The vision of an open and global Internet of Services (IoS) is driven by globalization and fast changing settings when trading on a world-wide scope. It requires automated on-line techniques for handling services and resources themselves, for advertising and discovery as well as for the on-the-flynegotiation of proper terms for their use. In such a setting covering completely different branches and traditions of business, a flexible infrastructure for negotiating service level agreements is mandatory. In this paper, we propose an extended service usage cycle suitable for IoS along with an expressive but still machine manageable protocol description language capable of specifying a multitude of different negotiation protocols. It supports the extended usage cycle and permits choosing services with appropriate SLA negotiation styles as well as performing SLA negotiations based on the style agreed by potential business partners.