Software systems dealing with distributed applications in changing environments normally require human supervision to continue operation in all conditions. These (re-)configuring, troubleshooting, and in general maintenance tasks lead to costly and time-consuming procedures during the operating phase. These problems are primarily due to the open-loop structure often followed in software development. Therefore, there is a high demand for management complexity reduction, management automation, robustness, and achieving all of the desired quality requirements within a reasonable cost and time range during operation. Self-adaptive software is a response to these demands; it is a closed-loop system with a feedback loop aiming to adjust itself to changes during its operation. These changes may stem from the software system's self (internal causes, e.g., failure) or context (external events, e.g., increasing requests from users). Such a system is required to monitor itself and its context, detect significant changes, decide how to react, and act to execute such decisions. These processes depend on adaptation properties (called self-a properties), domain characteristics (context information or models), and preferences of stakeholders. Noting these requirements, it is widely believed that new models and frameworks are needed to design self-adaptive software. This survey article presents a taxonomy, based on concerns of adaptation, that is, how, what, when and where, towards providing a unified view of this emerging area. Moreover, as adaptive systems are encountered in many disciplines, it is imperative to learn from the theories and models developed in these other areas. This survey article presents a landscape of research in self-adaptive software by highlighting relevant disciplines and some prominent research projects. This landscape helps to identify the underlying research gaps and elaborates on the corresponding challenges.

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Self-adaptive software: Landscape and research challenges

This paper presents FRACTAL, a hierarchical and reflective component model with sharing. Components in this model can be endowed with arbitrary reflective capabilities, from plain black-box objects to components that allow a fine-grained manipulation of their internal structure. The paper describes JULIA, a Java implementation of the model, a small but efficient runtime framework, which relies on a combination of interceptors and mixins for the programming of reflective features of components. The paper presents a qualitative and quantitative evaluation of this implementation, showing that component-based programming in FRACTAL can be made very efficient. Copyright © 2006 John Wiley & Sons, Ltd.

The FRACTAL component model and its support in Java

Inevitably, reading is one of the requirements to be undergone. To improve the performance and quality, someone needs to have something new every day. It will suggest you to have more inspirations, then. However, the needs of inspirations will make you searching for some sources. Even from the other people experience, internet, and many books. Books and internet are the recommended media to help you improving your quality and performance.

Feature-Oriented Software Product Lines

This paper describes the implementation of advice weaving in AspectJ. The AspectJ language picks out dynamic join points in a program's execution with pointcuts and uses advice to change the behavior at those join points. The core task of AspectJ's advice weaver is to statically transform a program so that at runtime it will behave according to the AspeetJ language semantics. This paper describes the 1.1 implementation which is based on transforming bytecode. We describe how AspectJ's join points are mapped to regions of bytecode, how these regions are efficiently matched by AspectJ's pointcuts, and how pieces of advice are efficiently implemented at these regions. We also discuss both run-time and compile-time performance of this implementation.

/pdf/advice-weaving-in-aspectj-ll99bbegre.pdf

Advice weaving in AspectJ

This paper presents FRACTAL, a hierarchical and reflective component model with sharing. Components in this model can be endowed with arbitrary reflective capabilities, from black-boxes to components that allow a fine-grained manipulation of their internal structure. The paper describes JULIA, a Java implementation of the model, a small but efficient run-time framework, which relies on a combination of interceptors and mixins for the programming of reflective features of components. The paper presents a qualitative and quantitative evaluation of this implementation, showing that component-based programming in FRACTAL can be made very efficient.

An open component model and its support in Java

When using Aspect Oriented Programming in the development of software components, a developer must understand the program units actually changed by weaving, how they behave, and possibly correct the aspects used. Support for rapid AOP prototyping and debugging is therefore crucial in such situations. Rapid prototyping is difficult with current aspect weaving tools because they do not support dynamic changes. This paper describes PROSE (PROgrammable extenSions of sErvices), a platform based on Java which addresses dynamic AOP. Aspects are expressed in the same source language as the application (Java), and PROSE allows aspects to be woven, unwoven, or replaced at run-time.

https://www.lst.ethz.ch/research/publications/AOSD_2002/AOSD_2002.pdf

Dynamic weaving for aspect-oriented programming

Recent developments in service architectures suggest that run-time adaptations could be implemented with dynamic AOP. In this paper we discuss application requirements on run-time AOP support and present a system that addresses these requirements. We provide basic support for weaving using the Just-In-Time compiler, while the AOP system is treated as an exchangeable module on top of the basic support. This approach allows us to provide low run-time overhead, AOP system flexibility, and secure weaving. We provide an extensive empirical evaluation and discuss the tradeoffs resulting from using the JIT compiler and a modularized architecture.

Just-in-time aspects: efficient dynamic weaving for Java

An obvious prerequisite for mobile computing devices is the ability to adapt to different computing environments. Otherwise the devices are forced to carry with them everything they may eventually need during their operational life time. This is neither desirable nor feasible, thereby hinting at the need for dynamic adaptation. The idea would be to let the environment be proactive and adapt the application rather than forcing the application to adapt itself to every possible environment. In this paper we present a platform for doing exactly this. Applications running on our modified JVM can be extended at run time with new functionality. Through this platform, mobile devices can acquire on-the-fly any functionality extension they may need to work properly in a given environment. The functionality extensions are local in time and space: they are active only on a specific site and just for the time they are needed. The platform can be used in both centralized settings (with a base station providing the extensions) or in self configuring mode (extensions are provided by peers). In this paper we describe the platform, how to use it and report on one of the several prototypes that have been constructed.

/pdf/a-proactive-middleware-platform-for-mobile-computing-1v352lzwgn.pdf

A proactive middleware platform for mobile computing

Container technology (e.g., Enterprise Java Beans) was designed for fixed network applications. This is unfortunate, because the ability of containers to adapt components transparently (e.g., with persistence and transactions) would be of great advantage in mobile computing. In this paper, we generalize the container model into a new software architecture, the spontaneous container. A spontaneous container allows to homogeneously extend all applications of a network, even if they spontaneously join or leave the network. In the paper we show how to build a spontaneous container by unifying different technologies into one coherent architecture: (i) dynamic aspect-oriented programming, (ii) containers, and (iii) infrastructures for mobile computing. Dynamic aspect-orientation makes a spontaneous container much more flexible than existing commercial containers. Inheriting the container programming model allows a single focus point for modifications for all applications in a network. Basing the overall architecture on dynamic service brokerage and discovery allows a seamless integration with existing infrastructures for both mobile and fixed computing. Following these ideas, we have built and evaluated a spontaneous container prototype that effectively and efficiently transforms applications within a network into a distributed system capable of transactional interaction, access control, and orthogonal persistence.

Spontaneous Container Services

New developments in battery technology, networking, and devices allow the creation of new business models based on mobile computing and not requiring any fixed infrastructure. Mobile electronic commerce is today limited in size but future mobile networks will grow dramatically. In such environments, the participating nodes must be selforganized to collaboratively implement all the services a fixed network would provide. In this paper we present the design and implementation of a system that supports the development of adaptive electronic services. We focus our attention on the problem of transactional interaction between nodes, which is an essential requirement in electronic commerce. To support, this feature, our system allows us to dynamically incorporate the transactional support in mobile nodes and provides the foundation for a self-organizing transaction system. The paper discusses then how groups of collaborating nodes can execute electronic transactions on an infrastructure-less, ad-hoc environment. We conclude with a preliminary performance evaluation.

Andrei Popovici

Papers

Dynamic weaving for aspect-oriented programming

Just-in-time aspects: efficient dynamic weaving for Java

A proactive middleware platform for mobile computing

Spontaneous Container Services

Ad-Hoc Transactions for Mobile Services