Alexander Egyed

Using the WinWin spiral model: a case study

Fifteen teams used the WinWin spiral model to prototype, plan, specify, and build multimedia applications for USCs Integrated Library System. The authors report lessons learned from this case study and how they extended the models utility and cost-effectiveness in a second round of projects.

Automating requirements traceability: Beyond the record & replay paradigm

Requirements traceability (RT) aims at defining relationships between stakeholder requirements and artifacts produced during the software development life-cycle. Although techniques for generating and validating RT are available, RT in practice often suffers from the enormous effort and complexity of creating and maintaining traces or from incomplete trace information that cannot assist engineers in real-world problems. In this paper we will present a tool-supported technique easing trace acquisition by generating trace information automatically. We will explain the approach using a video-on-demand system and show that the generated traces can be used in various engineering scenarios to solve RT-related problems.

Reconciling software requirements and architectures with intermediate models

Little guidance and few methods are available for the refinement of software requirements into an architecture satisfying those requirements. Part of the challenge stems from the fact that requirements and architectures use different terms and concepts to capture the model elements relevant to each. In this paper we will present CBSP, a lightweight approach intended to provide a systematic way of reconciling requirements and architectures using intermediate models. CBSP leverages a simple set of architectural concepts (components, connectors, overall systems, and their properties) to recast and refine the requirements into an intermediate model facilitating their mapping to architectures. Furthermore, the intermediate CBSP model eases capturing and maintaining arbitrarily complex relationships between requirements and architectural model elements, as well as among CBSP model elements. We have applied CBSP within the context of different requirements and architecture definition techniques. We leverage that experience in this paper to demonstrate the CBSP method and tool support using a large-scale example.

Scalable consistency checking between diagrams - the VIEWINTEGRA approach

The Unified Modeling Language (UML) supports a wide range of diagrams for modeling software development concerns. UML diagrams are independent but connected; their meta-model describes them under a common roof. Despite the advances of UML, we found that the problem of ensuring consistency between UML diagrams has not been solved. We have developed an approach for automated consistency checking, called VIEWINTEGRA.. Our approach provides excellent support for active (preventive) and passive (detective) consistency checking. We make use of consistent transformation to translate diagrams into interpretations and we use consistency comparison to compare those interpretations to other diagrams. Our approach was applied to a number of applications where we found the separation of transformation and comparison to be highly beneficial in addressing consistency-checking scalability and usability issues. The paper introduces our UML-based transformation framework, discusses how it aids comparison, and demonstrates how it improves consistency checking.

A stakeholder win–win approach to software engineering education

We have been applying the stakeholder win–win approach to software engineering education. The key stakeholders we are trying to simultaneously satisfy are the students; the industry recipients of our graduates; the software engineering community as parties interested in improved practices; and ourselves as instructors and teaching assistants. In order to satisfy the objectives or win conditions of these stakeholders, we have formed a strategic alliance with the USC Libraries to have software engineering student teams work with Library clients to define, develop, and transition USC digital library applications into operational use. This adds another set of key stakeholders: the Library clients of our class projects. This paper summarizes our experience in developing, conducting, and iterating the course. It concludes by evaluating the degree to which we have been able to meet the stakeholder-determined course objectives.

SUPPORTING SOFTWARE UNDERSTANDING WITH AUTOMATED REQUIREMENTS TRACEABILITY

Requirements traceability (RT) aims at defining and utilizing relationships between stakeholder requirements and artifacts produced during the software development life-cycle and provides an important means to foster software understanding. Although techniques for generating and validating traceability information are available, RT in practice often suffers from the enormous effort and complexity of creating and maintaining traces. This results in invalid or incomplete trace information which cannot support engineers in real-world problems. In this paper we present a tool-supported approach that requires the designer to specify some trace dependencies but eases trace acquisition by generating others automatically. We illustrate the approach using a video-on-demand system and show how the generated traces can be used in various engineering scenarios to improve software understanding. In a case study using an open source software application we demonstrate that the approach is capable of dealing with large-scale systems and delivers valid results.

Software requirements negotiation: some lessons learned

Negotiating requirements is one of the first steps in any software system life cycle, but its results have probably the most significant impact on the systems value. However, the processes of requirements negotiation are not well understood. We have had the opportunity to capture and analyze requirements negotiation behavior for groups of projects developing library multimedia archive systems, using an instrumented version of the USC WinWin groupware system for requirements negotiation. Some of the more illuminating results were: most stakeholder Win Conditions were noncontroversial (were not involved in issues); negotiation activity varied by stakeholder role; LCO package quality (measured by grading criteria) could be predicted by negotiation attributes; and WinWin increased cooperativeness, reduced friction, and helped focus on key issues.

Developing multimedia applications with the WinWin spiral model

Fifteen teams recently used the WinWin Spiral Model to perform the system engineering and architecting of a set of multimedia applications for the USC Library Information Systems. Six of the applications were then developed into an Initial Operational Capability. The teams consisted of USC graduate students in computer science. The applications involved extensions of USCs UNIX-based, text-oriented, client-server Library Information System to provide access to various multimedia archives (films, videos, photos, maps, manuscripts, etc.).

Determining the cost-quality trade-off for automated software traceability

Major software development standards mandate the establishment of trace links among software artifacts such as requirements, architectural elements, or source code without explicitly stating the required level of detail of these links. However, the level of detail vastly affects the cost and quality of trace link generation and important applications of trace analysis such as conflict analysis, consistency checking, or change impact analysis. In this paper, we explore these cost-quality trade-offs with three case study systems from different contexts - the open-source ArgoUML modeling tool, an industrial route-planning system, and a movie player. We report the cost-quality trade-off of automated trace generation with the Trace Analyzer approach and discuss its expected impact onto several applications that consume its trace information. In the study we explore simple techniques to predict and manipulate the cost-benefit trade-off with threshold-based filtering. We found that (a) 80% of the benefit comes from only 20% of the cost and (b) weak trace links are predominantly false trace links and can be efficiently eliminated through thresholds.

A value-based approach for understanding cost-benefit trade-offs during automated software traceability

Many software development standards mandate establishing trace links among software artifacts such as requirements, architectural elements, or source code. However, for typical real-world systems it is currently too expensive and error prone to generate highly detailed trace links. We previously developed an approach to semi-automatically generate trace links and analyzed cost-benefit trade-offs in this context. We consider it as imperative to include value considerations into planning the generation of trace dependencies. This paper discusses three key trade-off decisions for planning the trace generation process: (a) the level of detail of traces among artifacts; (b) the value of the artifacts that are traced; and (c) the points in time of trace generation (early vs. late). We present cost-benefit considerations, empirical data, and argue for a pragmatic value-based planning approach.