Decision of Trusted Software Behavior

User´s behaviors in information systems have different formats in different working modes, they mean users´ intention actually. API callings, menu selections or requests are the familiar base elements of software behaviors, and different technologies are required to monitor and understand them. In information systems, it is necessary to insure that users´ software behavior is trusted while processing. Client-Server mode is widely used in distributed computing system, the decision technology of trusted software behaviors from software of client meets the demand of forward defense in information systems. This paper puts forward the definition of software behavior and behavior set in client-server mode, software behavior is composed of requests from client, Request is the component of one or more software behaviors easy to be monitored. The expression of software behavior has been studied, and decision model of trusted software behavior has been built based on fuzzy matching algorithm, it can decide whether the processing software behavior is trusted or not.