A metrics framework for a WS-CDL process under evolution

Choreography of different web services in Service Oriented Architecture is expressed using Web Service Choreography Description Language (WS-CDL). A WS-CDL process consists of interactions and roles for participants. It evolves over time due to different types of changes in the participants, roles and interactions. In this paper, metrics are proposed under two categories. Metrics under first category deals with syntactic evolution in which changes in structure of the process are quantized whereas metric under second category deals with semantic evolution to measure change in usefulness of the process. There are three metrics under first category: Additive Evolution Metric (AEM), Subtractive Evolution metric (SEM) and Evolution Metric (EM). AEM is a measure for the changes in process entities, which are additive in nature such as additions or splits. SEM measure changes which are subtractive in nature such as deletions or merge. EM which is sum total of AEM and SEM is also proposed. The metric proposed under second category is Evolved Usefulness Metric (EUM). It gives a measure for the change in usefulness of the process when it evolves. Proposed metrics helps in analyzing the evolution in process and change in usefulness of the process as it evolves. Metrics are theoretically validated using Zuse framework and found to be above the ordinal scale. To show the applicability of metrics, they are empirically validated using case study of WS-CDL process.