A Service Pattern Model and its Instantiation Using Rule-Based Reasoning

Although reuse is the main goal of SOA, composing existing services to realize different user requirements is still a difficult and time-consuming task. There have been research works on workflow templates and design patterns that facilitates reuse and assist with the process composition task. Nevertheless, existing workflow templates are too specific, whereas design patterns may be too abstract; their effectiveness in assisting the composition process may be limited. In this paper, we propose a comprehensive service pattern model that is more flexible than existing workflow/service templates while allowing systematic instantiation into the concrete workflows. The service pattern model supports adaptive control flow and incorporates abstract services and prospect services (similar to a node in a design pattern but with formalservices and prospect services (similar to a node in a design pattern but with formal partial definitions). We also design a reasoning process to automatically instantiate the service pattern and generate the desired workflow by following the rules of data type compatibility and precondition-effect matching. Service pattern model enables the integration of flexible pattern-based reuse and efficient and automated generation of workflows. Experimental study shows that the automated reasoning process is very efficient due to the use of service patterns.