This paper presents a series of models and algorithms to implement OLAPing on graph data. The major contributions include (1) proposing a graph-oriented data warehouse model, called a double star model, (2) proposing the concept of graph data cube and its building algorithm, (3) designing an informational OLAPing algorithm, I-OLAPing, (4) designing topological dimensional OLAPing algorithm, T-OLAPing, and (5) building a Graph OLAPing prototype, Graph OLAPer1.0, based on the proposed approaches. Experimental results show that the Graph OLAPing algorithms designed and implemented in this paper, together with Graph OLAPing prototype, Graph OLAPer1.0 can work effectively on Co-Author Networks.