The GridX1 computational Grid: from a set of service-specific protocols to a service-oriented approach. - Gabriel Mateescu; Wayne Podaima; Andre Charbonneau; Roger Impey; Meera Viswanathan; Ashok Agarwal; Patrick Armstrong; Ronald J. Desmarais; Ian Gable; Sergey Popov; Simon Ramage; Randall J. Sobie; et al. (HPCS, 2007)