Service classification and recommendation are two important problems in service management and composition.This paper,utilizing service composition histories,investigates the method for service classification and recommendation from a topological perspective of service-oriented software(SOS).It proposes a software network model for SOS to Abstract its topological structures;it uses a community detection algorithm to cluster software networks and realizes service classification;it uses software networks to describe compositional strength between services and proposes an algorithm for service recommendation.API services and mashup applications in ProgrammableWeb are used as subjects to demonstrate the feasibility of the proposed approach.Experimental results show a high cluster purity of 86.8%.Finally we discuss the implications of our approach on service computing.