Commitment-Based Enhancement of E-Commerce Protocols Pınar Yolum and Munindar P. Singh Department of Computer Science North Carolina State University Raleigh, NC 27695-7534, USA pyolum, mpsingh @eos.ncsu.edu Abstract Protocols represent the allowed interactions among communicating components. Protocols are essential in electronic commerce to constrain the behaviors of au- tonomous entities. Traditional representations of protocols include the actions, but not their content, which limits their applicability in settings where autonomous entities must flexibly interact to handle exceptions and exploit opportuni- ties. We develop a commitment-based representation, which provides a content to the protocols, enabling flexible execu- tion. We show how an existing protocol can be systemat- ically enhanced to yield a protocol that allows the given actions as well as other legal moves. 1 Introduction Although many e-commerce protocols have been devel- oped in recent years, limitations caused by their rigid spec- ification have remained. Traditionally, protocols have been specified directly in terms of legal sequences of actions without considering the fundamental meaning behind the actions. However, e-commerce protocols should not only con- strain the actions of the participating components, but also accommodate the open, dynamic nature of e-commerce in- teractions: Autonomy. Components must retain their autonomy and be minimally constrained in their interactions, i.e., only to the extent necessary. Exceptions. Components must be able to modify their interactions to handle any unexpected conditions. This research was supported by the National Science Foundation un- der grants IIS-9529179 and IIS-9624425 (Career Award). Opportunities. Components should be able to take advantage of available opportunities to improve their choices or to simplify their interactions. Traditional approaches are based on the study of network protocols, and lack the key abstractions to handle the above dynamic aspects of e-commerce. By contrast, we develop an agent-based approach that incorporates the key abstrac- tion of commitments. Agents are persistent computations that can perceive, reason, act, and communicate. Agents can be autonomous and heterogeneous, and can represent different interacting components. The agents’ communi- cations affect and are affected by their commitments. The agents’ commitments reflect the protocols they are follow- ing and the communications they have made. By stepping through a running example, we first show the different interactions that can take place among the par- ties and then show how these interactions can be added to the original protocol to yield an enhanced protocol. Section 2 reviews the keys concepts and challenges deal- ing with communication. Section 3 describes our proposed approach. Section 4 describes our contributions in relation to the most relevant literature. 2 Semantic Analysis We now analyze the concepts and challenges underly- ing communication, especially with regard to the execution of activities. As a running example, we consider the Net- Bill protocol that has been developed to handle buying and selling of electronic goods, such as software and electronic documents over the Internet [10]. Example 1 As shown in Figure 1, the protocol starts with a customer requesting a quote for a particular good, followed by the merchant sending the quote. If the customer accepts the quote, then the merchant delivers the good and waits for an Electronic Payment Order (EPO). The good delivered at this point is encrypted, i.e., not usable. After receiving the 1