From grid middleware to grid applications: Bridging the gap with HOCs

This paper deals with the problem of application programming for grid systems that combine heterogeneous data and computational resources via the Internet. We argue that grid programming is still too complex because of the big gap between the currently used and anticipated grid middleware, (e.g., Globus or WSRF) and the application level. We suggest that this gap needs to be closed in future-generation grids and propose a novel approach to bridging the gap by using Higher-Order Components (HOCs) - recurring patterns of parallel behaviour that are provided to the user as program building blocks with pre-packaged implementation and middleware setup. The presentation is illustrated with a simple case study of computing fractal images. Our experiments demonstrate that HOCs can simplify grid application programming significantly, without serious performance loss.