LOW-BANDWIDTH COMMUNICATION LINKS AND MULTIMEDIA DATA: A GIS APPLICATION FOR HANDHELD PCs

Thomas Kunz, Salim Omar, and Hervé Rivano

Systems and Computer Engineering

Carleton University

http://kunz-pc.sce.carleton.ca/

tkunz@sce.carleton.ca

Tourist Guides

Tourist Guides

Most (all?) guides include mapping component

Location information possibly provided by GPS or other location tracking sensors

Data has to be served from a server

client devices very constraint (space, memory, CPU)

data changes dynamically (overlay of busses, traffic congestion, accidents, …)

Question: can we design “mapviewer” client on PDAs?

On The Move: CityGuide works under Windows 95

Citikey: Maps static and stored locally (if available at all)

Use Java for ease of portability/development

Ottawa Maps: 5 Levels of Resolution

Map Prefetching

Java Problems

popup menus

Solaris: buttons trigger popup menus

Windows NT/CE: no trigger (independent of JVM)

object serialization: WinCE does not write signature

System.currentTimeMillis(): wrong time resolution

mouse events: main frame does not transmit mouse events to a panel contained by this frame

repaint(): does not trigger update()

performance: slow slow slow

Conclusions and Future Work

Dynamically updated maps on a HP/C is feasible and attractive

JVMs for PDAs too immature to be used to develop mobile applications

inconsistent behavior between JVMs for NT and CE

performance problems

Waba, Java 2 Micro Edition, Just In Time compilers (JIT) for WinCE may address latter problem

Explore tradeoff between caching, prefetching, compression

Alternative ways to adapt to client limitations: active networks, mobile code

Additional features: group communication, pushing data


	Thomas Kunz, Salim Omar, and Hervé Rivano
	Systems and Computer Engineering
	Carleton University
	http://kunz-pc.sce.carleton.ca/
	tkunz@sce.carleton.ca


	Most (all?) guides include mapping component
	Location information possibly provided by GPS or other location tracking sensors
	Data has to be served from a server
		client devices very constraint (space, memory, CPU)
		data changes dynamically (overlay of busses, traffic congestion, accidents, …)
	Question: can we design “mapviewer” client on PDAs?
		On The Move: CityGuide works under Windows 95
		Citikey: Maps static and stored locally (if available at all)
		Use Java for ease of portability/development


	popup menus
		Solaris: buttons trigger popup menus
		Windows NT/CE: no trigger (independent of JVM)
	object serialization: WinCE does not write signature
	System.currentTimeMillis(): wrong time resolution
	mouse events: main frame does not transmit mouse events to a panel contained by this frame
	repaint(): does not trigger update()
	performance: slow slow slow


	Dynamically updated maps on a HP/C is feasible and attractive
	JVMs for PDAs too immature to be used to develop mobile applications
		inconsistent behavior between JVMs for NT and CE
		performance problems
		Waba, Java 2 Micro Edition, Just In Time compilers (JIT) for WinCE may address latter problem
	Explore tradeoff between caching, prefetching, compression
	Alternative ways to adapt to client limitations: active networks, mobile code
	Additional features: group communication, pushing data