1. An information processing apparatus comprising: a processor; a display part configured on the processor to receive an input from a user and display a message to the user; a constraint processing part configured to process constraints among functions of a printer based on the input which the display part has received, and generate constraint information; and a message generating part configured to manage a plurality of terms in a form of a term list, and combine terms of the plurality of terms to generate the message to be displayed by said display part based on the constraint information generated by said constraint processing part; a constraint definition information storing part configured to store constraint definition information describing definitions of the constraints based on a type and specification of the printer; and a term information storing part configured to store the plurality of terms; wherein said constraint processing part reads the constraint definition information, and generates the constraint information based on contents of a change in a setting of the function of the printer received by the display part; and said message generating part reads terms of the plurality of terms and combine the terms to generate the message based on the constraint information; wherein said constraint information comprises identification information for identifying each function and a value which each function may have, information concerning a structure of conditions in which each function and the value which the each function have are subject to constraint, and information concerning whether the conditions which are elements of the structure are currently valid.