An integrated system for the ATLAS High Level Triggers:Concept, General Conclusions on Architecture Studies,Final Results of Prototyping with ATM

This paper recalls the concept of a proposed integrated system forthe "ATLAS High Level Triggers" that has been investigated over thelast 5 years of our involvment in the ATLAS collaboration. We givethe rationale that justifies our proposed model and list a number ofarchitecture principles that could be a basis for the final system.We detail the major results of implementation studies made during the"LVL2 demonstrator program" and the "LVL2 Pilot Project". We presentthe final results of our investigations on ATM networking technology.