A method for ensuring the integrity of a receiving system in a distributed computing environment includes receiving information from a transmitting system. The node is identified as an entry point, and the selection, testing, and identification operations are repeated for at least one additional node of the hierarchical structure to identify at least a second node as a respective second entry point for the hierarchical structure. Formations on the piston and on the housing seal between the piston and the housing around the vent hole only when the piston is in the rear position.