Parameter Settings

When a user parameter is created two checkbox options exist; one is labelled Published and the other Optional.

Published Parameters

The purpose of this option is to expose or hide the parameter from the end user. If the Published box is checked, then the user will be prompted to enter a value. If the box is unchecked then they will not be prompted, and the parameter will be treated as "private".

Private Parameters have two uses.

Firstly a private parameter is a way for a workspace author to create a shared parameter without having it exposed to the user.

For example, if they want to supply the same tolerance value to several Snapper transformers – but that value is set by the author, not the user – then a private parameter is used.

A second use of a private parameter is to embed a user's partial input into a larger parameter.

For example, here the workspace author wants the user to enter a filename to be written as output, but the name of the folder to write it in is determined by the author (here as a mix of fixed path and a job ID):

Optional Parameters

The Optional checkbox tells FME whether the user parameter is compulsory or optional.

If, for example, the user parameter provides a tolerance value to a Generalizer transformer, the author will want to turn off this checkbox and make the parameter compulsory. A Generalizer that is not given a tolerance value will usually fail and making tolerance compulsory is one way to prevent that happening:

Alternatively, a parameter might exist for the user to set the color of a set of features. In this case the checkbox might be left checked so that it is optional and the user does not have to select a color. In that scenario the translation will not fail; the features will simply retain their original color.