Philipp Offermann

Introducing Preferences over NFPs into Service Selection in SOA

When implementing a business or software activity in SOA, a match is sought between the required functionality and that provided by a web service. In selecting services to perform a certain business functionality, often only hard constraints are considered. However, client requirements over QoS or other NFP types are often soft and allow tradeoffs. We use a graphical language for specifying hard constraints, preferences and tradeoffs over NFPs as well as service level objectives (SLO). In particular, we use the TCP and UCP network formalisms to allow for a simple yet very flexible specification of hard constraints, preferences, and tradeoffs over these properties. Algorithms for selecting web services according to the hard constraints, as well as for optimizing the selected web service configuration, according to the specification, were developed.

SOAM – Eine Methode zur Konzeption betrieblicher Software mit einer Serviceorientierten Architektur

ZusammenfassungEine große Herausforderung bei der Einführung einer Serviceorientierten Architektur (SOA) für betriebliche Software liegt nicht nur in der technischen Umsetzung, sondern auch in der Konzeption. Insbesondere die Sicherstellung der Servicedesignprinzipien erfordert ein methodisches Vorgehen. Bekannte Methoden sind bezüglich ihrer Architekturbereiche unterspezifiziert oder bezüglich ihrer Merkmale unvollständig. Es wurde eine Methode entwickelt, die werkzeugunterstützt klar definierte Architekturbereiche der SOA umsetzt. Sie baut auf in der Literatur beschriebenen Ansätzen auf und wurde durch Aktionsforschung bei Vattenfall Europe evaluiert und verfeinert. Die Zweckmäßigkeit der durch die Methode erstellten Artefakte wurde durch eine erfolgreiche Implementierung erstmals bestätigt.AbstractA big challenge when introducing service-oriented architecture for software is not only the technical implementation, but also the software design. In particular the enforcement of service design principles demands a methodical approach. Existing methods either support only partial aspects of SOA or are incomplete in respect to the method’s characteristics. A tool-supported method that realises clearly defined architecture realms has been developed. It builds on top of known approaches and has been in evaluated and refined using action research at Vattenfall Europe. The usefulness of artefacts generated by the method has been confirmed for the first time by a successful implementation.

A Flexible Approach to Service Management-Related Service Description in SOAs

In order for service-oriented architectures (SOAs) to deliver their true value for the business, e.g. flexibility and transparency, a holistic service management needs to be set up in the enterprise. To perform all the service management tasks efficiently heavy support by automated processes and tools is necessary. This article describes a service description approach that is based on OWL-S (Web Ontology Language for Services) and focuses on nonfunctional criteria. It starts with the necessary service management tasks and explains non-functional data elements and statements for its automated support. After covering related work it explains the proposed flexible extension to OWL-S. This extension is twofold. Firstly, simple service lifecycle elements are added using the normal extension mechanism. Secondly for adding QoS (Quality of Service) capabilities, the approach combines this extension mechanism with UML (Unified Modeling Language) Profile for QoS. A prototype delivers the proof-of-concept.

Implementing non-functional service descriptions in SOAs

This article describes a framework for extended service descriptions based on OWL-S (Web Ontology Language for Services) focusing on nonfunctional criteria. Necessary service management tasks will be introduced and extended by corresponding data elements and statements for its automated support. After a short comparative description of several existing approaches to semantic service descriptions the paper addresses the actual extension of OWL-S. Non-functional extensions as service lifecycle elements and Quality of Services (QoS) are added. To extend QoS capabilities, the approach combines the common extension mechanism with UML (Unified Modeling Language) Profile for QoS. A prototype delivers the proof-of-concept for the first part of the extension. The prototype implements SOA-specific authentications and all basic features for a tool-supported service management using extended semantic service descriptions by defining an ontology-based service taxonomy and service annotation.

Extending the UN/CEFACT modeling methodology and core components for intra-organizational service orchestration

When creating a companys IT structure based on a service-oriented architecture (SOA), it is necessary to first analyze the business domains and process areas of the company, then to model the business processes to be supported by the SOA and finally to convert the models into a service orchestration description. Currently, few methodologies exist to support this. At our department, we have proven that the UN/CEFACT Modeling Methodology (UMM) can be used for intra-organizational process integration. In this article we analyze if the UMM is sufficient for SOA, which artifacts are missing and how the UMM could be extended. The UMM was created to model the collaboration between different legal entities to perform collaborative business processes. There exist methods to convert these models into executable service choreography descriptions expressed in the Business Process Specification Schema (BPSS) or the Business Process Execution Language (BPEL). However, the business process models can also be used as a basis for an intra-organizational service orchestration. By extending the UMM it is possible to enable the automated generation of service orchestrations using Core Components and the Business Process Modeling Notation (BPMN).