Meanwhile web-services are starting to be established through out the business world, but web-services only offer stateless operation calls. Since workflow management systems are widely accepted to execute long-term (stateful) business processes within companies, the next step of great interest is to make stateful cooperative processes available through the web, so that two or more partners can collaborate in a long-term business process. BPEL is a joint attempt of Microsoft and IBM to establish a standard to make such cooperative processes available through the web. We attempt to enhance robustness and flexibility of these processes by introducing quality constraints. The whole of all quality constraints referring to a process instance should provide a frame, in which the flow of this process instance is correct. To prove the concept of our quality constraint approach called WEPD (Web-Flow Extended Process Description) we implemented MaX (Monitoring and eXception handling component). This book defines WEPD and explains the implementation of the monitoring component of MaX. It is written for computer science graduate students as well as IT professionals and IT managers.