A method of scheduling a request for a plurality of Web services can include providing service activation rules. Each service activation rule can specify a trigger condition and a state condition for causing a watcher to invoke a particular Web service. The method also can include receiving an event indicating a change in a common memory, wherein each event specifies trigger information, comparing the trigger conditions of the service activation rules with the trigger information of the event, adding the service activation rules that match the event to a trigger list, and comparing the state conditions of service activation rules in the trigger list with a state of the common memory. The service activation rules of the trigger list that match the state of the common memory can be selected thereby causing the invocation of at least one watcher and corresponding Web service.