will likely be managed locally. Even with this information available it is still extremely 

difficult to correlate QoS of different components and diagnose how a service is performing 

overall. Extensive research to correlate QoS between service components has been 

conducted [5 7]. 

1.2.1 The End User Perspective 

To say that all the components in a Web delivered service were available 100% in a 20 day 

period has very little relevance as to how a service performs, as perceived by the end user. 

Why? not being able to describe end user perceived performance has been one of the major 

faults with service management to date and is even more of a problem now with ASPs. 

Looking at our CRM example, the end user is interested neither in the QoS guarantees of the 

Webserver that their browser connects to or the guarantees of the network over which they 

are accessing a service. End users view the quality of any Web delivered service in simple 

terms, 

accessibility

 and 

performance,

 as 

they

 perceive it. 

What is also worth remembering is that end user QoS encompasses the failure or success of 

all other forms of QoS of the components in the service delivery chain and offers a truly 

meaningful way to determine how a service is performing overall. The fact that the Service 

Provider typically has no idea of how service performance and availability is perceived, by 

the user in the scenario described previously is a particular problem. In what other industry 

in today's market forces will a supplier be content to remain unaware of it's customers 

perspective on it's products. Were this information available, not alone could it offer the 

Service Provider a useful diagnostic tool and the customer an ability to specify performance 

and availability criteria that mean something to them. The ability of Service Providers to 

offer some level of guarantee to customers on the performance and availability of services 

from the end user perspective means that it would finally be possible to define meaningful 

SLAs for Web delivered services. The result    clarity and accountability!