Patent ID: 8922812

Claim:
A network printer comprising: a communication unit for carrying out transmission/reception of data with a communication terminal connected via a network; an expansion unit for expanding print data received by the communication unit into raster data; and a recording unit for printing out the raster data expanded by the expansion unit on paper; wherein the communication unit includes, a priority level determination unit, when a reception request signal of second print data is newly accepted in the middle of reception of previously-accepted first print data, for determining priority between the first and second print data, and a first persistent connection control unit for, when the priority level determination unit determines a priority level of the second print data to be lower than a priority level of the first print data, until reception of the first print data is completed, executing a persistent connection control that prohibits a transmission source of the second print data from transmitting the second print data while a session is being maintained, and for, when the priority level determination unit determines the priority level of the second print data to be higher than the priority level of the first print data, permitting the transmission source of the second print data to transmit the second print data, and prohibiting a transmission source of the first print data to transmit the first print data in the middle of reception of the second print data while the session is being maintained, and the first persistent connection control unit executes the persistent connection control by transmitting in accordance with a TCP/IP irrespective of a receivable amount of data in a receive buffer of the network printer, information indicating that there is no space in the receive buffer to a transmission source of print data determined as lower priority data in response to a regular inquiry about whether or not there is any space available in the receive buffer.