Summary 

With the advent of Web based delivery of business applications and increasing dependency 

on these services, management of availability and performance are critical. For service 

providers to offer guarantees on Web based application performance of services delivered 

via Hypertext Transfer Protocol (HTTP), they must implement Quality of Service (QoS) and 

have a composite view of service quality across all the components in the service delivery 

chain including databases, networks and webservers. In most cases this is not possible as 

different parts of the infrastructure are outsourced to different service providers or managed 

by the customer. Even with all this information available it is still extremely difficult to 

diagnose how service performance is perceived by the end user.  

This dissertation describes the design and implementation of a framework that supports the 

monitoring of Web delivered services from the end users perspective. The service 

performance and availability can then be compared against a Service Level Agreement.  

The framework consists of a number of components. These include a local proxy on the end 

user's host that intercepts HTTP requests and replies. This allows the monitoring of 

availability and performance parameters as perceived by the end user. The framework also 

involved the design of a SLA template specifically for Web delivered services that can map 

these parameters captured by the proxy in a meaningful way so that it is possible to specify 

how a service delivered over HTTP should perform from the end user perspective. The 

proxy encompasses a number of features including automatic retrieval of a Service Level 

Agreement (SLA) with a server. 

Finally an application was developed that demonstrated how the framework can be applied 

to monitor SLA compliance for a Web delivered service.