Image Processing Reference
In-Depth Information
App 1
App 5
Primary
transmission
channel
App 6
App 2
App 7
App 3
Base
station
App 4
App 8
Secondary transmission channel
FIGURE .
Communication channels in SeNeTs.
Node 1
Commands
Application
server
Host: speedy
Node 2
Network
server
Host: spice
Graphical
user interface
Node 3
Application
server
Host: rtl
Scripts
Node 4
Visualization, evaluation
Network configuration
Application configuration
Node applications
FIGURE .
SeNeTs components using the secondary transmission channel.
Thus, in wireless sensor networks with thousands of nodes, the bottleneck effect becomes the
dominant part.
To eliminate the bottleneck effect, SeNeTs contains two independent communications channels
as illustrated in Figure .. ..The primary communication channel is defined by the sensor network
application. It uses the communication method required by SNAs, for example, Bluetooth or ZigBee.
The secondary communication channel is an administration channel only used by SeNeTs compo-
nents. This channel transmits controlling and logging messages. It is independent of the primary
communication channel and uses a different communication method, for example, Ethernet for Ultra-
sound. The separation into two communication channels simplifies the decoupling of application
modules and administration modules after testing.
The parallel execution of applications on different host systems requires a cascaded infrastructure
to administrate the network. Figure . displays important modules in SeNeTs: node applications,
application servers (ASs), a network server (NS), and optional evaluation or visualization modules.
All of these modules are connected via the secondary transmission channel.
12.4.3.2 Network Server
The NS administrates sensor networks and associated sensor nodes. The NS starts, stops, or queries
SNAs. In an SeNeTs network, exactly one NS exists. However, this NS is able to manage several sensor
networks simultaneously. Usually, the NS runs as service of the OS.
A NS opens additional communication ports. External programs, such as scripts, websites, or telnet
clients can connect to these ports to send commands. hese commands may be addressed and for-
warded to groups or stand-alone components. Furthermore, the NS receives logging messages from
