25.02.2013 Views

TCP/IP Tutorial and Technical Overview - IBM Redbooks

TCP/IP Tutorial and Technical Overview - IBM Redbooks

TCP/IP Tutorial and Technical Overview - IBM Redbooks

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

► WAP-specific data, such as the WML capabilities <strong>and</strong> WAP version<br />

Additionally, an origin server or proxy server can cache this information to<br />

expedite the a client’s requests.<br />

18.9 Wireless protocols<br />

The wireless application protocol consists of numerous subprotocols, each<br />

providing a different functionality for wireless applications. This section describes<br />

these protocols <strong>and</strong> the scenarios for which they are appropriate.<br />

18.9.1 Wireless Datagram Protocol (WDP)<br />

WDP provides a consistent service to the upper layers (security, transaction, <strong>and</strong><br />

session) of the WAP architecture. It is defined in the OMA<br />

WAP-259-WDP-20010614-a specification, <strong>and</strong> allows applications to operate<br />

transparently over different available bearer services. It communicates<br />

transparently over the different bearer services supported by multiple network<br />

types. WDP is a connection-less, unreliable datagram service. It supports port<br />

number addressing. The port number points to the higher-layer level of WDP.<br />

This can be WTP, WTLS, WSP, or an application.<br />

In order to support the different bearer services with its specific capabilities <strong>and</strong><br />

characteristics, an adaptation is required to keep WDP as a common layer for<br />

the various bearer services. Therefore, WDP, with its type of adaptation layer,<br />

cooperates with its underlying bearer layer. Figure 18-7 on page 673 shows the<br />

general WDP structure.<br />

672 <strong>TCP</strong>/<strong>IP</strong> <strong>Tutorial</strong> <strong>and</strong> <strong>Technical</strong> <strong>Overview</strong>

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!