Abstract
Numerous service models have been proposed in the form of “as a Service” or “aaS” in the past. This is especially eminent in the era of the Cloud under the term of anything as a service or everything as a service(XaaS). An unified view of XaaS can aid efficient classification of services for service registration, discovery, and composition. In view of that there lacks such an unified view which is demanded by systematic application of XaaS in the Web Service Ecosystem, towards proposing a taxonomy of “aaS”, we present in this work a collection of “aaS” based on a throughout literature survey.