7. The computer program product of claim 6 , wherein: said clustering comprises service influence based probabilistic clustering based on a uniform neighborhood random walk distance measure; and said co-ranking comprises service influence based ranking.
6. A computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions being executable by a processor to cause the processor to: carry out offline functionality-based co-ranking and clustering on a knowledge base, said knowledge base characterizing a heterogeneous information technology services network comprising a plurality of services, a plurality of providers, and a plurality of attributes; store results of said functionality-based co-ranking and clustering as annotations of said services and said providers in said knowledge base, to obtain an annotated knowledge base; obtain a service requirement from a customer requiring information technology services; query said annotated knowledge base, based on said service requirement; and return to said customer an ordered list of at least given ones of said services, based on said querying, wherein said program instructions executable by said processor to cause the processor to carry out offline functionality-based co-ranking and clustering on said knowledge base comprise program instructions executable by said processor to cause the processor to: calculate an initial service clustering for said heterogeneous information technology services network; classify said providers into a plurality of service clusters; within each of said service clusters, rank each of said providers; integrate ranking and clustering distances between said providers into a uniform provider distance to obtain updated provider similarity; classify said services into a plurality of provider clusters; within each of said provider clusters, rank each of said services; and integrate ranking and clustering distances between said services into a uniform service distance to obtain updated service similarity.