The Wireless Application Protocol

1. The Wireless Application Protocol

2. WAP • A standard for delivery of information, data and services to both enterprise and consumer users over wireless networks. • Consists of components • Network transport protocols • Security capabilities • An application environment – browser ML, scripting and telephony • A modular architecture – which allows • Variety of physical implementations • Deployment configurations • Integration points with existing web and information services

3. Origins of WAP • Many successes with No Success • Companies designed technologies to deliver wireless data to mobile but none were able to form a standard. • Analog Modem Technologies • Supports analog data communications – 4800 to 9600 bps – effective throughput varies based on signal strength and quality • Eg. Enhanced Throughput Cellular (ETC) Technology • Developed by AT & T Paradyne , 1994 • ETC equipped Cellular modems operate on the physical and link layer protocols. • Reduces signal transmission by 6 dB – to improve reliability of data transmission over a wireless connection that is optimized for voice traffic. • Monitors network and dynamically adjusts the transmission speed every five seconds • Transmits small, 32-byte chunks to reduce retransmission time and improve throughput • Similar techs: EC2 (Enhanced Control Cellular) – Motorola, Enhanced Cellular - Microcom

4. Origins of WAP – contd… • Wireless Middleware Solutions Extend the transport protocols to improve throughput, reliability or user experience. • Secureway Wireless Gateway (Artour) – IBM • Software in client and server transparently manage the use of air link beneath any standard TCP/IP application. • Compressing the data • encrypting the packets • shutting down the cellular link during inactivity • Fast reconnection • Delayed acknowledgements • Application middleware: provides caching and data reduction capabilities

5. ExpressQ – NetTech Systems (now BroadBeam) • Provides asynchronous messaging • Push • Encryption • Roaming capabilities on a variety of network and devices • Includes a developer’s kit for building applications • Handheld Device Markup Language (HDML) and Handheld Device Transport Protocol (HDTP) – Unwired Planet (now Phone.com) – It includes: • A micro-browser • Optimized protocol stack for supporting web access from mobile phones • Content written in HDML and sent to gateway for encoding and then transmitted

6. AirMobile – Motorola • Provides optimized access to Lotus Notes and cc:Mail over wireless networks • Narrowband Sockets (NBS) - Nokia and Intel • Provides optimized data transport services for UDP over circuit-switched data and GSM SMS • Supports both delivery of notifications and pushed contents • Now part of Nokia Smart Messaging Platform Each of these middlewares have achieved some success within particular markets and industries, but none of them were mass deployed for Mobile Internet

7. Data-Optimized Networks • Wireless networks that support wireless data • CDPD • Cellular Digital Packet Data • Transmits in idle space within an analog voice network. • Effective data throughputs 9.6 to 14.4 Kbps. • Network latency approx. 1 sec • Coverage – throughout United States and Canada • ARDIS • Motorola and IBM • Packet network • Throughput approx. 2.4 Kbps • Network latency 4 to 10 seconds • Coverage – major US metropolitan markets • RAM Mobile Data • RAM and BellSouth • Packet network • Effective data throughputs approx 4 Kbps. • Network latency 4 to 8 secs • The network is used to support Palm.net service offered by Palm Computing

8. Data-Optimized Networks (DONs) • Ricochet • Metricom • Packet network – uses low power base stations placed atop light poles • Throughput upto 128 Kbps • Network latency 1 sec • Limited Coverage – in campus or corporate env • Commonalities in these DONs • Limited coverage • Special radios required • High per-packet costs • So market penetration limited to specialized vertical application like public safety industries – not for mass consumer market

9. Need for a Mobile Internet Standard • Why all the above efforts failed? • Content and application developers reluctant to support as they didn’t have mass consumer market • Handset manufacturers reluctant to build device unless sufficient number of network operators and service providers were willing to market and distribute those handsets • s/w and h/w providers- didn’t find enough sales volume to recover development costs itself • n/w and service providers didn’t want to get locked into a single infrastructure vendor , with not enough set of services and quality handsets

10. Need for a Mobile Internet Standard

11. Need for a Mobile Internet Standard • Why a single standard needed? • Content and application developers develop content in a single format which can be delivered over all networks and to all phones • s/w , h/w and tools vendors – develop technologies which will be useful to a broad set of people • Handset manufacturers can rationalize their product line and sell the handsets through network operators • Network operators would be assured on an open, competitive market for handsets, infrastructure, applications and services

12. Initiation of WAP standard • AT & T Wireless Services (AWS) sought to develop a wireless data infrastructure that was supported by multiple handset manufacturers. • AWS hosted a meeting in Seattle, Washington – calling people from Ericsson, Motorola, Nokia and Phone.com. • They announced a joint effort – WAP on 26th June ’97 • WAP Forum – Board of Directors – Representatives of the 4 companies “The initiative is aimed at aligning the companies efforts to bring advanced applications and Internet content to digital mobile phones. This alignment will result in numerous benefits, among them providing operators differentiation and new business opportunities. In addition, developers of applications and content will be aided, since a single protocol and markup language will work with any vendor’s compatible handsets”

13. Initiation of WAP standard • The 4 companies promised to publish a public standard by september 97. Other few companies also joined in two weeks. • They decided that WAP standard would incorporate 3 existing technologies • HDML – Phone.com’s – would be the common markup language • NBS – Nokia – would become the optimized transport protocol and HDTP – Phone.com’s would be the optimized session protocol • Intelligent Terminal Transfer Protocol (ITTP) – Ericsson would provide foundation for the telephony application services

14. Initiation of WAP standard • Throughout summer and fall of 97, they tried to integrate these technologies into a single standard – very complex • All the 4 companies didn’t want to develop a standard which would benefit any one of them at the other’s expense. • So, by september 97, they were able to publish only a WAP architecture document.

15. Initiation of WAP standard • Key issues faced during the specification design process • Should the standard be layered? • Tightly integrated stack – greater n/w optimization, efficient implementation, but complex to integrate the core technologies • Layered approach – allows partial implementations of the standard, can provide APIs at each layer, better segmentation of design responsibilities • Resolution: • WAP Forum’s Directors decided, the WAP will be layered, but implementer can merge layers to provide smaller implementations • Adv: allowed for purity and manageability of design, supported efficient implementations • Disadv: designers could not define standard interlayer APIs

16. Initiation of WAP standard • Should IR-OBEX or HDTP be used as the session layer? • The IrDA (Infrared Data Association) – developed a session-layer protocol – IrOBEX – binary protocol • Supports both push and pull semantics for accessing data • HTTP-like semantics for Wireless devices • Met many needs of WAP. But not enough to run over a wide range of wireless networks • Resolution: • WAP included an new protocol stack – which borrowed ideas from both NBS and HDTP but differed significantly from both

17. Initiation of WAP standard • How should connection-oriented and connectionless sessions be supported? • Fig (next slide) – HDTP rested on optional security layer which in turn was on NBS – conflicted with each other. • Redundancy was there – both provided data reliability. • NBS – offered both connctn-oriented and connectnless abstraction • So security layer was forced to support both • HDTP had to provide 4 configurations • Secure connection • Insecure connection • Secure datagram • Insecure datagram

18. Initiation of WAP standard • Security layer ran on top of a datagram layer – so susceptible to attack from intruder • Resolution: Resolved in two stages • (1) During fall of 97 all the three protocols were redesigned • HDTP – Wireless Session Protocol (WSP)– similar to HTTP • Security layer – Wireless Transport Layer Security (WTLS) • NBS – Wireless Transport Protocol (WTP) - – reliable datagram, request-response transactions. • (2) During first quarter of 98, WTLS protocol was moved beneath WTP – to enable only secure datagrams • By early 98, first version of WAP standard was nearing completion.