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

1
HTTP-NG andClient-Agent-ServerNetworkingA
Mobile/Wireless Perspective

• Author
• Spencer Dawkins - Nortel (Northern Telecom)
• sdawkins_at_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
Todays 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
MNCP-specific Protocols
Standard 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
Mowgli-specific Protocols
Standard Protocols
8
WAP at 50,000 feet
WAP-specific Server
WAP-specific Client
WML
WML
WSP
WSP
WAP-specific Relay
WTP-C
WTP-C Relay
WTP-C
USSD
IP
IP
USSD
WAP-specific Protocols
Standard Protocols
9
The Doomsday Scenario
WWW Client
Double-Duty Server
Not-WWW Client
HTML
Not-HTML
HTML
Not-HTML
HTTP
HTTP
Not-HTTP
Not-HTTP
TCP
TCP
Not-TCP
Not-TCP
IP
IP
Not-IP
Not-IP
Different Standard Protocols
Standard Protocols
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The Doomsday Scenario - Lowend Devices
WWW Server
Double-Duty Overworked Client
Not-WWW Agent
HTML
Not-HTML
HTML
Not-HTML
HTTP
HTTP
Not-HTTP
Not-HTTP
TCP
TCP
Not-TCP
Not-TCP
IP
IP
Not-IP
Not-IP
Different Standard Protocols
Standard Protocols
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What might/should Agents do?

• Todays 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

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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

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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!

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HTTP-NG HeReferences

• MNCP
• lthttp//www.ietf.cnri.reston.va.us/internet-drafts
  /draft-piscitello-mncp-00.txtgt
• WAP
• lthttp//www.wapforum.org/docs/WAPArch-Sep-97.pdfgt
• Mowgli
• lthttp//www.cs.helsinki.fi/research/mowgli/arch/mo
  wgli-arch.htmlgt
• MNCRS
• lthttp//www.mncrs.org/gt, and specifically
• lthttp//www.oadg.or.jp/activity/mncrs/mobcomm/modl
  tabl/network-model-feb98.htmlgt