Traditionally, negotiation support was based on normative and prescriptive research; its users were analysts and experts. The purpose of the recently developed e-negotiation systems is to provide negotiators with services and to satisfy their requirements rather than direct their activities so that they conform to rationality and optimality principles. This orientation is typical to software engineering. Due to the difficulties in reconciling results of prescriptive and descriptive studies the e-negotiation design specifications are often based on selected descriptive approaches at the expense of the prescriptive support. This paper presents selected results from negotiation and e-negotiation research and discusses methodological foundations for e-negotiation system design and development. Based on review of methodological foundations and the scientific and engineering perspectives on negotiations, an e-negotiation view integration model is proposed. The purpose of the model is to allow for the integration of behavioural, scientific and engineering views on e-negotiations.