Stephen Smaldone

RoadSpeak: enabling voice chat on roadways using vehicular social networks

A great number of people spend one or more hours each day driving between home and the office. These daily roadway commutes are highly predictable and regular, and provide a great opportunity to form virtual mobile communities. However, even though these commuters are already physically present in the same location, they are limited in their ability to communicate with each other. This paper presents a framework for building such communities, which we call Vehicular Social Networks (VSNs), to facilitate better communication between commuters driving on roadways. As a proof of concept, we present the design of RoadSpeak, a VSN-based system which allows drivers to automatically join VSNs along popular roadways, and communicate with each other by means of voice chat messages.

Recovering Internet service sessions from operating system failures

Current Internet service architectures lack support for salvaging stateful client sessions when the underlying operating system fails due to hangs, crashes, deadlocks, or panics. The backdoors (BD) system is designed to detect such failures and recover service sessions in clusters of Internet servers by extracting lightweight state associated with client service sessions from server memory. The BD architecture combines hardware and software mechanisms to enable accurate monitoring and remote healing actions, even in the presence of failures that render a system unavailable.

Lane Reservation for Highways (Position Paper)

The only way to keep up with the ever-increasing number of cars on roads is through constant change and improvement in the transportation infrastructure. Construction of new roads is constrained by space and financial resources. Therefore, there is a need to devise ways to make optimal use of the existing infrastructure. In this position paper, we describe a lane reservation system for highways. The idea is to allow drivers to reserve a slot on a high-priority lane by paying a premium price. The high-priority lane would provide congestion free travel between any two points on the highway. We describe the design of our system, the challenges that need to be solved and the evaluation methodology we are planning to adopt.

Active Highways (Position Paper)

Highways are an essential component of our society because they are critical to quality of life and to local and national economies. Under good conditions, highways provide a safe and efficient route for people and goods to reach their destinations. However, as a direct consequence of their use, traffic congestion is ever-increasing, undermining the ability of highways to adequately provide an acceptable quality of service. It has become imperative for highway traffic to provide the same time guarantee quality as other transportation methods such as air and rail travel, while maintaining the convenience of flexible scheduling and destination for the individual traveler. In this position paper, we propose Active Highways, a fundamental departure from todaypsilas highway traffic management approaches that shifts the highway paradigm from a transportation infrastructure that monitors and controls traffic at the aggregate level, to a computer-based service that operates at the level of individual vehicles. In this sense, highways will become active managers of their own traffic similar to air traffic control. In our vision, future highways and future vehicles will communicate with one another, making the highway system aware of the driverspsila travel plans and allowing it to cooperate with and actively instruct the driver on achieving them. In particular, Active Highways will allow drivers to reserve slots in special high-priority intelligent lanes. This fine-grained traffic management model will guarantee travel time bounds, handle exceptions and enforce global community and environmental policies using real-time information from vehicle- and infrastructure-based sensors.

Leveraging smart phones to reduce mobility footprints

Mobility footprint refers to the size, weight, and energy demand of the hardware that must be carried by a mobile user to be effective at any time and place. The ideal of a zero mobility footprint is achievable by encapsulating personal computing state in a virtual machine (VM) and delivering it over the Internet to a locally-obtained computer close to the user. In locations with poor Internet connectivity, the demands placed on WAN bandwidth can result in unacceptable user experience. We show how this challenge can be overcome by using nascent smart phone technology as a trusted personal assistant called Horatio that serves as a self-cleaning portable cache for VM state. Since most users already carry cell phones for voice calls and texting, Horatio does not increase the size or weight aspects of a users mobility footprint - there is only a small increase in the energy aspect. We have built an experimental prototype of Horatio, and measurements confirm its ability to improve user experience even with current smart phone limitations.

FileWall: A Firewall for Network File Systems

Access control in network file systems relies on primitive mechanisms like access control lists and permission bits, which are not enough when operating in a hostile network environment. Network middleboxes, e.g., firewalls, completely ignore file system semantics when defining policies. Therefore, implementing simple context-aware access policies requires modifications to file servers and/or clients, which is impractical. We present FileWall, a network middlebox that allows administrators to define context-aware access policies for file systems using both the network context and the file system context. FileWall interposes on the client-server network path and implements administrator defined policies through message transformation without modifying either clients or servers. In this paper, we present the design and implementation of FileWall for the NFS protocol. Our evaluation demonstrates that FileWall imposes minimal overheads for common file system operations, even under heavy loads.

Target container: A target-centric parallel programming abstraction for video-based surveillance

We introduce a novel abstraction, the target container (TC), which serves as a parallel programming model and execution framework for developing complex applications for tracking multiple targets in a large-scale camera network. The key insight is to allow the domain expert (e.g., a vision researcher) to focus on the algorithmic details of target tracking and let the system deal with providing the computational resources (cameras, networking, and processing) to enable target tracking. Each TC has a one-to-one correspondence with a target, possibly tracked from multiple cameras. The domain expert provides the code modules for target tracking (such as detectors and trackers) as handlers to the TC system. The handlers are invoked dynamically by the TC system to discover new targets (detector) and to follow existing targets (tracker). The TC system also provides an interface for merging TCs whenever they are determined to be corresponding to the same target. This paper presents the design of the TC system, details of an experimental prototype, and an example application to demonstrate the simplicity of using the TC programming model.

Ad-hoc voice-based group communication

People waste many hours driving each day. Although unavoidable, this time can be very boring to motorists. Similar to people taking mass transit who often pass the time socializing with those around them, motorists could benefit from social interactions if they were given broader social opportunities. Unfortunately, existing Multiparty Voice Communication (MVC) systems do not scale to large numbers of users and do not provide adequate access controls. We present RoadSpeak, a scalable MVC system that allows motorists to automatically join Voice Chat Groups (VCGs) along popular roadways. RoadSpeak achieves interruption-free communication through the use of voice chat message buffering, flow control and in-order delivery of voice messages to participants. We have implemented a RoadSpeak prototype on Nokia N95 smart phones using 3G cellular networking for voice message transfer. We have also built an MVC simulator to perform large-scale simulations that compare RoadSpeak with existing MVC systems. The results of our evaluation prove the feasibility of RoadSpeak and demonstrate that it performs similarly to a traditional MVC systems while supporting substantially larger groups of users.

The cyber-physical bike: a step towards safer green transportation

To improve road cycling safety, we present an approach that augments bicycles with video processing and computational capabilities. This Cyber-Physical bicycle system continuously monitors the environment behind the biker, automatically detects rear-approaching vehicles, and alerts the biker prior to the approach. In this paper, we (i) identify biker safety as a problem that can be addressed using mobile video sensing and processing, (ii) present the design of a Cyber-Physical bicycle system, which applies video processing techniques to perform automated vehicle detection, and (iii) demonstrate the feasibility of this system through the evaluation of our prototype implementation. Early results show that our approach operates with good accuracy at normal frame rates, and can perform detection in real time with reduced frame rates.

FRAC: Implementing Role-Based Access Control for Network File Systems

We present FRAC, a Framework for role-based access control in network file systems. FRAC is a reference monitor that controls the message flow between file system clients and servers. FRAC supports role hierarchies, user sessions, and static and dynamic separation of duty constraints. It also allows administrators to define dynamic policies based on access history and the environment, e.g., time of day. FRAC introduces a virtual control namespace (VCN) that provides an interface to query and update the state of the access control framework over the standard file system protocol. This namespace eliminates the need for executing specialized user agents either at the client or at the server. Therefore, FRAC does not require any modification to either the file system client or the file server. We have implemented FRAC for the widely deployed NFS protocol using FileWall, a file system proxy previously developed by us. Our experimental evaluation shows that FRAC imposes minimal overheads for the common file system operations.