Bamberger Beiträge zur Wirtschaftsinformatik und Angewandten Informatik
Analyzing the Interoperability of WS-Security and WS-ReliableMessaging Implementations
- Since their invention as lightweight integration technology about a decade ago, Web Services have matured significantly. Today, major middleware solution vendors as well as industry communities like RosettaNet are propagating Web services even for exchanging business-critical data and implementing inter-organizational business processes. Core enablers for using Web services in this domain are stateful interactions using the Web Services Business Process Execution Language (WS-BPEL) as well as advanced communication features like security and reliability using the WS-Security and WS-ReliableMessaging standard specifications. However, advanced communication features come at the price of complexity which challenges interoperability across different Web services stack implementations. Interoperability, in turn, is a predominant requirement for an integration technology such as Web services, in particular if inter-organizational business processes are supposed to be implemented on top of that technology. This paper approaches the problem of testing the interoperability of the so-called WS-* standards, advanced Web services communication features that are typically defined as SOAP extensions and configured using WS-Policy. Being essential to business process integration, WS-Security and WS-ReliableMessaging are selected as representatives of this group and the two major Java-based Web services stack implementations Metro and Axis2 are tested for interoperability. We operationalize the notion of interoperability for testing WS-* standards, suppose an approach for deriving test cases from WS-* specifications as well as a method for performing the test cases, and we provide a comprehensive interoperability review of the two selected Web services stack implementations.
QoS-Enabled B2B Integration
- Business-To-Business Integration (B2Bi) is a key mechanism for enterprises to gain competitive advantage. However, developing B2Bi applications is far from trivial. Inter alia, agreement among integration partners about the business documents and the control flow of business document exchanges as well as applying suitable communication technologies for overcoming heterogeneous IT landscapes are major challenges. At the same time, choreography languages such as ebXML BPSS (ebBP), orchestration languages such as WS-BPEL and Web Services are promising to provide the foundations for seamless interactions among business partners. Automatically translating choreography agreements of integration partners into partner-specific orchestrations is an obvious idea for ensuring conformance of orchestration models to choreography models. Moreover, the application of such model-driven development methods facilitates productivity and cost-effectiveness whereas applying a service oriented architecture (SOA) based on WS-BPEL and Web Services leverages standardization and decoupling. By now, the realization of QoS attributes has not yet received the necessary attention that makes such approaches suitable for B2Bi. In this report, we describe a proof-of-concept implementation of the translation of ebBP choreographies into WS-BPEL orchestrations that respects B2Bi-relevant QoS attributes.
Modelling and Validating Business Collaborations: A Case Study on RosettaNet
- The way business processes are organised heavily influences the flexibility and the expenses of enterprises. The capability to address changing market needs in a timely manner and to provide appropriate pricing is indispensable in a world of internationalisation and growing competition. Optimising processes that cross enterprise boundaries potentially is a key success factor in achieving this goal but it requires the information systems of the participating enterprises to be consistently integrated. This gives rise to some challenging tasks. The personnel involved in building up business collaborations comes from different enterprises with different business vocabulary and background which requires extensive communication support. The lack of central technical infrastructure, typically prohibited by business politics, often calls for a distributed and computer-aided collaboration structure, so that the resulting complexity must be handled somehow. Nevertheless robustness is an important factor in building business collaborations as these may exchange goods of considerable value. This technical report proposes the use of a two step modelling approach that separates business logic, modelled in the so-called centralised perspective (CP), from its distributed implementation, modelled in the so-called distributed perspective (DP). The separation of these perspectives enables business people to concentrate on business issues and to solve communication problems in the CP whereas technical staff can concentrate on distribution issues. The use of stringent modelling rules is advised in order to provide the basis for formal analysis techniques as one means to achieve robustness. Considering the choreography of RosettaNet Partner Interface Processes (PIPs) as the subject of my analysis, UML activity diagrams for modelling the CP and WSBPEL for modelling the DP are described as enabling techniques for implementing the proposed two step modelling approach. Further, model checking is applied to validate the CP and DP models in order to detect errors in early design phases. As the adequacy of model checking tools highly depends on the detailed modelling techniques as well as the properties to be checked, a major part of our discussion covers relevant properties and requirements for a model checker.