Java Reference
In-Depth Information
N
OTE
For a good list of WAP gateway products, visit the WirelessDevNet WAP Channel at
http://www.wirelessdevnet.com/channels/wap/
.
WAP Architecture
The Wireless Application Protocol architecture consists of a series of software layers designed
to mimic the International Standards Organization (ISO) Open Systems Interconnection (OSI)
network model. If you are familiar with this model, you know that it defines seven independent
layers that can be used to architect a computer network. These seven layers are
•
Physical Layer
•
Data Link Layer
•
Network Layer
•
Transport Layer
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•
Session Layer
•
Presentation Layer
•
Application Layer
In an OSI-approved network, each of these layers operates independently of the other layers so
that any one layer can be replaced without disrupting the functionality of the network.
The WAP Protocol Stack is designed as a series of layers as well. These layers are
•
Bearers
—Typical bearers include communications technologies such as SMS, CDPD,
and CDMA.
•
Wireless Datagram Protocol (WDP)
—Defines how information is passed across the
network.
•
Wireless Transport Layer Security (WTLS)
—Provides security and authentication ser-
vices based on SSL encryption.
•
Wireless Transaction Protocol (WTP)
—Provides facilities for performing both reliable
and non-reliable transactions; WTP supports unreliable one-way requests, reliable one-
way requests, and reliable two-way requests. The typical transaction request to an HTTP
server is of the “reliable two-way” variety. Sending a simple text message with no verifi-
cation would be an example of a reliable one-way request.
