The WAP Forum
In
1997, Ericsson, Motorola, Nokia, and Unwired Planet formed the WAP Forum(www.wapforum.org).
More than 90 companies in the wireless telecommunications business are members
of the WAP Forum. WAP is the standard developed by the WAP Forum, a consortium
formed by device manufacturers, service providers, content providers, and application providers. WAP specifies an
application framework and protocols for wireless devices. WAP is a kind of
fusion of mobile networking technologies and Internet technologies.
The WAP Forum’s
objectives include :
·
To bring Internet content and advanced data
services to digital cellular phones and other
wireless terminals.
·
To create
an interoperable wireless protocol specification that will work across differing wireless network technologies.
·
To enable
the creation of content and applications that could scale across a wide range
of wireless bearer networks and device types.
·
To embrace and extend existing standards and
technologies
The key features provided
by WAP include :
·
A programming model similar to the Internet
·
Wireless Markup Language(WML)
·
WML Script
·
Wireless Telephony Application(WTA)
·
Optimized protocol stack
The WAP architecture provides a scalable and extensible
environment for application development
on mobile communication devices. It achieves this through a layered protocol design,
covering protocols at Layer 4 and above. The WAP protocol stack is independent
of the underlying network, which could take the form of GSM, CDMA, CDPD, iDEN,
etc. Hence, WAP is essentially an application stack specification; it is not
network-centric.
Wireless Application
Environment(WAE)
Generally, WAE enables a spectrum of applications to be supported over
WAP. WAE has two main elements, namely: (a) user agents, and (b) services and
formats. The former includes the WML and WTA(Wireless Telephone Application)
user agents. The latter consists of WML scripts, image formats, etc. A user
agent can take the form of a Web browser. The WML user agent is responsible for the interpretation of
WML and WMLScript. WAP employs the same addressing model as in the Internet,
that is, it use Uniformed Resource Locators(URLs). AURL uniquely identifies an
available resource. WAP also uses Uniform Resource Identifiers (URIs) to
address resources that are not accessed via well-known protocols.
Wireless Session Protocol(WSP)
The WSP provides both connection-oriented and connectionless services. It
is optimized for low-bandwidth networks with relatively long latency. WSP is a
binary version of HTTP version 1.1, but
with the additions of : (a) session migrations, (b) header caching, etc. WAP
connection mode allows the establishment of sessions between a client and the
WAP gateway or proxy. It can handle
session interruptions as a result of mobility and reestablish session states at
a later point in time. Header caching allows better bearer utilization since in
HTTP, most of the requests contain
static headers that need to be re-sent again.
Wireless Transaction Protocol(WTP)
WTP is designed for transaction-style communications on wireless devices.
In a transaction, users express their intentions and financial commitments to service
providers for processing Very often, such transactions demand reliable, fast,
and secure communications. WTP is a lightweight
protocol suitable for implementation in thin clients. WTP implements selective retransmission of lost segments.
Wireless Transport Layer
Security(WTLS)
WTLS is needed for WAP to ensure data integrity, privacy, authentication,
and protection from denial-of-service. It is based on Transport Layer
Security(TLS) 1.0, but optimized for wireless
channels. It provides transport layer security between a WAP client and the WAP
gateway/proxy. Digital certificates are used for authentication and non repudiation
of server and client. Encryption is also used to enhance the degree of
confidentiality.
Wireless Datagram Protocol(WDP)
WDP is the transport layer protocol in WAP. It has the same functionality
provided by the Internet User Datagram
Protocol(UDP). Whether WAP uses UDP or WDP, datagram delivery services are provided by port number functionality
and the characteristics of different beare services are hidden from the upper
layers. WDP can be extended to provide segmentation and
reassembly
functions
