Ports


Ports are the points of connection that connect the "inside" world of the component (the process code) with the "outside" world (the network).  Think of a house at, say, 27 Main Street:  the houseowner may say, "Someone is ringing the front door bell", not, "Someone is ringing the bell at 27 Main Street."   Conversely, the person ringing the bell is seeing 27 Main Street, not 27 Maple Street.

All connections between processes (whether simple or composite) will have two port names - an upstream one and a downstream one.  When one of the blocks being connected is an IIP or an External Port, only the process end of the connection will have a port name (upstream or downstream as appropriate).    By definition, an IIP is always "upstream".

When an arrow is first drawn, the tail end is assigned the name OUT and the head end is IN - unless these names have already been used for the respective blocks, in which case the user should fill in names (of course IN and OUT can be modified as desired).

Files and Reports usually show connections, but no port names are required.  Legends may or may not have connections.