Web Performance
David Lee
Two metrics:
- bandwidth
- latency (user response time)
Composition:
- many small documents
- ~5k average for text
- ~18k average for images
- increasing use to replace FTP
HTTP Performance Problems
Short Documents
TCP Round Trip/Slow Start
30% of transfer time is connection time
"Stateless" - Duplication of information (86-95%)
Text based
Pro: Simplicity and easily extendible
Con: Requires additional bandwidth
HTTP Improvements
Binary protocol (unlikely)
Persistent connections
Caching
Data compression (large potential but unused)
Multiple instances
Partial document retrieval
Security and other non-performance features
Document Caching
Essentially move document closer to the user
Three types:
Browser (User) caching
Proxy caching
Server caching
Post and pre-fetch caching (user models)
Alternative Distribution
Multicast delivery
FTP-Like remote distribution