Introduction

The paradigm of Service Oriented Architecture (SOA) stands for an architectural concept that caters to the pressing need of today’s companies for a flexible integration into an industry’s value chain. The participation in a network of enterprises collaborating to deliver a service — a so-called inter-organizational workflow — requires a company to couple its internal workflows to those of its partners. A business producing consumer goods may wait for supplier parts needed for further processing, a content provider may be waiting for credit information from the customer’s banking institution before initiating services delivery. Orders are posted over the internet, maybe even automatically by the company’s enterprise resource planning system, order confirmations and invoices are delivered by mail. In a healthcare scenario, a doctor may issue an electronic prescription for medication and refer a patient to a radiologist by issuing an electronic referral: in e-government, a company may forward its financial statement to tax authorities whereas in public procurement the process of tendering heavily relies on electronic systems.