MetaSockets: Run-Time Support for Adaptive Communication Services

Rapid improvements in mobile computing devices and wireless networks promise to provide a foundation for ubiquitous computing. However, comparable advances are needed in the design of mobile computing applications and supporting middleware. Distributed software must be able to adapt to dynamic situations related to several cross-cutting concerns, including quality-of-service, fault-tolerance, energy management, and security. We previously introduced Adaptive Java, an extension to the Java programming language, which provides language constructs and compiler support for the development of adaptive software. This paper describes the use of Adaptive Java to develop an adaptable communication component called the MetaSocket. MetaSockets are created from existing Java socket classes, but their structure and behavior can be adapted at run time in response to external stimuli. MetaSockets can be used for several distributed computing tasks, including audits of traffic patterns for intrusion detection, adaptive error control on wireless networks, and dynamic energy management for handheld and wearable computers. This paper focuses on the internal architecture and operation of MetaSockets. We describe how their adaptive behavior is implemented using Adaptive Java programming language constructs, as well as how MetaSockets interact with other adaptive components, such as decision makers and event mediators. Results of experiments on a mobile computing testbed demonstrate how MetaSockets respond to dynamic wireless channel conditions in order to improve the quality of interactive audio streams delivered to iPAQ handheld computers.