Parameters are placeholders that represent values in a mapping or mapplet. Use parameters to hold values that you want to define at run-time such as a source connection, a target object, or the join condition for a Joiner transformation. You can also use parameters to hold values that change between task runs such as a time stamp that is incremented each time a mapping runs.
You can create the following kinds of parameters in a mapping or mapplet:
Input Parameters
An input parameter is a placeholder for a value or values in a mapping or mapplet. Input parameters help you control the logical aspects of a data flow or to set other variables that you can use to manage different targets.
When you define an input parameter in a mapping, you set the value of the parameter when you configure a mapping task.
In-Out Parameters
An in-out parameter holds a variable value that can change each time a task runs, to handle things like incremental data loading. When you define an in-out parameter, you can set a default value in the mapping but you typically set the value at run time using an Expression transformation. You can also change the value in the mapping task.