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"CSC8530 Distributed Systems", Summer 20021
WAP OverviewWAP OverviewAmarnath Chitti
"CSC8530 Distributed Systems", Summer 20022
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
"CSC8530 Distributed Systems", Summer 20023
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
"CSC8530 Distributed Systems", Summer 20024
Introduction (contd..) Introduction (contd..) WAP Overview Diagram:
"CSC8530 Distributed Systems", Summer 20025
Introduction (contd..) Introduction (contd..) Protocol Diagram at a WAP Gateway:
"CSC8530 Distributed Systems", Summer 20026
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.
"CSC8530 Distributed Systems", Summer 20027
WAP with reference to WAP with reference to Distributed Systems (contd.)Distributed Systems (contd.)
IS 136IS 136 GSM GSM
MSC MSC
WAP Gateway
"CSC8530 Distributed Systems", Summer 20028
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
"CSC8530 Distributed Systems", Summer 20029
WAP interface to various Air WAP interface to various Air Interface TechnologiesInterface Technologies
"CSC8530 Distributed Systems", Summer 200210
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
"CSC8530 Distributed Systems", Summer 200211
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
"CSC8530 Distributed Systems", Summer 200212
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.
"CSC8530 Distributed Systems", Summer 200213
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.
"CSC8530 Distributed Systems", Summer 200214
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
"CSC8530 Distributed Systems", Summer 200215
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.
"CSC8530 Distributed Systems", Summer 200216
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
"CSC8530 Distributed Systems", Summer 200217
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.
"CSC8530 Distributed Systems", Summer 200218
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.
"CSC8530 Distributed Systems", Summer 200219
WDP vs. UDP (contd.)WDP vs. UDP (contd.)
"CSC8530 Distributed Systems", Summer 200220
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)
"CSC8530 Distributed Systems", Summer 200221
WCMP vs. ICMPWCMP vs. ICMP Obsolete
– Included in WAP 1.0
– Removed in WAP 1.1
"CSC8530 Distributed Systems", Summer 200222
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.
"CSC8530 Distributed Systems", Summer 200223
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
"CSC8530 Distributed Systems", Summer 200224
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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