Tahir Azim

The κ factor: inferring protocol performance using inter-link reception correlation

This paper explores metrics that capture to what degree packet reception on different links is correlated. Specifically, it explores metrics that shed light on when and why opportunistic routing and network coding protocols perform well (or badly). It presents a new metric, κ that, unlike existing widely used metrics, has no bias based on the packet reception ratios of links. This lack of bias makes κ a better predictor of performance of opportunistic routing and network coding protocols. Comparing Deluge and Rateless Deluge, Deluges network coding counterpart, we find that κ can predict which of the two is best suited for a given environment. For example, irrespective of the packet reception ratios of the links, if the average κ of the link pairs is very high (close to 1.0), then using a protocol that does not code works better than using a network coding protocol. Measuring κ on several 802.15.4 and 802.11 testbeds, we find that it varies significantly across network topologies and link layers. κ can be a metric for quantifying what kind of a network is present and help decide which protocols to use for that network.

The Clarens Web service framework for distributed scientific analysis in grid projects

Large scientific collaborations are moving towards service oriented architectures for implementation and deployment of globally distributed systems. Clarens is a high performance, easy to deploy Web service framework that supports the construction of such globally distributed systems. This paper discusses some of the core functionality of Clarens that the authors believe is important for building distributed systems based on Web services that support scientific analysis.

The Clarens Grid-enabled Web Services Framework : Services and Implementation

This paper describes progress made in the development of the Clarens Web Services Framework, including a second Java-based server implementation, improved performance, a global lookup and discovery service leveraging of the MonALISA monitoring system, and adapting the framework to a secure message-based transport protocol.

Scaling Virtual Worlds with a Physical Metaphor

Outlines the Meru Project at Stanford University is designing and implementing an architecture for the virtual worlds of the future. The hope is that we can avoid some of the complexities the Web has encountered by learning how to build applications and services before they are subject to the short-term necessities of commercial development. While Meru cannot compete with the content creation of commercial virtual worlds, it can, like the original World Wide Web at CERN, investigate basic questions about system design. By doing so, the door can be opened to a future where physical sensors in the real world seed their virtual reflections, users can visually browse a sea of information, and virtual avatars convey physical social cues to bring distance interaction to the level of actual presence.

Resource management services for a grid analysis environment

Selecting optimal resources for submitting jobs on a computational grid or accessing data from a data grid is one of the most important tasks of any grid middleware. Most modern grid software today satisfies this responsibility and gives a best-effort performance to solve this problem. Almost all decisions regarding scheduling and data access are made by the software automatically, giving users little or no control over the entire process. To solve this problem, a more interactive set of services and middleware is desired that provides users more information about grid weather, and gives them more control over the decision making process. This paper presents a set of services that have been developed to provide more interactive resource management capabilities within the grid analysis environment (GAE) being developed collaboratively by Caltech, NUST and several other institutes. These include a steering service, a job monitoring service and an estimator service that have been designed and written using a common grid-enabled Web services framework named Clarens. The paper also presents a performance analysis of the developed services to show that they have indeed resulted in a more interactive and powerful system for user-centric grid-enabled physics analysis.

Grid Enabled Analysis : Architecture, prototype and status

The Grid Analysis Environment (GAE), which is a continuation of the CAIGEE project [5], is an effort to develop, integrate and deploy a system for distributed analysis. The current focus within the GAE is on the CMS experiment [1] however the GAE design abstracts from any specific scientific experiment and focuses on scientific analysis in general. The GAE project does not intend to reinvent services, but rather to integrate existing services into a collaborative system of web services.

JClarens: a Java based interactive physics analysis environment for data intensive applications

In this paper we describe JClarens; a Java based implementation of the Clarens remote data server. JClarens provides Web services for an interactive analysis environment to dynamically access and analyze the tremendous amount of data scattered across various locations. Additionally this research is aimed to develop a service oriented grid enabled portal (GEP) that provides interface and access to several grid services to give a homogeneous and optimized view of the distributed and heterogeneous environment. Other than showing platform independent behavior provided by Java, the use of XML-RPC based Web services enabled JClarens to be a language neutral server and demonstrated interoperability with its Python variant. Extreme care has been taken in the usage and manipulation of various Java libraries to cater the needs of high performance computing. The overall exercise has yielded in a prototype with strong emphasis on security and virtual organization management (VOM). This shall provide a common platform to support development of larger, more flexible framework with future aims to integrate it with a loosely coupled, decentralized, and autonomous framework for grid enabled analysis environment (GAE).

Distributed Analysis and Load Balancing System for Grid Enabled Analysis on Hand-Held Devices Using Multi-agents Systems

Handheld devices, while growing rapidly, are inherently constrained and lack the capability of executing resource hungry applications. This paper presents the design and implementation of distributed analysis and load-balancing system for hand-held devices using multi-agents system. This system enables low resource mobile handheld devices to act as potential clients for Grid enabled applications and analysis environments. We propose a system, in which mobile agents will transport, schedule, execute and return results for heavy computational jobs submitted by handheld devices. Moreover, in this way, our system provides high throughput computing environment for hand-held devices.

Grid enabled data analysis on handheld devices

The requirement for information on portable, handheld devices demands the realization of increasingly complex applications for increasingly small and ubiquitous devices. This trend promotes the migration of technologies that were originally developed for desktop computers to handheld devices. With the onset of grid computing, users of handheld devices should be able to accomplish much more complex tasks, by accessing the processing and storage resources of the grid. This paper describes the development, features, and performance aspects of a grid enabled analysis environment designed for handheld devices. We also describe some differences in the technologies required to run these applications on desktop machines and handheld devices. In addition, we propose a prototype agent-based distributed architecture for carrying out high-speed analysis of physics data on handheld devices.

Experimentally studying the sensornet point-to-point routing techniques spectrum

The performance of point-to-point routing protocols is limited by a trade-off between routing state and routing stretch. A wireless sensor network (WSN) designer can choose from a whole spectrum of routing techniques that exploit this trade-off at varying granularity. We aim to make such choices more informed; our contributions are twofold. First, we present the first point-to-point routing framework for WSNs that provides uniform implementations of four routing techniques that, from the state-stretch trade-off perspective, represent the entire spectrum. Second, using the framework we conduct an unprecedented experimental comparison of the techniques in TOSSIM and on two testbeds. In particular, we show that most techniques with sub-linear state offer a small stretch in WSNs. These results can guide the initial choice of potential routing techniques for a given WSN; the framework can facilitate the choice of a particular technique by enabling experiments in ones own settings.