The Flow.tcl file

The normal name for a flow description is Flow.tcl. The first flow you will write will reproduce the flow created in the user tutorial:

# This is the first Flow.tcl
J vw cp bb cc
J vw cp cc dd
J vw cp cc ee
J vw cp aa bb  ;# Deliberately out of order.

The token J in this file is the name of a Tcl procedure, one of those that comprise the Flow Description Language. J means that we want our flow to include the job whose command line has been passed as argument.

In this case we want our flow to contain 4 jobs. We list the jobs in arbitrary order, since FlowTracer has the ability to determine or discover the correct order anyway.

The flow description can be this simple because it need not be concerned with issues like environment setup, job scheduling, job control, capturing of stdout and stderr, license checking, error checking, detection of parallelism, since all these services are automatically provided by FlowTracer. This means that a flow description file is typically several times smaller than an equivalent Makefile or shell script.