Ian Gorton

A survey of architecture design rationale

Many claims have been made about the consequences of not documenting design rationale. The general perception is that designers and architects usually do not fully understand the critical role of systematic use and capture of design rationale. However, there is to date little empirical evidence available on what design rationale mean to practitioners, how valuable they consider it, and how they use and document it during the design process. This paper reports a survey of practitioners to probe their perception of the value of design rationale and how they use and document the background knowledge related to their design decisions. Based on 81 valid responses, this study has discovered that practitioners recognize the importance of documenting design rationale and frequently use them to reason about their design choices. However, they have indicated barriers to the use and documentation of design rationale. Based on the findings, we conclude that further research is needed to develop methodology and tool support for design rationale capture and usage. Furthermore, we put forward some specific research questions about design rationale that could be further investigated to benefit industry practice.

Issues in co-operative software engineering using globally distributed teams

Abstract The use of geographically separated software development groups is proposed as a method for enabling 24-hour software development, or software shift work. The advantages of such an approach are explained, and potential organizational models for such virtual teams are described. Virtual team co-operation, information requirements and communication channels are explored. Activities in the software development life-cycle in which virtual teams can be advantageously utilized are explained, and examples of the successful use of virtual teams are cited. Finally a measure of the effectiveness of virtual teams known as the distributed working overhead is defined, which will enable project managers to clearly see the benefits and associated costs of employing virtual teams on a project.

Rigorous evaluation of COTS middleware technology

The adoption of commercial off-the-shelf middleware products across the software industry has gathered significant momentum. While COTS middleware products demonstrably solve many problems, their adoption and use are by no means straightforward. Competition among products that apparently offer identical services complicates the COTS middleware selection process, especially when competing products provide different implementations of standards-based technologies, such as CORBA and Java 2 Enterprise Edition. The article discusses the Middleware Technology Evaluation project, which represents a significant attempt to provide rigorously derived, in-depth evaluations of technology for use by middleware product adopters.

Evaluating the performance of EJB components

As part of the Middleware Technology Evaluation (MTE) project, we conducted several experiments to explore the performance implications of two common application architectures supported by J2EEs enterprise JavaBean (EJB) component technology. One architecture promises simpler engineering and maintenance of the resulting component collection. For applications that require high performance and scalability, however, the alternative architecture might offer a better solution. Such knowledge is crucial to software architects, who must make initial design decisions early in a project, before extensive engineering has begun. An examination of two EJB-based architectures reveals differences that can significantly affect the performance and scalability of applications built on them.

Model driven benchmark generation for web services

Web services solutions are being increasingly adopted in enterprise systems. However, ensuring the quality of service of Web services applications remains a costly and complicated performance engineering task. Some of the new challenges include limited controls over consumers of a service, unforeseeable operational scenarios and vastly different XML payloads. These challenges make existing manual performance analysis and benchmarking methods difficult to use effectively. This paper describes an approach for generating customized benchmark suites for Web services applications from a software architecture description following a Model Driven Architecture (MDA) approach. We have provided a performance-tailored version of the UML 2.0 Testing Profile so architects can model a flexible and reusable load testing architecture, including test data, in a standards compatible way. We extended our MDABench [27] tool to provide a Web service performance testing cartridge associated with the tailored testing profile. A load testing suite and automatic performance measurement infrastructure are generated using the new cartridge. Best practices in Web service testing are embodied in the cartridge and inherited by the generated code. This greatly reduces the effort needed for Web service performance benchmarking while being fully MDA compatible. We illustrate the approach using a case study on the Apache Axis platform.

Software engineering for parallel systems

Abstract Current approaches to software engineering practice for parallel systems are reviewed. The parallel software designer has not only to address the issues involved in the characterization of the application domain and the underlying hardware platform, but, in many instances, the production of portable, scalable software is desirable. In order to accommodate these requirements, a number of specific techniques and tools have been proposed, and these are discussed in this review in the framework of the parallel software life-cycle. The paper outlines the role of formal methods in the practical production of parallel software, but its main focus is the emergence of development methodologies and environments. These include CASE tools and run-time support systems, as well as the use of methods taken from experience of conventional software development. Because of the particular emphasis on performance of parallel systems, work on performance evaluation and monitoring systems is considered.

MDABench: Customized benchmark generation using MDA

This paper describes an approach for generating customized benchmark suites from a software architecture description following a Model Driven Architecture (MDA) approach. The benchmark generation and performance data capture tool implementation (MDABench) is based on widely used open source MDA frameworks. The benchmark application is modeled in UML and generated by taking advantage of the existing community-maintained code generation cartridges so that current component technology can be exploited. We have also tailored the UML 2.0 Testing Profile so architects can model the performance testing and data collection architecture in a standards compatible way. We then extended the MDA framework to generate a load testing suite and automatic performance measurement infrastructure. This greatly reduces the effort and expertise needed for benchmarking with complex component and Web service technologies while being fully MDA standard compatible. The approach complements current model-based performance prediction and analysis methods by generating the benchmark application from the same application architecture that the performance models are derived from. We illustrate the approach using two case studies based on Enterprise JavaBean component technology and Web services.

Accuracy of performance prediction for EJB applications: a statistical analysis

A challenging software engineering problem is the design and implementation of component-based (CB) applications that can meet specified performance requirements. Our PPCB approach has been developed to facilitate performance prediction of CB applications built using black-box component infrastructures such as J2EE. Such deployment scenarios are problematic for traditional performance modeling approaches, which typically focus on modeling application component performance and neglect the complex influence of the specific component technology that hosts the application. In this paper, an overview of the PPCB modeling approach is given. Example results from predicting the performance of a J2EE application are presented. These results are then statistically analyzed to quantify the uncertainty in the predicted results. The contribution of the paper is the presentation of concrete measures of the confidence an architect can have in the performance predictions produced by the PPCB.

An Infrastructure for Indexing and Organizing Best Practices

Industry best practices are widely held but not necessarily empirically verified software engineering beliefs. Best practices can be documented in distributed web-based public repositories as pattern catalogues or practice libraries. There is a need to systematically index and organize these practices to enable their better practical use and scientific evaluation. In this paper, we propose a semi-automatic approach to index and organise best practices. A central repository acts as an information overlay on top of other pre-existing resources to facilitate organization, navigation, annotation and meta-analysis while maintaining synchronization with those resources. An initial population of the central repository is automated using Yahoo! contextual search services. The collected data is organized using semantic web technologies so that the data can be more easily shared and used for innovative analyses. A prototype has demonstrated the capability of the approach.

Engineering High Quality Parallel Software Using PARSE

The PARSE design methodology provides a hierarchical, object-based approach to the development of high quality, reliable parallel software systems. A system design is initially structured into a collection of concurrently executing objects which communicate via message-passing. A graphical notation known as process graphs is then used to capture the structural and important dynamic properties of the system. Process graph designs can then be semi-mechanically transformed into complete Petri nets to give a detailed, executable and formally verifiable design specification.