32
V. Liberatore
Pervasive Computing
Transport Layer
*Design choice
nTCP or RTP/UDP
*Three rules:
nReal-time data: RTP/UDP
*Sensor data
*Video, sound, I/O
*Control
nBulk data: TCP
*Log download
*Software upgrades
*Coarse supervision
nMiddleware rules
*E.g., RealAudio over UDP
*E.g., HTTP over TCP
*Usually, right choice made by middleware designer
*However, bad choices can propagate
Application
(the control application, e.g., close-lever)
Middleware
(common to multiple applications, e.g., resource discovery)
Transport
(e.g., TCP, RTP/UDP)
Data Link
(low level communication,
e.g. Ethernet, Infinet, etc.)
Network
(convergence layer: IP)