Abstract:
Managing a plurality of network devices on a network by detecting the presence of at least one of the plurality of network devices on the network by using a first communication protocol, obtaining, by using the first communication protocol, an information block from each of the detected network devices, wherein the information block contains information related to the corresponding network device, formatting each information block into a directory entry, and sending each directory entry to a directory server via a second communication protocol.

Description:
This application is a division of application Ser. No. 09/661,030, filed Sep. 13, 2000, the contents of which are incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention concerns the use of a directory-enabled server to monitor and manage devices on a network enterprise. Specifically, the invention relates to the use of an LDAP directory proxy to detect and interface with legacy devices in order to incorporate such legacy devices into the directory-enabled server network management scheme. 
   2. Description of the Related Art 
   Typically, computing network environments are comprised of numerous computing devices, such as workstations and servers, and other network devices, such as printers, scanners, and the like. Maintaining and administrating these numerous computing devices and network devices in a networked environment usually requires a significant amount of time and effort by a network administrator. For example, a network administrator typically configures each network device for integration into the network by setting appropriate network information such as a server domain name and an IP (Internet Protocol) address corresponding to the network device. The network administrator also configures each network device according to its capabilities and according to the desired functionality of the network device in the networked environment. 
   Unlike a simple personal computer having an operating system with plug-and-play capability which can automatically recognize and configure a local peripheral, a networked environment typically requires the network administrator to manually connect and configure each new device that is added to the network. In addition, network configurations can change frequently as new network devices are connected and as existing network devices are moved around within the network. In addition, a given network device may need to be reconfigured by the network administrator in order the change the network-accessible functionality of the network device according to the needs of the network users. For example, the sorting capability of a network printer may initially have been made unavailable by the network administrator because sorting is time consuming and the printer is located in a busy office area. If the printer is later moved to a less busy office location in which sorting is desired, the network administrator would have to reconfigure the network printer in order to support the sorting capability. A network device would also be reconfigured when a new option is installed on a network device, such as the installation of an envelope feeder on a network printer. Accordingly, it can be appreciated that the level of effort required by the network administrator to configure and maintain the network devices on a network increases dramatically with the number of network devices on the network. 
   The administration of each network device by the network administrator is often performed locally at the location of the network device. One conventional administrative technique is for the network administrator to enter and/or select network settings and capabilities of a network device from a user interface of the network device, such as a front panel and/or keypad. Another known technique is for the network administrator to use a standardized network administration tool for remotely accessing a particular network device in order to enter and select the network settings and capabilities for the network device. For example, the network administrator may use a centralized SNMP tool to remotely access a network printer via the SNMP protocol in order to change its IP Address or to change one of its functional options, such as sorting. 
   Regardless of the whether the settings and capabilities of a network device are entered in the network device locally or remotely by the network administrator, the selected settings and capabilities of the network device are also typically entered by the network administrator into a centralized network location, such as a network configuration file on a network server, to publish the network settings and capabilities of the network device for access by other network devices on the network. In this manner, other network devices can become aware of, and can utilize, the shared network functionality of each particular network device. Of course, it can be appreciated that problems can arise if the configured settings and capabilities of the network device do not actually correspond to the published settings and capabilities of the network device. If the published IP address of a given network device does not match the actual IP address which was set in the network device, other network devices will be unable to access and utilize the given network device via the network. 
   In addition, a user at a workstation may read from the published capabilities of a network printer that it supports printing on legal-size paper and then try to send a print job to the network printer which requires legal-size paper, when the network printer actually only supports printing on standard, letter-size paper. Accordingly, the detailed and duplicative network administration tasks of configuring each network device and of entering the configured settings and capabilities of each network device into a centralized network location can become overwhelming and can result in synchronization errors between the data in the centralized network location and the actual configuration of the corresponding network device. It can be appreciated that the frequency of such discrepancies increases dramatically with a large number of network devices on the network. 
   One solution to the aforementioned administration problems is reflected in the recent trend towards the use of directory servers for maintaining and managing network devices within a network enterprise. Such directory-enabled management tools use a directory structure for the centralized network location in which to store and maintain the selected network settings and capabilities corresponding to each network device in the network enterprise. A separate entry is provided within the directory structure to contain the aforementioned information related to each network device. The entries are organized in the directory structure in a hierarchical fashion wherein the directory structure has separate branches for each type of network device. For example, the directory structure would have a branch for network printers, a branch for network computers and other branches for other types of network devices, wherein the branch for network printers has a sub-branch for ink jet printers, a sub-branch for laser jet printers and a sub-branch for dot matrix printers. The sub-branch for ink jet printers would have a plurality of entries for storing the selected settings and capabilities corresponding to each of the ink jet printers on the network. 
   Preferably, a standardized schema is utilized to define the format for each entry in the directory structure, thereby providing a uniform format for containing the network settings and capabilities of each network device. In this manner, the directory structure residing on a directory-enabled server provides a centralized location in which the network settings and capabilities of each network device is published for access by all other network devices. Access to such directory-enabled servers is typically implemented via some type of standardized directory protocol for efficient publication and retrieval of information to and from the directory structure. Examples of such protocols are the x.500 directory access protocol and its lightweight relative, the Lightweight Directory Access Protocol (LDAP). The use of such a directory-enabled server to maintain and manage network devices in a network enterprise provides a very efficient network management scheme when coupled with a directory-enabled management tool which provides an interface for a user, such as a network administrator, to access and modify the information in the directory structure of the directory-enabled server. Such a directory-enabled management scheme would preferably utilize LDAP over x.500 for a communication protocol with the directory-enabled server because LDAP generally creates less network traffic than x.500. 
   The use of a directory-enabled network management scheme can significantly reduce the time and complexity required for the network administration of all network devices on a network enterprise. For example, a directory-enabled management tool can utilize standard directory functions such as complex queries, batch mode operations, and generalized entry modifications, in order to manage and modify entries within the directory structure of the directory-enabled server on a large scale. Therefore, network devices in a network enterprise having a directory-enabled server can be centrally managed and accessed anywhere on the network by accessing the directory-enabled server with a directory-enabled client, such as a directory-enabled management tool. 
   For example, a network administrator can efficiently access and modify a common group of network devices via directory query and modify commands from a remote location via the internet. It can be appreciated that such network management capabilities can greatly increase the efficiency of network management in large-scale network environments. In addition, directory-enabled network management schemes provide for the extension of the capabilities of the network devices over a larger network enterprise, such as the internet. Accordingly, it can be appreciated that a large-scale network enterprise may have several directory-enabled servers distributed across various networks which comprise the overall network enterprise, in order to manage the network enterprises within the domain of each particular network. 
   The trend towards the use of directory-enabled servers for network management has been reflected in the efforts of the Desktop Management Task Force (DMTF), and specifically in the Directory Enabled Network (DEN) initiative and the Common Information Model (CIM) initiative. These efforts have focused on the broad concept of using directory structures for the management of network devices on a network, and on creating a common data format for representing network elements on a network within the data structure of a directory-enabled server. The DMTF, DEN and CIM initiatives, however, have not provided solutions to the problems associated with implementation of a directory structure for managing network devices in a network enterprise. Specifically, the use of a directory-enabled server to manage network devices raises problems similar to those of the traditional approach to network management regarding how the information related to each network device is entered and maintained in the directory structure. It is desirable to reduce the effort required by a network administrator to enter and update information related to each network device within the directory structure. Accordingly, an implementation of a directory-enabled network management scheme is needed which provides a mechanism for efficient publication of entries corresponding to each network device into the directory structure. 
   In addition, problems can arise with the use of a directory-enabled network management scheme when mismatches occur between the actual network settings and capabilities of the network device and the published network settings and capabilities in the entry of the data structure corresponding to the network device. These mismatches can occur because changes to the network settings and capabilities of the network device may be made manually at the network device, via a conventional SNMP network management tool, or may be made directly to the entry in the directory structure by a user, such as a network administrator. Accordingly, an implementation of a directory-enabled management scheme is needed which provides reliable synchronization between the network settings and capabilities published in the entry of the directory structure and those of the network device itself, regardless of where the changes to the settings are made. 
   Lastly, the implementation of a directory-enabled network management scheme generally assumes that all network devices in the network enterprise are directory-enabled in order to support the directory-enabled server. For this assumption to be correct, each network device must have the ability to communicate via the selected directory protocol, such as LDAP, and must also have appropriate logic in order to support the directory-enabled management functions. Such a network management scheme does not take into account the large number of legacy network devices currently in use which do not have the capability to communicate using a directory protocol, such as LDAP, and which to not have logic incorporated to support such directory-enabled network management functions. Given that these legacy devices will still be useful for many years to come, it is preferable for a directory-enabled network management scheme to accommodate such legacy devices in a mixed, heterogeneous, network enterprise which includes both directory-enabled network devices and legacy devices. Accordingly, a directory-enabled network management scheme is desired which resolves the foregoing problems. 
   SUMMARY OF THE INVENTION 
   The present invention addresses the foregoing problems by providing a directory-enabled network management scheme in which legacy devices are automatically discovered, and information related to the settings and capabilities of each legacy network device is obtained by utilizing the legacy protocol, such as SNMP. The set of information corresponding to each legacy network device is then formatted into a data entry and the data entry is forwarded to a directory server via a directory communication protocol, such as LDAP. The directory-enabled network management scheme of the present invention provides for synchronization of the settings and capabilities of each network device with the corresponding entry in the directory server by monitoring for changes in both the network devices and their corresponding directory entries. In this manner, a directory-enabled network management scheme is provided which reduces the effort required by a network administrator to manage the network devices, and which manages a heterogeneous network enterprise having both directory-enabled network devices and legacy network devices. 
   Accordingly, one aspect of the invention concerns the management of a plurality of network devices on a network by detecting the presence of at least one of the plurality of network devices on the network by using a first communication protocol, obtaining, by using the first communication protocol, an information block from each of the detected network devices, wherein the information block contains information related to the corresponding network device, formatting each information block into a directory entry, and sending each directory entry to a directory server via a second communication protocol. 
   Preferably, the communication protocol used to communicate with the directory server is LDAP, and the communication protocol for communicating with the legacy network devices is SNMP. In addition, the information block from each of the detected network devices preferably includes network setting data, such as an IP address, in addition to network capabilities, such as print speed, paper types and the like. The format of each directory entry is preferably a standardized schema for consistency among directory entries. 
   By virtue of the foregoing, a directory-enabled network management scheme is provided which supports both legacy network devices and directory-enabled devices in a network enterprise. In this manner, the present invention provides a directory proxy which extends LDAP support to the legacy network devices for inclusion in the directory-enabled network management scheme. In addition, synchronization capability provides for reliable consistency between the settings and capabilities of each network device and the settings and capabilities published in the corresponding directory entry. 
   According to another aspect, the invention concerns the management of a plurality of network devices on a network by detecting the presence of at least one of the plurality of network devices on the network by using a first communication protocol, obtaining, by using the first communication protocol, an information block from each of the detected network devices, wherein the information block contains information related to the corresponding network device, formatting each information block into a separate directory entry, and sending each directory entry to a directory server by using a second communication protocol. The management further includes monitoring, by using the first protocol, each of the detected network devices for an update of the information in the information block of the network device, and obtaining, in the case that the information in the information block of one of the detected network devices has been updated, the updated information of the information block from the corresponding network device by using the first communication protocol, and sending the updated information to the directory server by using the second communication protocol for placement into the directory entry for the corresponding network device. In addition, the management includes monitoring, by using a third communication protocol, for issuance of an update message from the directory server indicating that a directory entry has been updated in the directory server, and obtaining, in the case that an update message is issued, the updated directory entry from the directory server by using the second communication protocol, extracting updated data from the updated directory entry, and sending the updated data to the network device which corresponds to the updated directory entry for placement into the information block of the corresponding network device. 
   Preferably, the communication protocol used to communicate with the directory server is LDAP, and the communication protocol for communicating with the legacy network devices is SNMP. In addition, the information block from each of the detected network devices preferably includes network setting data, such as an IP address, in addition to network capabilities, such as print speed, paper types and the like. The format of each directory entry is preferably a standardized schema for consistency among directory entries. In addition, the monitoring of the detected network devices for updated information is preferably performed on a frequent basis. Lastly, the issuance of an update message from the directory server is preferably provided by a directory plug-in which issues an update message using a standard IP protocol. 
   By virtue of the foregoing, a directory-enabled network management scheme is provided which supports both legacy network devices and directory-enabled devices in a network enterprise. In this manner, the present invention provides a directory proxy which extends LDAP support to the legacy network devices for inclusion in the directory-enabled network management scheme. In addition, synchronization capability provides for reliable consistency between the settings and capabilities of each network device and the settings and capabilities published in the corresponding directory entry. 
   This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiment thereof in connection with the attached drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an view of a network system in which the invention may be employed. 
       FIG. 2  depicts an architecture of communication between devices on the network of  FIG. 1 . 
       FIG. 3  depicts an internal architecture of a server shown in  FIG. 1 . 
       FIG. 4  depicts an architecture of a directory server that utilizes plug-ins. 
       FIG. 5  depicts a more detailed configuration of the internal architecture of a directory proxy and its communication with various devices on the network. 
       FIG. 6  is a flowchart of process steps for the management of changes to the configuration of the devices on the network of  FIG. 1 . 
       FIG. 7  is a flowchart of process steps for a discover module of a directory proxy. 
       FIG. 8  is a flowchart of process steps for a monitoring/polling module of a directory proxy. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  depicts a network environment in which the invention may be employed. As seen in  FIG. 1 , network  10  may include servers  11  and  12 , client workstation  13 , and peripheral devices  14 ,  15 ,  16  and  17  connected to network  18 . Network connection  18  may be a local area network (LAN), a wide area network (WAN), or any other type of network. Of course, the invention is not limited to the network shown in  FIG. 1  and many other devices may be included within the network environment. For instance, network  10  may include routers, additional computer workstations, additional servers, and additional peripheral devices. Therefore, since virtually an unlimited number of devices could be included within network  10 ,  FIG. 1  merely depicts a few of the devices that may be included for the sake of brevity. 
   Client workstation  13  is preferably a computer workstation and may be, for example, an IBM-compatible personal computer, a Macintosh personal computer, a UNIX workstation, a Sun MicroSystems workstation, or any other type of workstation. Client workstation  13  preferably includes an LDAP client application program that allows users to access a directory server application program in servers  11  and/or  12 , and to make changes in the directory server application (hereinafter referred to as a “directory server”. Some examples of directory server application programs are Microsoft Active Directory Server, Netscape Directory Server and Novell Directory Server. Of course, these are merely examples of some directory server application programs that may be utilized in practicing the invention and the invention is not limited to these particular applications, but may be implemented with any directory server application. Client workstation  13  is also preferably capable of communication utilizing a TCP/IP protocol. As will be described below, TCP/IP is utilized for receiving multicast messages that are multicast by a plug-in in the directory server. 
   The LDAP client application program in client workstation  13  communicates with the directory server application running in servers  11  and  12  via network  18 . Communication between client workstation  13  and the directory server in servers  11  and  12  will be described in more detail below with regard to  FIG. 3 . Additionally, the LDAP client application program receives and processes multicast messages that are multicast by a multicast plug-in of the directory server in servers  11  and  12 . It should be noted that the LDAP client application in client workstation  13  may be configured to either allow a user to make changes in the directory server, but not to receive multicast messages from the multicast plug-in, to only receive multicast messages from the multicast plug-in, but not to allow a user to make changes in the directory server, or to allow user to make changes in the directory server and to also receive multicast messages. Additionally, it is not necessary that the LDAP client application in client workstation  13  correspond to the directory server application in servers  11  and  12  in order for the LDAP client application to be able to make changes in the directory server. That is, if the directory server application in servers  11  and  12  is Netscape Directory Server, the LDAP client application in client workstation  13  does not have to be a Netscape Directory Server LDAP client in order for a user to make changes in the directory server. Since the communication between the LDAP client and the directory server is being performed with the LDAP protocol, any LDAP client application could be utilized in client workstation  13  to make changes in the Netscape Directory Server in servers  11  and  12 . 
   An LDAP client application in client workstation  13  is not the only way to make changes in the directory server application in servers  11  and  12 . Changes could also be made in the directory server in servers  11  and  12  via a native application in servers  11  and  12  themselves. Additionally, changes could be made by an embedded LDAP client within a device on the network, or via a directory proxy. Accordingly, the invention does not require that changes be made in the directory server by an LDAP client application in client workstation  13  and it is an object of the invention to manage communication between various different types of devices on the network and the directory server for changes made in the directory server. 
   Peripheral devices  14 ,  15 ,  16  and  17  may be any type of peripheral device that may be included within network  10 . That is, they may be printers, copiers, facsimiles, routers, etc., and although  FIG. 1  depicts them as being printers and copiers, they are not limited to such. However, for the sake of brevity, peripheral devices  14 ,  15  and  16  will be described as printers and peripheral device  17  will be described as a network copier. 
   It can readily be recognized that various types of printers and copiers may be included within network  10 . For instance, network  10  may include some printers that include newer network communication technology and some that include older network communication technology. That is, some of the printers may include the latest technology that provides the ability to communicate with the directory server directly. This type of printer may include an embedded LDAP client. On the other hand, some of the printers on the network may be older printers, such as a legacy printer, that communicate via SNMP and do not have the ability to communicate with the directory server directly. As such, this type of printer may require an intermediary device to be able to communicate with the directory server utilizing the LDAP protocol. Moreover, some of the printers on the network may be hybrid devices that include both an embedded LDAP client that can communicate directly with the directory server utilizing the LDAP protocol, and also include an SNMP client that requires an intermediary for communicating with the directory server. For the sake of brevity, in network  10 , printer  14  is assumed to be a printer that includes an embedded LDAP client that communicates directly with the directory server, printer  16  and copier  17  are assumed to be a legacy printer and a legacy copier, respectively, and therefore communicate utilizing SNMP, and printer  15  is assumed to be a hybrid printer that includes an embedded LDAP client and also communicates utilizing SNMP. 
     FIG. 2  depicts an architecture of the communication protocols between each of devices  13  to  17  and the directory server in, for example, server  11 . As seen in  FIG. 2 , directory server  25  communicates with LDAP client  27 , embedded LDAP client device  28 , directory proxy  29 , and hybrid device  31  utilizing the LDAP protocol. LDAP client  27  may be, for example, an LDAP client application as described above running in client workstation  13 . Thus, LDAP client  27  communicates directly with directory server  25  for making changes in the directory server. Embedded LDAP client  28  and hybrid device  31  may be printers, such as printers  14  and  15  respectively, that each include an embedded LDAP client. One difference between embedded LDAP client  28  and hybrid device  31  may be that hybrid device  31  also includes the capability of performing communication via SNMP while embedded LDAP client  28  communicates via LDAP alone. Directory proxy  29  communicates with directory server  25  via LDAP for making changes in directory server  25  and acts as an intermediary, or translator between SNMP device  30  and hybrid device  31  with directory server  25 . Directory proxy  29  will be discussed in more detail below. 
   Directory server  25  also includes plug-ins  26  and  40  to  43 . Plug-in  26  is a notification plug-in and will be described in more detail below, but briefly, notification plug-in  26  is called by directory server  25  whenever a change is made in directory server  25 . When the notification plug-in is called, it manages notification processes for notifying the appropriate devices on the network of the change. For instance, notification plug-in  26  may send out a unicast message to LDAP enabled devices on the network, or it may call one of the multicast plug-ins ( 40  to  43 ) for sending a multicast message. When multicast plug-ins  40  to  43  are called by notification plug-in  26 , they generate an information packet about the change made in directory server  25  and multicast the packet to a multicast IP address. Multicasting and unicasting will be described in more detail below. 
     FIG. 3  depicts a more detailed view of the internal architecture of server  11 . Server  12  may be similar to server  11  and for brevity, only server  11  will be discussed. Server  11  may be a server such as a Compaq Prosignia server or any other type of server. However, server  11  does not have to be a server per se, but may be any computer that is capable of running a directory server application program. As shown in  FIG. 3 , server  11  is connected to network  18  by connection  19  which is interfaced to network interface  35 . Network interface  35  is preferably a network card which controls transmission and reception of information by server  11  over the network. Interfaced with network interface  35  is TCP/IP layer  36 . TCP/IP is the preferred protocol for performing unicasting and multicasting, but any other protocol could be used instead. For a better understanding of unicasting and multicasting using TCP/IP, consider the following. 
   There are generally three different categories of IP addresses: communication, broadcast and multicast. For the present discussion, only communication and multicast are pertinent and therefore, a discussion of broadcast will be omitted. For communication, a range of IP addresses are assigned that are utilized to specifically identify each device on the network. For example, each device attached to the network shown in  FIG. 1  would be assigned a different IP address that identifies that device on the network. Each device may be manually assigned an IP address that it maintains, or an IP address may be automatically assigned by an application program each time the device is connected to the network. Therefore, in performing unicasting, the IP address of each device that is to receive an information packet from the directory server plug-in  26  is setup in the plug-in configuration. As such, when the notification plug-in generates an information packet after a change has been made in the directory server, it transmits the packet to each device on the network that has been setup in the notification plug-in configuration. 
   In multicasting, a range of IP addresses are assigned in which messages transmitted to one of the IP addresses are received only by members who have registered with the IP address. Unlike the communication IP addresses, the IP addresses in the multicast range are not assigned to a specific device. Rather, they are virtual addresses that represent a multicast group that receives messages sent to it and which then distribute the received messages to members who have registered with the group. Thus, information packets are multicast by the directory server multicast plug-ins to a designated multicast group whereby they are distributed to registered members of the group. 
   Returning to  FIG. 3 , interfaced to TCP/IP layer  36  is LDAP protocol layer  37 . LDAP protocol layer  37  provides for communication between an LDAP client and the directory server, such as directory server  25  in server  11 . The LDAP protocol layer is utilized to communicate with directory server  25  regardless of whether the LDAP client performing a change in the directory server is an LDAP client in client workstation  13 , an embedded LDAP client in embedded LDAP client  28  or hybrid device  31 , or an LDAP client in directory proxy  29 . Thus, utilizing the LDAP protocol, an LDAP client can make changes in a directory server. 
     FIG. 4  depicts an example of an architecture of a messaging system and flow of multicast messages from server  11  to clients that have registered as members of at least one multicast group.  FIG. 4  only depicts an architecture for performing multicasting and unicasting will be described in more detail below. The messaging system of  FIG. 4  preferably uses a plug-in feature of the directory server application program. That is, when a change is made in the directory server, and the notification plug-in determines that a multicast message is to be sent out, the directory server calls the multicast plug-in which generates an information packet and multicasts it to a multicast group. However, a plug-in is not required and any other implementation which generates multicast information packets and multicasts them to a corresponding multicast group could be employed. In the present discussion, plug-ins that are supported as part of Netscape Directory Server will be described, although plug-ins particular to other applications may be implemented similarly. 
   As seen in  FIG. 4 , four types of multicast plug-ins may be implemented in Netscape Directory Server  25 : ADD plug-in  40 , DELETE plug-in  41 , MODIFY plug-in  42 , and SEARCH plug-in  43 . One type of plug-in supported by Netscape Directory Server are post-operation plug-ins. As such, each of the foregoing multicast plug-ins for Directory Server  25  are preferably implemented as a post-operation plug-in. A post-operation plug-in is one in which, after an operation has been performed (i.e. post-operation), the appropriate plug-in is called. Accordingly, when a change is made in the directory server, the directory server calls the appropriate multicast plug-in corresponding to the type of change made. That is, if a new object was added in the directory server, then the directory server would call an ADD plug-in. When the ADD plug-in is called, it generates an information packet about the ADD change and multicasts it to a multicast group corresponding to the type of change, whereby registered members of the multicast group receive the information packet. 
   To send the information packet by multicasting, multicast addresses corresponding to each of the plug-ins are established. As such, each multicast plug-in has a corresponding multicast address that it sends the information packet to. For example, as seen in  FIG. 4 , ADD plug-in  40  sends information packets to multicast group  45  that is designated to receive the ADD information multicast packets. Likewise, DELETE plug-in  41  has corresponding multicast group  46 , MODIFY plug-in  42  has corresponding multicast group  47  and SEARCH plug-in  43  has corresponding multicast group  47 . An example of multicast IP addresses for each of the foregoing multicast groups may be as follows: 
   
     
       
             
             
             
           
         
             
                 
                 
             
             
                 
               Operation/Multicast Group 
               IP Address 
             
             
                 
                 
             
           
           
             
                 
               ADD Operation 
               225.6.7.8 
             
             
                 
               (multicast group 45): 
             
             
                 
               DELETE Operation 
               225.6.7.9 
             
             
                 
               (multicast group 46): 
             
             
                 
               MODIFY Operation 
               225.6.7.10 
             
             
                 
               (multicast group 47): 
             
             
                 
               SEARCH Operation 
               225.6.7.11 
             
             
                 
               (multicast group 48): 
             
             
                 
                 
             
           
        
       
     
   
   When changes are made in the directory server by the LDAP client, the notification plug-in calls the appropriate multicast plug-in, if required, whereby the multicast plug-in generates an information packet and multicasts the packet over the network to its corresponding multicast IP address. 
   In order to receive the multicast messages, members register with each multicast group corresponding to the type of change information packet that they wish to receive. For example, as seen in  FIG. 4 , client  50  registers as a member of multicast groups  45  and  46 . Therefore, it receives multicast messages corresponding to ADD and DELETE operations performed in directory server  25 . Client  51  registers with multicast groups  45 ,  46 ,  47  and  48  and therefore receives multicast messages about ADD, DELETE, MODIFY and SEARCH operations performed in directory server  25 . Client  52  registers as a member of multicast groups  47  and  48  and therefore only receives multicast messages relating to MODIFY and SEARCH operations performed in directory server  25 . In the present discussion, directory proxy  29  may register as a member of each of the foregoing multicast groups. 
   Thus, as described above, an LDAP client interfaces with the directory server to make changes in the directory server, the directory server calls a notification plug-in that, when required, calls a multicast plug-in corresponding to the type of change made, the multicast plug-in generates a post-operation information packet and multicasts it over the network to a multicast group corresponding to the type of change, and clients who have registered with the multicast group receive the multicast message. 
   For unicasting, notification plug-in  26  would be configured to send a change information packet for a change operation performed on a specific LDAP enabled device on the network at an appropriate time. For example, notification plug-in  26  may be configured so that when a change is initiated by the directory server for a directory entry of an LDAP enabled device, it generates an information packet and unicasts it to the device. Notification plug-in  26  only sends a unicast message to the particular device that was changed in the directory server and not to other devices on the network. For instance, if the configuration of printer  14  were changed in directory server  25 , notification plug-in  26  would unicast a message only to printer  14  and not to printer  15  (which is a hybrid printer that is also LDAP enabled). However, as will be described below, one caveat with unicasting is that, before the notification plug-in sends the unicast message, it first determines what LDAP client performed the change operation. That is, if the LDAP client in printer  14  initiated the change, then the plug-in would not send a unicast message to printer  14  informing it of the change since it was the LDAP client in printer  14  that initiated the change. However, if the change was initiated by the LDAP client in client workstation  13 , then the notification plug-in would send a unicast message to printer  14  to inform it of the change since the change was not initiated by the LDAP client in printer  14 . 
     FIG. 5  depicts a more detailed configuration of the internal architecture of directory proxy  29  and its communication with various devices on the network. As shown in  FIG. 5 , directory proxy  29  includes LDAP client  60 , SNMP device discovery module  61 , SNMP device monitoring/polling module  62 , SNMP client  63  and LDAP/SNMP translator  64 . LDAP client  60  communicates with directory server  25  utilizing the LDAP protocol for performing changes in directory server  25  and for receiving LDAP commands from directory server  25  that are to be translated and sent to SNMP enabled devices on the network. LDAP client  60  also receives multicast messages from various multicast groups, such as multicast groups  45  to  48  described above with regard to  FIG. 4 . Additionally, LDAP client  60  receives LDAP commands from, and sends LDAP commands to LDAP/SNMP translator  64 . 
   SNMP client  63  communicates with all SNMP enabled devices on the network, including legacy (SNMP) printer  16  and hybrid (SNMP/LDAP) printer  15 . SNMP client  63  sends SNMP commands to, and receives SNMP commands from all SNMP enabled devices on the network. Additionally, SNMP client  63  communicates with SNMP discovery module  61  and SNMP device monitoring/polling module  62  to transmit messages between modules  61  and  62  and all SNMP enabled devices on the network. Further, SNMP client  63  communicates with LDAP/SNMP translator  64  to send SNMP commands to, and to receive SNMP commands from the translator. LDAP/SNMP translator formats SNMP commands received from SNMP client  63  into LDAP format and sends the LDAP commands to LDAP client  60 . Additionally, LDAP/SNMP translator  64  receives LDAP commands from LDAP client  60 , formats them into SNMP commands, and sends them to SNMP client  63 . 
   SNMP device discovery module  61  performs query operations through SNMP client  63  to obtain information about all SNMP devices on the network. Additionally, SNMP device discovery module  61  receives responses to the queries from all SNMP devices on the network and sends SNMP commands to SNMP client  63  based on the responses. SNMP device monitoring/polling module  62  also performs query operations through SNMP client  63  to obtain information about all SNMP devices on the network. One difference between modules  61  and  62  is that module  61  generally performs queries on startup of the directory proxy, whereas, module  62  generally performs periodic queries after startup to obtain update information from all of the SNMP enabled devices. The operations of modules  61  and  62  will be discussed in more detail below. 
   Generally, there are three different types of devices that are connected to network  18 , a device with an embedded LDAP client, an SNMP device that does not have an embedded LDAP client, and a hybrid device that is both an SNMP device and also has an embedded LDAP client. Each of the devices on the network, their configuration information is maintained in a directory entry in directory server  25 . That is, directory server  25  includes a directory of all SNMP enabled devices, all embedded LDAP client devices and all hybrid devices. The directory entry is generally formatted according to a standardized schema and may include a schema extension. The standardized schema includes a source flag that indicates the source of changes made in the directory entry for the device. The source flag is set by notification plug-in  26  and may be set to 0 if the change is initiated by the directory server, i.e. by a native application or by an LDAP client in workstation  13 , or may be set to 1 if the change is initiated by the device. Each of these three types of devices, and how changes to the configuration of each of them may be made in the directory server will now be discussed with reference to  FIG. 6 . 
     FIG. 6  depicts three possible scenarios of how changes may be initiated for each of the three device types. In one scenario, changes are initiated for a device with an embedded LDAP client. The changes for embedded LDAP client devices may be initiated by the embedded LDAP client in the device itself, or by the directory server, i.e. by an LDAP client in workstation  13  or by a native application in server  11 . In a second scenario, changes are initiated for an SNMP device. The changes may be initiated by the SNMP device itself or by the directory server. In a third scenario, changes are initiated for a hybrid device. Again, the changes may be initiated by the device itself, in this case by either the SNMP client in the device or by the embedded LDAP client in the device, or the changes may be initiated by the directory server. Each of these three scenarios will now be discussed in more detail. 
   It should be noted that the following discussion generally describes changes being made to the configuration of devices for which an entry in directory server  25  already exists. However, it can readily be understood that other changes, such as deletion of devices from the network and addition of new devices to the network, would operate in a similar manner. Therefore, for the sake of brevity, only operations involving changes to the configuration of devices already existing on the network will be discussed. As stated above, changes in the configuration of each of the devices on the network could be initiated either by the device itself or by the directory server. In the following discussion, both of these will be discussed by presenting two examples, one with a network administrator changing the IP address of the device at the device itself, and the another with the network administrator changing the IP address of the device in the directory server. 
   The first type of device that will be discussed is a device with an embedded LDAP client, such as printer  14 . Printer  14  includes an embedded LDAP client and does not include an SNMP client. As such, it is a pure LDAP enabled device and is not a hybrid device. As previously discussed with regard to  FIG. 2 , the embedded LDAP client communicates directly with the directory server via the LDAP protocol. Therefore, changes in the configuration of the device are communicated between the device and the directory server directly via LDAP, without the need for a translator. 
     FIG. 6  depicts a flowchart of process steps of how changes in each of the three types of devices are managed, including how changes in a device with an embedded LDAP client are managed. In the first example of the embedded LDAP client scenario, the administrator changes the IP address utilizing the embedded LDAP client in printer  14  itself. 
   In the first example, in step S 601  the administrator performs a process utilizing the embedded LDAP client in printer  14  to change the IP address in printer  14 . When the change has been committed to printer  14  by the embedded LDAP client, the embedded LDAP client initiates communication with directory server  25  via the LDAP protocol. Once communication has been established, the embedded LDAP client self publishes the change to the directory server utilizing an LDAP_MODIFY command. The embedded LDAP client also sets the source flag to 1. When the change has been committed to directory server  25 , notification plug-in  26  is called (step S 602 ). 
   Once the change has been committed to the directory server, in step S 603 , the directory server notification plug-in  26  looks at the source flag to determine what notification process is to be performed. If the flag is set to 1, then notification plug-in  26  knows that the change was initiated by the device and that it does not need to notify the device of the change. Therefore, in the present example flow proceeds to step S 604  whereby notification plug-in  26  resets the source flag to 0 and the notification process ends. 
   In the second example of the embedded LDAP client scenario, the administrator changes the IP address of printer  14  in directory server  25  utilizing an LDAP client at client workstation  13 . To make the change, the administrator activates the LDAP client application at workstation  13 . The LDAP client application is configured to access directory server  25  and more particularly, to access the objectclass that contains printer  14 . Once the LDAP client has been configured, the LDAP client establishes communication with directory server  25  via the LDAP protocol. Once communication has been established, the LDAP client application presents the administrator with a display of the directory structure for the objectclass that contains printer  14  on a display of client workstation  13 . Utilizing the LDAP client at workstation  13 , the administrator changes the IP address of printer  14  in directory server  25  (step S 601 ). The LDAP client application also sets the source flag to 0. When the change has been made, the directory server calls notification plug-in  26  (step S 602 ). 
   In step S 603 , notification plug-in  26  determines if the source flag is set to 0. In the present example, the source flag is set to 0 and therefore flow proceeds to step S 605 . In step S 605 , notification plug-in  26  looks at the directory entry for printer  14  to determine if the device is LDAP enabled. This determination is performed in order for the notification plug-in to determine whether it is to send a unicast message to the LDAP enabled device, or if it is to call one of the multicast plug-ins for sending a multicast message to be received by the directory proxy. If the notification plug-in determines that the device is LDAP enabled, and in the present example printer  14  is LDAP enabled since it has an embedded LDAP client, then flow proceeds to step S 606 . 
   In step S 606 , notification plug-in  26  generates a unicast message to inform the embedded LDAP client of printer  14  that a change has been made in the directory entry of directory server  25  for printer  14 . The unicast message sent by notification plug-in  26  is merely a notification to the embedded LDAP client that a change has occurred and does not contain any specific information about the change itself. Upon receiving the unicast message, the embedded LDAP client of printer  14  establishes communication with directory server  25  and reads the directory entry to obtain the change information (step S 607 ). Having obtained the change information, the embedded LDAP client then updates the configuration of the device (step S 608 ) and the process is complete. 
   As a result of the foregoing second example, the IP address of printer  14  was changed in the directory server by an LDAP client in workstation  13 , a notification plug-in in the directory server notified the embedded LDAP client in printer  14  that a change has occurred in the directory server, and the embedded LDAP client read the change information in the directory server and updated the configuration of printer  14 . 
   In the second scenario, a pure SNMP device will be discussed.  FIG. 6  also depicts process steps for how changes in SNMP devices are managed. Before describing examples of changes for SNMP devices, however, a more detailed description will be made of how the directory proxy obtains information about SNMP devices on the network, including obtaining information on startup (SNMP device discovery module  61  and it associated flowchart of  FIG. 7 ) and obtaining updates to all SNMP devices on the network (SNMP monitoring/polling module  62  and its associated flowchart of  FIG. 8 ). 
   In  FIG. 7 , SNMP device discovery module  61  generally obtains network information about all SNMP enabled devices on the network and then the information is processed through the directory proxy to the directory server. Discovery module  61  obtains the network information from the devices either on startup of the directory proxy or during periodic polling operations for new devices. When the directory proxy is started, discovery module  61  detects all SNMP devices on the network. To detect SNMP devices on the network, discovery module  61  sends out a query (SNMP_QUERY) for network identification information about all SNMP devices on the network (step S 701 ). All SNMP enabled devices on the network submit a reply to the query to discovery module  61  (step S 702 ). The reply from the SNMP enabled devices includes network identification information such as the device&#39;s IP address, device type, model, Mac address, device name, and MIB board type. 
   When discovery module  61  receives the reply from each device, it utilizes the network identification information of each device and sends out SNMP_GET commands to each of the devices that replied to the query (step S 703 ). The SNMP_GET commands are sent to the SNMP devices to obtain information from the SNMP device&#39;s MIB, such as the network settings of the device, the status of the device and features of the device. Each SNMP device that receives the request reply with the requested information to discovery module  61  (step S 704 ). Upon receiving the requested information, discovery module  61  then communicates with SNMP client  63  and sends the SNMP device&#39;s information to SNMP client  63  (step S 705 ). SNMP client  63  then sends the SNMP device&#39;s information to LDAP/SNMP translator  64  (step S 706 ). Translator  64  formats the device&#39;s information into LDAP format, communicates with LDAP client  60  and sends the LDAP formatted SNMP device&#39;s information to LDAP client  60  (step S 707 ). LDAP client  60  then establishes communication with directory server  25  to self publish the SNMP device&#39;s information to the directory server (step S 708 ). LDAP client  60  first utilizes an LDAP_ADD command to attempt to add the SNMP device&#39;s information in directory server  25 . If an entry for the SNMP device is already present in directory server  25 , then an error message is returned by the directory server to LDAP client  60 . LDAP client  60  then utilizes an LDAP_MODIFY command to replace the directory entry information in the directory entry of directory server  25  for the existing device. 
   Thus, changes can be initiated by the directory proxy on startup if a new device is detected on the network, or if the configuration of an existing device is changed prior to the directory proxy being started. This process of performing changes by the directory proxy on startup results in the same device management operations as if a change is initiated in the device. Therefore, the discussion below regarding changes initiated in the device and the monitoring/polling module applies equally to changes that are initiated by the directory proxy&#39;s discovery module. 
     FIG. 8  depicts process steps performed by SNMP device monitoring/polling module  62 . SNMP device monitoring/polling module  62  may operate in one of two modes, monitoring or polling. In a polling mode, module  62  generally performs periodic queries on the network to determine if any of the SNMP devices have been updated. In this mode, after startup of directory proxy  29  and after discovery module  61  has completed its processing, monitoring/polling module  62  may perform periodic polling operations by sending out a change query message for updated information. For instance, module  62  may be configured to perform a polling operation every one second to query for selected MIB data updates from all of the SNMP devices detected on the network (step S 801 ). If no updates have been performed, then none of the devices respond and the process ends after a set time-out period. If the configuration of any of the devices has been changed, then upon receiving the query, only those devices on the network which have been updated reply to the query with a change information reply indicating to monitoring/polling module  62  that a change has been made (step S 802 ). Upon receiving the change information reply message, module  62  then sends a request for the updated information to each device that replied (step S 803 ). When the SNMP device receives the request, it sends the updated information to module  62  (step S 804 ). Then, like module  61 , module  62  sends the information to SNMP client  63  (step S 805 ), SNMP client  63  sends the information to LDAP/SNMP translator  64  (step S 806 ) which formats the SNMP information into LDAP and sends the LDAP formatted information to LDAP client  60  (step S 807 ), with LDAP client  60  establishing communication with directory server  25  and self publishing the change in the directory server (step S 808 ). 
   Rather than polling the network for updates, monitoring/polling module  62  could also monitor the network to listen for update messages from all SNMP devices on the network regarding updates. In this regard, each SNMP device on the network could send out a message on the network when a change has been made in the device. Module  62  listens for the update messages and upon receiving a message, performs a request for the device that sent out the message to reply with the updated information. In this manner, steps S 803  to S 808  would be performed in the same manner as described above, with steps S 801  and S 802  merely being changed to listen for messages rather than polling the network for updates. 
   Returning now to the description of  FIG. 6 , changes in SNMP devices and directory proxy  29  will now be discussed. As described above with regard to  FIG. 7 , upon startup of directory proxy  29 , discovery module  61  obtains information about all devices on the network and the information is processed through directory proxy  29  to LDAP client  60 . LDAP client  60  attempts to perform an LDAP_ADD operation in directory server  25 , but receives an error message if an entry for the SNMP device is already present in the directory server. LDAP client  60  then performs an LDAP_MODIFY command to replace the directory entry of the SNMP device in the directory server (step S 601 ). LDAP client  60  also sets the source flag to 1 for all SNMP devices that have been added or modified. Upon making the change in the directory server, notification plug-in  26  is called (step S 602 ). Then, in step S 603  notification plug-in  26  determines that the source flag is set to 1 and flow proceeds to step S 604  where the notification plug-in resets the source flag to 0 and the process ends. 
   Next, an example where the IP address of an SNMP device, such as printer  16 , has been changed at the device itself will be discussed. It will be assumed that the directory proxy has been started and that monitoring/polling module  62  is currently polling the network for updates. An administrator changes the IP address of printer  16  at the printer. After the change has been committed to printer  16 , a polling operation of module  62  sends out an update query message on the network. Since the configuration of printer  16  has been updated, printer  16  replies with an update information reply message. Module  62  then sends a request to printer  16  for the updated information and printer  16  sends the updated information to module  62 . Module  62  then sends the updated information to SNMP client  63 , SNMP client  63  sends the information to LDAP/SNMP translator  64 , and translator  64  formats the information from SNMP into LDAP and sends the LDAP information to LDAP client  60 . LDAP client  60  establishes communication with directory server  25 , performs the change in directory server  25  and sets the source flag to 1 (step S 601 ). Then, notification plug-in  26  is called (step S 602 ). In step S 603 , notification plug-in  26  determines that the source flag is set to 1 and therefore flow proceeds to step S 604  where notification plug-in  26  resets the source flag to 0 and the process ends. 
   Thus, the configuration of an SNMP enabled device is changed at the device itself, the change is detected by the directory proxy by polling the network for updated information, and the change is performed in the directory server by the LDAP client of the directory proxy. A description will now be made of a change to the IP address of an SNMP enabled device (printer  16 ) being made in the directory server utilizing an LDAP client application in client workstation  13 . 
   The IP address for printer  16  is changed in directory server  25  utilizing the LDAP client of workstation  13  in the same manner described above with reference to the IP address being changed for embedded LDAP client printer  14 . Therefore, the discussion of the change being made in the directory server and the source flag being set to 0 (step S 601 ) will not be repeated here. 
   Once the IP address for printer  16  has been committed in the directory server, notification plug-in  26  is called (step S 602 ). Then, in step S 603  notification plug-in  26  determines that the flag has been set to 0 in step S 601  and therefore it knows that it needs to notify the device of the change and flow proceeds to step S 605 . In step S 605 , notification plug-in  26  determines from the directory entry for printer  16  that printer  16  is an SNMP enabled device and that it does not include an embedded LDAP client. Therefore, flow proceeds to step S 609  where notification plug-in  26  calls one of multicast plug-ins  40  to  43 , depending on the type of change operation made in the directory server. In the present case, MODIFY plug-in  42  is called since a modify operation has been performed in directory server  25 . MODIFY plug-in  42  generates an information packet and multicasts it to multicast group  47 . All registered members of multicast group  47  receive the information packet. In this regard, directory proxy  29 , and possibly other directory proxies on the network, register as members of multicast group  47  and therefore receive the information packet from the multicast plug-in (step S 610 ). As such, directory proxy  29  may monitor the network for multicast messages about changes made in directory server  25 . The multicast message generally includes information that a change has been made and directory entry identification information of which directory entry was changed. 
   Upon receiving the multicast message, LDAP client  60  of directory proxy  29  establishes communication with directory server  25  and reads the updated directory entry (step S 610 ). Upon obtaining the updated information, LDAP client  60  sends the information to LDAP/SNMP translator  64  where the updated information is formatted into SNMP and then sent to SNMP client  63  (step S 611 ). SNMP client  63  communicates the updated information to printer  16  (step S 611 ) where the new IP address is set in the MIB of printer  16 . 
   Thus, as described above, changes in the configuration of SNMP devices on the network are made in the directory server, the directory server notification plug-in calls a multicast plug-in that sends out a multicast message that is received by the directory proxy, the LDAP client of the directory proxy communicates with the directory server, reads the updated information and sends it to the translator in the directory proxy, the translator formats the information from LDAP into SNMP and sends it to the SNMP client in the directory proxy, and the SNMP client sends the information to the SNMP device where the new information is updated in the device. 
   In the third scenario, i.e. a hybrid SNMP enabled and LDAP enabled device such as printer  15 , two examples will be discussed: one where changes are initiated in the directory server, and another where changes are initiated at the device itself. 
   As previously discussed with regard to  FIG. 2 , a hybrid device communicates directly with the directory server via LDAP and also communicates with the directory server via the directory proxy (SNMP). Therefore, the flow of communication in hybrid devices may include parallel processes (LDAP and SNMP) being performed at the same time. For example, during the discovery mode when printer  15  is first connected to the network, during startup of the directory proxy or during periodic polling operations of discovery module  61  for new devices, printer  15  may attempt to communicate with the directory server via two communication protocols, LDAP and SNMP. In this scenario, both protocols perform parallel processes to attempt to add an entry to the directory server for the new device at the same time. 
   For instance, printer  15  includes an embedded LDAP client that, when printer  15  is connected to the network, the embedded LDAP client establishes communication with directory server  25  and attempts to add a new directory entry for printer  15 . However, printer  15  also communicates with directory proxy  29  via SNMP and therefore, when the new device is connected to the network, discovery module  61  in directory proxy  29  detects the new device and obtains the device&#39;s SNMP information as described above with regard to  FIG. 7 . Then, LDAP client  60  of directory proxy  29  establishes communication with directory server  25  and attempts to add a new directory entry for printer  15 . 
   In this scenario where parallel processes are being performed, i.e. both LDAP and SNMP, the process that establishes communication with the directory server first is the process that performs the ADD operation and the other process is managed, as will be described below, by the notification plug-in logic. That is, the notification plug-in in the directory server controls the management of hybrid devices. Therefore, if the embedded LDAP client in printer  15  establishes communication with directory server  25  first, it publishes the new entry for printer  15  in directory server  25 . Then, when LDAP client  60  establishes communication with directory server  25  and attempts to perform an LDAP_ADD operation, it receives an error message because the embedded LDAP client in printer  15  has already added the directory entry. Therefore, LDAP client  60  performs an LDAP_MODIFY operation to change the directory entry. As such, the notification plug-in in directory server  25  sees that the source flag has been set to 1 and does not perform further processing to notify printer  15  of the change by directory proxy  29 . 
   However, if LDAP client  60  of directory proxy  29  establishes communication with directory server  25  first, it adds the new directory entry for printer  15 . Then, when the embedded LDAP client of printer  15  establishes communication with directory server  25 , it performs the change and the notification plug-in sees that the source flag is 1 and therefore it does not perform further processing to change notify the device of the change. 
   Changes in the configuration of hybrid printer  15  may also be made to the directory entry in directory server  25  utilizing an LDAP client in client workstation  13  or a native application program in server  11  as described above. The process for making changes in the configuration of printer  15  utilizing the LDAP client of workstation  13  or a native application is the same as that described above for the embedded LDAP client printer and the SNMP printer and therefore, this process will not be repeated here. When the change is made in the directory entry of directory server  25  in step S 601  the source flag is set to 0 and notification plug-in  26  is called (step S 602 ). Notification plug-in  26  determines in step S 603  that the source flag is set to 0, and determines in step S 605  that printer  15  is LDAP enabled by referring to the directory entry. Since notification plug-in  26  detects that printer  15  is LDAP enabled, notification plug-in  26  unicasts a message to the embedded LDAP client in printer  15  (step S 606 ). The remaining process is the same as described above for printer  14  in that the embedded LDAP client of printer  14  establishes communication with directory server  25  and reads the changed information (step S 607 ), and the embedded LDAP client performs the change in printer  15  (step S 608 ). 
   However, because printer  15  is a hybrid device, once the change is made in the-configuration of printer  15  by the embedded LDAP client, directory proxy  29  detects the change via monitoring/polling module  62 . Upon detecting the change, module  62  then operates as described above to obtain the updated information from printer  15  and the updated information is processed through directory proxy  29  to LDAP client  60 . LDAP client  60  in directory proxy  29  establishes communication with the directory server  25  and may update the directory entry. In this regard, directory proxy  29  may be configured to recognize LDAP enabled devices and to not perform further processing for these devices. That is, if directory proxy recognizes that a device is a hybrid device, it may be configured so that when it detects a change in a hybrid device, it allows the LDAP client to handle the change and the directory proxy does attempt to perform the change. On the other hand, directory proxy  29  may overwrite the directory entry even if it has already been made by the LDAP client. In this case, the source flag is set to 1 by the directory proxy when it makes the change. When notification plug-in  26  sees that the source flag is set to 1, flow proceeds to step S 604  where notification plug-in  26  resets the source flag to 0 and the notification process ends. 
   Updates in the configuration of printer  15  may also be made at printer  15  itself. In this case, the update is performed in the same manner described above for updates in embedded LDAP client devices. As described above, the embedded LDAP client establishes communication with the directory server and the LDAP client self publishes the change in the directory entry. Upon committing the change to the directory server, the embedded LDAP client set the source flag to 1. Then, notification plug-in  26  is called in step S 602 . In step S 603 , notification plug-in  26  determines that the source flag is set to 1 and flow proceeds to step S 604  where the plug-in resets the flag to 0 and the notification process ends. 
   When the change is made in printer  15  utilizing its embedded LDAP client, monitoring/polling module  62  of directory proxy  29  detects the change and obtains the changed information, whereby it is processed through directory proxy  29  to LDAP client  60 . Again, directory proxy  29  may be configured to ignore changes in LDAP enabled devices. However, in a case where directory proxy  29  processes the change, LDAP client  60  establishes communication with directory server  25 , publishes the change again and sets the source flag to 1. Notification plug-in  26  is called (step S 602 ) and detects that the source flag is set to 1 (step S 603 ). Therefore, notification plug-in  26  resets the source flag to 0 and the process ends (step S 604 ). 
   Thus, for hybrid devices, changes made at the device are communicated to the directory server via the embedded LDAP client, and in some cases the directory proxy detects the change made by the embedded LDAP client and performs the change again. In other cases, the directory proxy detects the change but determines that the device is LDAP enabled and therefore allows the LDAP client to handle the change. For changes made in the directory server, the change is communicated to the hybrid device via the embedded LDAP client and the directory proxy detects the change and either allows the LDAP client to handle the change or performs the change again. 
   The invention has been described with particular illustrative embodiments. It is to be understood that the invention is not limited to the above-described embodiments and that various changes and modifications may be made by those of ordinary skill in the art without departing from the spirit and scope of the invention.