Since the revenue of IT service providers depends on reliable service hosting, quality of service is the backbone of their business. Their customers expect high-quality spatial web services so they can use spatial data in decision making, improving productivity and creating innovative products and services. By monitoring their customers’ spatial web services, IT service providers can prove that they are meeting the promised service level as well as find the sources of errors. Opening new spatial web services or gaining media visibility for existing services might result in unexpectedly high peaks in user amounts. In these cases, heavy load can result in serious technical problems and dissapointed end users if the IT service provider hasn’t tested the performance of the services beforehand.