A growing trend in developing large and complex applications on today?s Teraflop computers is to integrate stand-alone and/or semi-independent program components into a comprehensive simulation package. One example is the climate system model which consists of atmosphere, ocean, land-surface and sea-ice. Each component is semi-independent and has been developed at different institutions. We study how this multi-component multi-executable application can run effectively on distributed memory architectures. We identify five effective execution modes and develop the MPH library to support application developments utilizing these modes. MPH performs component-name registration, resource allocation and initial component handshaking in a flexible way.