Peyman Oreizy

An architecture-based approach to self-adaptive software

Self-adaptive software requires high dependability robustness, adaptability, and availability. The article describes an infrastructure supporting two simultaneous processes in self-adaptive software: system evolution, the consistent application of change over time, and system adaptation, the cycle of detecting changing circumstances and planning and deploying responsive modifications.

Architecture-based runtime software evolution

Continuous availability is a critical requirement for an important class of software systems. For these systems, runtime system evolution can mitigate the costs and risks associated with shutting down and restarting the system for an update. We present an architecture-based approach to runtime software evolution and highlight the role of software connectors in supporting runtime change. An initial implementation of a tool suite for supporting the runtime modification of software architectures, called ArchStudio, is presented.

Runtime software adaptation: framework, approaches, and styles

Our ICSE 1998 paper showed how an application can be adapted at runtime by manipulating its architectural model. In particular, our paper demonstrated the beneficial role of (1) software connectors in aiding runtime change, (2) an explicit architectural model fielded with the system and used as the basis for runtime change, and (3) architectural style in providing both structural and behavioral constraints over runtime change. This paper examines runtime evolution in the decade hence. A broad framework for studying and describing evolution is introduced that serves to unify the wide range of work now found in the field of dynamic software adaptation. This paper also looks to the future, identifying what we believe to be highly promising directions.

Reuse of off-the-shelf components in C2-style architectures

Reuse of large-grain software components offers the potential for significant savings in application development cost and time. Successful component reuse and substitutability depends both on qualities of the components reused as well as the software context in which the reuse is attempted. Disciplined approaches to the structure and design of software applications offers the potential of providing a hospitable setting for such reuse. We present the results of a series of exercises designed to determine how well “offthe-shelf” components could be reused in applications designed in accordance with the C2 software architectural style. The exercises involved the reuse of two user-interface constraint solvers, two graphics toolkits, a World Wide Web browser, and a persistent object manager. A subset of these components was used to construct numerous variations of a single application (thus an application family). The exercises also included construction of a simple development environment for locating and downloading a component off the Web and incorporating it into an application. The paper summarizes the style rules that facilitate reuse and presents the results from the exercises. The exercises were successful in a variety of dimensions; one conclusion is that the C2 style offers significant reuse potential to application developers. At the same time, wider trials and additional tool support are needed.1 Index Terms -software reuse, architectural styles, messagebased architectures, component-based development, graphical user interfaces (GUI).

On the role of software architectures in runtime system reconfiguration

Societys increasing dependence on software-intensive systems is driving the need for dependable, robust, continuously available systems. Runtime system reconfiguration is one aspect of achieving continuous availability. We present an architecture-based approach to runtime software reconfiguration, highlighting the beneficial role of architectural styles and software connectors in facilitating runtime change. We conclude by describing the implementation of our tool suite, called ArchStudio, that supports runtime reconfiguration using our architecture-based approach.

Architectural styles for runtime software adaptation

Runtime software adaptability — the ability to change an applications behavior during runtime — is an increasingly important capability for systems, both to support continuous operation and to support a good user experience. Achieving such adaptability may be very hard or easy; the degree of difficulty will largely reflect choices made in a systems architecture. Some architectural styles are much more supportive of dynamic change than others. This paper examines a range of styles and assesses them with respect to a four-element evaluation framework, called BASE. The framework considers how a style supports changes to behavior, state, its execution context, and supports asynchrony of change. Styles considered include REST, event-based, service-oriented, and peer-to-peer.

The Web as enabling technology for software development and distribution

When confronted with a new technology, we instinctively consider it within the context of existing work and practices. Such is the case with the World Wide Web. But the Web is more than a new technology for leveraging existing work. It is, in fact, an enabling technology with the potential to change software development as dramatically as the transistor and microprocessor changed computer architecture. An enabling technology changes the fundamental assumptions ingrained in a discipline. The microprocessor, for example, changed the reliability, cost, circuit density, and performance assumptions underlying hardware design. As a result, new applications and design approaches for hardware systems became feasible. Just as the microprocessor changed the fundamental assumptions of hardware design, the Web changes some of the assumptions underlying software development. Thus it has the potential to change our notion of the software artifact and the collaborative processes used to construct it.

Reflections on the REST architectural style and "principled design of the modern web architecture" (impact paper award)

Seventeen years after its initial publication at ICSE 2000, the Representational State Transfer (REST) architectural style continues to hold significance as both a guide for understanding how the World Wide Web is designed to work and an example of how principled design, through the application of architectural styles, can impact the development and understanding of large-scale software architecture. However, REST has also become an industry buzzword: frequently abused to suit a particular argument, confused with the general notion of using HTTP, and denigrated for not being more like a programming methodology or implementation framework. In this paper, we chart the history, evolution, and shortcomings of REST, as well as several related architectural styles that it inspired, from the perspective of a chain of doctoral dissertations produced by the University of Californias Institute for Software Research at UC Irvine. These successive theses share a common theme: extending the insights of REST to new domains and, in their own way, exploring the boundary of software engineering as it applies to decentralized software architectures and architectural design. We conclude with discussion of the circumstances, environment, and organizational characteristics that gave rise to this body of work.