Service Level Agreements (SLAs) are an essential foundation for the realisation of Business Grids as they provide a mechanism for a service provider to charge a customer for meeting an agreed quality of service. However, once an SLA has been formed it may need to be renegotiated as the requirements of the SLA participants change. This paper describes an abstract, domain-independent protocol for the re-negotiation of an agreement, including SLAs formed using the WS-Agreement standard. The protocol is based on the principles of contract law to make the new agreements formed using it legally-compliant. It allows for multiround re-negotiation in a network environment where messages may be lost, delayed, duplicated and re-ordered.
View full paper: nfpsla-soc08.pdf.