Bridge apparatus and bridge system

Abstract

A bridge apparatus is disclosed, the bridge apparatus being connected between a first network and a second network and achieving a communication between equipment connected to the first network and equipment connected to the second network. This apparatus accepts communication from the equipment over the first network to equipment disconnected from the second network, and then, preserves contents of the communication even in the case where the equipment over the second network has been disconnected from the second network for reasons such as electric power cut. In the case where the disconnected equipment has been connected to the second network again, this apparatus transmits the accepted contents of the communication to the reconnected equipment.

1 . A bridge apparatus connected between a first network to which first equipment is connected and a second network to which second equipment is connected, the apparatus comprising: 
 a connection detecting device configured to detect connection of the second equipment to the second network;    a management device configured to allocate a virtual device processor to the second equipment in accordance with detection of the connection of the second equipment to the second network, wherein the virtual device processor makes a bridge operation between the first network and the second network;    a disconnection detecting device configured to detect disconnection of the second equipment from the second network; and    a bridge operation control device configured to direct the virtual device processor to change contents of the bridge operation in accordance with detection of the disconnection of the second equipment from the second network.    
   
   
       2 . The apparatus according to  claim 1 , wherein the virtual device processor comprises: 
 a determining device configured to determine whether or not to preserve a control command because the virtual device processor cannot process the control command from the first equipment;    a preserving device configured to preserve the control command until the second equipment is connected to the second network again if the control command should be preserved; and    a transmitting device configured to transmit to the second equipment a control command preserved by the preserving device when the second equipment is connected to the second network again.    
   
   
       3 . The apparatus according to  claim 1 , further comprising a notifying device configured to notify to the first equipment a power supply state of the second equipment as a source device that corresponds to the virtual device processor.  
   
   
       4 . The apparatus according to  claim 1 , further comprising an acquisition device configured to acquire a validity period of a control command from the first equipment to the second equipment.  
   
   
       5 . The apparatus according to  claim 1 , wherein the virtual device processor comprises an update device configured to update contents of the bridge operation in accordance with bridge operation attribute information assigned from the bridge operation control device, and the bridge operation attribute information indicates whether or not to maintain at least a bridge processing operation.  
   
   
       6 . The apparatus according to  claim 5 , wherein the bridge operation attribute information further includes specifying a time period for maintaining the bridge processing operation.  
   
   
       7 . The apparatus according to  claim 5 , wherein the bridge operation attribute information indicates any of keeping the bridge processing operation running for a set period, immediate stoppage of the bridge processing operation, and keeping the bridge processing operation permanently.  
   
   
       8 . The apparatus according to  claim 5 , wherein the virtual device processor: 
 if a control command from the first equipment intends to make a search for equipment that belongs to the second network, responds to the first equipment the fact that the second equipment exists;    if the control command intends to acquire attribute information on the second equipment, responds to the first equipment, attribute information on the second equipment that has been acquired in advance; and    if the control command intends to a request for notifying a state change of the second equipment, responds to the first equipment the fact that the notifies request has been accepted and notifying to the first equipment the attribute information as an initial state.    
   
   
       9 . The apparatus according to  claim 8 , wherein the bridge operation attribute information indicates: 
 response enable or disable determination information in the case where the control command from the first equipment intends to make a search for equipment that belongs to the second network;    response enable or disable determination information in the case where the control command from the first equipment intends to acquire equipment information on the equipment that belongs to the second network; and    response enable or disable determination information in the case where the control command from the first equipment intends to acquire attribute information on the equipment that belongs to the second network.    
   
   
       10 . The apparatus according to  claim 2 , wherein the determining device determines whether or not to preserve a control command in accordance with whether an attribute value of the second equipment targeted for use in the control command from the first equipment is a variable value or a fixed value.  
   
   
       11 . The apparatus according to  claim 10 , wherein, if the attribute value of the second equipment targeted for use in the control command from the first equipment is a variable value, the determining device determines whether or not to preserve the control command depending on which of acquisition, setting, and notification requests corresponds to an operation type of the control command.  
   
   
       12 . A bridge system comprising: 
 a first bridge apparatus connected between a first network to which first equipment is connected and a second network to which second equipment is connected; and a second bridge apparatus connected between the first network and a third network, wherein the first bridge apparatus comprises:    a connection detecting device configured to detect connection of the second equipment to the second network;    a management device configured to allocate a virtual device processor to the second equipment in accordance with detection of the connection of the second equipment to the second network, wherein the virtual device processor makes a bridge operation between the first network and the second network;    a disconnection detecting device configured to detect disconnection of the second equipment from the second network; and    a bridge operation control device configured to direct the virtual device processor to change contents of the bridge operation in accordance with detection of the disconnection of the second equipment from the second network, and    the second bridge apparatus comprises:    a bridge apparatus disconnection detecting device configured to detect disconnection of the first bridge apparatus from the first network; and    an inheriting device configured to inherit a bridge processing operation by the virtual bridge processor of the first bridge apparatus in a period in which the first bridge apparatus is disconnected from the first network.    
   
   
       13 . A method for operating a bridge apparatus connected between a first network to which first equipment is connected and a second network to which second equipment is connected, the method comprising: 
 detecting connection of the second equipment to the second network;    allocating a virtual device processor to the second equipment in accordance with detection of the connection of the second equipment to the second network, wherein the virtual device processor makes a bridge operation between the first network and the second network;    detecting disconnection of the second equipment from the second network; and    directing the virtual device processor to change contents of the bridge operation in accordance with detection of the disconnection of the second equipment from the second network.