The aim of e-business applications is to make businesses agile by supporting dynamic internal and external boundary-crossing business processes. This study defines a three-level architecture for developing e-business. The architecture includes (L1) business processes as front-end components; (L2) a business interactions manager (BIM) as a middle component; and (L3) disparate information systems (i.e., the information systems of enterprise, partners, suppliers, and customers) as back-end components. It specifies the requirements for the implementing technology platform to adopt it to a web services-oriented architecture (WSOA). Finally, the WSOA is used as a methodology for deploying e-business through steady instantiation for each business interactions category.