced as UMIACS-TR-95-2

Analytical and Empirical Evaluation of Software Reuse Metrics

How much can be saved by using pre-existing (or somewhat modified) software components when developing new software systems? With the increasing adoption of reuse methods and technologies, this question becomes critical. However, directly tracking the actual cost savings due to reuse is difficult. A worthy goal would be to develop a method of measuring the savings indirectly by analyzing the code for reuse of components. The focus of this paper is to evaluate how well several published software reuse metrics measure the ``time, money and quality'' benefits of software reuse. We conduct this evaluation both analytically and empirically. On the analytic front, we first develop some properties that should arguably hold of any measure of ``time, money and quality'' benefit due to reuse. We assess several existing software reuse metrics using these properties. Empirically, we constructed a toolset (using GEN++) to gather data on all published reuse metrics from C++ code; then, using some productivity and quality data from ``nearly replicated'' student projects at the University of Maryland, we evaluate the relationship the known metrics and the process data. The results show that different reuse metrics can be used as predictors of different quality attributes, and suggest possible directions for improving the known measures. (Also cross-referenced as UMIACS-TR-95-82

Characterizing and Assessing a Large-Scale Software Maintenance Organization

One important component of a software process is the organizational context in which the process is enacted. This component is often missing or incomplete in current process modeling approaches. One technique for modeling this perspective is the Actor-Dependency (AD) Model. This paper reports on a case study which used this approach to analyze and assess a large software maintenance organization. Our goal was to identify the approach's strengths and weaknesses while providing practical recommendations for improvement. The AD model was found to be very useful in capturing the important properties of the organizational context of the maintenance process, and aided in the understanding of the flaws found in this process. However, a number of opportunities for extending and improving the AD model were identified. Among others, there is a need to incorporate quantitative information to complement the qualitative model. (Also cross-referenced as UMIACS-TR-94-112

Understanding and Predicting the Process of Software Maintenance Releases

One of the major concerns of any maintenance organization is how to estimate the cost of subsequent releases of software systems. Planning the next release, maximizing the increase in functionality and improving the quality are vital to successful maintenance management. The objective of this paper is to present the results of a case study in which an incremental and inductive approach was used to build a model for predicting software maintenance releases in a large-scale software maintenance organization. This study was conducted in the Flight Dynamics Division (FDD) of the NASA Goddard Space Flight Center (GSFC). This organization is representative of many other software maintenance organizations. Over one hundred software systems totalling about 4.5 million lines of code are maintained by this organization. Many of these systems have been maintained for many years and regularly produce new releases. The maintenance costs in this organization have increased considerably over the last few years. This paper shows the predictive model developed for the FDD's software maintenance release process. Lessons learned during the establishment of a measurement-based software maintenance improvement program in this organization are also described and future work is outlined. (Also cross-referenced as UMIACS-TR-95-79

Qualitative Analysis for Maintenance Process Assessment

In order to improve software maintenance processes, we first need to be able to characterize and assess them. These tasks must be performed in depth and with objectivity since the problems are complex. One approach is to set up a measurement-based software process improvement program specifically aimed at maintenance. However, establishing a measurement program requires that one understands the problems to be addressed by the measurement program and is able to characterize the maintenance environment and processes in order to collect suitable and cost-effective data. Also, enacting such a program and getting usable data sets takes time. A short term substitute is therefore needed. We propose in this paper a characterization process aimed specifically at maintenance and based on a general qualitative analysis methodology. This process is rigorously defined in order to be repeatable and usable by people who are not acquainted with such analysis procedures. A basic feature of our approach is that actual implemented software changes are analyzed in order to understand the flaws in the maintenance process. Guidelines are provided and a case study is shown that demonstrates the usefulness of the approach. (Also cross-referenced as UMIACS-TR-96-7

white paper Enhancing Rational Unified Process for Capability Maturity Model Integration Compliance: A Methodological Approach

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Supporting Software Process Evolution in Adele/Tempo

Software process evolution corresponds to the act of improving the existing prescriptive software process models in a controlled and supported way. As software processes change constantly, it is therefore necessary to support one or more methods for assisting environment administrators in improving models. Changes are made in order to adapt software process models to new requirements, correct inconsistencies encountered in the course of execution, and modify, add or remove certain constraints. This article shows how software process evolution is supported in the Tempo. Tempo is a process-oriented software engineering environment where software processes are formally described in an object-oriented process schema. In Tempo, a process schema is comprised of descriptions of software agents, software products and software processes. A new approach is presented which supports the dynamic evolution of software process descriptions. In this approach, software process change is the result of tailoring the behavior of software objects manipulated during software process enaction