Expressions and Parameters

You can define an expression that sets the value of a parameter when the expression is evaluated. Optimization Process Composer evaluates expressions in the following order:

Expressions for input parameters, in/out parameters, and neutral parameters are evaluated when the activity begins running.
Expressions for output parameters are evaluated after the activity runs.

Note: You can encounter unexpected behavior if an input parameter or an in/out parameter has an expression defined to set its value and the parameter is also mapped to another parameter. Under these circumstances, the expression overwrites the mapping value and, thus, Optimization Process Composer uses the expression to set the value before the activity runs. Therefore, it is recommended that you do not configure both an expression and dataflow mapping for a single parameter.

Expressions are not evaluated while a step runs. Mathematical expressions are not supported. You can use the Calculator adapter to define mathematical expressions.

Note: Whenever possible, you should use dataflow mapping instead of expressions. Using dataflow mapping can result in better execution performance.

An expression is a string containing substitutions of other quantities such as:


Parameters associated with the same activity. Note: Any conflict with system-defined key words (defined below) yield to the key word.	`${PARAMETER[<NAME>]}, ${<NAME>}`
Parent object	`..`
Various key words used to refer to useful information available during execution. Key words use to reference various information about an activity. Key words are case insensitive.	`${USER}`, `${WORKID}`, `${JOBID}`, `${RUNDIR}`, `${LOCALHOST}${NAME}`, `${TYPE}`, `${REVISION}`, `${TITLE}`, `${DESCRIPTION}`, `${STATE}`, `${MODIFIED}`, `${ORIGINATED}`, `${OWNER}` `${<keyword>}`
Attributes associated with the same activity or content defined for that activity. Attributes associated with other activities in the process or content defined for those activities.	`${ATTRIBUTE[name]}` To reference content attributes, you must use the `${OBJECT[<name>]}` prefix.
Environment variables of the host and station.	`${ENV[<name>]}`

For information about attributes, refer to the Process Composer for Dashboard Guide.

Expressions are case insensitive; for example, ${Type} is the same as ${TYPE}. However, the title of a parameter is case sensitive; for example, ${Material density} is unlike ${Material Density}.