In order to fully realize semantic interoperability among distributed and heterogeneous applications on the web, a set of effective interoperability mechanisms is presented. This mechanism adopts service interactive interfaces (SII) and service aggregative interfaces (SAI) modeled with abstract state machine (ASM) to abstractly describe the behavior of the invoked web service instances, which makes business processing accurately specify tasks and effectively solves the problems of communication and collaboration between service providers and service requesters. The mechanism also uses appropriate mediators to solve the problems of information and coinmunication incompatibility during the course of service interaction, which is convenient for service interoperability, sharing and integration. The mechanism' s working principle and interoperability implementation are illustrated by a use case in detail.