Abstract:
According to an aspect of the invention, there is provided a device management system, which comprises a first device connected to a network, an information processing device connected to the network, a second device connected to the information processing device, and a management device connected to the network. The management device comprises: a request judgment unit configured to accept a request regarding management and to judge whether a target device of the request is the first device or the second device based on a database; a first management unit configured to transmit the first management command to the first device in accordance with a first protocol; and a second management unit configured to transmit the second management command to the information processing device in accordance with a second protocol. The information processing device comprises a command relaying unit configured to send the second management command to the second device.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority under 35 U.S.C. §119 from Japanese Patent Application No. 2006-198126, filed on Jul. 20, 2006. The entire subject matter of the application is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    Aspects of the present invention relate to a device management system for managing devices in a network. 
         [0004]    2. Related Art 
         [0005]    Device management systems configured to manage devices directly connected to a network in accordance with a network device management protocol such as an SNMP (Simple Network Management Protocol) have been proposed. In such a system, an application program having a management function (e.g., a SNMP manager function) of managing network devices (devices connected to the network) is used. 
         [0006]    The SNMP is able to manage network devices directly connected to the network. However, the SNMP is not able to manage devices (local devices) connected, for example, to a personal computer (which is connected to the network) through an interface such as a USB (Universal Serial Bus) or a parallel port because the local devices are managed under control of the personal computer. 
         [0007]    Japanese Patent Provisional Publication No. 2000-293324 (hereafter, referred to as JP2000-293324A) discloses a device management system configured to manage a local device by implementing a dedicated program on a PC (personal computer) to which the local device is connected. The dedicated program has a function of responding to a packet under SNMP. 
         [0008]    However, the dedicated program implemented on the PC has a relatively complicated structure. Therefore, the system disclosed in JP2000-293324A has a drawback that the development of the dedicated application program increases the cost of the system. In addition, in the system disclosed in JP2000-293324A, it is impossible to control, on a management device, local and network devices while appropriately distinguishing a local device from a network device. Further, the system is not able to support management of the case where more than one local device is connected to the PC. 
       SUMMARY 
       [0009]    Aspects of the present invention are advantageous in that it provides a device management system capable of managing both local and network devices in a network while making it possible to distinguish a local device from a network device. 
         [0010]    According to an aspect of the invention, there is provided a device management system, which comprises at least one first device connected to a network, an information processing device connected to the network, at least one second device connected to the information processing device, and a management device connected to the network. The management device comprises: a request judgment unit configured to accept a request regarding management of one of the at least one first device and the at least one second device and to judge whether a target device of the request is the at least one first device or the at least one second device; a database in which first commands for the at least one first device and second commands for the at least one second device are stored such that, for each of types of requests regarding management of one of the at least one first device and the at least one second device, each of the first commands is associated with corresponding one of the second commands; a first management command generation unit configured such that if the request judgment unit judges that the target device of the accepted request is the at least one first device, the first management command generation unit reads the first command matching the accepted request from the database, generates a first management command to be processed by the at least one first device using the read first command, and transmits the first management command to the at least one first device in accordance with a first protocol; and a second management command generation unit configured such that if the request judgment unit judges that the target device of the accepted request is the at least one second device, the second management command generation unit reads the second command matching the accepted request from the database, generates a second management command to be processed by the at least one second device using the read second command, and transmits the second management command to the information processing device in accordance with a second protocol. 
         [0011]    In this configuration, the information processing device comprises a command relaying unit configured to receive the second management command from the management device and to send the second management command to the at least one second device. 
         [0012]    The above mentioned configuration of the management system eliminates the need for implementing a dedicated application (enabling the information processing device to support a network management protocol) on the information processing device. Therefore, it becomes possible to manage local devices on the management device in a concentrated manner, It is possible to appropriately manage the local and network devices while enabling a user to appropriately distinguish the local device from the network device. 
         [0013]    According to another aspect of the invention, there is provided a management device connected to a network. The management device comprises: a request judgment unit configured to accept a request regarding management of one of at least one first device connected to a network and at least one second device connected to an information processing device connected to the network, and to judge whether a target device of the request is the at least one first device or the at least one second device; a database in which first commands for the at least one first device and second commands for the at least one second device are stored such that, for each of types of requests regarding management of one of the at least one first device and the at least one second device, each of the first commands is associated with corresponding one of the second commands; a first management command generation unit configured such that if the request judgment unit judges that the target device of the accepted request is the at least one first device, the first management command generation unit reads the first command matching the accepted request from the database, generates a first management command to be processed by the at least one first device using the read first command, and transmits the first management command to the at least one first device in accordance with a first protocol; and a second management command generation unit configured such that if the request judgment unit judges that the target device of the accepted request is the at least one second device, the second management command generation unit reads the second command matching the accepted request from the database, generates a second management command to be processed by the at least one second device using the read second command, and transmits the second management command to the information processing device in accordance with a second protocol. 
         [0014]    The above mentioned configuration of the management device eliminates the need for implementing a dedicated application (enabling the information processing device to support a network management protocol) on the information processing device. Therefore, it becomes possible to manage local devices on the management device in a concentrated manner. It is possible to appropriately manage the local and network devices while enabling a user to appropriately distinguish the local device from the network device. 
         [0015]    According to another aspect of the invention, there is provided a computer readable medium having computer readable instruction stored thereon, which, when executed by a processor of a management device, configures the processor to perform the steps of: accepting a request regarding management of one of at least one first device connected to a network and at least one second device connected to an information processing device connected to the network; judging whether a target device of the request is the at least one first device or the at least one second device; if it is judged that the target device of the accepted request is the at least one first device, reading a first command matching the accepted request from a database in which first commands for the at least one first device and second commands for the at least one second device are stored such that, for each of types of requests regarding management of one of the at least one first device and the at least one second device, each of the first commands is associated with corresponding one of the second commands, generating a first management command to be processed by the at least one first device using the read first command, and transmitting the first management command to the at least one first device in accordance with a first protocol; and if it is judged that the target device of the accepted request is the at least one second device, reading the second command matching the accepted request from the database, generating a second management command to be processed by the at least one second device using the read second command, and transmitting the second management command to the information processing device in accordance with a second protocol. 
         [0016]    The above mentioned configuration for the management device eliminates the need for implementing a dedicated application (enabling the information processing device to support a network management protocol) on the information processing device. Therefore, it becomes possible to manage local devices on the management device in a concentrated manner. It is possible to appropriately manage the local and network devices while enabling a user to appropriately distinguish the local device from the network device. 
         [0017]    According to another aspect of the invention, there is provided a device management system, which comprises at least one first device connected to a network; an information processing device connected to the network; at least one second device connected to the information processing device; and a management device connected to the network. The management device comprises a request accepting unit configured to accept a request regarding management of one of the at least one first device and the at least one second device; and a controller that converts information inputted as the request through the request accepting unit to a command according to whether the request is targeted for the at least one first device or the at least one second device, and that transmits the command to one of the at least one first device and the information processing device according to whether the request is targeted for the at least one first device or the at least one second device. The information processing device comprises a command relaying unit configured to receive the command from the controller of the management device and to send the received command to the at least one second device. 
         [0018]    The above mentioned configuration for the management device eliminates the need for implementing a dedicated application (enabling the information processing device to support a network management protocol) on the information processing device. Therefore, it becomes possible to manage local devices on the management device in a concentrated manner. It is possible to appropriately manage the local and network devices while enabling a user to appropriately distinguish the local device from the network device. 
         [0019]    According to another aspect of the invention, there is provided a device management system, which comprises at least one first device connected to a network; an information processing device connected to the network; a plurality of second devices connected to the information processing device; and a management device connected to the network. The management device comprises a request accepting unit configured to accept a request regarding management of one of the at least one first device and the plurality of second devices; and a controller configured such that if one of the plurality of second devices is designated as a target device in the inputted request, the controller transmits a command corresponding to the request to the information processing device together with an identification of the target device. The information processing device comprises a command relaying unit configured to receive the command from the controller of the management device and to send the received command to the target device in accordance with the identification transmitted from the management device together with the command. 
         [0020]    Such a configuration makes it possible to manage local devices on the management device in a concentrated manner even if a plurality of second devices (e.g., a plurality of local printers) are connected to the information processing device. 
         [0021]    It is noted that various connections are set forth between elements in the following description. It is noted that these connections in general and unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. Aspects of the invention may be implemented in computer software as programs storable on computer-readable media including but not limited to RAMs, ROMs, flash memory, EEPROMs, CD-media, DVD-media, temporary storage, hard disk drives, floppy drives, permanent storage, and the like. 
     
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
         [0022]      FIG. 1  is a block diagram illustrating an entire configuration of a printer management system  100  according to an embodiment of the invention. 
           [0023]      FIG. 2  illustrates an example of a printer list screen displayed on a PC by a web browser running on the PC. 
           [0024]      FIG. 3  illustrates an example of a setting input screen displayed on the PC. 
           [0025]      FIG. 4  is a flowchart illustrating a process in which the web browser of the PC transmits a CGI parameter requesting change of setting information of target printing devices to a management application. 
           [0026]      FIG. 5  illustrates an example of a CGI parameter transmitted from the web browser of the PC during the process shown in  FIG. 4 . 
           [0027]      FIG. 6  is a flowchart illustrating a process executed by a CGI program “Wbcgi.exe” executed under control of the management application. 
           [0028]      FIG. 7  illustrates a data structure of a command table stored in a storage unit of a device management server. 
           [0029]      FIG. 8  is a flowchart illustrating a process which is executed by a relaying application when the relaying application receives a command packet from the device management server. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    Hereafter, an embodiment according to the invention will be described with reference to the accompanying drawings. 
         [0031]      FIG. 1  is a block diagram illustrating an entire configuration of a printer management system  100  according to an embodiment of the invention. As shown in  FIG. 1 , the printer management system  100  includes a device management server  1 , a PC (personal computer)  2 , PCs (personal computers)  3   a  and  3   b , an MFP (multifunction peripheral)  12   a  locally connected to the PC  3   a , a printer (local printer)  12   b  locally connected to the PC  3   a , an MFP (multifunction peripheral)  12   c  locally connected to the PC  3   b , an MFP (multifunction peripheral)  11   a , and a printer  11   b . The device management server  1 , the PCs  2 ,  3   a  and  3   b , the MFP  11   a , and the printer  11   b  are cummunicatably connected to a LAN (Local Area Network)  21 . 
         [0032]    The device management server  1  may be formed of a server having relatively high processing performance. As shown in  FIG. 1 , the device management server  1  includes a control unit  11  having a CPU, ROM and RAM, a storage unit  12  (i.e., a hard disk drive), an input unit  12  through which user instructions are inputted, and an output unit  13  through which information is outputted. The device management server  1  may be formed of a personal computer. 
         [0033]    Since the PCs  2 ,  3   a , and  3   b  have the same configuration, a detailed configuration is explained only for the PC  3   a  and explanations of configuration of the PCs  2  and  3   b  are not repeated. The PC  3   a  includes a control unit  31  (having a CPU, ROM and RAM), a display unit  32 , a USB interface  33 , a LAN interface  34 , an operation unit  35  (e.g., a keyboard and a mouse), and an HDD (functioning as a storage unit)  36 . 
         [0034]    The PC  2  is provided with a function as a web browser for browsing a web page. To the PC  3   a , the MFP  12   a  and the printer  1   b  are connected through the USB interface  33 . Device drivers for controlling the MFP  12   a  and the printer  12   b  are installed on the PC  3   a . To the PC  3   b , the MFP  12   c  is connected through the USB interface  33  of the PC  3   b . A device driver for controlling the MFP  12   c  is installed on the PC  3   b.    
         [0035]    A relaying application is installed on each of the PCs  3   a  and  3   b . On each of the PCs  2 ,  3   a  and  3   b , the relaying application is running continuously during a power-on state. The relaying application has a function of returning device information (e.g., a printer name and a serial number) of a printer locally connected to a PC ( 3   a  or  3   b ) on which the relaying application runs, to the device management server  1  which has transmitted an inquiry to the PC ( 3   a  or  3   b ), as a response to the inquiry. In addition, the relaying application has a function of transmitting a PJL command received from the device management server  1 , to a printer locally connected the PC on which the relaying application runs. Since the PCs  3   a  and  3   b  have the same function, each of the PCs  3   a  and  3   b  is generically called a PC  3 . 
         [0036]    Since the MFPs  11   a ,  12   a  and  12   c  have the same configuration and the same function, a detailed configuration is explained only for the MFP  12   a  and explanations of configuration of the MFPs  11   a  and  12   c  are not repeated. As shown in  FIG. 1 , the MFP  12   a  has a printing function, a copying function, a scanner function and a facsimile function. The MFP  12   a  includes a USB interface  121 , a control unit  122 , a recording unit  123 , a reading unit  124 , am operation unit (e.g., operation keys)  123 , a display panel  126 , a nonvolatile RAM  127  and a modem  128 . 
         [0037]    The control unit  122  includes a CPU, a ROM and a RAM, and controls internal components of the MFP  12   a . The recording unit  123  functions as a printing device which forms images on a recording medium (e.g., a sheet of paper). The reading unit  124  function as a scanner device which reads information from an original placed on a original base through an image pick-up device (e.g., a CCD) and generates image data of the image. 
         [0038]    The operation unit  125  includes keys through which user operation is conducted. Data (instructions or information) inputted by a user through the operation unit  125  is processed by the control unit  122 . The display panel  126  is, for example, a liquid crystal display, and is used to display information. The nonvolatile RAM is used to store various types of information to be used as setting for the various functions of the MFP  12   a . The modem  128  is connected to a PSTN (Public Switched Telephone Network) and is used to execute facsimile communication with an external facsimile device connected to the PSTN. 
         [0039]    Each of the printers  11   b  and  12   b  is configured to have a single printing function. As shown in  FIG. 9 , the printer  11   b  includes a control unit  111 , a recording unit  112 , a nonvolatile RAM  113 , a operation unit  114  (e.g., operation keys), a display panel  115 , and a communication interface (a LAN interface and a USB interface)  116 . These internal components of the printer  11   b  are also provided in the printer  12   b.    
         [0040]    Each of the MFP  11   a  and the printer  11   b  has a LAN interface as a communication interface. That is, each of the MFP  11   a  and the printer  11   b  is a network device connected directly to the LAN  21  via the LAN interface. Each of the MFP  11   a  and the printer  11   b  has a communication function supporting a SNMP (Simple Network Management Protocol) and has a function of functioning as an agent as a management target under the SNMP. The SNMP is a protocol for monitoring and controlling devices connected to a network. Each of management target devices has a MIB (Management Information base) in which information to be used under SNMP is described. A device functioning as a management device under the SNMP refers to the MIB of a target device and changes data of MIB of a target device on an as needed basis. In the printer management system  100 , the device management server  1  function as a management device under SNMP. 
         [0041]    Each of the MFPs  12   a  and  12   c  and the printer  12   b  has an USB interface as a communication interface. Each of the MFP  12   a  and the printer  12   b  is locally connected to the USB interface  33  of the PC  3   a , and the MFP  12   c  is locally connected to the USB interface of the PC  3   b . That is, each of the MFP  12   a  the printer  12   b  is a local device controlled by the PC  3   a , and the MFP  12   c  is a local device controlled by the PC  3   b . Since each of the MFPs  12   a  and  12   c  and the printer  12   b  has a printing function, each of the MFPs  12   a  and  12   c  and the printer  12   b  is frequently referred to as a local printer hereinafter. These local printers support PJL (Printer Job Language). PJL is a command language for controlling various functions implemented in printers (e.g., the MFPs  12   a  and  12   c  and the printer  12   b ). 
         [0042]    Since the MFP  11   a  and the printer  11   b  are directly connected to the LAN  21 , these devices are frequently referred to as network printers hereinafter. In the following, the term “printing device” as used herein means a device having a printing function (i.e., the local and network printers are generally called “printing devices”). 
         [0043]    As described in detail below, the device management server  1  has a function of managing device information (information on a device). The managing of device information includes obtaining device information from a management target and changing device information of a management target. 
         [0044]    On the device management server  1 , a management application is running as one of application programs. The management application has a function of collecting device information of the network printers (i.e., MFP  11   a  and the printer  11   b ) and the local printers (i.e., the MFPs  12   a  and  12   c  and the printer  12   b ), generating printer management information based on the collected device information, and providing the printer management information to the PC  2  in the form of a web page. The management application further has a function of accepting a request regarding management of each printing device inputted by an administrator through a form described in the web page, and generating a management command corresponding to the request, and transmitting the management command to a management target. 
         [0045]    The management application has a GUI (Graphical User Interface) used for a printer management screen. The GUI includes a screen for displaying device information concerning printing devices (see  FIG. 2 ) and an input screen through which setting information for printing devices is inputted (see  FIG. 3 ). The GUI is generated in the form of a web page described by an HTML (HyperText Markup Language). The web page is provided for the PC  2 , and is displayed on the display unit of the PC 2  by a web browser running on the PC  2 . 
         [0046]    In the printer management system  100 , the administrator is allowed to access the management application running on the device management server  1  through the web browser of the PC  2  so that management of printing devices can be achieved through the screens (see  FIGS. 2 and 3 ) displayed on the PC  2  as web pages. 
         [0047]    Hereafter, one of functions to be achieved by the management application is described. In the following, a procedure for changing setting information of printing devices by the administrator is described. 
         [0048]    When the administrator instructs the management application running on the device management server  1  to search for printing devices existing on the network (i.e., the LAN  21 ), the management application collects device information on printing devices on the network. 
         [0049]    The collection of the device information on printing devices is performed as follows. regarding network printers, the management application transmits an SNMP command requesting for transmission of an address by broadcast for all the network printers. After receiving addresses of network printers, the management application transmits a SNMP command requesting for detailed information to a target network printer. The targeted network printer returns a response to the management application. Thus, the management application collects the device information on targeted network printers. The communication between the device management server  1  and the network printer may be executed under a standard protocol based on an RFC (Requests For Comments) 1157. 
         [0050]    Regarding local printers, the management application transmits a command requesting for detailed information on a local printer to the PC  3   a  or  3   b  by broadcast so that device information on local printers can be collected and the collected information can be displayed on the device management server  1 . In this phase, the relaying application running on the PC  3   a  or  3   b  receives the command from the device management server  1 , and obtains information on a connection port of a printer driver installed on the PC ( 3   a  or  3   b ) and a model name of a local printer directly connected to the PC ( 3   a  or  3   b ). The relaying application then obtains a serial number of a local printer through the printer driver, and returns the obtained information to the device management server  1  together with its own name, IP address and MAC address. The communication between the device management server  1  and the PC  3   a  or  3   b  may be executed under one of standard protocol based on an RFC (Requests For Comments). A protocol to be used may be determined by negotiation between the device management server  1  and the PC ( 3   a  or  3   b ). 
         [0051]    Based on the device information on printing devices collected as described above, the management application generates a web page for displaying device information, and transmits the web page to web browser of the PC  2  under HTTP (HyperText Transfer Protocol). 
         [0052]    The web browser displays a printer list screen  31  (see  FIG. 2 ) based on data of a web page for processing device information on printing devices. As shown in  FIG. 2 , on the printer list screen  31 , an icon ( 32   a  to  32   e ), a device type, a connection type (local connection/network connection), an IP address of a HOST computer are displayed for each of the printing devices. The printer list screen  31  is configured such that the administrator is able to designate a target printing device (for which the administrator wants to change device information) by moving a cursor to an icon ( 32   a  to  32   e ) of the target printing device and pressing (clicking) a button using a pointing device. It is also possible to designate more than one printing device on the printer list screen  31 . 
         [0053]    After the target printing device is designated, the web browser of the PC ( 3   a  or  3   b ) provides information for designation target printing devices for the management application running on the device management server  1 . The management application then obtains a list of target printing devices from the information provided by the web browser, and generates data of a web page for displaying an input screen through various types of setting information for each of target printing devices can be inputted. The generated data is then transmitted to the web browser on the PC  2  under HTTP. The above mentioned sequence of data transmission can be achieved, for example, by a CGI (Common Gateway Interface). 
         [0054]    Under control of the web browser of the PC  2 , a setting input screen  41  is displayed on the PC  2  based on the data of the web page for displaying an input screen received from the management application. As shown in  FIG. 3 , the setting input screen  41  includes a list  42  of the target printing devices designated on the printer list screen  31 , a form  43  for inputting setting information for each of the target printing devices. The form is described by HTML. 
         [0055]    As shown in  FIG. 3 , the form  43  includes a pull-down menu, a radio button, and a text box for each of setting items of “Emulation”, “Feeder”, “Duplex Mode”, “Duplex Binding”, etc. The administrator is allowed to change data of the form by using a keyboard and a pointing device (provided in the operation unit), and is allowed to request the management application to apply change of the setting information for all of the target printing devices displayed on the target printer list  42  at a time. 
         [0056]    A unique ID is assigned to each of the setting items. Therefore, when a “Submit” button  44  is pressed, the web browser generates a CGI parameter representing an ID number of setting items for which the setting information is changed and changed setting values, and to transmit the CGI (Common Gateway Interface) parameter to a CGI program of the management application so as to activate the CGI program. 
         [0057]      FIG. 4  is a flowchart illustrating a process in which the web browser of the PC  2  transmits a CGI parameter requesting change of setting information of target printing devices to the management application. When the “Submit” button  44  is pressed, the web browser judges whether there is a setting item for which setting information is changed (step S 10 ). If no item for which setting information is changed is found (S 10 : NO), the process terminates. If a setting item for which setting information is changed is found (S 10 : YES), an ID number of the setting item and a CGI parameter representing a changed value of the setting item are transmitted to the management application of the device management server  1  (step S 20 ). 
         [0058]      FIG. 5  illustrates an example of a CGI parameter transmitted from the web browser of the PC  2  during the process shown in  FIG. 4 . More specifically, the CGI parameter shown in  FIG. 5  is an example of a CGI parameter generated to change setting information of the setting item “Power Save” used to designate a waiting time that elapses until the printing device moves to a power saving mode. 
         [0059]    If the standby time is set for five minutes, the administrator inputs “5,” to the text input box  43   a  of the setting input screen  41  using, for example, the keyboard. Then, the administrator presses “Submit” button  44 . When the “Submit” button  44  is pressed, the web browser generates the CGI parameter configured such that the ID number assigned to the setting item of “Power Save” and the changed setting value are combined. 
         [0060]    In the example shown in  FIG. 5 , an ID number (GUIID)  008  is assigned to the setting item “Power Save”. Consequently, a CGI parameter “Webcgi.exe?GUIID008=5” is generated. The CGI parameter “Webcgi.exe?GUIID008=5” means that the ID number “008” and the setting value “5” are passed to a CGI program “Webcgi.exe” to be executed under control of the management application of the device management server  1 . 
         [0061]    When the management application received the CGI parameter requesting the change of the setting information of the printing device, the management application executes the CGI program “Webcg.exe” reflecting the CGI parameter. 
         [0062]      FIG. 6  is a flowchart illustrating a process executed by the CGI program “Wbcgi.exe” executed under control of the management application. As shown in  FIG. 6 , when the management application receives the CGI parameter requesting the change of the setting information of the printing device from the web browser of the PC  2 , the ID number and the setting value are extracted from the CGI parameter (step S 110 ). Based on the ID number obtained in step S 110 , the management application searches a command table  51  (see  FIG. 7 ) for a command matching the ID number (step S 120 ). 
         [0063]      FIG. 7  illustrates a data structure of the command table  51  stored in the storage unit  12  of the device management server  1 . As shown in  FIG. 7 , the command table  51  is a database in which a command for changing setting information used for a network printer and a command for changing setting information used for a local printer are associated with an ID number for each of the setting items. More specifically, the command table  51  stores, for each of the ID numbers, an MIB object used under SNMP as a command supporting a network printer, and a PJL command (a command described by PJL) as a command supporting a local printer. 
         [0064]    The OID of the MIB means an identifier assigned to each of pieces of information stored in the MIB of the SNMP agent (i.e., the network printer). The SNMP manager (i.e., the management application) is able to obtain and change an object corresponding to a designated OID by communicating the agent to designate the OID. 
         [0065]    Referring back to  FIG. 6 , after searching the command table in step S 120 , the management application selects one printing device (i.e., an unprocessed printing device) from the targeted printing devices, and reads information of the selected device from the table (step S 130 ). Then, the management application judges whether the selected printing device is a network printer or a local printer (step S 140 ). 
         [0066]    If the selected printing device is a network printer (S 140 : “network printer”), the management application reads OID of the selected from the filed of the command searched for in step S 120  (step S 150 ). Then, the management application writes the OID and the setting value in a packet (hereafter, referred to as “SetRequest packet”) used for transmitting a management command “SetRequest” which is one of management commands under SNMP (step S 160 ). The “SetRequest” is a command requesting for change of information of the object corresponding to the designated OID. 
         [0067]    Next, the management application transmits the Setrequest packet to the address of the targeted network printer. (step S 170 ). It should be noted that the sequence of steps S 150  to S 170  is based on management of network devices under SNMP. 
         [0068]    When the network printer receives the SetRequest packet from the device management server  1 , the network printer changes information of the object of MIB to the designated setting value based on the OID and the setting value contained in the received packet. Thus, the change of setting information for the network printer is achieved. 
         [0069]    For example, change of setting information for a network printer is performed as follows. When a value of the setting item “Power Save” is changed to 5 on the setting input screen  41 , an OID  52  “1.3.6.1.4.12435.2.3.9.4.2.1.0.1.1.1.0” corresponding to an ID number 008 of a setting item “Power Save” is read from the command table  51  (see  FIG. 7 ). The OID 52  is an identifier of an object defining a waiting time that elapses until a printing device moves to a power saving mode. Then, the OID 52  and the setting value “5” are included in a SetRequest packet requesting for change of the waiting time, and the SetRequest packet is sent to the targeted network printer. 
         [0070]    Referring back to  FIG. 6 , if it is judged in step S 140  that the selected printing device is a local printer (S 140 : “local printer”), a PJL command is read from the field of the command searched for in step S 120  (step S 180 ). Then, the setting value is included in the PJL command (step S 190 ). 
         [0071]    Next, the management application writes the PJL command to which the setting value is added and serial number of the selected local printer in a packet (hereafter, referred to as a command packet) used for transmitting a management command to the relaying application of the PC  3  to which the targeted local printer is connected (step S 200 ). Then, the management application transmits the command packet to the relaying application of the PC  3  to which the targeted local printer is connected (step S 210 ). 
         [0072]    For example, change of setting information for a local printer is performed as follows. When a value of a setting item “Power Save” is changed to “5” on the setting input screen  41 , a PJL command  53  “@PJL SET POWERSAVETIME=” corresponding to an ID number 008 of the setting item “Power Save” is read from the command table  51  (see  FIG. 7 ). The PJL command  53  is a PJL command for defining a waiting time that elapses until a printing device moves to a power saving mode. In this case, the setting value “5” is set to the PJL command  53 . That is, a character string “@PJL SET POWERSAVETIME=5” is created. 
         [0073]    Next, the PJL command  53  to which the setting value “5” is set and serial number of the targeted local printer are included in the command packet for transmitting the management command to the relaying application of the PC  3 . Then, the command packet is transmitted to the relaying application of the PC  3  to which the targeted local printer is connected. 
         [0074]    Referring back to  FIG. 6 , after transmitting the packet of the management command in step S 170  or S 210 , the management application judges whether the transmission of the management command is completed for all of the printing devices included in the list of the targeted printing devices (step S 220 ). If all the targeted printing devices have not been processed (S 220 : NO), control returns to step S 130  to processes a next unprocessed printing device. If all of the targeted printing devices have been processed (S 220 : YES), the process of “Webegi.exe” terminates. 
         [0075]      FIG. 8  is a flowchart illustrating a process which is executed by the relaying application when the relaying application receives a command packet from the device management server  1 . When the relaying application receives a command packet from the device management server  1 , the relaying application reads a serial number of a targeted printing device from the received command packet (step S 210 ). Then, the relaying application judges whether a printing device matching the read serial number is connected to the PC on which the relaying application runs (step S 220 ). 
         [0076]    If the relaying application judges that a printing device matching the serial number is connected to the PC on which the relaying application runs (S 220 : YES), the relaying application reads a PJL command from the command packet and sends the PJL command to the targeted printing device (step S 230 ). Then, the process terminates. 
         [0077]    The local printer which received the PJL command from the relaying application changes its setting information to the value designated by the PJL command. The change of setting information for a local printer is thus achieved. 
         [0078]    If it is judged in step S 220  that a printing device matching the serial number is not connected to the PC on which the relaying application runs (S 220 : NO), the process terminates. 
         [0079]    In the above mentioned process executed by the relaying application, the PJL command is transmitted only to a local printer matching the serial number designed by the command packet even if more than one local printer is connected to the PC on which the relaying application runs. 
         [0080]    As according to the embodiment, there is no need to cause the PC  3   a  or  3   b  (to which a local printer is connected) to function as a management target device under SNMP. In other words, the PC to which a local printer is connected is not required to have a dedicated application functioning to enable the PC to which a local printer is connected to support SNMP. 
         [0081]    The device management server  1  stores commands (OIDs) for network printers and PJL commends for local printers in the command table  51  such that an OID and a PJL command are associated with an ID of corresponding setting item. Further, the device management server  1  reads the OID or the PJL command from the command table  51  in accordance with the type of a printing device (local printer or network printer) and generates the management command to transmit the command. With this configuration, it is possible to appropriately apply changed setting information to a targeted printing device regardless of whether the targeted printing device is a network printer or a local printer. That is, it is possible to appropriately manage the local and network printers while enabling the administrator appropriately distinguishing the local printer from the network printer. 
         [0082]    When the device management server  1  transmits the management command to be applied to a local printer, the device management server  1  transmits the PJL command to the PC  3   a  or  3   b  together with the serial number of the targeted local printer. Therefore, the PC  3   a  or  3   b  is able to identify a targeted local printer to which the setting information is to be applied through use of the serial number. Such a configuration makes it possible to cause only an appropriate PC selected from one or more PCs to execute the PJL command. Consequently, even if more than one local printer is connected to the PC  3   a  or  3   b , the device management server  1  is able to change setting information only for a targeted local printer. 
         [0083]    As described above, the printer list screen  31  is generated based on information on printing devices collected by the device management server  1  and the printer list screen  31  is provided for the PC  2  in the form of a web page. Since the information indicating whether a printing device is a local printer or a network printer is displayed on the web browser on the PC 2 , the administrator is able to easily recognize a targeted printing device is a local printer or a network printer. 
         [0084]    Since the administrator is able to select more than one printing device as a target through the printer list screen  31 , the administrator is able to request change of the settings for all of the targeted printing devices at a time. 
         [0085]    Although the present invention has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. 
         [0086]    For example, although in the above mentioned embodiment the administrator accesses the device management server  1  from the PC  2  and management of printing devices is achieved through the printer list screen  31  or the setting input screen  41  displayed on the PC  2  by the web browser, the printer management system  100  may be configured such that the administrator is allowed to directly manage the printing devices through the device management server  1 . In this case, the GUI screens (e.g., the printer list screen  31  or the setting input screen  41 ) are displayed on the display of the device management server  1  and the administrator is able to directly operate the device management server  1  to manage the printing devices.