Universal plug and play based network system and method of controlling the same

A network system comprising:

• a first printing command transmission unit to store a first printing command transmission unit description and to transmit a first command message together with a first printing command transmission unit description position information to an external network device, so that the external network device performs an operation according to the first command message and recognizes the first printing command transmission unit sending the first command message,
• wherein the first printing command transmission unit generates the first command message including the first printing command transmission unit description position information to indicate a storage position of the first printing command transmission unit description, and
• wherein the network device operates according to the first command message from the first printing command transmission unit and distinguishes the first printing command transmission unit from a second printing command transmission unit that transmits a second command message with a second printing command transmission unit description position information to the external network device by receiving the first printing command transmission unit description stored in the first printing command transmission unit from the first printing command transmission unit according to the first printing command transmission unit description position information and a second printing command transmission unit description stored in the second printing command transmission unit according to the second printing command transmission unit description position information.