The estimation of Invocation Cost for Composite Services

When a new electronic service is composed from existing ones, the characteristics of the component services will naturally have a major influence on both the functional and the non-functional characteristics of the composite service. When more than one service satisfy the specified functional requirements of a given component for a composite service, these services can be differentiated on the basis of their nonfunctional properties. To ensure proper evaluation of various composition options, we propose to estimate the corresponding non-functional properties of a composite service during design time by taking into account the characteristics of the candidate services and the composition constructs used to integrate these services. In this paper, we describe the specification and estimation of the invocation cost based on different pricing models and the composition constructs possible in the workflow patterns for composite services.