[kepler-dev] [Bug 2959] - Need for Multiport input for RExpression actor

[bugzilla-daemon@ecoinformatics.org]

http://bugzilla.ecoinformatics.org/show_bug.cgi?id=2959





------- Comment #2 from leinfelder at nceas.ucsb.edu  2008-02-08 10:09 -------
A note on variable naming conflicts:
-Take the case of 2 EML actors sitting upstream from an RExpression actor. 
Both EML actors are configured such that their output format is "as column
based record".  This sets their output ports to be named "Record" and requires
that those names not be changed.  When both EML actors feed into the same
multiport on the R actor, the "Record" variable name is reused (which
essentially overwrites the first "Record" value).
How to best resolve this case?
1.  Append index numbers to the upstream variable name (Record1, Record2,
...RecordN)
2.  Abandon the use of the upstream port name so that the RExpression actor is
more autonomous (and portable) and as such does not rely on the configuration
of other actors in any particular workflow.  Any multiport input would use the
name of the input multiport on the R actor with index numbers appended to the
port name as variables available in R.  (Multiport1, Multiport2,
...Multiport3).

By abandoning the upstream portnames, we loose the slight metadata advantage
those names might give us, but we also ensure that RExpression actors can be
reused in any workflow without the need to script modification.