Generation and verification of heterogeneous purchase processes

Complex purchase protocols allow several participants (merchants and clients) to be involved within a single purchase transaction. Moreover, they provide the possibility to merge different heterogeneous payments into one atomic transaction. Although such complex purchases are urgently required, they are, so far, neither provided by existing protocols nor by available products or research prototypes. In this paper we show how to dynamically build such complex heterogeneous purchase processes in a reliable way, by modeling complex interactions between several merchants and clients as transactional processes. Apart from the distribution aspect, we focus on the heterogeneity of the electronic purchase, by allowing different existing protocols for payment or goods transfer to be merged incrementally, as the user performs a distributed purchase on the Internet. Before executing such a complex purchase, we provide a (technical) analysis of the resulting process which yields the properties of the compound transaction like atomicity, debit/credit character, or anonymity. We have implemented a Purchase Coordinator prototype which allows for an incremental analysis of compound purchase transactions and which supports the execution of the corresponding purchase processes.