Improving Temporal-Awareness of WS-Agreement

Abstract

WS-Agreement (WS-Ag) is a proposed recommendation of the Open Grid Forum that provides a schema to describe SLAs and a protocol to create them based on a mechanism of templates. However, although it identifies the necessity of specifying temporal-aware agreement terms (e.g. the response time is 30 ms from 8:00h to 17:00h and 15 ms from 17:00h to 8:00h), to the best of our knowledge, there are no existing proposals that deal with that necessity. We propose an extension that gives WS-Ag support to temporality. This allows describing expressive validity periods such as those composed by several periodic or non-periodic intervals and it applies not only to the agreement terms themselves but also to other parts of WS-Ag such as creation constraints and preferences about the service properties. in addition, in this paper we propose a preference XML schema to describe preferences over any set of service properties using any kind of utility function. in further research we will study a concrete specification for those utility functions.