This paper describes development of architecture for integrated informational Web-based e-trading business process management system. An approach is justified for formation of embedded informational system architecture based on typical IT solutions. A Service Oriented Architecture (SOA) using Enterprise Service Bus (ESB) concept is offered for architectural implementation of the Web-based system. Typical informational systems that belong to the Web-system are used as services. The web-services implement SOAP protocol based on WSDL (Web Services Description Language) and UDDI (Universal Description, Discovery and Integration) specifications. Application of ESB and SOA provides scalability of Web-based e-trading management system, possibility for their enhancement and upgrading. The principle of basic architecture of Internet has been implemented in the architecture of integrated trading informational system taking into account transition to informational level.