The Mobile and Pervasive Computing Group's research revolves around software engineering issues related to mobile and pervasive computing. We are a member of UT's Center for Excellence in Distributed Global Environments (EDGE). Some information about our specific ongoing and completed research projects can be found on this page. Also see our Publications
for up-to-date pending and published papers.
Table of Contents
- Gander: Search mechanisms for pervasive computing environments
Gander is a distributed search engine for mobile networked environments characterized
by high volumes of short-lived data. We refer to these emerging types of environments
as Personalized Networked Spaces (PNetS).
PNetS are comprised of digital devices, both mobile and embedded in the environment
(e.g., smart phones, sensors, RFID tags), connected by a dynamic network topology. As
in the Internet, large volumes of data motivate the need for expressive search mechanisms
that efficiently identify and provide access to information relevant to users' needs.
However, the volatile and heterogeneous nature of PNetS' network and data preclude traditional
information retrieval techniques.
This project aims to address the novel research and software engineering challenges that arise
from the new requirements in this emerging search space.
- Jonas Michel, Dr. Christine Julien, Dr. Jamie Payton, Dr. Gruia-Catalin Roman
- Grapevine: Efficient situational awareness in pervasive computing environments
Grapevine is a framework that enables applications to share context information in a localized
region of a pervasive computing network, use that information to dynamically form groups defined
by their shared situations, and assess the aggregate context of that group.
Moving beyond more typical egocentric world views, Grapevine allows an application to distribute its own context
information while simultaneously leveraging the context information it receives to modify its behavior and
aggregate task-relevant group context information that can also distributed within the network. We use novel data
structures such as probabilistic Bloomier filters to represent context information efficiently and minimize the
network resources required to support Grapevine's use.
Our long term vision is a framework that allows a pervasive computing application developer to delegate all
context related functionality to Grapevine and focus solely on the task at hand. Instead of spending time
determining what context information is needed, who it should be sent to, and managing the lifecycle of the
information it has received, a Grapevine-enabled application can merely indicate the context information it has to
offer and the context information it is interested in receiving. Achieving this vision leaves many interesting
research challenges such as communicating and responding to interest gradients within the network, determining the
frequency with which information should be sent, assessing a quality metric for the context information on hand,
and finding ways to provide all this functionality without placing undue burden on the limited resources available to
pervasive computing platforms.
- Evan Grim, Dr. Chien-Liang Fok, and Dr. Christine Julien
- Delay Tolerant Networking
The delay tolerant networking project is a multi-disciplinary research effort
that spans software engineering, network protocols, all the way to the physical
layer. It is a joint effort of three professors in the Department of Electrical
and Computer Engineering at the Univeristy of Texas: Dr. Christine Julien,
Dr. Sanjay Shakkottai, and Dr. Sriram Vishwanath.
We are researching delay-tolerant middleware which will enable nodes to
opportunistically and automatically adapt to changes in network and user
context to make more intelligent use of the limited resources available
in a delay-tolerant network. Our work is in the sensing and aggregation of
context, as well as in the adaptation mechanisms as they apply to
delay-tolerant routing and transport protocols.
This project is sponsored by the Department of Defense.
- Tony Petz, Justin Enderle, and Dr. Christine Julien
MaDMAN Middleware Page:
Old Project Page (no longer supported):
- Programming Abstractions for Ubiquitous Computing
This project is developing programming abstractions and development tools that enable application developers to
effeciently interact with ubiquitous and pervasive systems. Traditional pervasive systems are typically designed for a
specific application and can afford tight coupling between applications and the deployment technologies of the
application's evironment. These application-specific deployments will soon give way to more generic and flexible
deployments which will support multiple applications developed by disjoint development teams. To support this transistion
we must provide consistent programming interfaces and flexible support to application developers.
At the heart of this project is the need to find the proper level of abstraction for ubiquitous environments,
and developing programming metaphors that are appropriate. Currently, we are pursuing two lines of research in
this area. The Application Sessions Middleware project unifies the tasks of resource discovery and
connection maintenance into a single session. The Evolving Tuples project provides a generic
platform which is deployed to nodes in a pervasive environment. The Evolving Tuples platform can be leveraged
by new applications without requiring updates to the individual nodes, while still protecting them from
- Dr. Drew Stovall and Dr. Christine Julien
- Pervasive Computing Test Bed (Pharos Project)
The PCTB is an interdisciplinary facility conceived to support research goals in a variety of fields related to mobile, ad-hoc, pervasive, and cyber-physical systems. By providing a central repository for hardware, software, and knowledge, the PCTB reduces the barriers to practical, hand-on testing and evaluation of new concepts, protocols, techniques, and methods.
The PCTB is co-sponsored by the MPC Lab and the LINC Lab.
- Dr. Drew Stovall, Tony Petz, Justin Enderle, and Dr. Christine Julien
- Simplifying the Programming of Intelligent Environments
Intelligent environments, a research and sci-fi favorite, are lagging woefully behind predictions. Researchers alone cannot make smart spaces into a reality; we must open the development to everyone. This work aims to lower the barrier for entry of programming intelligent environments in two distinct ways: first, by providing an easy-to-understand middleware that allows average programmers to develop pervasive computing applications without a deep understanding of sensors and actuators and second, by providing an intuitive end-user programming framework that brings the power of intelligent environments to the masses.
- Seth Holloway and Dr. Christine Julien
- Query Semantics for Dynamic Networks
Self organized networks like mobile ad hoc networks and sensor networks enable pervasive computing applications to observe and monitor the physical world. Queries present an application-friendly abstraction to gather information from these emerging opportunistic networks. However, these networks are inherently dynamic because of changes induced by mobility and the unpredictable lifetime inherent to battery operated devices. Consequently, the state of the environment changes during the execution of a query. We propose to explore techniques to interpret the quality of information obtained from networks in the face of such dynamics. This project investigates the quality dimensions for both applications that require both immediate information just once and those that require periodic monitoring. Our ultimate goal is to present a software framework that allows software engineers the ability to exercise control over the data collection process and subsequently interpret how well the response represents the actual state of the environment. Interpreting the degree of dynamics allows application developers to write adaptive query processing applications easily where the application changes its behavior in response to changes in the environment constantly.
- Vasanth Rajamani and Dr. Christine Julien
- Dr Jamie Payton and Dr. Gruia-Catalin Roman
- Chameleon: Rapid Deployment of Adaptive Communication-Aware Applications
This project addresses a framework that facilitates real-time routing protocol decisions based on given application and environmental characteristics. Our approach develops analytical models for important network layer performance measures capturing various inter-dependent factors that affect routing protocol behavior. In this project, we provide an analytical framework that expresses protocol performance metrics in terms of environment-, protocol-, and application-dependent parameters.
My proposed framework will result in detailed models for two important metrics: end-to-end delay and throughput. We specify detailed models for the parameters embedded in the models with respect to the ability of network deployers, protocol designers, and application developers to reasonably provide the information. In a systematic manner, the project proposes the Chameleon software framework to integrate the analytical models with parameters specified by these three groups of stakeholders.
- Taesoo Jun and Dr. Christine Julien
- Cross-Layer Discovery and Routing
In pervasive computing environments, applications find themselves in constantly changing operating conditions. Such applications often need to discover locally available resources on-demand. Communication protocols that base discovery not on the unique address of the destination but on application-level characteristics of the destination host can more closely match application requirements. Our Cross-Layer Discovery and Routing (CDR) protocol is one such example; using a simple extension to standard source routing used in mobile ad hoc networks, we have demostrated the ability to efficiently discover and maintain routes to resources using application information to define the target of discovery. In addition, because the types of resources desired may be common across pervasive computing applications, the discovery and routing tasks may benefit from some degree of proactivity. Following this motivation, we have extended our CDR protocol to an adaptive version that incorporates resource advertisement. We have built mechanisms to allow CDR to dynamically tune its behavior to optimize itself for a dynamic operating environment.
- Dr. Angela Dalton (Johns Hopkins Applied Research Labs)
- Resource and Task Allocation in Pervasive Computing Networks
Given the scale and complexity of network-centric computing, enabling a sensor network to support multiple applications simultaneously is of paramount importance. In this project, we are investigating a formal framework for specifying the allocation of resources to the potentially competing tasks comprising these applications. We take the commonly used tiered sensor network architecture a step further, defining a range of tiers that, moving up and away from individual nodes, can provide increasingly abstract and application-specific behaviors. Within this sensor network, we categorize the tasks the network performs into three groups: capture tasks, storage tasks, and distribution tasks. Our goal is to allocate resources in the network, e.g, computation, storage and communication capabilities, to these tasks. In conjunction with our hierarchical model, we are defining a distributed algorithmic framework for dynamically determining how the task and resources in the sensor network can be best allocated to multiple concurrent and potentially competing applications.
- Dr. Nirmalya Roy, Vasanth Rajamani, and Dr. Christine Julien
- Quality-of-Inference (QoINF)-Aware Context Determination
Energy-efficient determination of an individual's context (both physiological and activity) is an important technical challenge for pervasive computing environments. Given the expected availability of multiple sensors, context determination may be viewed as an estimation problem over multiple sensor data streams. In this project we are developing a formal and practically applicable model to capture the tradeoff between the accuracy of context estimation and the communication overheads of sensing. In particular, we propose the use of tolerance ranges to reduce an individual sensor's reporting frequency, while ensuring acceptable accuracy of the derived context. In our vision, applications specify their minimally acceptable value for a Quality-of Inference (QoINF) metric. We introduce an optimization technique allowing a Context Service to compute both the best set of sensors, and their associated tolerance values, that satisfy the QoINF target at minimum communication cost. This approach is validated using a SunSPOT sensors testbed.
- Dr. Nirmalya Roy and Dr. Christine Julien
- Dr. Archan Misra (Telcordia Research) and Dr. Sajal K. Das (National Science Foundation)
- Passive Sensing for Context-Aware Mobile Computing
As computing devices and their users become increasingly mobile, the demand for information about the application's environment, or context, becomes significantly important to the efficient and robust operation of mobile and pervasive computing systems. Applications must be able to adapt themselves to changing conditions to satisfy users' demands and expectations and to ensure that the application's resource usage matches the environment's capabilities. Sensing context using traditional means incurs network communication, which competes with the applications using the network and expends valuable network resources, especially communication bandwidth and battery power. In this project, we are exploring passively sensing context metrics. This results in measurements that are basically approximations of actual context, but can be collected with zero cost in terms of network communication. This project develops a model of passive context sensing and a general framework for building and deploying passively sensed context metrics.
- Dr. Nirmalya Roy, Taesoo Jun, and Dr. Christine Julien
- Dr. Angela Dalton (Johns Hopkins Applied Research Labs)
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- DAIS: Declarative Applications in Immersive Environments: In this project,
we are developing communication, coordination, and programming abstractions that allow a mobile application on a PDA to
interact directly with resource-constrained sensors in the local environment to retrieve information on-demand without using a
single network access point. The project includes novel abstractions for sensor data aggregation and fusion performed within
the network on the resource constrained devices.
- Julien, C. and Kabadayi, S. "Enabling
Programmable Ubiquitous Computing Environments: A Middleware Perspective,"In Advances in Ubiquitous Computing: Future Paradigms and Directions, S. Kouadri Mostefaoui, Z. Maamar, and G. M. Giaglis (Eds.) Hershey: Idea Group Publishing, 2008.
- Kabadayi, S. and Julien, C."Scenes: Abstracting Interaction in Immersive Sensor Networks,"Pervasive and Mobile Computing: Special Issue on Selected Papers from PerCom 2007, December 2007.
- O'Brien, W.J., Julien, C., Hammer, J., Kabadayi, S., and Luo, X."An Architecture for Local Decision Support in Ad Hoc Sensor Networks,"In Proceedings of the ASCE 2007 International Workshop on Computing in Civil Engineering,Pittsburgh, PA, July 2007.
- Kabadayi, S., Julien, C., O'Brien, W.J., and Stovall, D.,"Virtual Sensors: A Demonstration,"In 26th International Conference on Computer Communications (INFOCOM): Demonstrations Track, Anchorage, AK, May 2007.
- Kabadayi, S. and Julien, C.,"A Local Data Abstraction and Communication Paradigm for Pervasive Computing," In Proceedings of the 5th Annual IEEE International Conference on Pervasive Computing and Communications,
White Plains, NY, March 2007.
- Hammer, J., Hassan, I., Julien, C., Kabadayi, S., O'Brien, W.J., and Trujillo, J., "Dynamic
Decision Support in Direct Access Sensor Networks: A Demonstration," In Proceedings of the 3rd International Conference on Mobile Ad-Hoc and Sensor Systems, Vancouver, Canada, October 2006.
- Kabadayi, S., "Middleware for On-Demand Access to Sensor Networks," In Proceedings of the Grace Hopper Celebration of Women in Computing, PhD Forum, San Diego, CA, October 2006.
- Kabadayi, S., Pridgen, A., and Julien, C., "Virtual
Sensors: Abstracting Data from Physical Sensors," In Proceedings of the 4th
International Workshop on Mobile Distributed Computing (MDC'2006),
co-located with WoWMoM'06, Buffalo, NY (US), June 2006.
- Sliverware for Collaborative Mobile Applications: Despite computers'
widespread use for supporting personal applications, very few programming frameworks exist for creating synchronous
collaborative applications. Enabling real-time collaboration demands lightweight, modular middleware that enables the
fine-grained interactions requried by collaborative applications. We have introduced sliverware that provides
extreme modularity and customizability while at the same time realizing our goal of simplifying cooperative application
- SMASH: Secure Mobile Agent Middleware: As software components become able to
move among hosts in the network, a question arises in how to secure interactions between the agents and among the agents
and their host platforms. SMASH investigates the variety of these security requirements, provides a mobile agent
architecture that embodies them, and still allows agents to move and coordinate anonymously to a limited extent.
- Pridgen, A. and Julien, C., "SMASH: Modular Security for Mobile Agents," In Software Engineering for Large-Scale Multi-Agent Systems V, Lecture Notes in Computer Science, 2007.
- Pridgen, A. and Julien, C., "A
Secure Modular Mobile Agent System," in Proceedings
of the 5th International Workshop on Software Engineering for Large-Scale Multi-Agent Systems (SELMAS'2006)
co-located with ICSE'06, Shanghai (China), May 2006.
- Network Abstractions: The network abstractions model provides a
formal abstract characterization of an application's context that extends to encompass a neighborhood within the ad hoc
network. The model includes a context specification mechanism that allows individual applications to tailor their operating
contexts to their personalized needs. The associated communication protocol, source initiated context construction, or
SICC, provides this context abstraction in ad hoc networks through continuous evaluation of the context. This relieves the
application developer of the obligation of explicitly managing mobility and its implications on behavior.
- Julien, C. and Roman, G.-C., Supporting
Context-Aware Interaction in Dynamic Multi-Agent Systems, (invited paper), Environments for Multiagent Systems, D.
Weyns et al (editors), Lecture Notes in Computer Science 3374, February 2005, pp. 168-189.
- Roman, G.-C., Julien, C., and Huang, Q., Network
Abstractions for Context Aware Mobile Computing, in Proceedings of the 24th International Conference on Software
Engineering (ICSE'02), Orlando, FL (USA),May 2002, pp. 363-373.
- Julien, C., Roman, G.-C., and Huang, Q., SICC:
Source-Initiated Context Construction in Mobile Ad Hoc Networks," Technical Report, TR-UTEDGE-2005-003, Center for
Excellence in Distributed Global Environments, The University of Texas at Austin, 2005.
- EgoSpaces: EgoSpaces is a coordination model and middleware for ad hoc
mobile environments that focuses on the needs of application development in ad hoc environments by proposing an agent-centered notion of context, called a view, whose scope extends beyonr the local host to data and resources associated with hosts and
agents within a subnet surrounding the agent of interest. An agent may operate over multiple views whose definitions may
change over time. An agent uses declarative specifications to constrain the contents of each view by employing a rich set of
constraints that take into consideration properties of the individual data items, the agents that own them, the hosts on which
the agents reside, and the physical and logical topology of the ad hoc network. We have formalized the concept of view,
explored the notion of programming against views, discussed possible implementation strategies for transparent context
maintenance, and generated a protoype system.
- Julien, C., and Roman, G.-C.,
EgoSpaces: Facilitating Rapid Development of
Context-Aware Mobile Applications, IEEE Transactions on Software Engineering,
32(5):281-298, May 2006.
- Julien, C., and Roman, G.-C., Egocentric Context-Aware Programming in Ad Hoc Mobile
Environments, inProceedings of the 10th International Symposium on the Foundations of Software Engineering (FSE-10),
Charleston, SC (USA), November 2002, pp. 21-30.
- Julien, C. and Roman, G.-C., Active Coordination in Ad Hoc Networks, in
Proceedings of the 6th International Conference on Coordination Models and Languages, Pisa (Italy), February 2004, pp.
- Julien,C., Payton, J., and Roman, G.-C., "Adaptive Access Control in Coordination-Based Mobile Agent Systems, Software Engineering for Large-Scale Multi-Agent Systems III, R. Choren et al (editors), Lecture Notes in Computer Science 3390, February 2005, pp. 254-271.
- Context UNITY: Context-aware computing refers to a paradigm in which applications sense aspects of the environment and use this information to adjust their behavior in response to changing circumstances. We have created a formal model and notation (Context UNITY) for expressing quintessential aspects of context-aware computations; existential quantification, for instance, proves to be higly effective in capturing the notion of discovery in open systems. Furthermore, Context UNITY treats context in a manner that is relative to the specific needs of an individual applications and promotes an approach to context maintenance that is transparent to the application.
- Roman, G.-C., Julien, C., and Payton, J., Modeling Adaptive Behaviors in Context UNITY, Theoretical Computer Science, 376(3):185-204, May 2007.
- Julien, C., Payton, J., and Roman, G.-C., Reasoning About Context-Awareness in the Presence of
Mobility, Electronic Notes in Theoretical Computer Science 97 (revised selected papers from FOCLASA'03), July 2004, pp. 259--276.
- Roman, G.-G., Julien, C., and Payton, J., A Formal Treatment of Context-Awareness, (invited
paper) in Proceedings of the 7th International Conference on Fundamental Approaches to Software Engineering, Lecture
Notes in Computer Science 2984, Barcelona (Spain), March 2004, pp. 12-16.