Granularity Metrics for IT Services

Many articles discuss the design of fine- or coarse-grained IT services without defining what granularity exactly means. However, this is important to know since the granu-larity influence e.g. the reusability or the composition effort of services and thus the de-velopment, maintenance and composition costs of a service realization. Therefore, we present different metrics to evaluate and compare the granularity of various service re-alizations of a process where each metric represents a different perspective on service granularity. In addition, we discuss the advantages and disadvantages of these metrics and argue that a reasonable measurement of service granularity can usually be obtained by the combination of the metrics. Furthermore, we illustrate that the proposed metrics may constitute a first step towards the evaluation of the total costs of various service realizations. The application of the metrics as well as the discussion of the practical benefits is illustrated by a real world case