According to the specification, "Getting a property value for a name which has not been set is handled as if the the property exists with a null value." In the case of getStringProperty, does this mean a null value or a null string?

A: Either is permissible. The reason for this ambiguity is that some MOM systems do not have the native concept of a null string, so they convert all null-valued strings at send time to empty strings.
Category:JMS Interview Questions