Paco: Onloading Contextual Data to Mobile Devices

July 18, 2017
Versione stampabile

Time: Tuesday, 18 July 2017, h 02:15 pm
Location: FBK, Room 211, North Building, via Sommarive, 38123 Povo (Trento)


Christine Julien, The University of Texas at Austin


Modern mobile applications rely heavily on spatiotemporal context information to better predict events and users' behaviors. These applications require rich records of users' or devices' spatiotemporal histories. Maintaining these rich histories requires frequent sampling and indexed storage of spatiotemporal data that pushes the limits of resource-constrained mobile devices. Today’s apps predominantly offload both processing and storing of contextual information, but this approach increases query time, relies on the user’s data connection, and runs the very real risk of revealing sensitive personal information. This talk motivates a different approach: that of on-loading all contextual storage and query support; that is, a users' personal mobile device is the repository for that user's spatiotemporal contextual history. The user (and the user's device) becomes responsible for the user's personal data, and applications access the information only through user-controlled queries. The talk overviews PACO (Programming Abstraction for Contextual On-loading) an architecture that makes such on-loading feasible by optimizing for location and time while allowing flexibility in storing additional context data that is linked to the user's spatiotemporal trace. The PACO API’s innovations enable on-loading very dense traces of information, even given devices’resource constraints. Using real-world traces and an implementation of PACO for Android, PACO can support expressive application queries entirely on-device. The talk will include a quantitative evaluation that assesses PACO’s energy consumption, execution time, and spatiotemporal query accuracy. More importantly, we show how PACO can be used within canonical mobile computing applications to shift the perspective and ownership of personal contextual data. The talk closes with a look to the future, on building mechanisms to share contextual data stored in PACO and to add explicit privacy protections.

About the Speaker 

Dr. Julien is a professor in the Center for Advanced Research in Software Engineering (ARiSE) in the Department of Electrical and Computer Engineering at the University of Texas at Austin, which she joined in 2004. She is the director of the Mobile and Pervasive Computing Group, where her research is at the intersection of software engineering and dynamic, unpredictable networked environments. Her specific focus is on the development of models, abstractions, tools, and middleware whose goals are to ease the software engineering burden associated with building applications for pervasive and mobile computing environments. These environments include cyber-physical systems and the Internet of Things. Dr. Julien's research has been supported by the National Science Foundation (NSF), the Air Force Office of Scientific Research (AFOSR), the Department of Defense, and Freescale Semiconductors. Dr. Julien received her D.Sc. in 2004 from Washington University in Saint Louis. She earned her M.S. degree in 2003 and her B.S. with majors in Computer Science and Biology in 2000 (both also from Wash. U.).

Contact person regarding this talk: Gian Pietro Picco, gianpietro.picco [at]