The paper presents results of the research devoted to building context-aware decision support systems intended for functioning in distributed information environments. In the framework of this reserach an approach to operational information integration in the context of the current situation is proposed. The information to be integrated is considered to be received from heterogeneous sources located in the distributed environment. The approach relies upon usage of an ontology model for knowledge representation. The ontology is specified by means of the formalism of object-oriented constraint networks