1. A method for optimizing component composition in a distributed stream-processing environment having a plurality of nodes capable of being associated with one or more of a plurality of stream processing components, the method comprising the steps of: performing an adaptive composition probing (ACP) which probes a subset of the plurality of stream processing components to determine the optimal component composition in response to a stream processing request; and managing local and global information for use by said performing step in determining the optimal component composition, wherein said performing step adaptively determines the number of probes used for the stream processing request based on at least one of system performance targets and current system conditions, and wherein said performing step adaptively performs per-hop component selection based on at least one of coarse-grain global state information, accumulated probing results, and stream rate matching.