Review: Dryad Distributed Data-Parallel Programs from Sequential Building Blocks

Dryad is a general-purpose distributed execution engine for coarse-grain data-parallel applications presented as an alternative to MapReduce paradigm. The data flows are represented as directed acylic graphs (DAG). Relative to MapReduce, Dryad gives more flexibility to the programmers although at the expense of more complexities being presented to the programmers. Looking at the sample programs, I think that those complexities are not worth it, when the needed programs are substantial in size. I believe that another layer of abstraction (e.g. The nebula scripting language) is required. Its influence still needs to be questioned as this is a proprietary software written by Microsoft and thus, impact on the general programmers' community are barely seen. From the experiment results that are presented, this looks promising as the speed-up is pretty much linear.