9. A computer program product comprising a tangible computer readable recordable storage medium having computer readable program code for generating a distributed stream processing application, said computer program product including: computer readable program code for obtaining a declarative description of one or more data stream processing tasks from a graph of operators, wherein the declarative description expresses at least one stream processing task; computer readable program code for generating one or more execution units from the declarative description of one or more data stream processing tasks, wherein the one or more execution units are deployable across one or more distributed computing nodes, and comprise a distributed data stream processing application binary; computer readable program code for generating one or more coarse granularity containers that encompass one or more fine granularity stream processing operators; computer readable program code for using the one or more coarse granularity containers to generate a distributed stream processing application; computer readable program code for generating one or more containers that encompass a combination of one or more stream processing operators, wherein said generating comprises: coalescing a combination of one or more operators into one or more containers, wherein said coalescing comprises: using an optimizer to automatically decide which of the one or more operators are to be coalesced into which of the one or more containers; and using user input to manually group the one or more operators into the one or more containers; and computer readable program code for fusing an outflow of an operator into an inflow of a downstream operator within a same container.
9. A computer program product comprising a tangible computer readable recordable storage medium having computer readable program code for generating a distributed stream processing application, said computer program product including: computer readable program code for obtaining a declarative description of one or more data stream processing tasks from a graph of operators, wherein the declarative description expresses at least one stream processing task; computer readable program code for generating one or more execution units from the declarative description of one or more data stream processing tasks, wherein the one or more execution units are deployable across one or more distributed computing nodes, and comprise a distributed data stream processing application binary; computer readable program code for generating one or more coarse granularity containers that encompass one or more fine granularity stream processing operators; computer readable program code for using the one or more coarse granularity containers to generate a distributed stream processing application; computer readable program code for generating one or more containers that encompass a combination of one or more stream processing operators, wherein said generating comprises: coalescing a combination of one or more operators into one or more containers, wherein said coalescing comprises: using an optimizer to automatically decide which of the one or more operators are to be coalesced into which of the one or more containers; and using user input to manually group the one or more operators into the one or more containers; and computer readable program code for fusing an outflow of an operator into an inflow of a downstream operator within a same container. 13. The computer program product of claim 9 , further comprising computer readable program code for using one or more user-defined operators to wrap legacy code.