1 INTRODUCTION 

1.1 Web Delivered Services 

As the Internet expands, it presents new ways to provide information to individuals and 

organisations. Increasingly, the provision of information based services are taking the 

Application Service Provider (ASP) approach where the service is delivered over the Web 

and accessed via a web browser. These Web based services are not just basic web hosting 

services. They are often complex information management tools that offer data mining and 

remote analysis of large volumes of data via the Web with almost all of the content 

dynamically generated from backend databases. These Application Service Providers are 

targeting anything from small companies with a couple of employees that lack the skills in 

house to manage applications locally, to corporations with thousands of employees for 

which the ASP model offers a more manageable solution to deliver applications to vast 

numbers of desktops. The revenues from these complex applications are expected to grow 

rapidly in the next few years, and are estimated to reach $8 billion by 2002 [1]. 

1.2 Motivation 

The big issue is  can Web delivered services be relied on? . In particular, can performance 

and availability be comparable to more traditional methods of providing applications and 

how can this be monitored? ASP delivery has the potential to end up making services more 

unreliable that ever before due to the best effort nature of the Internet Protocol (IP).  Best 

effort  in the context of the Internet Protocol, is where a packet is delivered to its destination 

as soon as possible but without guarantees on the time taken to get to the destination or even 

that it will arrive at all. To add to the problem, any Web delivered service is dependent on 

multiple distributed components that may also implement  best effort  methodologies in 

how they operate. For some users,  best effort  is simply not good enough particularly when 

these applications must be depended on for organisation to be able to operate. There is a 

movement from the democratic system where everyone gets the same level of service, to one 

where those who are willing to pay more get a better that  best effort  service that is typical