Fabio Kon

The case for reflective middleware

Its flexible and reconfigurable yet simple for programmers to use, notably for building dynamic distributed applications operating on the Net.

Reflective Middleware: From Your Desk to Your Hand

Middleware has emerged as an important architectural component in modern distributedsystems. Its role is to offer users a high-level, platform-independent programming model(object-oriented or component-based) and to hide problems of distribution. Examples of keymiddleware platforms include CORBA, DCOM, .NET, and the Java-based series of technologies (RMI, Jini, and EJB).

InteGrade: object‐oriented Grid middleware leveraging the idle computing power of desktop machines

Grid computing technology improves the computing experiences at organizations by effectively integrating distributed computing resources. However, just a small fraction of currently available Grid infrastructures focuses on reutilization of existing commodity computing resources. This paper introduces InteGrade, a novel object‐oriented middleware Grid infrastructure that focuses on leveraging the idle computing power of shared desktop machines. Its features include support for a wide range of parallel applications and mechanisms to assure that the owners of shared resources do not perceive any loss in the quality of service. A prototype implementation is under construction and the current version is available for download. Copyright

2K: a distributed operating system for dynamic heterogeneous environments

The first decades of the new millennium will witness an explosive growth in the number and diversity of networked devices and portals. We foresee high degrees of mobility, heterogeneity, and interactions among computing devices connected to global networks. While previous research in distributed operating systems solved many problems related to resource management, they seldom addressed the problems of heterogeneity and dynamic adaptability. On the other hand, middleware solutions, like CORBA and Java/Jini, solve part of the heterogeneity problem by permitting seamless communication among different platforms. But, they do not address dynamic resource management and adaptability for applications requiring high-performance distributed computing. This paper presents 2K, an integrated operating system architecture that addresses the problems of resource management in heterogeneous networks, dynamic adaptability and configuration of component-based distributed applications.

Dependence management in component-based distributed systems

The authors present a generic model for reifying dependencies in distributed component systems. They discuss how a representation model makes it possible to develop efficient, reliable and dynamically configurable component-based systems.

Monitoring, security, and dynamic configuration with the dynamicTAO reflective ORB

Conventional middleware systems fail to address important issues related to dynamism. Modern computer systems have to deal not only with heterogeneity in the underlying hardware and software platforms but also with highly dynamic environments. Mobile and distributed applications are greatly affected by dynamic changes of the environment characteristics such as security constraints and resource availability. Existing middleware is not prepared to react to these changes. In many cases, application developers know when adaptive changes in communication and security strategies would improve system performance. But often, they are not able to benefit from it because the middleware lacks the mechanisms to support monitoring (to detect when adaptation should take place) and on-the-fly reconfiguration. dynamicTAO is a CORBA-compliant reflective ORB that supports dynamic configuration. It maintains an explicit representation of its own internal structure and uses it to carry out runtime customization safely. After describing dynamicTAOs design and implementation, we discuss our experience on the development of two systems benefiting from the reflective nature of our ORB: a flexible monitoring system for distributed objects and a mechanism for enforcing access control based on dynamic security policies.

A comprehensive view of Hadoop research—A systematic literature review

Context: In recent years, the valuable knowledge that can be retrieved from petabyte scale datasets – known as Big Data – led to the development of solutions to process information based on parallel and distributed computing. Lately, Apache Hadoop has attracted strong attention due to its applicability to Big Data processing. Problem: The support of Hadoop by the research community has provided the development of new features to the framework. Recently, the number of publications in journals and conferences about Hadoop has increased consistently, which makes it difficult for researchers to comprehend the full body of research and areas that require further investigation. Solution: We conducted a systematic literature review to assess research contributions to Apache Hadoop. Our objective was to identify gaps, providing motivation for new research, and outline collaborations to Apache Hadoop and its ecosystem, classifying and quantifying the main topics addressed in the literature. Results: Our analysis led to some relevant conclusions: many interesting solutions developed in the studies were never incorporated into the framework; most publications lack sufficient formal documentation of the experiments conducted by authors, hindering their reproducibility; finally, the systematic review presented in this paper demonstrates that Hadoop has evolved into a solid platform to process large datasets, but we were able to spot promising areas and suggest topics for future research within the framework.

Design and implementation of runtime reflection in communication middleware: the dynamicTAO case

Communication middleware systems provide a solid basis for the construction of distributed applications. Unfortunately they usually lack the mechanisms for runtime reconfiguration. The performance of distributed applications is greatly affected by dynamic changes on the characteristics of the environment such as memory, CPU, and network availability. Existing communication middleware does not react in front of these changes. Most of the time, applications have enough knowledge to decide what to do in front of an environmental change, but they cannot use that knowledge because the middleware does not allow on-the-fly reconfiguration. We developed dynamicTAO, a CORBA-compliant reflective ORB that supports runtime reconfiguration. DynamicTAO maintains an explicit representation of its own internal structure and uses it to carry out dynamic customization safely.

2K: A Reflective, Component-Based Operating System for Rapidly Changing Environments

Modern computing environments face both low-frequency infrastructural changes, such as software and hardware upgrades, and frequent changes, such as fluctuations in the network bandwidth and CPU load. However, existing operating systems are not designed to cope with rapidly changing environments. They provide no mechanism to permit the insertion of self-adapting components that can optimize system performance according to diversity, software and hardware changes, and variations in the environment. They are not designed to accommodate dynamic updates of software, or to deal with component interdependence.

Using dynamic configuration to manage a scalable multimedia distribution system

Multimedia applications and interfaces will change radically the way computer systems will look like in the coming years. Radio and TV broadcasting will assume a digital format and their distribution networks will be integrated to the Internet. Existing hardware and software infrastructures, however, are unable to provide all the scalability, flexibility, and quality of service (QoS) that these applications require. We present a framework for building scalable and flexible multimedia distribution systems that greatly improves the possibilities for the provision of quality of service in large-scale networks. We show how to use architectural-awareness, mobile agents, and a CORBA-based framework to support dynamic (re)configuration, efficient code distribution, and fault-tolerance. This approach can be applied not only for multimedia distribution, but also for any QoS-sensitive distributed application.