2.5.3 HTTP Proxies and Caching.............................................................................2 21 

2.6

Summary..............................................................................................................2 23

3

REQUIREMENTS....................................................................................................3 24

3.1

Introduction.........................................................................................................3 24

3.2

Motivations Revisited ..........................................................................................3 24

3.2.1 Motivations .....................................................................................................3 24 

3.2.2 Objectives........................................................................................................3 25 

3.3

Service Delivery using HTTP..............................................................................3 26

3.3.1 Anatomy of A Web Delivered Service ...........................................................3 26 

3.3.2 Where can Availability and Performance Issues Occur..................................3 28 

3.4

Monitoring HTTP Delivered Services.................................................................3 29

3.4.1 Service Performance Parameters.....................................................................3 30 

3.4.2 Service Availability Parameters ...................................................................... 3 32 

3.5

Parameter Capture.............................................................................................. 3 33

3.5.1 Server Side Monitoring...................................................................................3 34 

3.5.2 Monitoring via a Proxy on the Client Side .....................................................3 34 

3.5.3 What information needs to be captured?.........................................................3 35 

3.5.4 QoS Mappings.................................................................................................3 35 

3.6

Conclusion...........................................................................................................3 37

4

DESIGN .....................................................................................................................4 38

4.1

Introduction.........................................................................................................4 38

4.2

Architectures for Service Monitoring..................................................................4 38

4.2.1 A Single ASP and Multiple Services .............................................................. 4 39 

4.2.2 Multiple ASPs and Multiple Services .............................................................4 42 

4.3

Architecture in Operation ...................................................................................4 43

4.3.1 Additions and Modifications to Services Monitored ...................................... 4 44