1. A method for performing message-based business processes among a plurality of applications, comprising: storing configuration data in a data store in a gateway, the configuration data including information defining one or more simple transactions that can be performed by the gateway; receiving a gateway message at the gateway, the gateway message including a gateway message header and a payload, the gateway message header including a routing slip block providing a template of a complex transaction in which the gateway message is participating, the complex transaction comprising one or more simple transactions performed in a defined order; and executing at the gateway at least one simple transaction in accordance with the template in the routing slip and the configuration data defining the one or more simple transactions.