Transcript Limitations of Wireless - Pennsylvania State University

Understand WML
Chao-Hsien Chu, Ph.D.
School of Information Sciences and Technology
The Pennsylvania State University
Possible Service Types by WAP
Call
Handling
Information
Services
Electronic
Commerce
Messaging
Local
Development
Services
WAP
Gamming
Database
Access
Transport
Limitations of Wireless
Physical Devices:
Networks:
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
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
Size / Display
Memory / Cache Size
Battery
Data Entry Methods
Contents:


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
Different Standards
Micro browser
Scarcity of contents
Block internet surfing.
Character-based Info.
Bandwidth limitations.
Incomplete service coverage.
Lack of an installed user base.
High customer cost.
Changing communications
standards.
 Latency
 Connection reliability
Security.
Why New Standard
Telecom
services
Call
control
Unified E-mail
mailbox
Security
Message
Services
Info
services
Info
WWW
ITTP
HDML
SIM toolkit
Other
TTML
WAP
WAP Architecture
WSP/WTP
WAP
Client
WML
WMLScript
WTAI
HTTP
WAP
Gateway
WML Interpreter
WML Encoder
WML Script
Compiler
Protocol Bearers
Web
Server
Interne
t
CGI Scripts
(PERL, ASP,
Java)
WML and
WMLScript
Contents
Sketch of WAP Network Architecture
WAP
gateway
Web
server
Corporate
Firewall
Filter
HTML
WML
WAP
gateway
Web
server
Wireless
Network
WTA
server
Internet Protocol vs. WAP
HTML
JavaScript
Other
Services
and
Applications
Application Layer (WAE)
Session Layer (WSP)
HTTP
Transaction Layer (WTP)
Security Layer (WTLS)
TLS-SSL
Transport Layer (WPD)
TCP/IP
UDP/IP
Bearers
SMS
USSD
CSD
IS-136 CDMA
CDPD
PDC
Etc.
Wireless Application Protocol
Other
Services
And
Applications
Application Layer
Session Layer
Transaction Layer
Security Layer
Transport Layer (WPD)
Bearers
SMS
USSD
CSD
IS-136 CDMA
CDPD
PDC
Etc.
WAP Protocol Stack
OSI Layer
WAP Protocol
Application Layer
WAE
Wireless Application Environment
Session Layer
WSP
Wireless Session Protocol
Transaction Layer
WTP
Wireless Transaction Protocol
Security Layer
WTLS
Wireless Transport Layer Security
Transport Layer
WDP
Wireless Datagram Protocol
Server Configuration
File Type
Extension
MIME Type
HDML
.hdml
text/x-hdml
WML
.wml
text/vnd.wap.wml
WMLScript
.wmls
text/vnd.wap.wmlscript
Compiled WML
.wmlc
application/vnd.wap.wmlc
Compiled WMLScript
.wmlsc
application/vnd.wap.wmlscriptc
WBMP
.wbmp
image/vnd.wap.wbmp
WML Structure
•
•
•
•
•
•
Deck - File
Card – Screen
Head: XML, DTD Declarations
Template: <template>, </template>
Root Element: <wml>, </wml>
Card: <card>, </card>
WML Structure
Process Instruction
<?xml version="1.0"?>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML Document Type
1.2//EN" "http://www.wapforum.org/DTD/wml12.dtd">
Declaration
<wml>
<template>
…
</template>
<card>
<p>
…
</p>
</card>
</wml>
Root Element
Template
Cards
WML’s Functionality
• Text Presentation and Layout: text formatting,
line breaks, and alignment.
• Images – Wireless Bitmap (WBMP) and image
alignment.
• User Inputs – Choice lists, multilevel choices,
text entry, and task controls.
• Cards and Deck Organization.
• Navigation – URL Naming and anchored links,
between cards in a deck, between decks.
• State and Context Management – Variable
passing between decks, Cache both variables and
decks.
Text Presentations
There is no support for font
Paragraph
<p> </p>
Line break
<br/>
Big style
<big> </big>
Bold face
<b> </b>
Emphasis
<em> </em>
Italic
<i> </i>
Small
<small> </small>
Strong
<strong> </strong>
Underline
<u> </u>
Paragraph
•
•
•
•
<p> </p>
Two attributes:
align = “left”, “center” or “right”
mode = ‘wrap” or “nowrap”
Attribute
Effect
<p align=“left”> </p>
Left alignment of paragraph
<p align=“center”> </p>
Centered alignment of paragraph
<p align=“right”> </p>
Right alignment of paragraph
Special Characters
Name
Ampersand
Apostrophe
Dollar Sign
Greater Than
Less Than
Spaces
Quote
Soft Hyphen
ASCII Characters
Char
&
‘
$
>
<
“
-
ASCII
&#38;
&#39;
&#24;
&#62;
&#60;
&#160;
&#34;
&#173;
&#nn;
Escape Sequence
&amp;
&apos;
$dol; or $$
&gt;
&lt;
&nbsp;
&quot;
&shy;
Table
• <table </table>
• Attributes:
align
Alignment - left, center, right
title
Name a table
columns
Number of columns
<tr> </tr>
Define row
<td> </td>
Define column
Image - <img>
src
URL of the image to display
localsrc Local known icon
align
Top, middle,bottom
width
Width - Number of pixels or %
height
Height - Number of pixels or %
hspace Horizontal space -Number of pixels
vspace Vertical space - Number of pixels
alt
Alternative text to display
Navigation between Cards and Decks
• <a> … </a>
• <anchor> … </anchor>
Type of Links
Syntax
Link to another card
in the same deck
<a href=“#card2” title=“Card 2”>Second
Card </a>
Link to another card
in different deck on
same server
<a href=“xxx.wml#card2” title=“Other
Deck”>Another Deck</a>
Link to another deck <a href=“http://www.xxx.com/xxx.wml”>
on a different server Different Server </a>
Events and Tasks
Actions
Meaning
Example
accept
Cause task to occur
same as OK
<do type=“accept”>
<go href=“#card2”/> </do>
prev
Return to previous
<do type=“prev”> <prev />
</do>
help
Request help
<do type=“help”>
<go href=“#help”> </do>
reset
Reset the devices
<do type=“reset”> </do>
options
Ask for more operations
delete
Remove an item
unknown
Map a task to any key
Events
• <onenterforward>: Invoke a card via a GO
statement.
• <onenterbackward>: Navigate to a card via the
<prev> statement.
• <onpick>: Select an option.
• <ontimer>: Delay time for action.
• These events are invoked via an <onevent>
element, an <option> element, or as part of a
<template> or <card> element.
Input Attributes
Attribute
Description
name
Name of the variable to receive a value
value
Default value for the variable
maxlength Max. # of characters to accept use input
size
Number of characters for browser to display
type
Text or password
format
Format of input data (controlled by input mask)
emptyok
Boolean (returns a value of either true or false)
Input Mask
Specifier
A
a
N
X
x
M
m
*f
Nf
\v
Format Control
Uppercase, nonnumeric characters
Lowercase, nonnumeric characters
Numerical characters, including (+) and (-)
Uppercase, alphabetic, numeric, punctuation
Lowercase, alphabetic, numeric, punctuation
Any character, browser assumes uppercase
Any character, browser assumes lowercase
Any number of characters followed by format
Limited to “n” number of characters
Literal character is output, input prohibited.
Attributes of Do Element
Attribute
Description
type
Provide a hint to the browser about how it
should be displayed
Specify the string used for the label.
label
name
optional
Specify a programmatic name for the do
element binding, especially when multiple do
elements are bound to the same card
Determine whether the do element may be
ignored
Hardware Key Types
Key Type
Description
accept
Acknowledgement or acceptance
prev
Backward navigation
help
reset
options
Request for help
Clears or resets the state
Request for options or additional operations
delete
unknown
Delete an item or choice
Is equivalent to an empty string
Action Types
Action Type
Description
go
Goes forward
prev
Go backward using the history stack
refresh
Refresh the screen after updating variable
values
noop
Indicate no action should be taken
Example of Do Element
<do type=“options” label=“titles” name=“titles”>
<go href=“#titles”/>
</do>
<do type=“options” label=“Authors” name=“authors”>
<go href=“#authors”/>
</do>
<do type=“options” label=“Books” name=“books”>
<go href=“#booklist”/>
</do>
Thank You?
Any Question?