Depending on the volume of data flow, we may want to optimize the communication path.
The easiest way of doing this is to make the coupling between the three processes tighter. Instead of using a general-purpose connection-oriented protocol, we now choose a shared memory scheme (in the diagram, the thick lines indicate data flow; the thin lines, control flow):
Figure 1. System 2: Multiple operations, shared memory between processes.In this scheme, we've tightened up the coupling, resulting in faster and more efficient data flow. We may still use a “general-purpose” connection-oriented protocol to transfer “control” information around—we're not expecting the control information to consume a lot of bandwidth.