Wide-area monitoring, protection and control (WAMPAC) plays a critical role in smart grid, for protection against possible contingencies, by using the Supervisory Control and Data Acquisition (SCADA) system. However, a general consensus is that such a hierarchical system can be highly vulnerable to component (i.e., nodes and links) failures, calling for a robust and cost-effective communication system for smart grid. To this end, we consider a middleware approach to leverage the existing commercial communication infrastructure with abundant connectivity. In this approach, a natural question is how to use the middleware to cohesively 'glue' the power grid and the commercial communication infrastructure together, in order to enhance robustness and cost-effectiveness. We tackle this problem while taking into consideration the multi-stage deployment of power devices and their redundant connections. We show that this problem can be cast as a minimum-cost middleware design under incremental deployment - an 'online' problem where the input is provided gradually due to the incremental deployment. We design a randomized 'online' algorithm, and show that it achieves the order-optimal average competitive ratio. Simulation results demonstrate the performance of our proposed algorithm, compared to the optimal offline solution.