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HTTP-NG and Client-Agent-Server Networking A Mobile/Wireless Perspective

HTTP-NG and Client-Agent-Server Networking A Mobile/Wireless Perspective. Author: Spencer Dawkins - Nortel (Northern Telecom) sdawkins@nortel.com. Client-Agent-Server Networking. Mobile Network Computer Reference Specification Data Networking Team A “snapshot” of Work-in-Progress:

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HTTP-NG and Client-Agent-Server Networking A Mobile/Wireless Perspective

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  1. HTTP-NG andClient-Agent-ServerNetworkingA Mobile/Wireless Perspective Author: Spencer Dawkins - Nortel (Northern Telecom) sdawkins@nortel.com

  2. Client-Agent-Server Networking • Mobile Network Computer Reference Specification Data Networking Team • A “snapshot” of Work-in-Progress: • Mobile Network Computing Protocol (MNCP) • Wireless Application Protocol (WAP) • Mobile Office Workstations using GSM Links (Mowgli) • Moving Rapidly, in MNCRS and IETF • Combined MNCRS proposal expected within days • “TCP Performance-Enhancing Proxies” in IETF

  3. Low-end Device Challenges • Categories • “Professional Assistant” Devices • “Information Access” Devices • “Messaging, Paging, and Telephony” Devices • Limits on everything • Memory (4 MB RAM + 4 MB ROM is common) • Screen Size and Color Capabilities • Input Devices • Network Capabilities and Bandwidth • HTTP-NG as “part of the puzzle” • Taking a systems view of HTTP-NG

  4. Today’s HTTP Protocol Stacks WWW Server WWW Client HTTP Caching Proxy HTML HTML HTTP HTTP Relay HTTP TCP TCP TCP TCP IP IP IP IP Standard Protocols

  5. What “Breaks” for MNCRS Devices • HTML: • Perception of HTML as complex • HTTP: • Perception of HTTP as complex • Managing appropriate content variants • TCP: • Perception of TCP as complex • “Slow-start” and “Slow-restart” interactions • IP: • Perception of IP as redundant on wireless links These are widespread perceptions!

  6. MNCP at 50,000 feet WWW Server MNCP-specific Client MNCP-specific Relay HTML HTML HTTP HTTP Relay HTTP TCP TCP MNCP/UDP MNCP/UDP IP IP CDPD CDPD Standard Protocols MNCP-specific Protocols

  7. Mowgli at 50,000 feet WWW Server Mowgli-specific Client Mowgli-specific Relay HTML HTML HTTP Mowgli Proxy Mowgli Agent TCP TCP Mowgli Data Channel Service Mowgli Data Channel Service IP IP Standard Protocols Mowgli-specific Protocols

  8. WAP at 50,000 feet WAP-specific Client WAP-specific Server WML WML WSP WAP-specific Relay WSP WTP-C WTP-C Relay WTP-C USSD IP IP USSD Standard Protocols WAP-specific Protocols

  9. The Doomsday Scenario WWW Client Double-Duty Server Not-WWW Client HTML HTML Not-HTML Not-HTML HTTP HTTP Not-HTTP Not-HTTP TCP TCP Not-TCP Not-TCP IP IP Not-IP Not-IP Standard Protocols Different Standard Protocols

  10. The Doomsday Scenario - Lowend Devices WWW Server Double-Duty Client Not-WWW Agent HTML HTML Not-HTML Not-HTML HTTP HTTP Not-HTTP Not-HTTP TCP TCP Not-TCP Not-TCP IP IP Not-IP Not-IP Standard Protocols Different Standard Protocols

  11. What might/should “Agents” do? • Today’s Proxy/Firewall functionality • Access control, caching • Transforming Content • Scale content for small displays, compress HTML • Transforming HTTP • Binary Encoding • Transforming TCP • Preserving, or not preserving, TCP semantics • Transforming IP • Network Address/Port Translation • IPSec transport termination

  12. Suggested Principles • Change as little as possible • My suggestions - content, TCP • Minimize duplication of functionality • Change things at the edge of the network • Do not require Internet-wide changes • Change things that make sense for everyone • Content Negotiation • Markup language compression • Keep IP as the protocol stack “wasp-waist” • IP Addressing • IP Security

  13. References • MNCP: • <http://www.ietf.cnri.reston.va.us/internet-drafts/draft-piscitello-mncp-00.txt> • WAP: • <http://www.wapforum.org/docs/WAPArch-Sep-97.pdf> • Mowgli: • <http://www.cs.helsinki.fi/research/mowgli/arch/mowgli-arch.html> • MNCRS: • <http://www.mncrs.org/>, and specifically • <http://www.oadg.or.jp/activity/mncrs/mobcomm/modltabl/network-model-feb98.html>

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