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HTTP-NG and Client-Agent-Server Networking A Mobile/Wireless Perspective Author: Spencer Dawkins - Nortel (Northern Telecom) sdawkins@nortel.com
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Client-Agent-Server Computing Spencer Dawkins, Nortel Slide 2 Wednesday, April 08, 1998 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
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Client-Agent-Server Computing Spencer Dawkins, Nortel Slide 3 Wednesday, April 08, 1998 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
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Client-Agent-Server Computing Spencer Dawkins, Nortel Slide 4 Wednesday, April 08, 1998 Today’s HTTP Protocol Stacks TCP IP HTTP HTML TCP IP HTTP Relay TCP IP HTTP HTML WWW Server HTTP Caching Proxy WWW Client TCP IP Standard Protocols
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Client-Agent-Server Computing Spencer Dawkins, Nortel Slide 5 Wednesday, April 08, 1998 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!
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Client-Agent-Server Computing Spencer Dawkins, Nortel Slide 6 Wednesday, April 08, 1998 MNCP at 50,000 feet TCP IP HTTP HTML TCP IP HTTP Relay MNCP/UDP CDPD HTTP HTML WWW Server MNCP-specific Relay MNCP-specific Client MNCP/UDP CDPD MNCP-specific ProtocolsStandard Protocols
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Client-Agent-Server Computing Spencer Dawkins, Nortel Slide 7 Wednesday, April 08, 1998 Mowgli at 50,000 feet TCP IP HTTP HTML TCP IP Mowgli ProxyMowgli Agent HTML WWW Server Mowgli-specific Relay Mowgli-specific Client Mowgli Data Channel Service Mowgli-specific ProtocolsStandard Protocols Mowgli Data Channel Service
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Client-Agent-Server Computing Spencer Dawkins, Nortel Slide 8 Wednesday, April 08, 1998 WTP-C IP WSP WML WTP-C Relay IP WTP-C USSD WSP WML WAP-specific Server WAP-specific Relay WAP-specific Client USSD WAP-specific ProtocolsStandard Protocols WAP at 50,000 feet
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Client-Agent-Server Computing Spencer Dawkins, Nortel Slide 9 Wednesday, April 08, 1998 The Doomsday Scenario TCP IP HTTP HTML TCP IP HTTP Not-TCP Not-IP Not-HTTP Not-HTML WWW Client Double-Duty Server Not-WWW Client Not-TCP Not-IP Different Standard ProtocolsStandard Protocols HTMLNot-HTML Not-HTTP
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Client-Agent-Server Computing Spencer Dawkins, Nortel Slide 10 Wednesday, April 08, 1998 The Doomsday Scenario - Lowend Devices TCP IP HTTP HTML TCP IP HTTP Not-TCP Not-IP Not-HTTP Not-HTML WWW Server Double-Duty Client Not-WWW Agent Not-TCP Not-IP Different Standard ProtocolsStandard Protocols HTMLNot-HTML Not-HTTP
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Client-Agent-Server Computing Spencer Dawkins, Nortel Slide 11 Wednesday, April 08, 1998 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
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Client-Agent-Server Computing Spencer Dawkins, Nortel Slide 12 Wednesday, April 08, 1998 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
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Client-Agent-Server Computing Spencer Dawkins, Nortel Slide 13 Wednesday, April 08, 1998 References MNCP: WAP: Mowgli: MNCRS:, and specifically
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