In today's business world, enterprises are not only using Web Services for implementing B2Bi. Instead, AS2 for realizing Internet based EDI, ebXML Messaging and even SMTP and FTP are used for exchanging business documents. Harmonizing B2Bi communication technology in a way that solely uses Web Services is barely an option for large enterprises as this would result in losing investments in existing IT systems. Moreover, forcing a specific communication technology upon all business partners is neither intended nor realistic in practice. At the same time, existing business document exchanges frequently only implement B2Bi scenarios partly. This paper focuses on a method for composing existing and new business document exchanges without replacing communication technology already in use. First, ebXML BPSS is proposed for describing the choreography of business document exchanges in a technology agnostic way. Second, ebXML CPPA is used to define messaging characteristics at the level of ebBP BusinessTransactions. Third, an integration architecture for performing ebXML BPSS choreographies using BPEL processes that execute each integration partner's message exchanges is proposed. These BPEL processes assume Web service wrappers for reusing the functionality of messaging systems that are responsible for performing the actual business document exchanges and for providing sufficient status information to the caller. Different messaging systems then can be used for incorporating variable communication technologies in business collaborations.