Related terms
Activities, flows, and a few other rule types may have parameters that can be accepted as inputs (by value), used to convey results (by value), or serve as both inputs and outputs.
A parameter page contains parameter names and values. This page has no name or associated class. The stack of parameter pages for the current process is not part of the clipboard, and is not visible through the Clipboard tool. However, you can display the contents of the parameter page with the Tracer tool.
Each call or branch (or form SUBMIT by a user) that starts a new execution of an activity uses a parameter page to convey these input parameters and to access the results of the activity's execution.
Flow parameters and activity parameters are scalar and can hold only a single string. Within an activity or a flow rule, the keyword Param and a dot identifies a parameter (or its string value depending on context), as in:
Param.Width
Each activity of can define the names of the parameters it expects, the data type of each, and other constraints on the Parameters tab of the Activity form. The name of a parameter must be a Java identifier.
Local variables are also defined on the Parameter tab of the Activity form, but are passed within a StringBuffer rather than through a page, for efficiency reasons.
Sections and control rules accept both scalar and complex parameters. Complex parameters mimic the structure of the Value List, Value Group, Page List, and Page Group property types, though the parameters are not defined by properties.
Use the <pega:param .. > JSP tag (within the <pega:reference..> JSP tag) to set the value of a complex parameter.