One possible Solution:
#!/usr/bin/env python2.5
import os
import ecflow
defs = ecflow.Defs("back_archiving.def")
suite = defs.add_suite("back_archiving")
suite.add_repeat( ecflow.RepeatDay(1) )
suite.add_variable("ECF_HOME",os.getenv("HOME") + "/course")
suite.add_variable("ECF_INCLUDE",os.getenv("HOME") + "/course")
suite.add_variable("ECF_FILES",os.getenv("HOME") + "/course/back")
suite.add_variable("SLEEP","2")
suite.add_limit("access",2)
for kind in ( "analysis", "forecast", "climatology", "observations", "images" ):
find_fam = suite.add_family(kind);
find_fam.add_repeat( ecflow.RepeatDate("DATE",19900101,19950712) );
find_fam.add_variable("KIND",kind)
find_fam.add_task("get_old").add_inlimit("access")
find_fam.add_task("convert").add_trigger("get_old == complete")
find_fam.add_task("save_new").add_trigger("convert == complete")