Hasso-Plattner-Institut
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Dynamische Ressourcenverwaltung für dienstbasierte Software-Systemete

Service-oriented architectures (SOA) are an abstract concept for distributed software systems. These systems support the provisioning, discovery, and binding of business-aligned IT services over a network. The implementation is based on XML technologies such as SOAP, WSDL, and their standardized extensions.

Typical SOA research focuses on the composition and quality aspects of services, while ignoring the necessary underlying runtime environment for atomic services. Most of the SOA research assumes - implicitly or explicitly - an existing homogeneous service landscape. In contrast, most systems in practice provide heterogeneous and stateful service implementations for the higher layers in the SOA software stack. Resources in this execution environment are bounded statically to the single services, which leads to unreliable and non-scalable single services in the infrastructure.

One example for SOA research activities was the European integration project ''Adaptive Services Grid'' (ASG) with 21 partners from academia and industry. From 2004 to 2007, the project developed a service composition and enactment platform for semantically described services.

The following thesis presents the concept and implementation of ASG's Service Infrastructure layer, which acts as distributed runtime environment for heterogeneous atomic services. The architecture description is based on a technology-neutral system model, which combines the idea of unified service invocation and monitoring with the dynamic usage of execution resources for replicated services.

Based on the model description, the thesis analyses possible placement strategies for physical service instances, covers the problem of crash fault tolerance for service containers, introduces a new data model for service monitoring, and presents the influence of the work on the Open Grid Forum standardization body.

The implementations of the presented system model were successfully applied in two European research projects. Furthermore, the results of this work are integrated in industrial research cooperation’s.

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