In a group decision support system, the various decision-makers have their own information, constrains, decision strategies, preferences, and objectives which are generally not shared or communicated. This implies that the group decision process is distributed between the different entities implicated and impacted by various group members' characteristics. Solution to this problem is to find a decision that would be acceptable to all the decision-makers, following the necessity of a negotiation process that allows the elaboration of a common agreement for a group that faces a conflict on the decision to take. In the current study, the authors propose to establish a communication platform for a group decision support system (GDSS) based on web services, incorporating a multicriteria analysis methods and a negotiation protocol.