Zary Segall

When peer-to-peer comes face-to-face: collaborative peer-to-peer computing in mobile ad-hoc networks

This paper motivates and describes the notion of mobile ad-hoc information systems. Such a system consists of a decentralized and self-organizing network of autonomous, mobile devices that interact as peers. Connectivity is determined by distance between devices; as hosts change their physical location they establish pair-wise communication links based on mutual proximity. We describe application scenarios for mobile ad-hoc information systems and identify technical challenges of a generic software infrastructure. Moreover, we present the goals and architecture of Proem, a peer-to-peer system and development platform for mobile ad-hoc applications. Proem has successfully been used as instructional tool in an advanced software engineering course on peer-to-peer computing.

A collaborative wearable system with remote sensing

This paper presents a collaborative wearable system based on the notion of remote sensing. Remote sensing lets users of wearable or stationary computers perceive a remote environment through the sensors of a remote wearable computer. We describe a concrete system with remote sensing capability that is designed to enhance the communication and cooperation of highly mobile computer technicians.

Software organization for dynamic and adaptable wearable systems

There is a growing interest in a class of systems having dynamic and adaptable properties. In this paper we discuss our work on one subclass of such systems, that of wearable computers. In particular, our interest is in the software organization necessary to build wearable computing systems. We will examine some of the key properties of such a software organization such as the ability to rapidly and dynamically reconfigure software to meet both physical changes and information changes of the wearable system. This has lead us to study a middleware layer for a wearable system that supports dynamic reconfiguration. The middleware approach is studied in the context of the NETMAN-a network maintenance assistant. Current results from the system evaluations and the final system requirements and open issues are presented.

Disseminating Trust Information in Wearable Communities

This paper describes a framework for managing and distributing trust information in a community of mobile and wearable computer users. Trust information in the form of reputations are used to aid users during their social interactions with the rest of the community.

NETMAN: the design of a collaborative wearable computer system

This paper presents a wearable groupware system designed to enhance the communication and cooperation of highly mobile network technicians. It provides technicians in the field with the capabilities for real‐time audio‐conferencing, transmission of video images back to the office, and context‐sensitive access to a shared notebook. An infrared location‐tracking device allows for the automatic retrieval of notebook entries depending on the users current location.

Where are you pointing at? A study of remote collaboration in a wearable videoconference system

This paper reports on an empirical study aimed at evaluating the utility of a reality-augmenting telepointer in a wearable videoconference system. Results show that using this telepointer a remote expert can effectively guide and direct a field workers manual activities. By analyzing verbal communication behavior and pointing gestures, we were able to determine that experts overwhelmingly preferred pointing for guiding workers through physical tasks.

Wearable communities: augmenting social networks with wearable computers

Wearable communities-social networks based on computer-augmented face-to-face encounters-present both social and technical design challenges. Our WearCom design methodology permits rapid prototyping of wearable community systems to facilitate community building.

Fault-tolerance for off-the-shelf applications and hardware

The concept of middleware provides a transparent way to augment and change the characteristics of a service provider as seen from a client. Fault tolerant policies are ideal candidates for middleware implementation. We have defined and implemented operating system based middleware support that provides the power and flexibility needed by diverse fault tolerant policies. This mechanism, called the sentry, has been built into the UNIX 4.3 BSD operating system server running on a Mach 3.0 kernel. To demonstrate the effectiveness of the mechanism several policies have been implemented using sentries including checkpointing and journaling. The implementation shows that complex fault tolerant policies can be efficiently and transparently implemented as middleware. Performance overhead of input journaling is less than 5% and application suspension during the checkpoint is typically under 10 seconds in length. A standard hard disk is used to store journal and checkpoint information with dedicated storage requirements of less than 20 MB.<<ETX>>

Multishelf: an experiment in peer-to-peer infomediation

We describe the architecture and the implementation of Multishelf-a decentralized peer-to-peer infomediator. Multishelf was designed and built during a ten-week senior software methodology course using the Proem peer-to-peer platform. We discuss the infomediation problem, present our scalable peer-to-peer solution including the effectiveness of using the Proem peer-to-peer platform, and conclude with plans for future work.

A formal method for providing temporal equivalence in binary-to-binary translation of real-time applications

Presents a formal method to provide temporal equivalence in binary-to-binary translation of real-time applications. We first define three different levels of temporal equivalence, i.e. timing equivalence, invariance and divergence. We then find necessary and sufficient conditions for these three levels of temporal equivalence. We take an interval-based approach to test these conditions. If the generated target program is executable with timing equivalence or invariance, it has to be enforced to do so by inserting synchronization. Synchronization methods that enforce the temporal equivalence are also presented.