Mobile Service Clouds: A self-managing infrastructure for autonomic mobile computing services

Abstract. We recently introduced Service Clouds, a distributed infrastructure designed to facilitate rapid prototyping and deployment of autonomic communication services. In this paper, we propose a model that extends Service Clouds to the wireless edge of the Internet. This model, called Mobile Service Clouds, enables dynamic instantiation, composition, configuration, and reconfiguration of services on an overlay network to support mobile computing. We have implemented a prototype of this model and applied it to the problem of dynamically instantiating and migrating proxy services for mobile hosts. We conducted a case study involving data streaming across a combination of PlanetLab nodes, local proxies, and wireless hosts. Results are presented demonstrating the effectiveness of the prototype in establishing new proxies and migrating their functionality in response to node failures.

RTZen: Highly Predictable, Real-Time Java Middleware for Distributed and Embedded Systems

Distributed real-time and embedded (DRE) applications possess stringent quality of service (QoS) requirements, such as predictability, latency, and throughput constraints. Real-Time CORBA, an open middleware standard, allows DRE applications to allocate, schedule, and control resources to ensure predictable end-to-end QoS. The Real-Time Specification for Java (RTSJ) has been developed to provide extensions to Java so that it can be used for real-time systems, in order to bring Java's advantages, such as portability and ease of use, to real-time applications.In this paper, we describe RTZen, an implementation of a Real-Time CORBA Object Request Broker (ORB), designed to comply with the restrictions imposed by RTSJ. RTZen is designed to eliminate the unpredictability caused by garbage collection and improper support for thread scheduling through the use of appropriate data structures, threading models, and memory scopes. RTZen's architecture is also designed to hide the complexities of RTSJ related to distributed programming from the application developer. Empirical results show that RTZen is highly predictable and has acceptable performance. RTZen therefore demonstrates that Real-Time CORBA middleware implemented in real-time Java can meet stringent QoS requirements of DRE applications, while supporting safer, easier, cheaper, and faster development in real-time Java

Configuring Real-time Aspects in Component Middleware

This paper makes two contributions to the study of configuring real-time aspects into quality of service (QoS)-enabled component middleware and distributed real-time and embedded (DRE) systems. First, it compares and contrasts the process of integrating real-time aspects into DRE systems using conventional QoS-enabled distributed object computing (DOC) middleware versus QoS-enabled component middleware. Second, it presents empirical comparisons of several real-time aspects configured in The ACE ORB (TAO) (a widely used open-source ORB that implements the CORBA 2.x DOC middleware standard) vs. in the Component-Integrated ACE ORB (CIAO) (which extends TAO to support real-time aspects in the CORBA Component Model). Our results show that QoS-enabled component middleware implementations can offer real-time performance that is comparable to DOC middleware, while offering greater flexibility in composing and configuring key DRE system aspects