21
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 propagateApplication
(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, 802.11,
CAN, etc.)
Network
(convergence layer: IP)