Published Parameters
From Fmepedia
Published Parameters in a Workspace
Within a workspace, a published parameter is any parameter (setting) that has been made available for the user to change on running the workspace. In order to publish a parameter, look for it in the Workspace panel within FME Workbench. There will be categories for datasets and transformers. Each one of those can have one or more parameters. Navigate down to the one you want to publish, right-click on it and select "Publish Parameter". It will then show up in the Published Parameters category (and have a purple instead of a green icon).
Right-clicking on a parameter in the Published Parameters category lets you set the default value, parameter name and prompt.
The parameter may be set by either a prompt (within Workbench) or by passing a value (from the Command Line). Setting via the Command Line goes as follows:
--[parameter name] [parameter value]
e.g.
--min_x 100000
Published Parameters in a Custom Transformer
Within a Custom Transformer, a published parameter is any parameter (setting) that has been made available for the user to change on each instance of that custom transformer. For example, I have a custom transformer that contains a Bufferer transformer. I want a user to be able to place the custom transformer in a workspace and set the Buffer size parameter. However, each instance of the Custom Transformer may require a different buffer size. Therefore I publish the buffer size setting inside the custom transformer and it becomes available as one of the settings on the custom transformer.
See this page for an example of publishing parameters from a Custom Transformer.
The most common use of this functionality is to enable the user to select an attribute within a custom transformer. For example, a SubstringExtractor has a source attribute setting. However, attributes from the workspace are not automatically available inside the Custom Transformer. By publishing this setting the user is able to select the source attribute without having to expose it manually within the custom transformer.
Published Custom Transformer Published Parameters in a Workspace
When a parameter has been published from within a Custom Transformer it becomes available as a regular setting on any instance of that custom transformer. At that point it is possible to publish the published setting within the workspace so that the user is prompted for a value at runtime.
In other words these are published parameters from a custom transformer that are further published within the main workspace.
The one exception to this is where the custom transformer parameter published is one that selects an attribute. It is not permitted to prompt a user for such a value at runtime because there may be multiple instances of the custom transformer, each of which has different attributes; therefore it's impossible to pick which attributes should be in the prompt list.
