Sessions by WSP – Sessions are assumed to be long-lived, so problem of lost connections is addressed by allowing lost sessions to be resumed even when dynamically assigned IP addresses are used WTP… Since no connection is set up, the effects of lost connections and other times of inactivity are minimized The unpredictable nature of wireless connection means that small segments of message are often lost Selective retransmission – meaning that only lost segments arev retransmitted and not the entire message as in TCP CARDS & DECK Card - is a single unit of interaction with the end-user, such as a text-screen, a selection list or a combo of these. A card is typically small enuff to be displayed on a small screen DECK – Series of cards used for making an application
Mrs. Vasanthi Muniasamy
WHAT IS WAP?
WAP is Wireless Application Protocol
WAP is an open international standard for
application layer network communications
in a wireless communication environment.
Its main use is to enable access to the
Internet (HTTP) from a mobile phone or
WHAT IS PROTOCOL?
A Protocol is a set of guidelines or rules.
In computing and internet
FEATURES OF WAP
WAP stands for W ireless A pplication P rotocol
WAP is an application communication protocol
WAP is used to access services and information
WAP is inherited from Internet standards
WAP is for handheld devices such as mobile
WAP is a protocol designed for micro browsers
WAP enables the creating of web applications for
WAP uses the mark-up language WML (not HTML)
WML is defined as an XML 1.0 application
WAP Micro Browsers
To fit into a small wireless terminal, WAP uses a
A Micro Browser is a small piece of software that
makes minimal demands on hardware, memory
and CPU. It can display information written in a
restricted mark-up language called WML.
The Micro Browser can also interpret a reduced
COMPONENTS OF WAP
WML stands for W ireless M arkup L anguage. It
is a mark-up language inherited from HTML, but
WML is based on XML, so it is much stricter
Differs from HTML in the following
WML was specifically designed for wireless
terminals with a target screen that is only a few lines
long and about an inch wide.
WML is case sensitive , and all tags and attributes
should be in lowercase.
WML doesn't assume that a keyboard or a mouse is
available for user input
WAP Components (contd)…
Encoder: converts WML to binarized WML
Adaptor: provides additional information
through HTTP header
Translate HTTP requests to WSP.
Convert between SSL and WTLS
Convert transport protocols (TCP and WDP
WML uses WML Script to run simple code
on the client. WML Script is a light
scripts are not embedded in the WML
pages. WML pages only contains
references to script URLs. WML scripts
need to be compiled into byte code on a
server before they can run in a WAP
WAP homepages are not very different from
HTML homepages. The markup language used
for WAP is WML (Wireless Markup Language).
WML uses tags - just like HTML - but the syntax
is stricter and conforms to the XML 1.0 standard.
WML pages have the extension *.WML, just like
HTML pages have the extension *.HTML.
WML is mostly about text. Tags that would slow
down the communication with handheld devices
are not a part of the WML standard. The use of
tables and images is strongly restricted.
Since WML is an XML application, all tags are
case sensitive (<wml> is not the same as
<WML>), and all tags must be properly closed.
WML Decks and Cards
WML pages are called DECKS. They are
constructed as a set of CARDS, related to
each other with links. When a WML page
is accessed from a mobile phone, all the
cards in the page are downloaded from
the WAP server. Navigation between the
cards is done by the phone computer inside the phone - without any extra
access trips to the server.
Limitations of Internet for
Traditional Internet applications cannot run on
mobile devices because of the following
Low bandwidth network
High Latency network
Limited connection stability
Small display size
Limited input facility
Limited processing power
WAP brings Internet to Handheld Devices
WAP handles limited bandwidth
Minimizes traffic over wireless interface
WSP layer, too, is binary encoded
WTP is not only designed to minimize amount of data but also
number of transactions
WAP handles high latency
WAE uses scripting to avoid round trip delays, e.g. by validating
user input locally
WTAI environment introduces a repository to hold services
that should be started in response to an event in mobile network,
e.g. incoming call.
WAP brings (contd)…
WAP handles less stable
The sessions supported by WSP are assumed to be long-lived.
WTP layer has been kept very simple compared to TCP
WTP supports selective retransmission of data
WAP handles small displays
WML structures its documents in ‘Decks & Cards’
When an application is executed, user navigates through a series of cards
WAP brings (contd)…
WAP handles limited input
The WML elements can be easily be implemented without much
input required from the key-board
Deck & Cards model requires minimal navigation between pages
Soft buttons or user-definable keys are also supported by WML
WAP handles limited memory and
Defining a light weight protocol stack
Limited functionality provided by WML & WMLScript
Binary encoding of WML & WMLScript