DBI – Representation and Management of Data on the Internet

DBI – Representation and Management of Data on the Internet
WAP and WML DBI – Representation and Management of Data on the Internet

'putting the Internet in everyone's pocket'
Internet Connectivity Outlook Millions 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 1,400 1,200 1,000 800 600 400 200 Projected cellular subscribers More handsets than PCs connected to the Internet by the end of 2003! Projected Web handsets Projected PCs connected to the Internet (Dataquest 10/98) 'putting the Internet in everyone's pocket'

WAP WAP = Wireless Application Protocol
A protocol and set of specifications to connect wireless aplications to the Web

Needs for WAP Wireless networks and phones
have specific needs and requirements not addressed by existing Internet technologies WAP enables any data transport TCP/IP, UDP/IP, GUTS (IS-135/6), SMS, or USSD The WAP architecture several modular entities together form a fully compliant Internet entity all WML content is accessed via HTTP 1.1 requests

Advantages of WAP WAP utilizes standard Internet markup language technology (XML) Optimizing the content and airlink protocols The WML UI components map well onto existing mobile phone user interfaces no re-education of the end-users leveraging market penetration of mobile devices WAP utilizes plain Web HTTP 1.1 servers CGI, ASP, NSAPI, JAVA, Servlets, etc.

The Specification Includes
WAP Architecture Wireless Application Environment Protocol Layers Interoperability Security

WAP Architecture Web Server WAP Gateway Client HTTP WSP/WTP
Content CGI Scripts etc. with WML-Script WML Decks WAP Gateway WML Encoder WMLScript Compiler Protocol Adapters Client WML WML-Script WTAI Etc. HTTP WSP/WTP

Internet vs. WAP Wireless Application Protocol Internet HTML
JavaScript HTTP TLS - SSL TCP/IP UDP/IP SMS USSD CSD IS-136 CDMA CDPD PDC-P Etc.. Bearers: Wireless Application Protocol Wireless Application Environment (WAE) Session Layer (WSP) Security Layer (WTLS) Transport Layer (WDP) Transaction Layer (WTP) Other Services and Applications

WAP Specifies Wireless Application Environment Wireless Protocols
WML Microbrowser WMLScript Virtual Machine WMLScript Standard Library Wireless Telephony Application Interface WAP Content Types Wireless Protocols Wireless Session Protocol (WSP) Wireless Transport Layer Security (WTLS) Wireless Transaction Protocol (WTP) Wireless Datagram Protocol (WDP) Wireless network interface definitions WML

Big Pipe - Small Pipe Syndrome
Internet Wireless network <HTML> <HEAD> <TITLE>NNN Interactive</TITLE> <META HTTP-EQUIV="Refresh" CONTENT="1800, URL=/index.html"> </HEAD> <BODY BGCOLOR="#FFFFFF" BACKGROUND="/images/9607/bgbar5.gif" LINK="#0A3990" ALINK="#FF0000" VLINK="#FF0000" TEXT="000000" ONLOAD="if(parent.frames.length!=0)top.location=' <A NAME="#top"></A> <TABLE WIDTH=599 BORDER="0"> <TR ALIGN=LEFT> <TD WIDTH=117 VALIGN=TOP ALIGN=LEFT> HTTP/HTML <WML> <CARD> <DO TYPE="ACCEPT"> <GO URL="/submit?Name=$N"/> </DO> Enter name: <INPUT TYPE="TEXT" KEY="N"/> </CARD> </WML> WAP Content encoding

WAP Application Environment Goals
Network- neutral application environment For narrowband wireless devices With an Internet/WWW programming model And a high degree of interoperability

Device-Side Problems Device Independent Network Independent
Different vendors – requires interfaces Initial focus on phones Slow reactions Small memory Limited CPU Small screen Limited input model

Wireless Markup Language
WML Wireless Markup Language

WML Tag-based browsing language: W3C XML-based language
Screen management (text, images) Data input (text, selection lists, etc.) Hyperlinks & navigation support W3C XML-based language Inherits technology from HDML (Handheld Device Markup Language) and HTML

WML (cont.) Card metaphor Explicit inter-card navigation model
User interactions are split into cards Navigation occurs between cards Cards are put in to decks Explicit inter-card navigation model Hyperlinks User interface Event handling History State management and variables Reduce network traffic Results in better caching

All Decs Must Contain… Document prologue <WML> element
XML & document type declaration <WML> element Must contain one or more cards <?xml version="1.0"?> <!DOCTYPE WML PUBLIC "-//WAPFORUM//DTD WML 1.0//EN" " <WML> ... </WML>

Hello World Example <card> </card> -
<?xml version="1.0"?> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" " <wml> <card id="Card1" title="The dbi Course"> <p>  Hello World </p> </card> </wml> <card> </card> - It defines the beginning and the ending of a card <wml> </wml> - It defines the beginning and the ending of the page, like <html> </html>

== The DBI Course == Hello World __________________________________________ Back

The Result On a Different Device

Detecting a Click <?xml version="1.0"?> <wml>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" " <wml> <card id=“Card1” title=“The DBI Course”> <do type=“accept” label=“Next”> <go href=“#Card2”/> </do> <p> Select Next to go to Card 2. </p> </card> <card id=“Card2” title=“The DBI Course”> <p> I'm Card 2. </p> </wml>

== The DBI Course == Select Next to go to Card 2. __________________________________________Next Back == The DBI Course == I am Card 2. __________________________________________Next Back

Timer <wml> <?xml version="1.0"?>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" " <wml> <card id="Intro" ontimer="#Main" title=“DBI Course"> <timer value="150"/> <p> Welcome to the dbi site!! We will bring you to our main page after 15 seconds. </p> </card> <card id="Main" title="Menu"> <p> This is our main page. Under construction. </p> </card> </wml> Timer

After 15 seconds

=== Menu === This is our main page. Under construction. ___________________________ Back == DBI Course == Welcome to the dbi site!! We will bring you to our main page after 15 seconds. ___________________________ Back

Input <?xml version="1.0"?> <wml>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" " <wml> <card id="main" title=“DBI Example"> <do type="accept" label="Next"> <go href="#wel"/> </do> <p> Please enter your name: <input type="text" name="name"/> </p> </card> <card id="wel" title="Welcome"> <do type="prev" label="Back"> <prev/> </do> <p> Your name is $(name). Click Back to go to previous page. </p> </card> </wml> Input

Choosing the “Options”
Choosing the “Next” Entering a name Choosing the “Options”

Sending Data to the Server
<?xml version="1.0"?> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" " <wml> <card id="main" title=“DBI Example"> <do type="accept" label=“Send"> <go method="post" href=" <postfield name="firstname" value="$(first)"/> <postfield name=“course" value=“dbi"/> </go> </do> <p> Please enter your first name: <input type="text" name="first"/> </p> </card> </wml> Sending Data to the Server

WML Example Deck Card Navigation Variables Input Elements <WML>
<DO TYPE=“ACCEPT”> <GO URL=“#eCard”/> </DO Welcome! </CARD> <CARD NAME=“eCard”> <GO URL=“/submit?N=$(N)&S=$(S)”/> </DO> Enter name: <INPUT KEY=“N”/> Choose speed: <SELECT KEY=“S”> <OPTION VALUE=“0”>Fast</OPTION> <OPTION VALUE=“1”>Slow</OPTION> <SELECT> </WML> Deck Card Navigation Variables Input Elements

A Deck of Cards DBI Portal. Directory _____________ Next Services
<WML> <CARD> <DO TYPE="ACCEPT" LABEL="Next"> <GO URL="#card2"/> </DO> DBI Portal.<BR/>Directory </CARD> <CARD NAME="card2"> <DO TYPE="ACCEPT"> <GO URL="?send=$type"/> Services <SELECT KEY="type"> <OPTION VALUE="em"> </OPTION> <OPTION VALUE="ph">Phone</OPTION> <OPTION VALUE="fx">Fax</OPTION> </SELECT> </WML> DBI Portal. Directory _____________ Next Services 1> 2 Phone ____________ OK

Defining the Navigation Path
<CARD> <DO TYPE="ACCEPT" LABEL="Next"> <GO URL="#card2"/> </DO> First name: <INPUT KEY="fname"/> </CARD> <CARD NAME="card2"> <DO TYPE="ACCEPT" LABEL="Done"> <GO URL="?get=person" METHOD="POST" POSTDATA="first=$fname&last=$lname"/> Last name: <INPUT KEY="lname"/>

The DO Element Binds a task to a user action
Action type: ACCEPT, OPTIONS, HELP PREV, DELETE, RESET Label: Text string or image (optional) Task: GO PREV, REFRESH, NOOP Destination: URL Post data: if METHOD=POST <DO TYPE="ACCEPT" LABEL="Next"> <GO URL=" </DO>

Anchored Links Bind a task to the ACCEPT action, when cursor points to a link TITLE= sets the label string (default = “Link”) Links are not allowed in select list options <CARD> Please visit our <A TITLE="Visit"> <GO URL="home.wml"/>home page</A> for details. </CARD> Please visit our home page for ____________ Visit

Task Binding Rules User actions are scoped at three levels • Deck • Card • Anchored links & select list options (ACCEPT) When tasks are bound to an action at different levels, the action with narrower scope takes precedence Default task bindings User Action Task ACCEPT, PREV PREV Others NOOP

The TEMPLATE Element Defines actions & events for all cards in a deck
<WML> <TEMPLATE> <DO TYPE="OPTIONS" LABEL="Main"> <GO URL="main_menu.wml"/> </DO> </TEMPLATE> <CARD NAME="msg1"> <DO TYPE="ACCEPT" LABEL="Next"> <GO URL="#msg2"/> First story </CARD> <CARD NAME="msg2"> Second story </WML> First story … _____________ Next Main Second story ... _____________ OK Main

Handling User Input Select lists Input fields KEY variables
Choose from a list of options Input fields Enter a string of text or numbers KEY variables Set by SELECT and INPUT elements How user input is passed to other cards and the application server

The SELECT Element Display a list of options
Each option may set the KEY variable and/or bind a task to the ACCEPT key TITLE= dynamically sets the label string <CARD> <DO TYPE="ACCEPT" LABEL="View"> <GO URL="getcity.cgi?location=$city"/> </DO> Forecast <SELECT KEY="city"> <OPTION VALUE=“jer">Jerusalem</OPTION> <OPTION VALUE=“TA">Tel-Aviv</OPTION> <OPTION TITLE="Find" ONCLICK="find.cgi">New City</OPTION> </SELECT> </CARD> Forecast 1 Jerusalem 2 Tel-Aviv 3>New City ____________ Find

A Long Select List MULTIPLE and DEFAULT Attributes
<CARD> <DO TYPE="ACCEPT"> <GO URL="get_addr.cgi?id=$recid"/> </DO> Addr [1..9] <SELECT KEY="recid" MULTIPLE="TRUE" DEFAULT="1;3;5"> <OPTION VALUE="1">Bart</OPTION> <OPTION VALUE="2">Lisa</OPTION> <OPTION VALUE="3">Homer</OPTION> <OPTION VALUE="4">Marge</OPTION> <OPTION VALUE="5">Milhouse</OPTION> <OPTION VALUE="6">Nelson</OPTION> <OPTION VALUE="7">Smithers</OPTION> <OPTION VALUE="8">Maggie</OPTION> <OPTION VALUE="9">Burns</OPTION> <OPTION ONCLICK="#card2">More...</OPTION> </SELECT> </CARD>

The INPUT Element Prompts user to enter a string of text
Use FORMAT= to constrain input UP.Browser reserves soft key for text entry mode, if necessary Soc. Security: _ ____________ NUM <CARD> <DO TYPE="ACCEPT"> <GO URL="?get=person" METHOD="POST" POSTDATA="userid=$ssn"/> </DO> Soc Security: <INPUT KEY="ssn" FORMAT="NNN\-NN\-NNNN"/> </CARD> Soc. Security: ____________ OK

Other INPUT Attributes
DEFAULT=key_value Default KEY variable (displayed to user) FORMAT=format_specifier If omitted, free-form entry is allowed EMPTYOK="TRUE" Browser will accept null input, even with format TYPE="PASSWORD" Special entry mode handled by the browser MAXLENGTH=number Maximum number of allowed characters

FORMAT Control Characters
N Numeric character A, a Alphabetic character X, x Numeric or alphabetic character M, m Any character Leading backslash specifies forced characters Forced characters included in KEY variable value Leading * specifies 0 or more characters Password: FORMAT=“mmmm*m” Leading number specifies 0..N characters Zipcode: FORMAT=“NNNNN\-4N”

Displaying Images Insert app images or local icons within display text
1-bit BMP format Images are ignored by non-bitmapped devices <CARD> <DO TYPE="ACCEPT"> <GO URL="#c2"/> </DO> Continue <IMG LOCALSRC="righthand" ALT="forward..."/> </CARD> <CARD NAME="c2"> <IMG SRC="../images/logo.bmp" ALT="Unwired Planet"/> <BR/>Welcome!

Image Attributes alt=“..” src=".. width=".. height="..
‘Names’ the image If the image is not displayed by the browser the label is displayed instead src=".. Image source - where the image is located width=".. height=".. Sets the dimensions of the image. For example, the screen sizes of the devices is Nokia 7110 (48 x 96 pixels)

Content-type: image/vnd.wap.wbmp
Wap supports WBMP (Wireless Bitmap Picture) 2 bit images It is possible to convert existing images to wbmp The MIME type of the images is declered with the following header: Content-type: image/vnd.wap.wbmp

<card id="main" title="Where are you?">
<?xml version="1.0"?> <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" " <wml> <card id="main" title="Where are you?"> <timer value="10"/> <img src="snail2.wbmp" alt="A search snail"/> </card> <card id="look" title="I found you"> <img src="snail3.wbmp" alt="A looking snail"/> </wml>

Adding Images

Special WML Characters
Use character entities in display text " " & & ' ' < < > > Blank space Soft hyphen (discretionary line break) Replace the “&” character in URL strings URL="query.cgi?first=$fname&last=$lname" Use “$$” to display a single “$” character

Doing more with WML Setting card styles to create forms
Using variables to cache user data Using card intrinsic events to trigger transparent tasks Using timers Securing WML decks Bookmarking decks

WMLScript Scripting language: Derived from JavaScript™
Procedural logic, loops, conditionals, etc. Optimized for small-memory, small-cpu devices Derived from JavaScript™ Integrated with WML Reduces overall network traffic Bytecode-based virtual machine Stack-oriented design ROM-able

WMLScript Standard Libraries
Lang - VM constants, general-purpose math functionality, etc. String - string processing functions URL - URL processing Browser - WML browser interface Dialog - simple user interface Float - floating point functions

WMLScript Example Uses
Reduce network round-trips and enhance functionality Field validation Check for formatting, input ranges, etc. Device extensions Access device or vendor-specific API Conditional logic Download intelligence into the device

WMLScript Example Functions Variables Programming Constructs
function currencyConvertor(currency, exchRate) { return currency*exchRate; } function myDay(sunShines) { var myDay; if (sunShines) { myDay = “Good”; } else { myDay = “Not so good”; }; return myDay; Variables Programming Constructs

Wireless Telephony Applications
Tools for building telephony applications Designed primarily for: Network Operators / Carriers Equipment Vendors Network security and reliability a major consideration

WTA (cont.) WTA Browser WTAI includes:
Extensions added to standard WML/WMLScript browser Exposes additional API (WTAI) WTAI includes: Call control Network text messaging Phone book interface Indicator control Event processing

WTA (cont.) Network model for client/server interaction
Event signaling Client requests to server Security model: segregation Separate WTA browser Separate WTA port WTAI available in WML & WMLScript

Placing an outgoing call with WTAI:
WTA Example Placing an outgoing call with WTAI: Input Element WTAI Call <WML> <CARD> <DO TYPE=“ACCEPT”> <GO URL=“wtai:cc/mc;$(N)”/> </DO> Enter phone number: <INPUT TYPE=“TEXT” KEY=“N”/> </CARD> </WML>

Placing an outgoing call with WTAI:
WTA Example Placing an outgoing call with WTAI: WTAI Call function checkNumber(N) { if (Lang.isInt(N)) WTAI.makeCall(N); else Dialog.alert(“Bad phone number”); }

Content Formats Common interchange formats Promoting interoperability
Business cards: IMC vCard standard Calendar: IMC vCalendar standard Images: WBMP (Wireless BitMaP) Compiled WML, WMLScript

New WAP Content Formats
Newly defined formats: WML text and tokenized format WMLScript text and bytecode format WBMP image format Binary format for size reduction Bytecodes/tokens for common values and operators Compressed headers Data compression (e.g. images) General-purpose transport compression can still be applied

Content Format Example
Example Use of an Image: <WML> <CARD> Hello World!<BR/> <IMG SRC=“/world.wbmp” ALT=“[Globe]” /> </CARD> </WML> Image Element

Push Push is under development Network- push of content Goals:
Alerts or service indications Pre-caching of data Goals: Extensibility and simplicity Build upon WAP 1.0 End-to-end solution Security User friendly

User Agent Profiles (UAProf)
UAProf is under development Goal: content personalization, based upon: Device characteristics, user preferences Other profile information Working with W3C on CC/PP RDF-based content format Describes “capability and profile” info Efficient transport over wireless links, caching, etc.

WAP Protocol Layers Wireless Datagram Protocol
Wireless Session Service Access Point Wireless Session Protocol Wireless Transaction Service Access Point Wireless Transaction Protocol Transport Service Access Point (TSAP) Wireless Datagram Protocol Bearer Service D WCMP Bearer Service C Bearer Service B Bearer Service A Physical Layer Air Link Technology

Wireless Session Protocol Overview
Provides shared state between client and server used to optimize content transfer Provides semantics and mechanisms based on HTTP 1.1 Enhancements for WAE, wireless networks and “low-end” devices Compact encoding Push Efficient negotiation

Enhancements Beyond HTTP
Binary header encoding Session headers Confirmed and non-confirmed data push Capability negotiation Suspend and resume Fully asynchronous requests Connectionless service Why Not HTTP? Encoding not compact enough No push facility Inefficient capability negotiation

Header Encoding Defined compact binary encoding of headers, content type identifiers and other well-known textual or structured values Reduces the data actually sent over the network

Capabilities Capabilities are defined for:
Message Size, client and server Protocol Options: Confirmed Push Facility, Push Facility, Session Suspend Facility, Acknowledgement headers Maximum Outstanding Requests Extended Methods Header Code Pages

Suspend and Resume Server knows when client can accept a push
Multi-bearer devices Dynamic addressing Allows the release of underlying bearer resources

Session Context and Push
Push can take advantage of session headers Server knows when client can accept a push

Connection And Connectionless Modes
Connection-mode Long-lived communication Benefits of the session state Reliability Connectionless Stateless applications No session creation overhead No reliability overhead

WSP Work items Support for Quality of Service parameters
Multicast data Ordered pipelining WSP Management entities Support for isochronous multimedia objects

Wireless Transaction Protocol Overview
Purpose: Provide efficient request/reply based transport mechanism suitable for devices with limited resources over networks with low to medium bandwidth. Advantages: Operator Perspective - Load more subscribers on the same network due to reduced bandwidth utilization. Individual User - Performance is improved and cost is reduced.

WTP Services and Protocols
WAP provides reliable data transfer based on request/reply paradigm no explicit connection setup or tear down data carried in first packet of protocol exchange seeks to reduce 3-way handshake on initial request supports retransmission of lost packets selective-retransmission segmentation / re-assembly port number addressing (UDP ports numbers) flow control message oriented (not stream) supports an Abort function for outstanding requests supports concatenation of PDUs Since there is no connection setup phase there is no mechanism to negotiate parameters (actually some things can be negotiated but not in the full sense that a connection-oriented call setup would allow) to be used during the message exchange, such as packet size or window size (packet group). Therefore using WTP/T requires an a priori agreement between the mobile and server as to the default parameters to be used during a message exchange. Packet versus Streams -a packet interface allows the application more control over a partial transmission. It requires the application (Session layer) to segment its transmission data to fixed length packets, this allows the restarting of a failed transmission at the place of the last successful transmission - checkpointing. -a stream interface is what is most commonly implemented for TCP (sockets) and is widely used by TCP applications.

WTP Services and Protocols
WTP continued uses the service primitives T-TRInvoke.req .cnf. .ind .res T-TRResult.req .cnf .ind .res T-Abort.req .ind an example of a WTP protocol exchange Client Server Invoke Ack Result T-TRInvoke.req T-TRResult.ind T-TRInvoke.cnf T-TRResult.res (PDUs) T-TRInvoke.ind T-TRResult.req T-TRInvoke.res T-TRResult.cnf Ack may be piggybacked on a Result packet, therefore the Ack is shown with a dotted line.

WTP Classes of Operation
Class 0 Unconfirmed Invoke message with no Result message a datagram that can be sent within the context of an existing WSP (Session) connection Class 1 Confirmed Invoke message with no Result message used for data push, where no response from the destination is expected Class 2 Confirmed Invoke message with one confirmed Result message a single request produces a single reply HTTP 1.1 has a feature called Chunking which allows a message (HTML page) to be broken into several discreet chunks and sent to the destination over the same HTTP connection. An example would be a web page with several sub-components like advertisements, graphs, text, sound. Complexity decreases as class number increases. Class I is most complex and Class IV is least complex. Classes are presented in the following slides from least to most complex. Classes and protocols are all symmetrical but Client to Server initiated transfers are shown in examples since this is the most common scenario.

Wireless Datagram Protocol
Provide consistent interface to a fundamental transport service across all wireless bearer networks. Provides a connectionless, unreliable datagram service. WDP is adapted to each particular wireless network to provide the generic datagram transport. The basic datagram service is fundamental to all wireless networks and makes it possible to utilize WAP everywhere. WDP is replaced by UDP when used over an IP network layer. WDP over IP is UDP/IP

WDP (cont.) Supports port number addressing
WDP was initially specified for the following networks IS-136 (GUTS, R-Data, CSD, Packet Data) GSM (SMS, USSD, GPRS, CSD) CDPD iDEN Flex and ReFLEX WPG has since promoted specs for the following networks PHS PDC CDMA Example: WDP is UDP when used over an IP network layer.

Bearers Bearers currently supported by WAP
GSM SMS, USSD, C-S Data, GPRS IS-136 R-Data, C-S Data, Packet CDMA SMS, C-S Data PDC C-S Data, Packet PHS C-S Data CDPD iDEN SMS, C-S Data, Packet FLEX and ReFLEX DataTAC If IP is the network layer protocol for a bearer the definition of WTP/D over this bearer is trivial. WTP/T over UDP/IP will also be applicable to any bearer supporting UDP/IP.

Wireless Transport Layer Security
Specifies a framework for secure connections, using protocol elements from common Internet security protocols like SSL and TLS. Provides security facilities for encryption, strong authentication, integrity, and key management Compliance with regulations on the use of cryptographic algorithms and key lengths in different countries Provides end-to-end security between protocol end points Note to translator: I am going to talk a little bit around each of these items, in order to explain our motivation, and give some examples from the protocol

WTLS Internal Architecture
Record Protocol Handshake Protocol Alert Protocol Application Protocol Change Cipher Spec Protocol Transaction Protocol (WTP) Datagram Protocol (WDP/UDP) Bearer networks WTLS Record protocol Note to translator: Here I am going to explain and talk about each of the protocol elements in the WTLS layer

Goals and Requirements for WTLS
Interoperable protocols Scalability to allow large scale application deployment First class security level Support for public-key certificates Support for WAP transport protocols Note to translator: I am going to talk a little bit around each of these items, in order to explain our motivation, and give some examples from the protocol

WTLS Services and Characteristics
Provides connection security for two communicating applications privacy (encryption) data integrity (MACs) authentication (public-key and symmetric) Lightweight and efficient protocol with respect to bandwidth, memory and processing power Employs special adapted mechanisms for wireless usage Long lived secure sessions Optimised handshake procedures Provides simple data reliability for operation over datagram bearers Note to translator: I am going to talk a little bit around each of these items, in order to explain our motivation, and give some examples from the protocol

References WAP Forum. “Wireless Application Protocol Architecture Specification.” PDF File. April 30, WAP Forum. “Wireless Application Environment Overview.” PDF File. June 16, WAP Forum. “Wireless Transaction Protocol Specification.” PDF File. June 11, Unwired Planet, Inc. “Wireless Internet Today.” PDF File. February Nokia Wireless Data Forum. “ Wireless Application Protocol.” Web Page. Motorola “Wireless Application Development” PDF File If IP is the network layer protocol for a bearer the definition of WTP/D over this bearer is trivial. WTP/T over UDP/IP will also be applicable to any bearer supporting UDP/IP.

DBI – Representation and Management of Data on the Internet

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DBI – Representation and Management of Data on the Internet

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