[kepler-dev] [Bug 3735] New: - R actor produces 'null' message when R not found on PATH

[bugzilla-daemon at ecoinformatics.org]

http://bugzilla.ecoinformatics.org/show_bug.cgi?id=3735

           Summary: R actor produces 'null' message when R not found on PATH
           Product: Kepler
           Version: 1.0.0
          Platform: Other
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: actors
        AssignedTo: leinfelder at nceas.ucsb.edu
        ReportedBy: jones at nceas.ucsb.edu
         QAContact: kepler-dev at kepler-project.org


Edward Lee reports thatthe R actor produces a 'null' error message when one of
the demo workflows that requires R is run on a system lacking R.  

The R actor (and other external execution actors like Matlab) should check to
see if the R executable is available and the R system functioning before it
tries to execute.  Maybe this can be done on init() so that it happens before a
workflow is run.

When R is not found, a sensible error message should be displayed, one that
preferably points the user to an easy solution of the problem.

An alternative (and probably better) approach is to have the R actor formally
specify a dependency on the R system executable for the local platform, so that
when the R actor is installed, the module installer checks that its
dependencies are all satisfied.  This would be possible under the new
modularization system that includes the ability to formally specify dependency
graphs in module metadata.