The French project OpenPaaS aims at providing a social platform to help companies initiating and managing their collaborations. Nowadays, data exchange is no sufficient and collaborations need to be supported for every interaction between the actors of the collaboration. This paper concerns a PaaS in charge of supporting the deduction of collaborative business processes that involve subscribing organizations of the PaaS. In order to be applicable to industrial needs, the process deduction should require the minimum knowledge from users: collaborative objectives and a repository of all the capabilities made available by the subscribing organizations. Functional and non-functional gaps are filled simultaneously when building the process: (i) a collaborative ontology allows finding sets of capacities able to achieve the collaborative objectives and (ii) a non-functional assessment builds the optimal process i.e. the sequences of activities and also the set of partners with their corresponding capabilities. This article focuses on the first point and brings a methodology based on semantics to deduce a collaborative process.