Anthony D. Joseph

A view of cloud computing

Clearing the clouds away from the true potential and obstacles posed by this computing capability.

Tapestry: a resilient global-scale overlay for service deployment

We present Tapestry, a peer-to-peer overlay routing infrastructure offering efficient, scalable, location-independent routing of messages directly to nearby copies of an object or service using only localized resources. Tapestry supports a generic decentralized object location and routing applications programming interface using a self-repairing, soft-state-based routing layer. The paper presents the Tapestry architecture, algorithms, and implementation. It explores the behavior of a Tapestry deployment on PlanetLab, a global testbed of approximately 100 machines. Experimental results show that Tapestry exhibits stable behavior and performance as an overlay, despite the instability of the underlying network layers. Several widely distributed applications have been implemented on Tapestry, illustrating its utility as a deployment infrastructure.

Bayeux: an architecture for scalable and fault-tolerant wide-area data dissemination

The demand for streaming multimedia applications is growing at an incr edible rate. In this paper, we propose Bayeux, an efficient application-level multicast system that scales to arbitrarily large receiver groups while tolerating failures in routers and network links. Bayeux also includes specific mechanisms for load-balancing across replicate root nodes and more efficient bandwidth consumption. Our simulation results indicate that Bayeux maintains these properties while keeping transmission overhead low. To achieve these properties, Bayeux leverages the architecture of Tapestry, a fault-tolerant, wide-area overlay routing and location network.

An architecture for a secure service discovery service

The widespread deployment of inexpensive communications technology, computational resources in the networking infrastructure, and network-enabled end devices poses an interesting problem for end users: how to locate a particular network service or device out of hundreds of thousands of accessible services and devices. This paper presents the architecture and implementation of a secure Service Discovery Service (SDS). Service providers use the SDS to advertise complex descriptions of available or already running services, while clients use the SDS to compose complex queries for locating these services. Service descriptions and queries use the eXtensible Markup Language (XML) to encode such factors as cost, performance, location, and deviceor service-specific capabilities. The SDS provides a highlyavailable, fault-tolerant, incrementally scalable service for locating services in the wide-area. Security is a core component of the SDS and, where necessary, communications are both encrypted and authenticated. Furthermore, the SDS uses an hybrid access control list and capability system to control access to service information.

Rover: a toolkit for mobile information access

The Rover toolkit combines relocatable dynamic objects and queued remote procedure calls to provide unique services for roving mobile applications. A relocatable dynamic object is an object with a well-defined interface that can be dynamically loaded into a client computer from a server computer (or vice versa) to reduce client-server communication requirements. Queued remote procedure call is a communication system that permits applications to continue to make non-blocking remote procedure call requests even when a host is disconnected, with requests and responses being exchanged upon network reconnection. The challenges of mobile environments include intermittent connectivity, limited bandwidth, and channel-use optimization. Experimental results from a Rover-based mail reader, calendar program, and two non-blocking versions of World-Wide Web browsers show that Rovers services are a good match to these challenges. The Rover toolkit also offers advantages for workstation applications by providing a uniform distributed object architecture for code shipping, object caching, and asynchronous object invocation.

Mobile computing with the Rover toolkit

Rover is a software toolkit that supports the construction of both mobile-transparent and mobile-aware applications. The mobile-transparent approach aims to enable existing applications to run in a mobile environment without alteration. This transparency is achieved by developing proxies for system services that hide the mobile characteristics of the environment from applications. However, to excel, applications operating in the harsh conditions of a mobile environment must often be aware of and actively adapt to those conditions. Using the programming and communication abstractions present in the Rover toolkit, applications obtain increased availability, concurrency, resource allocation efficiency, fault tolerance, consistency, and adaptation. Experimental evaluation of a suite of mobile applications demonstrates that use of the toolkit requires relatively little programming overhead, allows correct operation, substantially increases interactive performance, and dramatically reduces network utilization.

Understanding TCP incast throughput collapse in datacenter networks

TCP Throughput Collapse, also known as Incast, is a pathological behavior of TCP that results in gross under-utilization of link capacity in certain many-to-one communication patterns. This phenomenon has been observed by others in distributed storage, MapReduce and web-search workloads. In this paper we focus on understanding the dynamics of Incast. We use empirical data to reason about the dynamic system of simultaneously communicating TCP entities. We propose an analytical model to account for the observed Incast symptoms, identify contributory factors, and explore the efficacy of solutions proposed by us and by others.

Brocade: Landmark Routing on Overlay Networks

Recent work such as Tapestry, Pastry, Chord and CAN provide efficient location utilities in the form of overlay infrastructures. These systems treat nodes as if they possessed uniform resources, such as network bandwidth and connectivity. In this paper, we propose a systemic design for a secondaryoverlay of super-nodes which can be used to deliver messages directly to the destinations local network, thus improving route efficiency. We demonstrate the potential performance benefits by proposing a name mapping scheme for a Tapestry-Tapestry secondary overlay, and show preliminary simulation results demonstrating significant routing performance improvement.

The security of machine learning

Machine learning’s ability to rapidly evolve to changing and complex situations has helped it become a fundamental tool for computer security. That adaptability is also a vulnerability: attackers can exploit machine learning systems. We present a taxonomy identifying and analyzing attacks against machine learning systems. We show how these classes influence the costs for the attacker and defender, and we give a formal structure defining their interaction. We use our framework to survey and analyze the literature of attacks against machine learning systems. We also illustrate our taxonomy by showing how it can guide attacks against SpamBayes, a popular statistical spam filter. Finally, we discuss how our taxonomy suggests new lines of defenses.

The Ninja architecture for robust Internet-scale systems and services373423

Abstract The Ninja project seeks to enable the broad innovation of robust, scalable, distributed Internet services, and to permit the emerging class of extremely heterogeneous devices to seamlessly access these services. Our architecture consists of four basic elements: bases, which are powerful workstation cluster environments with a software platform that simplifies scalable service construction; units, which are the devices by which users access the services; active proxies, which are transformational elements that are used for unit- or service-specific adaptation; and paths, which are an abstraction through which units, services, and active proxies are composed.