Physical Channels

Diamond also allows CONNECT statements to be mapped directly onto physical channels (WIREs) when necessary, completely eliminating the extra overhead. Communication performance is unlikely to be a big problem for our upper-casing example, but if we did want to use physical channels for the connections between the driver and upc tasks, we could change the two CONNECT statements as follows:

connect ? driver[0] upc[0] physical

connect ? upc[0] driver[0] physical

There is no need to re-compile or re-link either of the tasks.

You may also specify explicitly that particular channels must be virtual:

connect ? driver[0] upc[0] virtual

connect ? upc[0] driver[0] virtual

If a CONNECT statement does not specify either VIRTUAL or PHYSICAL, the configurer makes it virtual by default. Putting one of the following statements anywhere in a configuration file can change this default setting:

default connect physical

default connect virtual

The configurer also provides a command-line option to make all connections physical by default:

» 3L A -p …

The configurer reports any conflicts among these different ways of specifying default behaviour.