Abstract: There are always events with out-of-order timestamps in the Internet of Things (IoT) application systems.To deal with the problem,a semantic event definition about IoT was presented and the issue of out-of-order timestamps was also described.Meanwhile,according to the mixed driving space reclaim mechanism,an out-of-order revise framework of complex events based on Hash structure was established.What’s more,a complex event detection algorithm based on out-of-order revise framework (ORFCED) was proposed.To solve the issue of out-of-order timestamps,the algorithm extracts two characteristic parameters of events to compute the Hash address and stores events into circular linked list in the timestamp order to sort them locally.Simulation results show that the proposed ORFCED algorithm not only can process events with high accuracy and reliability,but also can respond timely to out-of-order streams,which makes up for the deficiency of the existing methods.Finally,a case study was made,which verifies the effectiveness and feasibility of the proposed algorithm.

Key words: IoT,Complex event detection,Out-of-order event streams,Out-of-order revising,Space reclaims mechanism