usage: make output should be:

--- Outputs --- [{«»: Hello World}, {«»: Hello World}, {«»: Hello World}]

--- done ---

see the source code in helloworld0d.drawio

The startup file main.odin injects the message "Hello World" into the input port. The message is routed to the front of the Sequential pipeline and to the front of the Parallel pipeline.

The Echo component, in this very simple example, sends its input, as is, to its no-name output.

The Sequential pipeline routes the message into the Echo component which outputs into another Echo component which finally outputs the result to the «» output port. (Note that the «» input port is distinct from the «» output port).

The Parallel pipeline routes the message into two parallel instances of the Echo component. Each of these simply echoes its input to its output (as above), but, the outputs go to the no-name output of the main Container at slightly different moments in time (the order is arbitrary).

Hence, we see 3 output messages to port «» (no-name, "" in ASCII). 1 of those is from the Sequential pipeline. 2 of those are from the Parallel pipeline.

Note that, in UNIX, the no-name input port would be called stdin and the no-name output port would be called stdout. 0D components can have 0 or more input ports and 0 or more output ports. This simple example doesn't include an output port for failure, but, if it did, it would probably have the name ✗.