1. HTTP-NG and Client-Agent-Server Networking A Mobile/Wireless Perspective Author: Spencer Dawkins - Nortel (Northern Telecom) sdawkins@nortel.com

2. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 2Wednesday, 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

3. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 3Wednesday, 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

4. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 4Wednesday, 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

5. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 5Wednesday, 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!

6. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 6Wednesday, 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

7. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 7Wednesday, 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

8. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 8Wednesday, 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

9. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 9Wednesday, 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

10. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 10Wednesday, 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 Overworked Client Not-WWW Agent Not-TCP Not-IP Different Standard ProtocolsStandard Protocols HTMLNot-HTML Not-HTTP

11. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 11Wednesday, April 08, 1998 What might/should “Agents” do? Today’s Application Proxy/Firewall functionality Access control, caching Transforming Content Scale content for small displays, compress HTML Transforming HTTP Binary Encoding Transforming TCP Anything from proxying to protocol conversion Preserving, or not preserving, TCP semantics Transforming IP Protocol conversion Network Address/Port Translation IPSec transport termination

12. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 12Wednesday, April 08, 1998 Suggested Principles for Client-Agent- Server 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 Changes that make sense for wireless and wireline Content Negotiation Markup language compression Keep IP as the protocol stack “wasp-waist” IP Addressing IP Security

13. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 13Wednesday, April 08, 1998 What I hope you remember from my talk today HTTP is part of an architecture This architecture is being used in very low-end devices This architecture is being used in bandwidth-limited devices The constraints these devices face are real and demanding There is real pressure to develop mobile/wireless-only solutions These devices must eventually support HTTP to meet user needs HTTP-NG can make this easier, or harder!

14. Client-Agent-Server ComputingSpencer Dawkins, Nortel Slide 14Wednesday, April 08, 1998 HTTP-NG HeReferences MNCP: WAP: Mowgli: MNCRS:, and specifically