WAP Overview.ppt

"CSC8530 Distributed Systems", Summer 20021

WAP OverviewWAP OverviewAmarnath Chitti


Introduction Introduction What is WAP ?

– Wireless Application Protocol What is its Purpose ?

– Defines standards for wireless application environment (WAE) Who coordinates the WAP standard meetings?

– WAP forum(www.wapforum.org) not IETF What part of OSI does WAP standards address?

– Session, Presentation and Application What are the main ingredients of WAP?

– WDP: WAP Datagram Protocol

– WTLS: Wireless Transport Layer Security

– WTP: Wireless Transaction Protocol

– WSP: WAP Session Protocol

– WML: Wireless Markup Language


Introduction (contd.)Introduction (contd.)

WAP Applications:– Wireless Web hosting– Location Based Services with WAP Push

Technology– Secure Mobile Connectivity to enterprise

networksExample: Nokia Activ Server 2.1Mobile Financial Services with Nokia Activ

ServerMobile Reservation systems


Introduction (contd..) Introduction (contd..) WAP Overview Diagram:


Introduction (contd..) Introduction (contd..) Protocol Diagram at a WAP Gateway:


WAP with reference to WAP with reference to Distributed SystemsDistributed Systems WAP needs to operate across different Air

Interface Technologies. Example: CDMA, IS 95, IS 136 etc.

DNS lookups of the servers by the WAP Gateway

WAP gateway contacting different Application Servers based on Client Requests.


WAP with reference to WAP with reference to Distributed Systems (contd.)Distributed Systems (contd.)

IS 136IS 136 GSM GSM

MSC MSC

WAP Gateway


Typical WAP Network redrawn Typical WAP Network redrawn from WAP Architecture from WAP Architecture DocumentDocument

Internet

Secure Network

App Server

App Server

App Server App Server

App Server

Wireless Network

Cell phone

Comm. Tower

WTA Server

Secure FullProxy

Master Pull Proxy

Server

Server

Supporting Servers


WAP interface to various Air WAP interface to various Air Interface TechnologiesInterface Technologies


Brief Description of WAP stackBrief Description of WAP stack

Elements of WAP Stack compared Internet Stack

– WML vs. HTML– WSP vs. HTTP– WTP vs. TCP– WTLS vs. TLS– WDP vs. UDP– WCMP vs. ICMP


WML vs. HTMLWML vs. HTML WML: Wireless Markup Language WML is an XML based markup language. XML and HTML are based on Structured

Generalized Markup Language (SGML). To support WML requirements, W3C created

XHTML standard. WAP 2.0 uses XHTML. Freeware available for converting HTML pages

to XHTML/XML pages.– Example:

http://www.vbxml.com/wap/articles/htmlwml/default.asp


WSP vs. HTTPWSP vs. HTTPWSP: Wireless Session ProtocolWSP defines two protocols:

– one provides connection-mode session services over a transaction service

– To provide non-confirmed, connectionless services over a datagram transport service.

WSP recodes existing RFC-822 style request and response messages in their own binary tokenization format

WSP cannot support IETF's Proposed Standard for distributed authoring over HTTP (WebDAV)

WSP does content-negotiation not by Content-Type:, but with explicitly deprecated User-Agent:

WAP 2.0 adopts HTTP/1.1 as a session layer protocol.


WTP vs. TCPWTP vs. TCP WTP: Wireless Transaction Protocol WTP tries to solve a mix of transport- and

application-layer problems. WTP optionally offers segmentation and re-

assembly and selective acks. (WDP ??) WTP offers three application message models:

– Class 0: Unreliable invoke message with no result message– Class 1: Reliable invoke message with no result message– Class 2: Reliable invoke message with one reliable result

message WTP is the heart of an independent WAP Gateway server project,

such as APiON's. WTP is the lowest layer the microbrowser absolutely requires WAP 2.0 features TCP/IP for wireless networks supporting Data

over IP.


WTLS vs. TLSWTLS vs. TLS WTLS: Wireless Transport Layer Security WTLS Requirements:

– Both datagram and connection oriented transport layer protocols must be supported

– To cope with long round-trip times of wireless networks

– Support limited bandwidth of some bearer networks

– Match the processing power of mobile terminals

– Match the memory requirements of mobile terminals


WTLS vs. TLS (contd.)WTLS vs. TLS (contd.) TCP/IP stack offers security at the packet- and

transport-layers with two technologies– Ipsec for unreliable datagram transport (UDP)

– TLS for reliable transport (TCP) WTLS applies TLS to both individual datagrams

and socket connections WTLS defines three levels of security

capabilities; only Class 1 is mandatory-to-implement.


WTLS vs. TLS (contd.)WTLS vs. TLS (contd.)WTLS Features Class 1 Class 2 Class 3Public-key exchange

M M M

Server Certificates

O M M

Client Certificates O O MShared Secret Handshake

O O O

Compression N/a O OEncryption M M MMAC M M MSmart Card Interface

N/a O O


WTLS vs. TLS (contd.)WTLS vs. TLS (contd.) WTLS specifies use of Certicom's elliptic curve public

key encryption (mentioned on page 281 of course text).– Not an IETF standard

– More details at http://www.certicom.com/resources/ecc_chall/challenge.html

Prone to Attacks– chosen plaintext data recovery attack– datagram truncation attack– message forgery attack, and – key-search shortcut for some exportable keys.– For more details visit http://www.cc.jyu.fi/~mjos/wtls.pdf

WAP 2.0 adopts TLS protocol.


WDP vs. UDPWDP vs. UDP WDP is almost equivalent to UDP Purpose:

– To enable applications to operate transparently over different available bearer services

Why WDP and not UDP ?– To accommodate airlink addresses ("MSISDN

number [handset serial number], IP address, X.25 address or other identifier")

– To overcome airlink restrictions on packet size and even character sets.


WDP vs. UDP (contd.)WDP vs. UDP (contd.)


WDP vs. UDP (contd.)WDP vs. UDP (contd.) Services offered by WDP :

– Application addressing by port numbers

– Segmentation and Re-assembly (optional)

– Error Detection (optional)


WCMP vs. ICMPWCMP vs. ICMP Obsolete

– Included in WAP 1.0

– Removed in WAP 1.1


Competing TechnologiesCompeting Technologies 3G

– If a mobile can tx/rx data at ~2Mbps, what is the use of WAP Gateway in between ?

– WAP is trying to survive with its WAP Push technology for location based services.

Mobile IP and Wireless LAN (802.11b) Lightweight & Efficient Application Protocols

(LEAP)– IETF standards, an alternative to WAP

– Rejected by big players like Nokia, Motorola etc. Seems to be no development is going on in this front.


ReferencesReferences

Attacks on WTLS: http://www.cc.jyu.fi/~mjos/wtls.pdf Converting HTML to WML:

http://www.vbxml.com/wap/articles/htmlwml/default.asp WAP God: http://www.wapforum.com Criticism:

http://www.4k-associates.com/4K-Associates/IEEE-L7-WAP-BIG.html

Possible Future: http://www.nokia.com/wap/wap.html Brief Tutorial: http://www.w3schools.com/wap/ Criticism: http://www.freeprotocols.org/wapTrap/one/ Tutorial on WML:

http://www.iec.org/online/tutorials/wap/index.html


SummarySummary

State what has been learned– WAP Applications– WAP for Distributed Environment– WAP internals in brief– WAP evolution and changes over time– Future prospects/demise ?!

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WAP Overview.ppt

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