Providing effective Grid resource allocation mechanisms is a key factor in realising the Grid vision. In this talk, we present the SLA negotiation component developed in the Ontogrid project. We present the Insurance use case between insurance companies and repair services, where negotiation occurs through a broker service. Various negotiation protocols are implemented to provision a damage report and these are the contract net protocol, bilateral protocol and English auctions with timeouts. Strategies, preferences, and evaluation results are discussed. In the second part of the talk, we discuss how the existing negotiation service can be extended for trust negotiation between semantic web services. VO authorisation and online trust systems lack the ability to securely negotiate suitable trust and privacy requirements. Given the limitations of current VO authorisation systems when faced with malicious parties, this talk argues that trust can be built incrementally through trust negotiation, but without actual exchange of credentials until an SLA has been reached of what to exchange specifically. Finally we discuss if trust can help in SLA agreement. For example, less guarantees are needed for more trustworthee partners, or less chance of SLA violation occurring to preserve trust relationships or reputations scores. |