In a Web service interaction activity, such as a receive, onMessage, onEvent, invoke, or reply activity, you usually select a WSDL message type variable for the input or output variable. However, if the WSDL operation uses a message containing exactly one part that itself is defined using an element, the Web service interaction activity can use the

<fromPart>

element for an input variable and a

<toPart>

element for the output variable. The

fromPart

or

toPart

declarations are used in place of the activity's input or output variable declaration.