A Modular WAP Reference Stack Protocol Implementation Johan Blom WAP Program Ericsson Radio AB

Content WAP Intro Background Standard Ericsson WAP Gateway Products WAP Reference System Erlang Implementation Usage Design ideas

WAP (Wireless Application Protocol) Purpose: Connect wireless data and internet Open standard: Specs available from http://www.wapforum.org General industry acceptance Based on existing (W3C, IETF) Internet standards Features: Saves bandwith, by encode messages and store static information Applications can be made bearer independent Possible to integrate telephone applications

More than 100 million users by the end of 2000 ? WAP Advantages Users Synergy of “mobile” and “internet” applications Manufactures Optimised for hand-held devices with limited capabilities Browser works on all networks Operators Visual interface to existing and new features Generates traffic in the network... Developers Possible to create applications using telephony events and push More than 100 million users by the end of 2000 ?

WAP Content Format The WAP Markup Language (WML) maps well onto existing mobile phone user interfaces Encoding compress content to approximately 75% of the original size Characteristics of WML: Card metaphor Variables with application scope <WML> <CARD> <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>

The Ericsson WAP Gateway/Proxy Brings advanced services to mobile users WTA Server WWW Server WWW Server WIRELESS NW INTERNET INTRANET Proxy Firewall WAP Gateway/ Proxy

Typical Internet Configuration Client Server HTML/JavaScript browser HTML/JavaScript application HTTP TCP HTTP TCP IP

Typical WAP Configuration Client WAP Gateway/Proxy Application Server Application WML/WMLScript browser WML/WMLScript application WAE WSP WTP WDP WSP WTP WDP HTTP TCP HTTP TCP IP/SMS/USSD/Mobitex... IP

WAP Standard still growing… WTA Framework for telephony applications handling of events originating in the mobile net WAP Encoding/Decoding WML, WTA etc. content compressing Graphics encoded to 2 bits Bitmap (WBMP) WIM Typically the SIM card in the GSM world Storing of cryptographic parameters Provisioning Bootstrapping, locking mechanisms Client side Provisioning WIM WTA WAP Content Decoding WSP WTP WTLS WDP Adaptation

WAP Standard still growing… WSP Session layer Corresponds to HTTP WTP Transport layer WTLS Security layer Data encryption, similar to TLS (formerly known as SSL) WDP Datagram layer Bearer Adaptations PUSH For pre-caching of data and to send Alerts UAPROF Profiling content to specific devices WCMP Error reporting, similar to ICMP Server side WAP Content Encoding Push UAPROF WSP WTP WTLS WDP WCMP Adaptation

Security aspects Application level security Encrypt only specifc content WMLScript Crypto API Transport level security Encrypt all content over a session WTLS Application Server owned by Bank WAP Gateway owned by Operator

Features for WAP Gateway/Proxy 1.0 WAP 1.1 compliant UDP/IP (CSD) Bearer Service SMS Bearer Service direct on MAP Connectionless & connection oriented mode WML encoding/decoding WML Script Compiling Subscriber Authentication HTTP 1.1 Caching Internet Security using SSL Storage of Subscriber Data Operation & Maintenance Process Supervision Fault Handling

Ericsson WAP Gateway/Proxy Products NT WAP Gateway NT only European market Jambala Gateway TelORB only North and South American market Non-product: WAP Reference System Any Erlang supported platform

WAP Reference System - Usage Various Demo/Prototyping projects WTA and WML/WMLScript applications Internal testing of products Both Ericsson client and server products Jambala Today communicating over CORBA in trials WapIDE WAP terminal emulator and application development tool Written in Erlang and Tcl/Tk

WapIDE - WAP Integrated Development Environment Components in the WAP Service Development Kit Browser – View WML decks and cards using a “standard” WAP device Device Designer – Simulate the “look and feel” of a device of your choice Application Designer – Create WML decks and cards in a WYSIWYG mode Server Toolset – Add dynamic WML content with server-side applications WAP Reference client stacks integrated part of WapIDE Downloadable free of charge: http://mobileinternet.ericsson.com

WAP Reference System - Implementation status Client and Server WAP stacks WSP Connection-less and Connection oriented versions (Complete WAP 1.1) WTP Message oriented transaction layer (Complete WAP 1.1 except SAR) WDP Only UDP/IP supported Management and operation Logging WAP Gateway/Proxy application features WML encoding Character encoding HTTP client CORBA interface

WAP Reference System - Design issues WAP standard architecture consists of several modular entities WAP is still evolving rapidly Implementation should support this !! Possible valid WAP stacks in current WAP standard WSP WSP WSP WSP WTP WTP WTLS WTLS WDP WDP WDP WDP

WAP Reference System - Design Observations C++ based WAP product design focused on performance issues Monolithic, much harder to add new components without redesign Regarded as successful project Erlang based WAP Reference system design focused on close relation to standard Reusable WAP components Well-defined WAP component interfaces Conclusions To make components reusable it is much more important to have a modular design than a modular (object-oriented) language Low-level language => low-level design