Abstract:
A computer readable medium having a computer program product stored thereon, the computer program product including instructions for ordering a computer to perform the following steps. The steps include a first receiving step of receiving a facsimile command from a client device configured to executes a facsimile application program, a first determining step of determining whether or not to allow communication with a facsimile device based on a predetermined condition when receiving the facsimile command at the first receiving step, and a transferring step of transferring the facsimile command received at the first receiving step to the facsimile device when the communication is allowed at the first determining step.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority from Japanese Patent Application No. 2009-252531 filed on Nov. 3, 2009. The entire content of this priority application is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a computer readable medium having a facsimile driver program, a facsimile system and a computer executable method using the facsimile driver program. 
     BACKGROUND 
     There has been known a facsimile device having a user restricting function that permits only correct users to perform facsimile transmission. In such a facsimile device, when receiving a call signal from an external information processing apparatus, the device decides the correctness of the user based on the identification information added to the call signal and the identification information that is previously registered. 
     However, to achieve a conventional user restricting function, the facsimile device should have a function for deciding the correctness of the user based on the identification information added to the call signal and the identification information that is previously registered. Therefore, the conventional user restricting function lacks versatility. 
     SUMMARY 
     According to an aspect of the present invention, a computer readable medium having a computer program product stored thereon, the computer program product including instructions for ordering a computer to perform the following steps. The steps include a first receiving step of receiving a facsimile command from a client device configured to executes a facsimile application program, a first determining step of determining whether or not to allow communication with a facsimile device based on a predetermined condition when receiving the facsimile command at the first receiving step, and a transferring step of transferring the facsimile command received at the first receiving step to the facsimile device when the communication is allowed at the first determining step. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative aspects in accordance with the present invention will be described in detail with reference to the following drawings wherein: 
         FIG. 1  is a block diagram illustrating a facsimile system according to an illustrative aspect of the present invention; 
         FIG. 2  is a block diagram illustrating a program configuration of a fax driver; 
         FIG. 3  is a sequence chart of fax transmission; 
         FIG. 4  is a sequence chart for general explanation of fax reception; 
         FIG. 5  is a sequence chart for informing of fax incoming according to a fax application; 
         FIG. 6  is a sequence chart for requesting fax reception to a fax modem; 
         FIG. 7  is a flowchart illustrating a determination flow when receiving a write request; 
         FIG. 8  is a flowchart illustrating a determination flow when receiving a read request; 
         FIG. 9  is a flowchart illustrating a flow of permission determination; 
         FIG. 10  is a flowchart illustrating a flow of permission determination according to another illustrative aspect of the present invention; and 
         FIG. 11  is a flowchart illustrating a flow of determination according to an additional illustrative aspect of the present invention when receiving a read request. 
     
    
    
     DETAILED DESCRIPTION 
     &lt;Illustrative Aspect&gt; 
     An illustrative aspect of the present invention will be hereinafter explained with reference to  FIGS. 1 to 9 . 
     (1) Construction of Facsimile System 
     As illustrated in  FIG. 1 , a facsimile system  1  comprises a client computer  10  and a multifunction apparatus  20 . In the illustrative aspect, the client computer  10  functions as a client device and a computer. In the illustrative aspect, a facsimile is abbreviated to fax. 
     (1-1) Electrical Configuration of Client Computer 
     The client computer  10  (an example of a client device and a computer) comprises a CPU  11 , a ROM  12 , a RAM  13 , a storing section  14 , a display section  15 , an operation section  16  and an USB interface (USB I/F)  17 . The client device is configured to execute a facsimile application program. 
     The CPU  11  (an example of a computer to perform a first receiving step, a first determining step, a transferring step, an obtaining step and a second determining step) executes various computations based on programs stored in the ROM  12  and the storing section  14  and controls each component in the client computer  10 . The ROM  12  stores various programs that are executed by the CPU  11  and data. The RAM  13  is a main memory that is used when the CPU  11  executes various processes. 
     The storing section  14  is an external memory for storing various programs and data using a non-volatile storing medium such as a hard disk or a flash memory. The storing section  14  stores an operating system (OS), a fax application (an example of a facsimile application program), a fax driver (an example of a facsimile driver program) and permission database (permission DB). In the present illustrative aspect, Linux (registered trademark) is used as an OS. The OS is not limited to Linux but may be other different OS. 
     The display section  15  is comprised of a display device such as a CRT or a liquid crystal display. 
     The operation section  16  (an example of a registering step) is comprised of an input device such as a mouse or a keyboard. 
     The USB interface  17  (an example of a second receiving step) is connected to the multifunction apparatus  20  via a USB cable. 
     In the present illustrative aspect, it is supposed that a plurality of users use a fax application via one client computer  10 . In such a case, each user may go to the client computer  10  to directly login the computer  10  and use the fax application or may use the fax application with remote login to the computer  10  from another computer via a communication network. 
     In the permission DB, transmission source information representing transmission sources of AT commands (an example of a facsimile command) that are permitted to communicate with the multifunction apparatus  20  is registered. 
     The transmission source represents a user who transmits the AT command, a group to which a user belong or a fax application. Namely, although the number of the client computer  10  is one, the transmission sources of the AT commands are not necessarily same. 
     In the permission DB, permission or prohibition of communication (permission or prohibition of fax transmission or fax reception) is set by a unit of, for example, a user, a group to which a user belong or a fax application. Hereinafter, the unit (a user, a group or a fax application) is simply referred to as a transmission source. 
     An administrator of the client computer  10  operates the operation section  16  to register the transmission source information in the permission DB and set permission or prohibition of communication in the permission DB. 
     (1-2) Electrical Configuration of Multifunction Apparatus 
     The multifunction apparatus  20  (an example of a facsimile device) has a fax transmission/reception function, a printing function, a scanning function and a copying function. The multifunction apparatus  20  includes a control section  21 , a facsimile section  22 , a printer section  23 , a scanner section  24 , an operation section  25  and a USB interface (USB I/F)  26 . 
     The control section  21  comprises a CPU, a ROM and a RAM. The CPU controls each component in the multifunction apparatus  20  based on various programs stored in the ROM. The ROM stores various programs and data used at the time of a control operation by the CPU. The RAM is a main memory used when the CPU executes various processing. 
     The facsimile section  22  comprises a fax modem  22 A and a fax data storing section  22 B and is connected to a telephone line. In the facsimile section  22 , the received fax data is printed by the printer section  23  and the image read by the scanner section  24  is transmitted via fax. 
     Further, the facsimile section  22  receives data from a PC via the USB I/F and transmits the received data to an external facsimile device via a telephone line and also the facsimile section  22  receives fax data from the external facsimile device and transmits the received fax data to the PC via the USB I/F. In such a case, the client computer  10  directly accesses to the fax modem  22 A via the USB interface  26 . The communication between the PC  10  and the fax modem  22 A is executed with using AT commands that have been known. 
     When the received fax data is transmitted to the client computer  10 , the whole fax data is temporally stored in the data storing section  22 B and a signal informing of incoming (RING) is transmitted to the client computer  10  after disconnection of the telephone line. The fax modem  22 A is different from an ordinary fax modem in this point. 
     The client computer  10  may reject to receive the fax data from an external facsimile device. However, in the multifunction apparatus  20  according to the present illustrative aspect, the received fax data is temporally stored in the fax data storing section  22 B and then transmitted to the client computer  10 . Accordingly, even if the client computer  10  rejects to receive the fax data, the external facsimile device already completes transmission of the fax data. Therefore, a user of the external facsimile device is not forced to transmit the fax data again even if the client computer  10  rejects to receive the fax data. 
     The printer section  23  forms images on a recording medium such as a paper by a laser method, an LED method or an ink jet method. 
     The scanner section  24  reads images formed on a document such as a paper by a linear image sensor under control of the CPU and generates image data. 
     The operation section  25  includes operation buttons with which a user controls the multifunction apparatus  20  and a display for displaying various information. 
     The USB interface  26  is connected to the client computer  10  via the USB cable. 
     (2) Program Configuration of Fax Driver 
     As illustrated in  FIG. 2 , the fax driver  30  is a program for relaying communication between the fax application  40  and the fax modem  22 A, and it comprises a driver R/W request processing program  31 , an AT command monitor program  32 , a RING monitor program  33  and a USB-FAX pipe monitor daemon program  34 . 
     The fax driver  30  other than the USB-FAX pipe monitor daemon program  34  is comprised as a kernel driver of Linux. A buffer  1  and a buffer  2  are buffer areas prepared in the RAM  13 . 
     The CPU  11  functions as a fax driver section according to the fax driver  30  and functions as a fax application section according to a fax application  40 . The CPU  11  functions as a driver R/W request processing program section according to the driver R/W request processing program  31 , functions as an AT command monitor program section according to the AT command monitor program  32 , functions as a RING monitor program section according to the RING monitor program  33 , and functions as a USB-FAX pipe monitor daemon program section according to the USB-FAX pipe monitor daemon program  34 . 
     The driver R/W request processing program  31  is executed for receiving a write request and a read request from the fax application  40 . The write request and the read request will be explained later. When receiving a write request, the driver R/W request processing program  31  transfers the write request to the AT command monitor program  32 . When receiving a read request, the driver R/W request processing program  31  transfers the read request to the RING monitor program  33 . 
     When the write request of data is received from the fax application  40 , the AT command monitor program  32  is executed for writing the data in the buffer  1 . The data that is written in the buffer  1  includes various AT commands transmitted to the fax modem  22 A and fax data transmitted to external facsimile devices. When writing data in the buffer  1 , the AT command monitor program  32  monitors the requested write data and changes control according to the data. This process will be explained later. 
     When a read request is received from the fax application  40 , the RING monitor program  33  is executed for transmitting the data written in the buffer  2  to the fax application  40  that has transmitted the read request. The data written in the buffer  2  includes a response code (result code) from the fax modem  22 A in response to the AT command transmitted to the fax modem  22 A, fax data received from external facsimile devices and error information. The RING monitor program  33  monitors data read from the buffer  2  and changes control according to the data. This process will be explained later. 
     The fax driver  30  also includes another program that is not illustrated in  FIG. 2 . According to the program, when a read request is received from the USB-FAX pipe monitor daemon  34 , the data written in the buffer  1  is transmitted to the USB-FAX pipe monitor daemon  34 , and when a write request is received from the USB-FAX pipe monitor daemon  34 , the data is written in the buffer  2 . 
     The USB-FAX pipe monitor daemon program (USB-FAX pipe monitor daemon)  34  is executed for monitoring the USB interface and relaying communication between the fax driver  30  and the fax modem  22 A. A USB standard is not defined such that data is voluntarily transmitted from the USB interface to the application side. Therefore, the USB-FAX pipe monitor daemon  34  is included in the fax driver  30  to monitor the USB interface  17  from the fax driver  30  side. 
     If RS-232C is used for an interface with the multifunction apparatus  20  for example, a monitor program such as the USB-FAX pipe monitor daemon program is not necessary. 
     (3) Fax Transmission, Fax Reception and Automatic Incoming Setting 
     (3-1) Sequence of Fax Transmission 
     A sequence of the fax transmission will be explained with reference to  FIG. 3 . The USB-FAX pipe monitor daemon  34  is illustrated as a separate program from the fax driver  30  in  FIG. 3  for easier explanation. 
     When receiving a command of fax transmission by a user, the fax application  40  transmits a write request of a command (ATD command) to which a dial number is followed to the fax driver  30 . After the transmission of the write request of the ATD command, the fax application  40  transmits a read request to the fax driver  30  at predetermined time intervals. 
     When receiving the write request of the ATD command from the fax application  40 , the fax driver  30  determines whether or not to permit communication with the fax modem  22 A according to the transmission source of the write request (permission determination, an example of determination that is made based on predetermined conditions). This determination will be explained later. 
     When determining that the communication is not permitted, the fax driver  30  writes a result code representing an error in the buffer  2 . When receiving a read request from the fax application  40  after writing of the error result code in the buffer  2 , the fax driver  30  transmits an error written in the buffer  2  to the fax application  40  in response to the read request. 
     Thus, the ATD command is not actually transmitted to the fax modem  22 A. However, the fax application  40  recognizes that the fax modem  22 A transmits an error in response to the ATD command. Therefore, the fax application  40  executes an error process that is executed for an ordinary error (for example, line disconnection). Namely, the fax application  40  is not required to execute any special processing and this provides versatility to the program. 
     When determining to allow the communication with the fax modem  22 A, the fax driver  30  writes the ATD command in the buffer  1 . 
     The USB-FAX pipe monitor daemon  34  transmits a read request to the fax driver  30  at predetermined time intervals. When receiving a read request from the USB-FAX pipe monitor daemon  34 , the fax driver  30  transmits the ATD command written in the buffer  1  to the USB-FAX pipe monitor daemon  34  in response to the read request. 
     When receiving the ATD command, the USB-FAX pipe monitor daemon program transmits a write request of the ATD command to the fax modem  22 A via the USB interface  17 . 
     The USB-FAX pipe monitor daemon  34  transmits a read request to the fax modem  22 A at predetermined time intervals. When receiving a result code representing whether fax transmission is available or not from the fax modem  22 A in response to the read request, the USB-FAX pipe monitor daemon  34  transmits a write request of the result code to the fax driver  30 . For example, if the result code is “CONNECT”, fax transmission is available, and if the result code is “BUSY” or “NO CARRIER”, fax transmission is not available. 
     When receiving the write request of the result code from the USB-FAX pipe monitor daemon  34 , the fax driver  30  writes the result code in the buffer  2 . When receiving a read request from the fax application  40  after writing of the result code in the buffer  2 , the fax driver  30  transmits the result code written in the buffer  2  to the fax application  40  in response to the read request. 
     The fax application  40  determines whether the received result code represents permission of fax transmission. If determining that the result code represents availability of fax transmission, the fax application  40  transmits a write request of fax data to the fax driver  30 . The fax data is transmitted to the fax modem  22 A and transmitted to an external facsimile device from the fax modem  22 A. If determining that the result code represents unavailability of fax transmission, the fax application  40  terminates the transmission process. 
     (3-2) Fax Reception 
     General explanation of fax reception will be made with reference to  FIG. 4 . The USB-FAX pipe monitor daemon program  34  is omitted here for easy understanding. 
     When receiving a connection request from an external facsimile device via the telephone line, the fax modem  22 A connects the line and receives fax data and stores the received fax data in the fax data storing section  22 B. When completing the fax reception, the fax modem  22 A disconnects the line. 
     Processing after the line disconnection is different in a case that the fax modem  22 A is set such that automatic incoming is not executed and in a case that the fax modem  22 A is set such that automatic incoming is executed. 
     a) Setting Without Automatic Answer 
     A sequence of the fax reception in which automatic answer is not set to the fax modem  22 A will be explained with reference to  FIG. 4 . When disconnecting the line, the fax modem  22 A transmits a signal informing of incoming (RING) to the fax application  40  to inform of the fax incoming. 
     When receiving RING, the fax application  40  transmits a forced answer command (ATA command) to the fax modem  22 A. If a user of the fax application  40  determines not to respond to the fax incoming, the command is not transmitted. 
     When receiving the ATA command from the fax application  40 , the fax modem  22 A transmits fax data stored in the fax data storing section  22 B to the fax application  40 . 
     b) Setting With Automatic Answer 
     When disconnecting the line, the fax modem  22 A transmits RING a predetermined number of times, and then, if no ATA command is transmitted from the client computer  10 , the fax modem  22 A automatically transmits fax data to the fax application  40 . 
     (3-2-1) Sequence of Fax Incoming 
     A sequence in which the fax modem  22 A informs the fax application  40  of fax incoming (RING) will be explained with reference to  FIG. 5 . 
     When receiving a read request from the USB-FAX pipe monitor daemon  34  after line disconnection, the fax modem  22 A transmits RING to the USB-FAX pipe monitor daemon  34 . 
     When receiving RING from the fax modem  22 A, the USB-FAX pipe monitor daemon  34  transmits a write request of the RING to the fax driver  30 . 
     When receiving the write request of the RING, the fax driver  30  writes the RING in the buffer  2 . When receiving a read request from the fax application  40 , the fax driver  30  determines whether or not to transfer the RING according to the transmission source of the read request. This determination will be explained later. 
     When determining to transfer the RING, the fax driver  30  transmits the RING stored in the buffer  2  to the fax application  40 . 
     When determining not to transfer the RING, the fax driver  30  deletes the RING from the buffer  2 . 
     (3-2-2) Sequence of Fax Reception 
     A sequence of fax reception will be explained with reference to  FIG. 6 . In the sequence, the fax application  40  that is informed of the fax incoming requests fax reception to the fax modem  22 A. 
     When receiving the RING, the fax application  40  transmits a forced answer command (ATT command) to the fax driver  30 . A flow of transmitting the ATA command from the fax application  40  to the fax modem  22 A is substantially same as the flow of the transmission of the ATD command, and therefore explanation will be omitted. 
     When receiving the ATA command, the fax modem  22 A transmits the fax data stored in the fax data storing section  22 B to the USB-FAX pipe monitor daemon  34 . 
     When receiving the fax data from the fax modem  22 A, the USB-FAX pipe monitor daemon  34  transmits a write request of the fax data to the fax driver  30 . 
     When receiving the write request of the fax data, the fax driver  30  writes the fax data in the buffer  2 . When receiving a read request from the fax application  40 , the fax driver  30  transmits the fax data stored in the buffer  2  to the fax application  40  in response to the read request. 
     (3-3) Automatic Answer Setting 
     Automatic answer is set by transmitting an ATS0 command to the fax modem  22 A. A command of ATSn=x represents that a setting value of x is set to the nth register. The register satisfying that n=0 stores the setting value of automatic answer. When x is 0, the automatic answer is not executed. When x is set to a value other than zero, the automatic answer is executed. A user can set automatic answer at any time while the fax modem  22 A is in an idle state. 
     The sequence for transmitting an ATS0 command is substantially same as the sequence for transmitting an ATD command or an ATA command. 
     (4) Determination Whether Communication with Fax Modem is Permitted or not 
     As described above, when receiving a write request from the fax application  40 , the fax driver  30  determines whether communication between the fax application  40  and the fax modem  22 A is permitted. The determination will be explained below. 
     A flow of determination when receiving a write request will be explained with reference to  FIG. 7 . The CPU  11  executes the AT command monitor program to execute this process. This process is started when the CPU  11  receives a write request via the fax application  40  or the USB-FAX pipe monitor daemon program  34 . 
     At step  101 , the CPU  11  determines whether the received write request is transmitted according to the USB-FAX pipe monitor daemon program  34 . If the CPU  11  determines that it is transmitted according to the USB-FAX pipe monitor daemon program  34 , the process proceeds to step  102  and if the CPU  11  determines that it is not transmitted according to the USB-FAX pipe monitor daemon program  34  (it is transmitted according to the fax application  40 ), the process proceeds to step  103 . 
     At step  102 , the CPU  11  writes the data (RING, a result code, fax data) received according to the USB-FAX pipe monitor daemon program  34  in the buffer  2 . 
     At step  103 , the CPU  11  obtains transmission source information representing a transmission source that transmitted the write request. The fax driver  30  is a kernel driver of Linux. Therefore, information representing a calling host in the kernel driver is automatically set to an internal variable. In the present illustrative aspect, the information is used as transmission source information. 
     The transmission source information includes, for example, a user ID (an example of user identification information) of a user who activates the fax application  40  to transmit the write request and a group ID of a group to which the user belongs. 
     At step  104 , the CPU  11  reads the permission DB from the storing section  14 . 
     At step  105 , the CPU  11  determines whether fax transmission or fax reception is allowed for the transmission source information with reference to the permission DB (permission determination). The permission determination will be explained later. If the CPU  11  determines that fax transmission and fax reception are not allowed, the process proceeds to step  106 , and if the CPU  11  determines that at least one of fax transmission and fax reception is allowed, the process proceeds to step  107 . 
     At step  106 , the CPU  11  writes an error in the buffer  2  and terminates the process. 
     At step  107 , the CPU  11  determines whether the data that is requested to be written by the write request is a forced answer command (ATA command). If the CPU  11  determines that the data is an ATA command, the process proceeds to step  108  and if the CPU  11  determines that the data is not an ATA command, the process proceeds to step  109 . 
     If the CPU  11  has determined that fax reception is allowed in step  108 , the process proceeds from step  108  to step  113 , and if the CPU  11  has determined that fax reception is not allowed, the process proceeds to step  106  and the CPU  11  writes an error in the buffer  2 . 
     At step  109 , the CPU  11  determines whether the data that is requested to be written is an automatic answer setting command (ATS0 command). If the CPU  11  determines that the data is an automatic answer setting command, the process proceeds to step  110 , and if the CPU  11  determines that the data is not an automatic answer setting command, the process proceeds to step  111 . 
     If the CPU  11  has determined that the fax reception is allowed in step  110 , the process proceeds from step  110  to step  113 , and if the CPU  11  has determined that the fax reception is not allowed, the process proceeds to step  106  and the CPU  11  writes an error in the buffer  2 . 
     At step  111 , the CPU  11  determines whether the data that is requested to be written is a dial command (ATD command). If the CPU  11  determines that the data is an ATD command, the process proceeds to step  112 , and if the CPU  11  determines that the data is not an ATD command, the process proceeds to step  113 . 
     If the CPU  11  has determined that the fax transmission is allowed in step  112 , the process proceeds from step  112  to step  113 , and if the CPU  11  has determined that the fax transmission is not allowed, the process proceeds to step  106  and the CPU  11  writes an error in the buffer  2 . 
     At step  113 , the CPU writes the data (AT command, fax data) that is transmitted according to the fax application  40  in the buffer  1 . 
     There are various kinds of AT commands. If the data that is requested to be written is a command other than an ATA command, an ATS0 command and an ATD command (examples of a predetermined facsimile command), it is transmitted to the fax modem  22 A without execution of the permission determination if at least one of fax transmission and fax reception is allowed. 
     (5) Determination Whether RING is Transferred or not 
     As described above, when receiving a read request from the fax application  40  with the RING being written in the buffer  2 , the fax driver  30  determines whether to transfer the RING. The determination will be explained below. 
     A determination flow at the time of reception of a read request will be explained with reference to  FIG. 8 . The CPU  11  executes the RING monitor program to execute this process. This process is started when the CPU  11  receives a read request according to the fax application  40  or the USB-FAX pipe monitor daemon program  34 . 
     At step  201 , the CPU  11  determines whether a read request is transmitted according to the USB-FAX pipe monitor daemon program  34 . If the CPU  11  determines that the read request is transmitted according to the USB-FAX pipe monitor daemon program  34 , the process proceeds to step  202 , and if the CPU  11  determines that the read request is not transmitted according to the USB-FAX pipe monitor daemon program  34  (the read request is transmitted according to the fax application  40 ), the process proceeds to step  204 . 
     At step  202 , the CPU  11  transmits the data written in the buffer  1  to the USB-FAX pipe monitor daemon  34 . 
     At step  203 , the CPU  11  deletes the data from the buffer  1 . 
     At step  204 , the CPU  11  reads data from the buffer  2 . 
     At step  205 , the CPU  11  determines whether the data read from the buffer  2  is empty. If the CPU  11  determines that the data read from the buffer  2  is empty, the process proceeds to step  206 , and if the CPU  11  determines that the data is not empty, the process proceeds to step  207 . 
     At step  206 , the CPU  11  transmits the empty data to the fax application  40  that has transmitted the read request and this process is terminated. 
     At step  207 , the CPU  11  obtains transmission source information like step  103 . 
     At step  208 , the CPU  11  reads the permission DB from the storing section  14 . 
     At step  209 , the CPU  11  determines whether the data read from the buffer  2  is RING. If the CPU  11  determines that the data is RING, the process proceeds to step  210  and if the CPU  11  determines that the data is not RING, the process proceeds to step  213 . 
     At step  210 , the CPU  11  determines whether a predetermined time has passed after the writing of the RING in the buffer  2 . If determining that the predetermined time has passed, the CPU  11  determines to be time out and the process proceeds to step  211 . If the CPU  11  determines that the predetermined time has not passed, the process proceeds to step  212 . 
     At step  211 , the CPU  11  deletes the RING from the buffer  2  and the process proceeds to step  206 . If a predetermined time has passed after the writing of the RING in the buffer  2 , the RING is already old and the fax modem  22 A may not wait for a response to the RING. Therefore, in the present illustrative aspect, if the predetermined time has passed, the RING is deleted from the buffer  2 . 
     When the RING is deleted from the buffer  2  and the fax modem  22 A is still waiting for a response to the RING, RING is transmitted again from the fax modem  22 A after a short time. 
     At step  212 , the CPU  11  determines whether fax reception is allowed for the transmission source information with reference to the permission DB (permission determination). The permission determination will be explained later. If the CPU  11  determines that the fax reception is allowed, the process proceeds to step  213 . If the CPU  11  determines that the fax reception is not allowed, the process proceeds to step  206  and empty data is transmitted to the fax application  40  that has transmitted the read request. Accordingly, the RING is not transferred to the fax application  40 , and therefore the fax application  40  cannot detect the RING. The fax application  40  does not start processing that is to be started in response to the RING (transmission of an ATA command). 
     Even if the CPU  11  determines that fax reception is not allowed and empty data is transmitted to the fax application  40 , the RING is not deleted but remains in the buffer  2 . Therefore, if new transmission source information that is registered to the permission DB, the determination at step  212  for a read request from the new transmission source is affirmative. 
     At step  213 , the CPU  11  transmits data read from the buffer  2  to the fax application  40 . 
     At step  214 , the CPU  11  deletes data from the buffer  2 . 
     (6) Permission Determination 
     Permission determination is made to determine whether fax transmission and fax reception are allowed for transmission source information with reference to the permission DB. 
     A flow of the permission determination will be explained with reference to  FIG. 9 . At step  301 , the CPU  11  determines whether permission (permission or prohibition of fax transmission and reception) is set for a user ID (an example of information as to a fax application program). If determining that permission is set for the user ID, the CPU  11  determines whether fax transmission and fax reception are allowed according to the permission setting of the user. 
     At step  302 , the CPU  11  determines whether permission is set for a group ID (an example of information concerning a fax application program). If determining that permission is set for the group ID, the CPU  11  determines whether fax transmission and fax reception are allowed according to the permission setting of a group to which the user belongs, the user activating the fax application  40 . 
     At step  303 , the CPU  11  determines whether a user is a root user. If determining that a user is a root user, the CPU  11  determines that fax transmission and fax reception are allowed. 
     At step  304 , the CPU  11  determines whether default permission is set. If determining that default permission is set, the CPU  11  determines whether fax transmission and fax reception are allowed according to the default permission setting. The default permission is applied to all users without exception. 
     If determining that the default permission is not set, the CPU  11  determines that fax transmission is allowed and fax reception is not allowed. 
     (7) Effects of Illustrative Aspect 
     In the illustrative aspect of the present invention, the restricting function for using the fax modem  22 A and performing facsimile transmission is achieved according to the fax driver  30 . Therefore, the restricting function is achieved with a fax modem  22 A that has no such a restricting function. According to the fax driver  30 , the restricting function with high versatility is achieved. 
     Further, according to the fax driver  30 , transmission sources that make communication with the fax modem  22 A are restricted to certain ones with reference to the permission DB. 
     Further, according to the fax driver  30 , the transmission source information representing the transmission source of the AT command is obtained from an OS. The AT command is not configured such that transmission source information representing a transmission source is added thereto, and therefore general fax applications  40  are not configured to have function of transmitting transmission source information to the fax driver  30 . Therefore, even if a facsimile device has a function of user permission, the function cannot be used in transmission and reception between a computer and the facsimile device. However, according to the fax driver  30 , the transmission source information representing the transmission source of the AT command is obtained from the OS. Therefore, the restricting function can be achieved with using general fax applications that does not have a function of transmitting transmission source information to the fax driver  30 . According to the fax driver  30 , the restricting function of high versatility is achieved. 
     Further, according to the fax driver  30 , a user ID of a user who executes a fax application  40  is used as the transmission source information. Therefore, the restricting function is achieved by a unit of a user. 
     Further, according to the fax driver  30 , it is determined whether communication with the fax modem  22 A is allowed for a predetermined facsimile command. Therefore, the restricting function is achieved with more precisely. 
     Further, according to the fax driver  30 , if a user who is not allowed to perform fax reception is a transmission source of a read request and even if RING is written in the buffer  2 , the RING is not transferred to the fax application  40  that has transmitted the read request. Therefore, unnecessary informing of incoming is not performed to a user who is not allowed to perform fax reception. 
     In the present illustrative aspect, concerning fax reception, in addition to the permission determination whether fax transmission and fax reception are allowed, the permission determination whether RING transmission is allowed is executed. According to some fax applications  40 , a pop-up screen may be displayed on the display section  15  at the time of reception of the RING to make a user to select permission or prohibition of the fax reception. In such a case, the pop-up screen may not be displayed on the display section  15  if it is determined that the RING transmission is not allowed. Accordingly, the following problem is not caused. Although allowance to the fax reception is input from the pop-up screen by the user, the fax reception is not performed according to the permission determination. 
     &lt;Another Illustrative Aspect&gt; 
     Another illustrative aspect of the present invention will be explained with reference to  FIG. 10 . 
     In the another illustrative aspect, a program name of a fax application  40  is obtained as information relating to the fax application  40 . 
     In the permission DB according to the another illustrative aspect, permission or prohibition of communication (permission or prohibition of fax transmission and permission or prohibition of fax reception) is registered by a unit of each program name of fax applications. 
     A flow of permission determination for a fax application  40  will be explained with reference to  FIG. 10 .  FIG. 10  illustrates a flowchart that is applied commonly to determination of a write request and determination of a read request, and for the flowchart of the permission determination that is not illustrated in  FIG. 10 , the flowchart in  FIG. 7  is applied to the determination of a write request and the flowchart in  FIG. 8  is applied to the determination of a read request. 
     At step  401 , the CPU  11  determines whether the received write request/read request is transmitted from the USB-FAX pipe monitor daemon  34 . If the CPU  11  determines that it is transmitted from the USB-FAX pipe monitor daemon  34 , the process proceeds to step  402 , and if the CPU  11  determines that it is not transmitted from the USB-FAX pipe monitor daemon  34  (it is transmitted from the fax application  40 ), the process proceeds to step  403 . 
     At step  402 , the CPU  11  writes data in the buffer  2  in response to the write request transmitted from the USB-FAX pipe monitor daemon  34  or transmits data written in the buffer  1  to the USB-FAX pipe monitor daemon  34  in response to the transmitted read request. 
     At step  403 , the CPU  11  obtains from the permission DB a list (allowance list) of fax applications  40  that are allowed to perform fax communication. 
     At step  404 , the CPU  11  obtains from the OS a program name of the fax application  40  according to which the write request or the read request is transmitted to the fax driver  30 , and determines whether the obtained program name is registered in the allowance list. 
     If determining that the obtained program name is registered in the allowance list, the CPU  11  determines that the obtained program is a fax application  40  that is allowed to perform fax communication. When a write request is received, the process proceeds to step  103  in  FIG. 7 , and when a read request is received, the process proceeds to step  204  in  FIG. 8 . 
     If determining that the obtained program name is not registered in the allowance list, the CPU  11  determines that the obtained program is a fax application  40  that is not allowed to perform fax communication, and the process proceeds to step  405 . 
     At step  405 , the CPU  11  writes an error in the buffer  2  and terminates the process. 
     According to the fax driver  30  of the another illustrative aspect, a program name of a fax application  40  is used as transmission source information. Therefore, the restricting function is achieved by a unit of a fax application  40 . 
     For example, log management may be performed for fax transmission and fax reception. The log management may be performed according to the fax driver  30  or the fax application  40 . In performing the log management according to the fax application  40 , logs are centrally managed by allowing to use only the fax application  40  having a function of writing a log in a common location. 
     &lt;Additional Illustrative Aspect&gt; 
     Next, an additional illustrative aspect of the present invention will be explained with reference to  FIG. 11 . 
     According to the additional illustrative aspect, if the number of transmission times of the RING is three or less, only a user having a first priority is allowed to perform fax reception, and if the number of transmission times of the RING is four or greater, among all the users who are allowed to perform fax reception, a user who transmits a read request first (a fax application  40  according to which a read request is transmitted first) is allowed to perform fax reception. 
     A determination flow in receiving a read request will be explained with reference to  FIG. 11 . The CPU  11  executes the RING monitor program to execute this process. This process is started when the CPU  11  receives a read request from the fax application  40  or the USB-FAX pipe monitor daemon  34 . 
     At step  501 , the CPU  11  determines whether the read request is transmitted from the USB-FAX pipe monitor daemon  34 . If the CPU  11  determines that it is transmitted from the USB-FAX pipe monitor daemon  34 , the process proceeds to step  202  in  FIG. 8 . If the CPU  11  determines that it is not transmitted from the USB-FAX pipe monitor daemon  34  (it is transmitted from the fax application  40 ), the process proceeds to step  502 . 
     At step  502 , the CPU  11  reads data from the buffer  2 . 
     At step  503 , the CPU  11  determines whether the data read from the buffer  2  is empty or not. If the CPU  11  determines that the data is not empty, the process proceeds to step  504 , and if the CPU  11  determines that the data is empty, the process proceeds to step  206  in  FIG. 8 . 
     At step  504 , the CPU  11  determines whether the data read from the buffer  2  is RING. If the CPU  11  determines that the data is RING, the process proceeds to step  505  and if the CPU  11  determines that the data is not RING, the process proceeds to step  213  in  FIG. 8 . 
     At step  505 , the CPU  11  counts the number of transmission times of the read RING. Specifically, a series of RING is transmitted from the fax modem  22 A to the fax application  40  after the disconnection of the line, and the series of RING is transmitted again after a predetermined time, if no response (ATA command) is transmitted from the fax application  40 . The number of transmission times of a series of RING is predetermined. Every time the CPU  11  receives a series of RING, the CPU  11  increments a counter by one to count the number of transmission times of RING. The counter is reset to zero when the fax application  40  responds to the RING or in case of time out. If the RING is ignored without being responded by the fax application  40  for a predetermined time or more and the series of RING is transmitted from the fax modem  22 A, the counter counts from one again. 
     At step  506 , the CPU  11  determines whether the number of transmission times of the RING is three or less. If the CPU  11  determines that the number of transmission times of the RING is three or less, the process proceeds to step  507 . If the CPU  11  determines that the number of transmission times of the RING is four or more, the process proceeds to step  510 . 
     At step  507 , the CPU  11  determines whether the user (who started the fax application  40  according to which the read request is transmitted) who transmitted the read request (that makes this process to be executed) has a first priority. If the CPU  11  determines that the user has a first priority, the process proceeds to step  508  and if the CPU  11  determines that the user does not have a first priority, the process proceeds to step  512 . 
     At step  508 , the CPU  11  transmit the RING to the fax application  40  that transmitted the read request. 
     At step  509 , the CPU  11  deletes the RING from the buffer  2 . 
     At step  510 , the CPU  11  determines whether a predetermined time has passed after the RING was written in the buffer  2 . If the CPU  11  determines that the predetermined time has not passed, the process proceeds to step  511 , and if determining that the predetermined time has passed, the CPU  11  determines to be time out and the process proceeds to step  513 . 
     At step  511 , the CPU  11  performs permission determination of the user who transmitted the read request to determine whether the fax reception is allowed. If the CPU  11  determines that the fax reception is allowed, the process proceeds to step  508  and if the CPU  11  determines that the fax reception is not allowed, the process proceeds to step  512 . 
     At step  512 , the CPU  11  transmits empty data to the fax application  40  that transmitted the read request and terminates the process. 
     At step  513 , the CPU  11  deletes the RING from the buffer  2 . 
     According to the fax driver  30  of the additional illustrative aspect, if a plurality of fax applications  40  (client devices) are allowed to perform communication with the fax modem  22 A, the CPU  11  determines to which one of the fax applications  40  the informing of incoming is transferred according to a predetermined priority order. Therefore, if a plurality of fax applications  40  are allowed to perform communication with the fax modem  22 A, the fax application  40  to which the RING is transferred is appropriately determined. 
     &lt;Other Illustrative Aspects&gt; 
     The present invention is not restricted to the aspects explained in the above description made with reference to the drawings. The following aspects may be included in the technical scope of the present invention, for example. 
     (1) In the above illustrative aspects, when a connection request is received from an external facsimile device via a telephone line, the line is connected to receive fax data and the received fax data is stored in the fax data storing section  22 B. When a connection request is received from an external facsimile device, the RING may be transmitted to the fax application  40  and the line may be connected after an ATA command is received. 
     (2) In the above illustrative aspects, the client computer  10  functions as a client device and a computer. However, a computer and a client device may be configured independently of each other. 
     (3) In the above illustrative aspects, the CPU  11  functions as a computer to execute the fax driver  30 , the fax application  40 , the driver R/W request processing program  31 , the AT command monitor program  32 , the RING monitor program  33 , the USB-FAX pipe monitor daemon  34 . However, an independent CPU may be provided for each of the programs.