need help for a web service for a decision support system

Hi everybody, we are a group of students. We are studying the basis of the web services technology. We have to create a complex informative system, part of which consists of a DSS (decision support system). We need to use something already existing, giving in input our alternatives and criteria and receiving in output a graph, or a classification of the alternatives. The criteria are 4 and fixed. We don't need constraints. the alternatives are not fixed.
We've been searching for a web service like this for 2 weeks; the best solution we found is this: http://www.decision-deck.org/ws/wsd-IRIS-CppXMCDA.html
Our teacher says we can do better, because this site doesn't provide any API and we should write down the DAOs by our own.
Does anyone know a better web service that could help us?
Thank you in advance