_ special character is not allowed in names of Pipeline, Stage, and Task; failing data sharing

[lee212]

To exchange or share data between tasks, e.g. copy_input_data, PST names are referenced but the underscore _ is used for parsing. The errors, otherwise, is seen like, if names contain this character:

p = Pipeline()
p.name = 'simple_mdff'
...
EnTKError: Value for attribute placeholder of object task incorrect.
 Expected value ('$Pipeline_(pipeline_name)_Stage_(stage_name)_Task_(task_name) 
or $SHARED',),
but got ['$Pipeline', 'simple', 'mdff', 'Stage', 'Generating a simulated density map', 
'Task', 'Starting to load the target PDB'].

pipeline name simple_mdff was accidentally sliced by the delimiter _.

A possible solution would be:

• encoding names by base64 as it contains three special characters only +, /, =
• prohibit using _ in names

radical.entk/src/radical/entk/execman/rp/task_processor.py

Line 59 in d249c2c

expected = '$Pipeline_(pipeline_name)_' \

[iparask]

I suggest excluding any special character from the pipeline, stage, and task names, apart from ..

[mturilli]

I would agree but then I think we should check for naming before execution and raise an error if a name uses illegal characters.