Web Service orchestration and choreography: a look at WSCI and BPEL4WS-Feature

A fluid-blending system supplies a constant preestablished ratio of two or more fluids through a common output conduit over a wide range of variations of the flow rate established through the output conduit by a pump controlling such flow rate. This constant ratio also is maintained in spite of variations in the different head pressures of the fluids supplied to the blender. Separate fluid supply chambers are used for each of the fluids to be blended and are connected in common to the output conduit. The inlet orifices for each of the fluid supply chambers are normally closed by diaphragm-controlled valves mounted in the chambers. The amount of valve opening is controlled by pressure-sensing diaphragms in response to a partial vacuum created by the demand for fluid in the output conduit. The operation of the diaphragms is such as to maintain the same absolute pressure in each of the fluid supply chambers, so that the blender system is unaffected by variations or differences in the head pressures of fluids supplied to the chambers.