This paper addresses the idea of using a server of negotiation protocols to facilitate negotiations in an open multi-agent system. The agents that do not know the negotiation protocols of the system can query the server for a description of the protocol and use it in negotiations. After pointing out some of the major problems encountered by the existing approaches, we propose a special type of agent (called strategy-agent) that knows how to negotiate using a fixed protocol and negotiation strategy. Such an agent will then negotiate for the benefit of other agents that do not know the required protocol.