Inter-organization business process collaboration is one of the most significant factors driving today's global business development. Such collaborations are typically composed by various processes executed by different organizations and are often difficult to specify and analyze, due to their distributed nature and to data interoperability issues. The standard notation for business process modeling, namely BPMN (Business Process Model and Notation), only provides a limited support to the specification of collaborations. This paper introduces a data model extension of BPMN inspired by the HLA (High Level Architecture) distributed simulation standard. In addition, the paper proposes a metamodel-based mapping from BPMN to HLA, which can be seen as a significant step towards the implementation of a conceptual framework for specifying and analyzing collaborative business processes by use of distributed simulation approaches.