Abstract:
A method and system for coordinating control of a remotely controllable electronic apparatus by a first and second control apparatus that use different standards to control the remotely controllable electronic apparatus. The remotely controllable electronic apparatus has a network connection and embedded software allowing a control apparatus to remotely control the remotely controllable electronic apparatus through a network. The first control apparatus has a network connection function and acquires the software from the remotely controllable electronic apparatus through the network. The first control apparatus remotely controls the remotely controllable electronic apparatus by execution of the software in the first control apparatus. The remotely controllable electronic apparatus has an exclusive-control-request-notifying means, which is used for informing the software being executed in the first control apparatus of a request for exclusive control in case the request for exclusive control is received from the second control apparatus.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an information processing technology. More particularly, the present invention relates to a technology effective for an application wherein an electronic apparatus such as a digital VTR having an IEEE1394 interface is controlled remotely in an exclusive manner by using another electronic apparatus such a digital TV or a digital broadcast tuner, which also has an IEEE1394 interface. 
     There have been developed a number of technologies to use an electronic apparatus for remotely controlling another electronic apparatus through a network in an environment in which a plurality of electronic apparatuses are connected to each other by the network. For example, the IEEE1394 bus, one of high-speed serial buses, draws attention as media for building a home network, which is used for digitally connecting AV apparatuses such as a digital broadcasting tuner and a digital TV to each other, and expected to become popular in future homes. 
     As a concrete method for remotely operating an AV apparatus through an IEEE1394 bus, there are an AV/C command standard and an HAVi (Home Audio-Video interoperability) standard. Provided for remotely controlling an AV apparatus Connected by an IEEE1394 bus, the AV/C command standard is a standard defining a low-level command protocol, which can be implemented even in a simple AV apparatus. For details, refer to “AV/C Digital Interface Command Set General Specification, version 3.0, 1394 Trade Association document number 1998003.” 
     On the other hand, the HAVi standard is a standard prescribing basic specifications of software for an AV apparatus connected by an IEEEE1394 bus. The HAVi standard defines an API (Application Programming Interface), which allows an AV apparatus with a relatively high performance to control another AV apparatus through an IEEE1394 network. 
     For details, refer to “Specification of the Home Audio/Video Interpretability Architecture, version 1.0, Home Audio/Video Interpretability Organization.” 
     In accordance with the HAVi specifications, control among AV apparatuses is executed by exchanging messages conforming to the HAVi standard among software modules, which are each called a software element. Messages conforming to the HAVi standard are each referred to as a HAVi message. A software element representing an AV apparatus serving as a control object is known as a DCM (Device Control Module) and a software element representing the function of an AV apparatus serving as a control object is known as an FCM (Functional Component Module). Assume that an AV apparatus serving as a controller makes an attempt to control an AV apparatus serving as a target. The AV apparatus serving as the controller is referred to as a controller device and the AV apparatus serving as the target is called a target device. In this case, an application module functioning as a software element in the controller device transmits a HAVi message to a DCM and an FCM of the target device in order to remotely control the target device. Receiving the HAVi message, the DCM or the FCM controls the target device in accordance with the HAVi message. 
     Control of a target device through a DCM or an FCM is a major characteristic of the HAVi standard. In actuality, the DCM and the FCM do not have to exist in the target device. That is to say, the DCM and the FCM may exist in another device. A FAV device is a device of a category functioning as a control device. A code unit is uploaded from a target device to an FAV device through an IEEE1394 bus. The code unit is software code of the DCM or the FCM of the target device. The FAV device is capable of executing the software code of the DCM and the software code of the FCM, which were uploaded to the FAV device. 
     The software code of the DCM and the software code of the FCM are written in one of programming languages called JAVA. The FAV device needs to provide an environment for executing code written in the JAVA programming language. 
     On the other hand, a target device is implemented as a BAV device, which is one of device categories of the HAVi standard. A BAV device has a configuration including embedded data called SDD data and allowing another apparatus to reference the SDD data through an IEEE1394 bus with a high degree of freedom. While a BAV device does not have an environment for executing a DCM and an FCM, the BAV&#39;s own DCM and FCM are stored in the SDD data as a code unit. 
     FIG. 8 is a diagram showing the configuration of a system in which a FAV device  101  loads a code unit of a BAV device  102 . The FAV device  101 , the BAV device  102  and a LAV device  103  are connected to an IEEE1394 bus  104 . The LAV device  103  is also one of device categories in the HAVi standard. Even though the LAV device  103  has a 1394 interface, it represents a device not conforming to the HAVi standard. The FAV device  101  reads out SDD data stored in a memory  202  of the BAV device  102  to upload a code unit  105  to a memory  201 . The code unit  105  includes a DCM  106  and an FCM  107  used for controlling the BAV  102 . The FAV device  101  executes the DCM  106  and the FCM  107  in the FAV device  101 . 
     An application module in the FAV device  101  sends an HAVi message to the DCM  106  and the FCM  107 , which control the BAV device  102  through the IEEE1394 bus  104  by adopting a method. The DCM  106  or the FCM  107  conceivably communicates with the BAV device  102  typically in accordance with the AV/C command standard. 
     As described above, an AV apparatus can be operated remotely by adopting the AV/C command or HAVi standard. However, a target device may have to respond to remote control commands issued by a plurality of control devices in an exclusive manner. Assume, for example, that a digital VTR serving as a target device and two digital TVs each functioning as a control device are connected to a network. In the exclusive-control scheme, while the digital VTR is playing back a video tape as remotely commanded by one of the digital TVs, the digital VTR is put in a state of being enabled to respond to a remote operation command issued by the other digital TV. A method to implement exclusive use of a target device is prescribed in the AV/C command standard and the HAVi standard. 
     In the AV/C command standard, a reserve command is prescribed. When a target device receives a reserve command from a controller device, the target device will reject all kinds of control, which are based on the AV/C command standard and executed by devices other than that issuing the reserve command. 
     In accordance with the HAVi standard, on the other hand, a software element successfully passing reserve processing of the FCM of a target device is capable of exclusively occupying the FCM. In this case, in order for a software element to exclusively occupying the FCM of a target device, it is thus necessary for the software element to have the reserve processing carried out by another software element known as a resource manager for controlling the utilization of the FCM. The resource manager must exist in an FAV device. 
     FIG. 9 shows the flow of first remote control processing of the exclusive control of the FCM. In the flowchart shown in FIG. 9, an FAV device  101  is making an attempt to remotely control a BAV device  102 . The FAV device  101  includes an application module  109 , a resource manager  110  and an FCM  107 , which was uploaded from the BAV device  102 . 
     First of all, in processing P 601 , the application module  109  issues an inquiry about the present state of reservation to the FCM  107 . In accordance with the HAVi specifications, the FCM  107  holds a record of a software element presently reserving the FCM  107  itself. A software element presently reserving the FCM  107  is referred to hereafter as a client. In response to the inquiry, in the processing P 601 , the FCM  107  provides the application module  109  with information indicating that no client is presently reserving the FCM  107 . 
     The information thus notifies the application module  109  of the fact that the FCM  107  can be reserved. In processing P 602 , the application module  109  issues a request to reserve the FCM  107  to the resource manager  110 . Receiving the reserve request from the application module  109 , the resource manager  110  carries out processing to reserve the FCM  107 . If the reserve processing is successful, the application module  109  sends a control message to the FCM  107  in processing P 603 . Receiving the control message, the FCM  107  remotely controls the BAV device  102  by using typically an AV/C command. 
     Assume that a network includes an LAV device not conforming to the HAVi standard in addition to an FAV device and a BAV device, which both conform to HAVi. In this case, if the FAV device makes an attempt to control the BAV device by using the HAVi mechanism while the LAV device functioning as a controller is controlling the BAV device by adopting a method other than the HAVi technique while, it is quite within the bounds of possibility that an exclusive-control mismatch occurs. An example of a method other than the HAVi technique is the AV/C command standard. 
     FIG. 10 shows the flow of second remote control processing in which a FAV device and a LAV device remotely control a BAV device at the same time. First of all, in processing P 701 , the LAV device  103  issues an inquiry about information on the present reserve state of the BAV  102  to the BAV  102  by using an AV/C command. In response to the inquiry, in the processing P 701 , the BAV device  702  provides the LAV device  103  with information indicating that no device is presently reserving the BAV device  102 . In the next processing P 702 , the LAV device  103  carries out processing to reserve the BAV device  102  by using an AV/C command. Then, in the next processing P 703 , control is executed by using an AV/C command. At this point, the BAV  102  can no longer be controlled by a device other than the LAV device  103  by using an AV/C command. 
     In the mean time, in the system shown in FIG. 9, the FAV device  101  makes an attempt to reserve and remotely control the BAV device  102  by adopting the HAVi mechanism. In this case, the application module  109  issues an inquiry about the present state of utilization to the FCM  107  in processing P 704 . Since the FCM  107  is not aware of the fact that the LAV device  103  has reserved the BAV device  102  by using an AV/C command, the FCM  107  provides the application module  109  with information indicating that no client is presently controlling the BAV device  102 . 
     The application module  109  thereby determines that the FCM  107  can be reserved. Therefore, in the next processing P 705 , the application module  109  issues a request for reservation of the FCM  109  to the resource manager  110 . The resource manager  110  reserves the FCM  107  at the request for reservation of the FCM  107  made by the application module  109 . Since the reserve processing is successful, the application module  109  sends a control message to the FCM  107  in processing P 706 . Receiving the control message, the FCM  107  makes an attempt to remotely control the BAV device  102  by using typically an AV/C command. However, the BAV device  102  rejects the AV/C command. 
     Thus, there is raised a problem that the application module  109  is not capable of controlling the BAV device  102  in spite of the fact that the application module  109  successfully passes the reserve processing. 
     SUMMARY OF THE INVENTION 
     It is thus an object of the present invention to provide a remotely controllable electronic apparatus, a controlling apparatus and a remote control method that are capable of remotely controlling the remotely controllable electronic apparatus without causing exclusive-control mismatching of the remotely controllable electronic apparatus in a remote operation through a network connecting the apparatuses, such as an IEEE1394 network, even if apparatuses conforming to the HAVi standard and apparatuses not conforming to the HAVi standard are both connected to the network. 
     Systems and methods described herein address the problems and needs described above. An exemplary system coordinates control of a remotely controllable electronic apparatus by a first and second control apparatus that use different standards to control the remotely controllable electronic apparatus. The remotely controllable electronic apparatus has a network connection function, and embedded software allowing another device to remotely control the electronic apparatus through a network. The first control apparatus has a network connection function and acquires the software from the remotely controllable electronic apparatus through said network. The first control apparatus remotely controls the electronic apparatus by execution of the software in the first control apparatus. The remotely controllable electronic apparatus has an exclusive-control-request-notifying means, which is used for informing the software being executed in the first control apparatus of a request for exclusive control received from the second control apparatus. 
     In one aspect, the exemplary system identifies whether the electronic apparatus is under exclusive control of an apparatus and passes such information to other apparatuses that are configured to control the electronic device. If necessary the system converts the information into formats complying with various standards such that apparatuses operating under different standards are able to determine/the status of the remotely controllable electronic device. In another aspect, the electronic apparatus indicates a usage status of the electronic apparatus. 
    
    
     Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description. wherein only an exemplary embodiment of the present disclosure is shown and described. simply by way of illustration of the best mode contemplated for carrying out the present disclosure. As will be realized, the present disclosure is capable of other and different embodiments. and its several details are capable of modifications in various obvious respects. all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. 
     BRIEF DESCRIPTION OF THE DIAGRAMS 
     FIG. 1 is a diagram showing a typical configuration of a remote control system implemented by a first embodiment of the present invention; 
     FIG. 2 is a diagram showing the internal software configuration of the FAV device employed in the embodiment of the present invention; 
     FIG. 3 is a diagram showing the internal software configuration of the BAV device employed in the embodiment of the present invention; 
     FIG. 4 is a diagram showing a communication flow of a typical exchange of commands in the embodiment; 
     FIG. 5 is a diagram showing the flow of first typical remote control processing of a remote control system implemented by the first embodiment of the present invention; 
     FIG. 6 is a diagram showing the flow of second typical remote control processing of a remote control system implemented by the first embodiment of the present invention; 
     FIG. 7 is a diagram showing the flow of third typical remote control processing of a remote control system implemented by another embodiment of the present invention; 
     FIG. 8 is a diagram showing the configuration of the conventional HAVi system; 
     FIG. 9 shows the flow of first remote control processing of the exclusive control adopting a HAVi standard adopted by the conventional system; and 
     FIG. 10 shows the flow of second remote control processing of the exclusive control adopting the HAVi standard adopted by the conventional system. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Next, some preferred embodiments of the present invention are described in detail by referring to diagrams. 
     FIG. 1 is a diagram showing a typical configuration of a remote control system implemented by a first embodiment of the present invention. In the remote control system shown in FIG. 1, a FAV device  101 , a BAV device  102  and a LAV device  103  are connected to each other by an IEEE1394 bus  104 . As the FAV device  101 , a digital TV or an STB (Set Top Box), which conforms to the HAVi standard is conceivable. As the BAV device  102 , on the other hand, a digital VTR conforming to the HAVi standard is conceivable. As for the LAV device  103 , a digital TV or an STB (Set Top Box), which does not conform to the HAVi standard but is capable of controlling a partner apparatus by using an AV/C command, is conceivable. 
     In this embodiment, the FAV device  101  and the LAV device  103  each function as a controller device. On the other hand, the BAV device  102  functions as a target device. The BAV device  102  has a code unit  105  embedded in SDD data. The FAV device  101  uploads the code unit  105  to itself and controls the BAV device  102  by using the code unit  105 . 
     The BAV device  102  can be controlled by an AV/C command and supports reserve processing based on the AV/C command standard. 
     The BAV device  102  has a memory  202  for storing SDD data. By the same token, the FAV device  101  has a memory  201  for storing the code unit  105  uploaded from the BAV device  102 . 
     The code unit  105  uploaded from the memory  202  employed in the BAV device  102  to the memory  201  employed in the FAV device  101  includes a DCM  106 , an FCM  107  and a proxy client  108 . The DCM  106  is a software element used by the FAV device  101  for controlling the BAV device  102  as a whole. For example, the DCM  106  is used for turning on the power supply of the BAV device  102 . On the other hand, the FCM  107  is a software element used by the FAV device  101  for controlling a variety of functions in the BAV device  102 . In the case of a digital VTR used as the BAV device  102 , for example, the FCM  107  is used for controlling operations of a video tape such as playback, halt and fast-feed operations. The proxy client  108  is a software element having a function to monitor the reserve state of the BAV device  102 . To put it in detail, when the LAV device  103  carries out reserve processing on the BAV device  102  by using an AV/C command, the proxy client  108  receives a notification from the BAV device  102 . The notification indicates that reserve processing is being carried out. Instead of being notified, the proxy client  108  detects a reserve-processing state of the BAV device  102 . In addition, the proxy client  108  also has a function to carry out reserve processing based on the HAVi mechanism on the FCM  107  when a request for reserve processing of the BAV device  102  made by the LAV device  103  is recognized. 
     Next, the internal software configuration of the FAV device  101  is explained. FIG. 2 is a diagram showing the internal software configuration of the FAV device  101 . To be more specific, the figure shows a state after an operation to upload the code unit  105  from the BAV device  102 . As shown in FIG. 2, the FAV device  101  has a configuration comprising the DCM  106 , the FCM  107 , the proxy client  108 , the application module  109 , the resource manager  110 , a messaging system  111  and a 1394 control module  112 . All the configuration elements each function as an HAVi software element. The DCM  106 , the FCM  107  and the proxy client  108  are included in the code unit  105  uploaded from the BAV device  102 . 
     The messaging system  111  has a message-relaying function for receiving HAVi messages from a variety of software elements and passing on the messages to destination software elements. The 1394 control module  112  has a function to transmit an HAVi message through the 1394 bus  104  if the message is sent to a destination outside the FAV device  101 . The 1394 control module  112  has a function to pass on an HAVi message to a software element inside the FAV device  101  if the message has been received from a destination outside the FAV device  101 . 
     The DCM  106 , the FCM  107  and the proxy client  108  each have a function for exchanging AV/C commands with the BAV device  102  by way of the messaging system  111  and the 1394 control module  112 . 
     Next, the internal software configuration of the BAV device  102  is explained. FIG. 3 is a diagram showing the internal software configuration of the BAV device  102 . As shown in FIG. 3, the BAV device  102  has a configuration comprising an 1394 module  121 , an AV/C-command processing module  122 , a control-command processing module  123 , a reserve-processing module  124  and an exclusive-control-request notifying module  125 . The 1394 control module  121  has a function for communicating with an apparatus external to the BAV device  102  through the 1394 bus  104 . The AV/C-command processing module  122  has a function to transmit an AV/C command issued by an upper-level software module to an apparatus serving as a destination of the command by way of the 1394 control module  121 . In addition, the AV/C-command processing module  122  also has a function to receive an AV/C command from an apparatus external to the BAV device  102  and deliver the command to a processing module in the BAV device  102  supposed to receive the AV/C command. The control-command processing module  123  processes an AV/C command for remotely controlling the BAV device  102  from an apparatus external to the BAV device  102 . The reserve-processing module  124  processes a reserve-requesting AV/C command received from an apparatus external to the BAV device  102 . The exclusive-control-request notifying module  125  is a module for exchanging AV/C commands with the proxy client  108  uploaded to the FAV device  101 . 
     When an AV/C command making a request for reserve processing is received from the LAV device  103 , the reserve processing module  124  informs the exclusive-control-request notifying module  125  of the request. The exclusive-control-request notifying module  125  passes on the request for reserve processing to the proxy client  108  as an AV/C command. When the exclusive-control-request notifying module  125  receives an AV/C command making a request for reserve processing from the proxy client  108 , the exclusive-control-request notifying module  125  passed on the AV/C command to the reserve-processing module  124 , which then carries out the requested reserve processing. 
     In this case, AV/C commands exchanged between the proxy client  108  and the exclusive-control-request notifying module  125  are not used in communications with other modules and other devices. Thus, as concrete command specifications, for example, it is conceivable to use a command set defined by a vendor manufacturing the BAV device  102  itself, that is, commands unique to the vendor. As an alternative, instead of commands unique to a vendor, communications between the proxy client  108  and the exclusive-control-request notifying module  125  can also be implemented by using newly defined commands. FIG. 4 is a diagram showing a communication flow of a typical exchange of commands between the proxy client  108  and the exclusive-control-request notifying module  125 . 
     As shown in FIG. 4, the flow begins with processing P 501  as a first communication. In the processing P 501 , the proxy client  108  uploaded to the FAV device  101  transmits network identification information for identifying the FAV device  101  on the 1394 network to the exclusive-control-request notifying module  125  as an AV/C command. The network identification information is an address of a transmission destination necessary for transmission of an AV/C command. The proxy client  108  was originally stored in the BAV device  102  as a code unit before being uploaded to the FAV device  101 . Thus, the proxy client  108  knows the network identifying information of the BAV device  102 , which is used for transmitting the AV/C command in the processing P 501 . For this reason, the proxy client  108  uploaded to the FAV device  101  is capable of issuing the AV/C command to the exclusive-control-request notifying module  125  as in the processing P 501 . 
     On the other hand, the exclusive-control-request notifying module  125 , which also exists in the BAV device  102 , does not know the network identification information of the FAV device  101  to which the proxy client  108  was uploaded. Thus, the exclusive-control-request notifying module  125  needs to receive the network identification information of the FAV device  101  in advance in the processing P 501  so that, in the next processing P 502 , the exclusive-control-request notifying module  125  is capable of transmitting an AV/C command to the proxy client  108  to make a request for reserve processing. 
     The following description explains remote control of the BAV device  102  executed by the LAV device  103  by referring to a first typical processing flow shown in FIG.  5 . In the processing shown in FIG. 5, the LAV device  103  makes a request for reserve processing of the BAV device  102  by using an AV/C command and, then, makes an attempt to remotely control the BAV device  102  in an exclusive manner. First of all, in the initial processing P 301 , the LAV device  103  issues an AV/C command making a request for reserve processing to the BAV device  102 . The BAV device  102  which has received the request for reserve made by the AC/C command transfers the request for reserve processing made by the LAV device  103  to the proxy client  108  existing in the FAV device  101 . If the request for reserve processing of the BAV device  102  made by the LAV device  103  is accepted, the proxy client  108  carries out reserve processing based on the HAVi mechanism on the FCM  107  through the resource manager  110 . If the reserve processing carried out on the FCM  107  is successful, the proxy client  108  is cataloged in the FCM  107  as a record of a client reserving the FCM  107 . 
     Receiving a result indicating successful reserve processing of the FCM  107 , the proxy client  108  transmits an AV/C command serving as a response indicating the successful reserve processing to the BAV device  102  . Receiving the AV/C command serving as a response from the proxy client  108 , the BAV device  102  transmits an AV/C command serving as a response indicating the successful reserve processing to the LAY device  103 . As a result of these pieces of processing, the BAV device  102  is reserved by the LAV device  103  and the FCM  107  in the FAV device  101  is reserved by the proxy client  108 . 
     Thus, in processing P 302 , the LAV device  103  is capable of remotely controlling the BAV device  102  in an exclusive manner by issuing an AV/C command for the remote control to the BAV device  102 . In order for the application module  109  in the FAV device  101  to remotely control the BAV device  102 , on the other hand, it is necessary first of all to carry out reserve processing of the FCM  107 . When the application module  109  transfers an HAVi message making an inquiry about the state of reservation to the FCM  107  in processing P 303 , however, the application module  109  receives a result indicating that the FCM  107  has already been reserved by the proxy client  108 . Thus, the application module  109  cancels the reservation of the FCM  107 . 
     Accordingly, by virtue of the processing described above, mismatching no longer occurs due to reserve processing of the FCM  107 , which is carried out by the application module  109  in the FAV device  101  while the LAV device  103  is remotely controlling the BAV device  102  in an exclusive manner after completing reserve processing. 
     The following description explains remote control of the BAV device  102  executed by the FAV device  101  by referring to the flow of second typical processing shown in FIG.  6 . In the processing shown in FIG. 6, the application module  109  in the FAV device  101  makes a request for reserve processing of the BAV device  102  by adopting the HAVi mechanism and, then, makes an attempt to remotely control the BAV device  102  in an exclusive manner through the FCM  107 . First of all, in the initial processing P 401 , the application module  109  issues an inquiry about the present state of reservation to the FCM  107 . In the. processing P 401 , the FCM  107  returns information indicating that the FCM  107  is not reserved by any client at the present time to the application module  109 . The information thus notifies the application module  109  that the FCM  107  can be reserved. Accordingly, in processing P 402 , the application module  109  issues a request for a reservation of the FCM  107  to the resource manager  110 . The resource manager  110  then reserves the FCM  107  on the basis of the request for a reservation of the FCM  107  made by the application module  109 . The FCM  107  transfers the request for a reservation received from the resource manager  110  to the proxy client  108 . Receiving the request for reservation transferred from the FCM  107 , the proxy client  108  executes a reserve command or carries out processing using an AV/C command to reserve the BAV device  102 . 
     At the present time, the BAV device  102  is not experiencing reserve processing requested by any device by using an AV/C command. Thus, the BAV device  102  transmits an AV/C command indicating a success of the reserve processing to the proxy client  108  as a result of the reservation made by the proxy client  108 . The proxy client  108  transfers the response indicating the success of the reserve processing from the BAV device  102  to the application module  109  by way of the FCM  107  and the resource manager  110 . This response informs the application module  109  that the reserve processing is successful. As a result of these pieces of processing, the application module  109  reserved the FCM  107  in the FAV device  101  and the proxy client  108  reserved the BAV device  102 . 
     Instead of transferring the request for a reservation to the proxy client  108 , the FCM  107  may also execute a reserve command or carry out processing using an AV/C command to reserve the BAV device  102 . 
     As a result, in processing P 403 , the application module  109  transmits a control message to the FCM  107 , making the FCM  107  capable of remotely controlling the BAV device  102  by using an AV/C command in an exclusive manner in accordance with the control message. In processing P 404 , on the other hand, in order for the LAV device  103  to remotely control the BAV device  102  in an exclusive manner, the LAV device  103  transmits an AV/C command making an inquiry about the present state of reservation to the BAV device  102 . Since the BAV device  102  transmits information indicating that the BAV device  102  has already been reserved in response to the inquiry, the LAV device  103  cancels the attempt to reserve the BAV device  102 . 
     In accordance with the processing procedure described above, when the FAV device  101  is remotely controlling the BAV device  102  in an exclusive manner or carrying out reserve processing of the BAV device  102 , an attempt made by the LAV device  103  to use the BAV device  102  can be rejected. 
     As described above, the proxy client  108  is a configuration element of the code unit  105 , which is uploaded along with the DCM  106  and the FCM  107  to the FAV device  101  and operates in the FAV device  101 . The proxy client  108  functions as a software element serving as an interface between the BAV device  102  and the FCM  107 . The proxy client  108  has a function to reserve the FCM  107  on the basis of the HAVi mechanism on behalf of the LAV device  102  when the LAV device  103  reserves the BAV device  102  by using an AV/C command. The proxy client  108  has a function to reserve the BAV device  102  by using an AV/C command on behalf of the application module  109  when the application module  109  carries out processing to reserve the FCM  107  on the basis of the HAVi mechanism. 
     Next, other embodiments of the present invention are explained. 
     FIG. 7 is a diagram showing the flow of third typical remote control processing of a remote control system implemented by another embodiment of the present invention. The FAV device  101 , the BAV device  102  and the LAV device  103  of the remote control system have the same functions as their counterparts employed in the embodiment explained previously. The FAV device  101  has a configuration of software modules including the application module  109 , the resource manager  110 , the FCM  107  and the proxy client  108 . Much like the embodiment described previously, the FCM  107  and the proxy client  108  are uploaded from the BAV device  102 . The BAV device  102  is capable of carrying out reserve processing requested by an AV/C command. 
     In the remote control system shown in FIG. 7, the LAV device  103  makes a request for reserve processing of the BAV device  102  by using an AV/C command and, then, makes an attempt to remotely control the BAV device  102  in an exclusive manner. First of all, in processing  801 , the proxy client  108  issues an AV/C command to request the BAV device  102  that the proxy client  108  be cataloged as a recipient of a reserve notification. Such a request is prescribed as a function of reserve processing to be implemented by an AV/C command. To put it in detail, when the BAV device  102  is reserved by a device other than the proxy client  108  through an AV/C command, the proxy client  108  issuing the request must be informed of the fact that the BAV device  102  has been reserved by the other device. 
     In the next processing P 802 , the LAV device  103  issues an AV/C command making a request for reserve processing to the BAV device  102 . Receiving the AV/C command making a request for reserve processing, the BAV device  102  notifies the proxy client  108  in the FAV device  101  of a result of the reservation made by the LAV device  103 . Receiving the notification of the reservation of the BAV device  102  by the LAV device  103 , the proxy client  108  carries out reserve processing of the FCM  107  based on the HAVi mechanism through the resource manager  110 . If the reserve processing of the FCM  107  is successful, the proxy client  108  is cataloged in the FCM  107  as a record indicating that the FCM  107  has been reserved by a client, namely, the proxy client  108 . In the pieces of processing described above, the BAV device  102  is reserved the LAV device  103  and, at the same time, the FCM  107  in the FAV device  101  is reserved by the proxy client  108 . 
     Thus, in processing P 803 , the LAV device  103  is capable of remotely controlling the BAV device  102  in an exclusive manner by issuing an AV/C command to the BAV device  102  for the remote control. In the mean time, in order for the application module  109  in the FAV device  101  to remotely control the BAV device  102 , first of all, the application module  109  needs to carry out reserve processing of the FCM  107 . When the application module  109  transfers a HAVi message making an inquiry about the present state of reservation to the FCM  107  in processing P 804 , however, the FCM  107  transmits information indicating that the FCM  107  has been reserved by the proxy client  108  as a response to the inquiry. As a result, the application module  109  cancels the attempt to reserve the FCM  107 . 
     In accordance with the processing procedure described above, when the LAV device  103  is remotely controlling the BAV device  102  in an exclusive manner or carrying out reserve processing of the BAV device  102 , there will be no mismatching of reserve processing of the FCM  107  caused by the application module  109  of the FAV device  101 . In addition, each AV/C command exchanged between the proxy client  108  and the BAV device  102  can be implemented by using an existing reserve command. Thus, it is not necessary to prescribe new commands. As a result, the BAV device  102  does not need to execute a new command. 
     In the embodiments described above, a command exchanged by way of the network is exemplified by an AV/C command. It should be noted, however, that the present invention can also be implemented as well by using another kind of command. In addition, while the network media has been explained by using the 1394 bus, the present invention can also be implemented as well by using other kinds of network media such as an Ethernet bus and a USB (Universal Serial Bus). 
     The present invention provides a remotely controllable electronic apparatus, a controlling apparatus and a remote control method that are capable of remotely controlling the remotely controllable electronic apparatus without causing exclusive-control mismatching of the remotely controllable electronic apparatus in a remote operation through an IEEE1394 network even if apparatuses conforming to the HAVi standard and apparatuses not conforming to the HAVi standard are both connected to the network.