Patent Publication Number: US-2009228591-A1

Title: Information processing apparatus, information processing apparatus control method, and computer product

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The embodiments discussed herein are directed to a technology for providing information processing apparatuses connected through a network with services. 
     2. Description of the Related Art 
     In recent years, along with the widespread use of network connection environment in homes and companies, network technologies for providing services via a network attract attention. In such a network technology, information processing apparatuses, for example, personal computers and peripheral apparatuses thereof, audio visual (AV) apparatuses, and home electronics are connected via a network so that services provided by them are comprehensively available. 
     As an example of the network technologies, Universal Plug and Play (UPnP) is known. UPnP is a standard that uses a protocol called simple service discovery protocol (SSDP) to detect information processing apparatuses connected to a network and UPnP services provided by the information processing apparatuses. Reference may be had to, for example, Published Japanese Translation No. 2005-526450 of the PCT International Publication. 
     An information processing apparatus supporting the SSDP sends other information processing apparatuses a packet (hereinafter, “broadcast packet”) including an address of the apparatus, information concerning UPnP services that the apparatus can provide, and a validity period while connected to the network. Hereinafter the information processing apparatus that transmits broadcast packets and provides UPnP services is referred to as “service providing apparatus”, and the information processing apparatus that receives the broadcast packets and uses the UPnP services is referred to as “service using apparatus”. 
     The service providing apparatus repeats processing for issuing a broadcast packet for each of UPnP services before the validity period (e.g., 60 seconds) expires. The service using apparatus updates the validity period of the UPnP service every time it receives the broadcast packet and recognizes that the UPnP service is available while periodically receiving broadcast packets before the validity period expires. On the other hand, when the validity period expires without receipt of no new broadcast packet, the service using apparatus recognizes that the UPnP service is not available. 
     Some UPnP service includes a plurality of UPnP services. For example, one UPnP service is divided into a plurality of UPnP services with respect to each of the functions. The UPnP service of this type is available only when all the UPnP services included therein are in operation. Hereinafter the UPnP service including a plurality of UPnP services is referred to as “complex UPnP service”, and the UPnP services included in the complex UPnP service are referred to as “sub-UPnP services”. 
     When providing a complex UPnP service, the service providing apparatus needs to transmit broadcast packets for the sub-UPnP services. In general, because the service providing apparatus transmits the broadcast packets for the sub-UPnP services at different timings, the service using apparatus also receives the broadcast packets at different timings for each of the sub-UPnP services. Therefore, timing for the service using apparatus to update the validity period is also different for each of the sub-UPnP services and the time the validity period expires is different for each of the sub-UPnP services. When the broadcast packet is not transmitted from the service providing apparatus because, for example, the service providing apparatus is disconnected from the network, the service using apparatus recognizes that the UPnP service is not available at timing different for each of the sub-UPnP services. 
     To provide a complex UPnP service in the conventional UPnP technology, when, for example, a complex UPnP service includes five sub-UPnP services and the service using apparatus recognizes that three of them are available due to a difference in the time their validity periods expire, the service using apparatus may use the three sub-UPnP services because it does not know that the three sub-UPnP services are part of the complex UPnP service. When using only part of sub-UPnP services included in a complex UPnP service, the service using apparatus needs to detect a sub-UPnP service that is not in operation. This increases processing load due to the detection and development cost for incorporating the detection processing in a program. 
     When the complex UPnP service is used, broadcast packets from the service providing apparatus increases. Therefore, load on the service providing apparatus for broadcast packet notification processing increases, load on the service using apparatus for broadcast packet reception processing increases, and traffic through the network increases. 
     Therefore, to provide a complex UPnP service, there is a need for a technology of setting the validity periods for sub-UPnP services included in the complex UPnP service to expire at the same time and thereby reducing necessary broadcast packets. 
     SUMMARY 
     It is an object of the present invention to at least partially solve the problems in the conventional technology. 
     According to an aspect of the present invention, there is provided an information processing apparatus that provides other information processing apparatus connected via a network with a plurality of services. The information processing apparatus includes: a storage unit that stores service identification numbers for identifying the services and operation state indicating whether the services are in operation; a service-start notifying unit that retrieves, when a service starts anew, all services in operation from the storage unit, and notifies the other information processing apparatus of service start information including information indicating that the retrieved services are in operation and a validity period in which the other information processing apparatus recognizes that the services are in operation; and a confirmation notifying unit that retrieves, before the validity period expires, all services in operation from the storage unit, and notifies the other information processing apparatus of service-time regular information including information indicating that the retrieved services are in operation and the validity period. 
     According to another aspect of the present invention, there is provided an information processing apparatus that provides other information processing apparatus connected via a network with a plurality of services. The information processing apparatus includes: a storage unit that stores service identification numbers for identifying the services, operation state indicating whether the services are in operation, and a relation identification number indicating, for a complex service including a combination of a plurality of services, that the plurality of services are related to one another; and a service-start notifying unit that retrieves, when a new service starts, all services that are related to the new service and are in operation from the storage unit, and notifies the other information processing apparatus of related service information indicating that the retrieved services are related to one another. 
     According to still another aspect of the present invention, there is provided an information processing apparatus that uses a plurality of services provided by a predetermined information processing apparatus as a service providing apparatus connected via a network. The information processing apparatus includes: a service-start notifying unit that, having received a request for monitoring the service providing apparatus from the service providing apparatus, detects that the service providing apparatus starts a new service, extracts all services in operation in the service providing apparatus, and notifies other information processing apparatus connected via the network than the service providing apparatus of service start information including information indicating that the extracted services are in operation and a validity period in which the other information processing apparatus recognizes that the services are in operation; and a confirmation notifying unit that, having received a request for monitoring the service providing apparatus from the service providing apparatus, extracts all services in operation in the service providing apparatus before the validity period expires, and notifies the other information processing apparatus of service-time regular information including information indicating that the extracted services are in operation and the validity period. 
     According to still another aspect of the present invention, there is provided a monitoring apparatus that monitors a radio information processing apparatus that provides other information processing apparatus connected via a network with a plurality of services. The monitoring apparatus includes: an acquiring unit that acquires terminal connection information managed by an access point connected via radio to the radio information processing apparatus; and a confirmation notifying unit that notifies, when it is detected based on the terminal connection information acquired by the acquiring unit that the radio information processing apparatus is disconnected from the network, the other information processing apparatus that the radio information processing apparatus is disconnected from the network. 
     According to still another aspect of the present invention, there is provided an information processing apparatus control method for controlling an information processing apparatus that provides other information processing apparatus connected via a network with a plurality of services. The information processing apparatus control method includes: storing, in the storage unit, service identification numbers for identifying the services and operation state indicating whether the services are in operation; retrieving, when a service starts anew, all services in operation from the storage unit; notifying the other information processing apparatus of service start information including information indicating that the retrieved services are in operation and a validity period in which the other information processing apparatus recognizes that the services are in operation; retrieving, before the validity period expires, all services in operation from the storage unit; and notifying the other information processing apparatus of service-time regular information including information indicating that the retrieved services are in operation and the validity period. 
     According to still another aspect of the present invention, there is provided an information processing apparatus control method for controlling an information processing apparatus that provides other information processing apparatus connected via a network with a plurality of services. The information processing apparatus control method includes: storing, in the storage unit, service identification numbers for identifying the services, operation state indicating whether the services are in operation, and a relation identification number indicating, for a complex service including a combination of a plurality of services, that the plurality of services are related to one another; retrieving, when a new service starts, all services that are related to the new service and are in operation from the storage unit; and notifying the other information processing apparatus of related service information indicating that the retrieved services are related to one another. 
     According to still another aspect of the present invention, there is provided a computer-readable recording medium that stores therein a computer program that implements the above method on a computer. 
     The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an example of a UPnP network; 
         FIG. 2  is a sequence chart of a processing flow in a conventional UPnP service provision system in a UPnP network; 
         FIG. 3  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to a first embodiment of the present invention; 
         FIG. 4  is a block diagram of the information processing apparatus according to the first embodiment; 
         FIG. 5  is an example of contents of a provided-service storage area; 
         FIG. 6  is an example of contents of a received-service storage area; 
         FIG. 7  is a flowchart of service-start-time broadcast packet transmission processing performed by a service-start notifying unit depicted in  FIG. 4 ; 
         FIG. 8  is a flowchart of service-time broadcast packet transmission processing performed by an existence-confirmation notifying unit depicted in  FIG. 4 ; 
         FIG. 9  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to a second embodiment of the present invention; 
         FIG. 10  is a block diagram of the information processing apparatus according to the second embodiment; 
         FIG. 11  is an example of contents of a received-service storage area; 
         FIG. 12  is a flowchart of service-start-time broadcast packet transmission processing performed by a service-start notifying unit depicted in  FIG. 10 ; 
         FIG. 13  is a flowchart of apparatus-ID notification packet transmission processing performed by an existence-confirmation notifying unit depicted in  FIG. 10 ; 
         FIG. 14  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to a third embodiment of the present invention; 
         FIG. 15  is a block diagram of the information processing apparatus according to the third embodiment; 
         FIG. 16  is an example of contents of a provided-service storage area; 
         FIG. 17  is an example of contents of a received-service storage area; 
         FIG. 18  is a flowchart of broadcast packet transmission processing and related-service broadcast packet transmission processing performed by a service-start notifying unit depicted in  FIG. 15 ; 
         FIG. 19  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to a fourth embodiment of the present invention; 
         FIG. 20  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to a fifth embodiment of the present invention; 
         FIG. 21  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to a sixth embodiment of the present invention; 
         FIG. 22  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to a seventh embodiment of the present invention; 
         FIG. 23  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to a eighth embodiment of the present invention; 
         FIG. 24  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to a ninth embodiment of the present invention; 
         FIG. 25  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to a tenth embodiment of the present invention; 
         FIG. 26  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to an eleventh embodiment of the present invention; 
         FIG. 27  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to a twelfth embodiment of the present invention; and 
         FIG. 28  is a block diagram of a computer that executes an information processing apparatus control program. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Exemplary embodiments of the present invention are explained in detail below with reference to the accompanying drawings. 
       FIG. 1  is a schematic diagram of a network in which UPnP is provided (hereinafter, “UPnP network”). In the UPnP network depicted in  FIG. 1 , information processing apparatuses  1   a  to  1   d  and a network  2  are connected. 
     The information processing apparatuses  1   a  to  1   d  are information processing apparatuses such as a personal computer, a portable terminal, and an AV apparatus. The information processing apparatus  1   a  provides the information processing apparatuses  1   b  to  1   d  with a UPnP service  10 . The UPnP service  10  is a complex UPnP service and includes UPnP services  10   a  and  10   b . The information processing apparatus  1   a  periodically sends, while the connected to the network  2 , the information processing apparatuses  1   b  to  1   d  broadcast packets including information concerning the UPnP services  10   a  and  10   b . Specifically, the broadcast packets include validity periods that are terms in which the information processing apparatuses  1   b  to  1   d  recognize that the UPnP services  10   a  and  10   b  are in operation. The information processing apparatus  1   a  issues the broadcast packets of the UPnP services  10   a  and  10   b  again before the validity period expires. 
     Every time the broadcast packet including the information concerning the UPnP service  10   a  is received from the information processing apparatus  1   a , the information processing apparatuses  1   b  to  1   d  update the validity period of the UPnP service  10   a . The information processing apparatuses  1   b  to  1   d  recognize that the UPnP service  10   a  is available while the broadcast packet of the UPnP service  10   a  is continuously received before the validity period expires. Similarly, every time the broadcast packet of the UPnP service  10   b  is received, the information processing apparatuses  1   b  to  1   d  update the validity period of the UPnP service  10   b  and recognize that the UPnP service  10   b  is available while the broadcast packet of the UPnP service  10   b  is continuously received before the validity period expires. 
     The UPnP network depicted in  FIG. 1  is a general example. The conventional information processing apparatus operates in the same environment as that of the information processing apparatus according to the first embodiment. 
       FIG. 2  is a sequence chart of a processing flow in a conventional UPnP service provision system in the UPnP network. Conventional information processing apparatuses  900   a  to  900   d  depicted in  FIG. 2  correspond to the information processing apparatuses  1   a  to  1   d  depicted in  FIG. 1 . In  FIG. 2 , for simplification of explanation, a flow of processing by the information processing apparatus  900   a  and the information processing apparatus  900   b  is explained. However, other information processing apparatuses (not shown) perform the same processing as that performed by the information processing apparatus  900   b.    
     As illustrated in  FIG. 2 , the conventional information processing apparatus  900   a  starts the UPnP service  10   a  (Step S 1001 ). The information processing apparatus  900   a  sends the information processing apparatus  900   b  a broadcast packet including information concerning the UPnP service  10   a  (Step S 1002 ). 
     The information processing apparatus  900   b  receives the broadcast packet of the UPnP service  10   a  and performs predetermined setting work for using the UPnP service  10   a  (Step S 1003 ). In the setting work, the information processing apparatus  900   b  recognizes that the UPnP service  10   a  is available. The information processing apparatus  900   b  stores a validity period included in the received broadcast packet in a predetermined storage unit. After the validity period expires, the information processing apparatus  900   b  recognizes that the UPnP service  10   a  is not available. 
     Subsequently, the information processing apparatus  900   b  starts the UPnP service  10   b  (Step S 1004 ). The information processing apparatus  900   a  sends the information processing apparatus  900   b  a broadcast packet including information concerning the UPnP service  10   b  (Step S 1005 ). The information processing apparatus  900   b  receives the broadcast packet of the UPnP service  10   b  and performs predetermined setting work for using the UPnP service  10   b  (Step S 1006 ). The information processing apparatus  900   b  recognizes that the UPnP service  10   b  is available until a validity period included in the received broadcast packet expires. 
     Thereafter, the information processing apparatus  900   a  sends the broadcast packet of the UPnP service  10   a  to the information processing apparatus  900   b  before the validity period included in the last broadcast packet expires (Step S 1007 ). The information processing apparatus  900   a  performs this broadcast packet notification processing while connected to the network  2 . Every time a broadcast packet is received, the information processing apparatus  900   b  updates the validity period of the UPnP service  10   a  (Step S 1008 ). 
     Similarly, the information processing apparatus  900   a  sends a broadcast packet of the UPnP service  10   b  to the information processing apparatus  900   b  before the validity period included in the last broadcast packet expires (Step S 1009 ). The information processing apparatus  900   b  receives the broadcast packet and updates the validity period of the UPnP service  10   b  (Step S 1010 ). 
     In this way, while the information processing apparatus  900   a  is connected to the network  2 , the information processing apparatus  900   b  recognizes that the UPnP services  10   a  and  10   b  are available and uses the UPnP service  10 . 
     However, in the conventional UPnP service provision system in the UPnP network, when a service providing apparatus provides the complex UPnP service, the timing of expiration of a validity period is different for each of sub-UPnP services. Therefore, it is likely that a service using apparatus uses only a part of sub-UPnP services included in the complex UPnP service. The load of processing for detecting that sub-UPnP services not started yet are present increases and development cost for incorporating the detection processing in a program increases. 
     When the complex UPnP service is used, the number of broadcast packets from the service providing apparatus increases. Therefore, the load of broadcast packet notification processing by the service providing apparatus increases, the load of broadcast packet reception processing by the service using apparatus increases, and traffic on the network increases. 
       FIG. 3  is a sequence chart of a processing flow in a UPnP service provision system in the UPnP network including information processing apparatuses according to the first embodiment. Information processing apparatuses  100   a  to  100   d  of  FIG. 3  correspond to the information processing apparatuses  1   a  to  1   d  of  FIG. 1 . In  FIG. 3 , for simplification of explanation, a flow of processing by the information processing apparatus  100   a  and the information processing apparatus  100   b  is explained. However, the information processing apparatus  100   a  applies the same processing as that applied to the information processing apparatus  100   b  to other information processing apparatuses (not shown). The other information processing apparatuses perform the same processing as that of the information processing apparatus  100   b.    
     As illustrated in  FIG. 3 , the information processing apparatus  100   a  starts the UPnP service  10   a  (Step S 1101 ). The information processing apparatus  100   a  generates a packet including information concerning all UPnP services in operation in the apparatus and only one validity period common to all the UPnP services (hereinafter, “service-start-time broadcast packet”) and sends the generated service-start-time broadcast packet to the information processing apparatus  100   b  (Step S 1102 ). Assuming that only the UPnP service  10   a  is in operation in the information processing apparatus  100   a , the information processing apparatus  100   a  sends the information processing apparatus  100   b  a service-start-time broadcast packet including information concerning the UPnP service  10   a  and a validity period. The service-start-time broadcast packet is a packet in which information concerning a plurality of UPnP services can be set in a broadcast packet (NOTIFY) in the SSDP. 
     The information processing apparatus  100   b  receives the service-start-time broadcast packet of the UPnP service  10   a  and performs predetermined setting work for using the UPnP service  10   a  (Step S 1103 ). The information processing apparatus  100   b  stores the validity period included in the received service-start-time broadcast packet in a predetermined storage unit. 
     Subsequently, the information processing apparatus  100   a  starts the UPnP service  10   b  (Step S 1104 ). The information processing apparatus  100   a  sends the information processing apparatus  100   b  a service-start-time broadcast packet including information concerning the UPnP services  10   a  and  10   b  and a validity period (Step S 1105 ). It is assumed that the UPnP services  10   a  and  10   b  are in operation. 
     The information processing apparatus  100   b  receives the service-start-time broadcast packet including the information concerning the UPnP services  10   a  and  10   b . The information processing apparatus  100   b  performs predetermined setting work for using the UPnP service  10   b  and updates the validity period of the UPnP service  10   a  stored in the predetermined storage unit to the validity period included in the service-start-time broadcast packet (Step S 1106 ). In this way, the information processing apparatus  100   b  simultaneously updates the validity periods of the UPnP services  10   a  and  10   b . Therefore, the validity periods of the UPnP services  10   a  and  10   b  expire at the same timing. 
     Thereafter, when predetermined notification timing comes, the information processing apparatus  100   a  generates a packet including information concerning all UPnP services in operation in the apparatus and a validity period common to all the UPnP services (hereinafter, “service-time broadcast packet”) and sends the generated service-time broadcast packet to the information processing apparatus  100   b  (Step S 1107 ). Assuming that the UPnP services  10   a  and  10   b  are in operation in the information processing apparatus  100   a , the information processing apparatus  100   a  sends the information processing apparatus  100   b  a service-time broadcast packet including information concerning the UPnP services  10   a  and  10   b  and a validity period. While connected to the network  2 , the information processing apparatus  100   a  continues the notification process using the service-time broadcast packet when the predetermined notification timing comes. 
     The service-time broadcast packet has the same structure as previously described for the service-start-time broadcast packet. The “predetermined notification timing” indicates timing at least before a validity period included in the last service-start-time broadcast packet or the last service-time broadcast packet expires. For example, in the case of a service-time broadcast packet in which “600 seconds” is set as a validity period, the information processing apparatus  100   a  issues the service-time broadcast packet before “600 seconds” elapses. 
     The information processing apparatus  100   b  that receives the service-time broadcast packet updates the validity periods of the UPnP services  10   a  and  10   b  stored in the predetermined storage unit to the validity period included in the service-time broadcast packet (Step S 1108 ). 
     In this way, each of the information processing apparatuses  100   a  to  100   d  according to the first embodiment sends the other information processing apparatuses a service-start-time broadcast packet or a service-time broadcast packet including information concerning all UPnP services in operation in the apparatus. Therefore, even when a complex UPnP service is provided, broadcast packets issued for each of sub-UPnP services in the conventional technology can be reduced to one packet (the service-start-time broadcast packet or the service-time broadcast packet). As a result, it is possible to reduce load on the service providing apparatus (in the example of  FIG. 3 , the information processing apparatus  100   a ) for broadcast packet notification processing, load on the service using apparatus (in the example of  FIG. 3 , the information processing apparatuses  100   b  to  100   d ) for broadcast packet reception processing, and traffic on the network. 
     A broadcast packet in the SSDP is described in the Extensible Markup Language (XML). Therefore, an information amount of header information fixedly set in the broadcast packet is large. However, a service-start-time broadcast packet or a service-time broadcast packet in which information concerning a plurality of UPnP services can be set has one piece of header information. Therefore, it is possible to reduce traffic on the network. 
     Because load on the broadcast packet notification processing and load on the broadcast packet reception processing can be reduced, for example, when an information processing apparatus is a portable terminal, it is possible to extend the life of a power supply battery of the portable terminal. 
     The information processing apparatuses  100   a  to  100   d  according to the first embodiment simultaneously updates validity periods of all UPnP services. Therefore, timing of expiration of a validity period is not different for each of sub-UPnP services. This makes it possible to prevent only part of sub-UPnP services included in a complex UPnP service from being used. 
       FIG. 4  is a block diagram of an information processing apparatus  100  according to the first embodiment. The information processing apparatus  100  of  FIG. 4  corresponds to the information processing apparatuses  100   a  to  100   d  explained above.  FIG. 4  depicts only components related to the UPnP. 
     As illustrated in  FIG. 4 , the information processing apparatus  100  includes an interface (I/F) unit  110 , an application-execution control unit  120 , a storage unit  130 , and a UPnP control unit  140 . 
     The I/F unit  110  is an interface for transmitting and receiving information via a network. The application-execution control unit  120  controls execution of various applications. The application-execution control unit  120  instructs, when necessary, the UPnP control unit  140  to perform, for example, provision of a UPnP service or notification processing by a service-start-time broadcast packet or a service-time broadcast packet. 
     The storage unit  130  stores various kinds of information. The storage unit  130  includes a provided-service storage area  131  and a received-service storage area  132 . The provided-service storage area  131  stores information indicating whether UPnP services that can be provided by the information processing apparatus  100  are in operation. 
       FIG. 5  illustrates an example of contents of the provided-service storage area  131 . As illustrated in  FIG. 5 , the contents of the provided-service storage area  131  includes items such as service ID and operation state. The service ID is an identification number for uniquely identifying a UPnP service. In the example of  FIG. 5 , signs affixed to the UPnP services  10   a  and  10   b  in FIG.  1  are service IDs. The operation state indicates whether a UPnP service corresponding to the service ID is in operation. The first row of the provided-service storage area  131  indicates that the UPnP service  10   a  is in operation. The second row of the provided-service storage area  131  indicates that the UPnP service  10   b  is in operation. 
     The received-service storage area  132  stores information concerning UPnP services provided by the other information processing apparatuses in the UPnP network.  FIG. 6  illustrates an example of contents of the received-service storage area  132 . As illustrated in  FIG. 6 , the contents of the received-service storage area  132  includes items such as service ID and validity period. Like the service ID explained above, the service ID is an identification number for uniquely identifying a UPnP service. The validity period is a period in which the UPnP service is valid. 
     The UPnP control unit  140  performs various kinds of control related to the UPnP. The UPnP control unit  140  includes a service providing unit  141 , a service-start notifying unit  142 , an existence-confirmation notifying unit  143 , and a broadcast receiving unit  144 . 
     The service providing unit  141  performs predetermined information processing in response to a request from a user to thereby start or stop a predetermined UPnP service and control provision of the UPnP service. When the predetermined UPnP service is started, the service providing unit  141  updates operation state in the provided-service storage area  131  corresponding to a service ID of the UPnP service to indicate that the UPnP service is in operation. When the predetermined UPnP service is stopped, the service providing unit  141  updates the operation state in the provided-service storage area  131  corresponding to the service ID of the UPnP service to indicate that the UPnP service is stopped. 
     The service-start notifying unit  142  generates, when a new UPnP service is started by the service providing unit  141 , a service-start-time broadcast packet and sends the other information processing apparatuses in the UPnP network the generated service-start-time broadcast packet. 
     Specifically, when a new UPnP service is started by the service providing unit  141 , the service-start notifying unit  142  acquires, from the provided-service storage area  131 , all service IDs each corresponding to operation state indicating that a UPnP service is in operation. The service-start notifying unit  142  generates a service-start-time broadcast packet including information concerning all the UPnP services (service IDs, service names, etc.) indicated by the acquired service IDs and a validity period common to all the UPnP services. The service-start notifying unit  142  sends the other information processing apparatuses in the UPnP network the generated service-start-time broadcast packet via the I/F unit  110 . 
     The existence-confirmation notifying unit  143  generates, when predetermined notification timing comes, a service-time broadcast packet and sends the other information processing apparatuses in the UPnP network the generated service-time broadcast packet. 
     Specifically, at least before a validity period included in the last service-start-time broadcast packet or the last service-time broadcast packet expires, the existence-confirmation notifying unit  143  acquires, from the provided-service storage area  131 , all service IDs each corresponding to operation state indicating that a UPnP service is in operation. The existence-confirmation notifying unit  143  generates a service-time broadcast packet including information concerning all the UPnP services (service IDs, service names, etc.) indicated by the acquired service IDs and a validity period common to all the UPnP services. The existence-confirmation notifying unit  143  sends the other information processing apparatuses in the UPnP network the generated service-time broadcast packet. The existence-confirmation notifying unit  143  continues the notification process using the service-time broadcast packet while the information processing apparatus  100  is connected to the network  2 . 
     The broadcast receiving unit  144  receives a service-start-time broadcast packet or a service-time broadcast packet from another information processing apparatus in the UPnP network and performs predetermined setting work for using a UPnP service based on various kinds of information included in the service-start-time broadcast packet or the service-time broadcast packet. 
     Specifically, when a service-start-time broadcast packet is received, the broadcast receiving unit  144  performs predetermined setting work for using a UPnP service included in the service-start-time broadcast packet. When a service-time broadcast packet is received, the broadcast receiving unit  144  extracts a service ID and a validity period from the service-time broadcast packet and updates a validity period in the received-service storage area  132  corresponding to the extracted service ID to the extracted validity period. 
       FIG. 7  is a flowchart of service-start-time broadcast packet transmission processing performed by the service-start notifying unit  142 . 
     As illustrated in  FIG. 7 , when a new UPnP service is started by the service providing unit  141  (Yes at Step S 101 ), the service-start notifying unit  142  acquires, from the provided-service storage area  131 , all service IDs each corresponding to operation state indicating that a UPnP service is in operation (Step S 102 ). 
     The service-start notifying unit  142  generates a service-start-time broadcast packet including information concerning all UPnP services indicated by the service ID acquired from the provided-service storage area  131  and a validity period common to all the UPnP services, and sends the other information processing apparatuses in the UPnP network the service-start-time broadcast packet (Step S 103 ). 
       FIG. 8  is a flowchart of service-time broadcast packet transmission processing performed by the existence-confirmation notifying unit  143 . 
     As illustrated in  FIG. 8 , when predetermined notification time comes (Yes at Step S 201 ), the existence-confirmation notifying unit  143  acquires, from the provided-service storage area  131 , all service IDs each corresponding to operation state indicating that a UPnP service is in operation (Step S 202 ). 
     The existence-confirmation notifying unit  143  generates a service-time broadcast packet including information concerning all UPnP services indicated by the service IDs acquired from the provided-service storage area  131  and a validity period common to all UPnP services, and sends the other information processing apparatuses in the UPnP network the service-time broadcast packet (Step S 203 ). 
     As explained above, in the information processing apparatus  100  according to the first embodiment, when a new UPnP service is started, the service-start notifying unit  142  generates a service-start-time broadcast packet and transmits the service-start-time broadcast packet to the other information processing apparatuses in the UPnP network. When the predetermined notification timing comes, the existence-confirmation notifying unit  143  generates a service-time broadcast packet and transmits the service-time broadcast packet to the other information processing apparatuses in the UPnP network. Therefore, even when a complex UPnP service is provided, it is possible to set validity periods for sub-UPnP services included in the complex UPnP service to expire at the same timing and to reduce the number of broadcast packets 
     In the first embodiment, when a new UPnP service is started, an information processing apparatus that provides such a UPnP service unilaterally sends the other information processing apparatuses a service-start-time broadcast packet. However, the service using apparatus can request the service providing apparatus to send the service-start-time broadcast packet thereto. In a second embodiment, when a new UPnP service is started, an information processing apparatus that uses the UPnP service requests an information processing apparatus that provides the UPnP service to send a service-start-time broadcast packet thereto. 
       FIG. 9  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to the second embodiment. Information processing apparatuses  200   a  and  200   b  according to the second embodiment in  FIG. 9  correspond to the information processing apparatuses  1   a  to  1   d  in  FIG. 1 . For simplification of explanation, a flow of processing by the two information processing apparatus  200   a  and  200   b  is explained. However, the information processing apparatus  200   a  can apply the same processing as is applied to the information processing apparatus  200   b  to other information processing apparatuses (not shown). The other information processing apparatuses perform the same processing as is performed by the information processing apparatus  200   b.    
     As illustrated in  FIG. 9 , the information processing apparatus  200   a  starts the UPnP service  10   a  (Step S 1201 ). The information processing apparatus  200   a  sends the information processing apparatus  200   b  a packet including an apparatus ID for uniquely identifying an information processing apparatus in the UPnP network (hereinafter, “service-start notification packet”) (Step S 1202 ). 
     The service-start notification packet is a packet for an information processing apparatus that provides a UPnP service to notify the other information processing apparatuses that a new UPnP service is started. Information set in the apparatus ID included in the service-start notification packet only has to be a value with which an information processing apparatus can be uniquely identified in the UPnP network. Examples of the information include a media access control (MAC) address of the information processing apparatus, and a serial number of the information processing apparatus. 
     The information processing apparatus  200   b  receives the service-start notification packet and requests the information processing apparatus  200   a  to send thereto a list of UPnP services in operation (hereinafter, “service list request”) (Step S 1203 ). The information processing apparatus  200   a  receives the service list request and sends the information processing apparatus  200   b  a service-start-time broadcast packet including information concerning the UPnP service  10   a  and a validity period (Step S 1204 ). It is assumed that the UPnP service  10   a  is in operation. 
     The information processing apparatus  200   b  receives the service-start-time broadcast packet of the UPnP service  10   a  and performs predetermined setting work for using the UPnP service  10   a  (Step S 1205 ). The information processing apparatus  200   b  stores the service ID and the validity period of the UPnP service  10   a  in a predetermined storage unit in association with the apparatus ID included in the received service-start notification packet. 
     Subsequently, the information processing apparatus  200   a  starts the UPnP service  10   b  (Step S 1206 ). The information processing apparatus  200   a  sends the service-start notification packet to the information processing apparatus  200   b  (Step S 1207 ). 
     The information processing apparatus  200   b  receives the service-start notification packet and sends a service list request to the information processing apparatus  200   a  (Step S 1208 ). The information processing apparatus  200   a  receives the service list request and sends the information processing apparatus  200   b  a service-start-time broadcast packet including information concerning the UPnP services  10   a  and  10   b  and a validity period (Step S 1209 ). It is assumed that the UPnP services  10   a  and  10   b  are in operation. 
     The information processing apparatus  200   b  receives the service-start-time broadcast packet of the UPnP services  10   a  and  10   b , performs predetermined setting work for using the UPnP service  10   b , and updates the validity period of the UPnP service  10   a  to the validity period included in the service-start-time broadcast packet (Step S 1210 ). The information processing apparatus  200   b  stores the service ID and the validity period of the UPnP service  10   b  in a predetermined storage unit in association with the apparatus ID included in the received service-start notification packet. In other words, the information processing apparatus  200   b  stores the service IDs and the validity periods of the UPnP services  10   a  and  10   b  in the predetermined storage unit in association with the apparatus ID of the information processing apparatus  200   a . 
     Thereafter, when predetermined notification timing comes, the information processing apparatus  200   a  generates a packet including the apparatus ID and the validity period (hereinafter, “apparatus-ID notification packet”) and sends the generated apparatus-ID notification packet to the information processing apparatus  200   b  (Step S 1211 ). 
     The “predetermined notification timing” indicates timing at least before a validity period included in the last service-start-time broadcast packet or the last service-time broadcast packet expires. 
     The information processing apparatus  200   b  receives the apparatus-ID notification packet from the information processing apparatus  200   a  and updates the validity period stored in the predetermined storage unit in association with the apparatus ID of the information processing apparatus  200   a  to the validity period included in the apparatus-ID notification packet (Step S 1212 ). 
       FIG. 10  is a block diagram of an information processing apparatus  200  according to the second embodiment. The information processing apparatus  200  in  FIG. 10  corresponds to the information processing apparatuses  200   a  and  200   b  explained above.  FIG. 10  depicts only components related to the UPnP. In  FIG. 10 , like reference numerals refer to corresponding components having the same functions as those of the components depicted in  FIG. 4 , and the detailed explanation thereof is omitted. 
     A received-service storage area  232  of a storage unit  230  stores, in information processing apparatus units, UPnP services provided by the other information processing apparatuses in the UPnP network.  FIG. 11  illustrates an example of contents of the received-service storage area  232 . As illustrated in  FIG. 11 , the contents of the received-service storage area  232  includes items such as apparatus ID, service ID, and validity period. The received-service storage area  232  is updated by a broadcast receiving unit  244  explained later. Update processing for the received-service storage area  232  by the broadcast receiving unit  244  is explained later. 
     When a new UPnP service is started by the service providing unit  141 , a service-start notifying unit  242  of a UPnP control unit  240  generates a service-start notification packet including an apparatus ID of the information processing apparatus  200  and sends the service-start notification packet to the other information processing apparatuses. When a service list request is received from another information processing apparatus that receives the service-start notification packet, the service-start notifying unit  242  generates a service-start-time broadcast packet and sends the generated service-start-time broadcast packet to only the information processing apparatus, which has sent the service list request. 
     An existence-confirmation notifying unit  243  of the UPnP control unit  240  generates an apparatus-ID notification packet and sends the apparatus-ID notification packet to the other information processing apparatuses in the UPnP network when predetermined notification timing comes. 
     Specifically, at least before a validity period included in the last service-start-time broadcast packet or the last apparatus-ID notification packet expires, the existence-confirmation notifying unit  243  acquires, from the provided-service storage area  131 , the number of records each corresponding to operation state indicating that a UPnP service is in operation. When the acquired number of records is equal to or larger than “1”, the existence-confirmation notifying unit  243  generates an apparatus-ID notification packet including an apparatus ID and a validity period, and sends the generated apparatus-ID notification packet to the other information processing apparatuses in the UPnP network. 
     The broadcast receiving unit  244  of the UPnP control unit  240  receives a service-start notification packet, a service-start-time broadcast packet, or an apparatus-ID notification packet from the other information processing apparatuses in the UPnP network and performs predetermined setting work for using a UPnP service. 
     Specifically, upon receipt of a service-start notification packet, the broadcast receiving unit  244  causes the received-service storage area  232  to store an apparatus ID included in the service-start notification packet. The broadcast receiving unit  244  sends a service list request to an information processing apparatus at a transmission source of the service-start notification packet (hereinafter, “transmission-source information processing apparatus”). When a service-start-time broadcast packet is received from the transmission-source information processing apparatus in response to the service list request, the broadcast receiving unit  244  performs predetermined setting work for using a UPnP service included in the service-start-time broadcast packet. The broadcast receiving unit  244  stores a service ID included in the service-start-time broadcast packet in the service ID in the received-service storage area  232  corresponding to the apparatus ID stored when the service-start notification packet is received. 
     Upon receipt of an apparatus-ID notification packet, the broadcast receiving unit  244  updates the validity period in the received-service storage area  232  corresponding to an apparatus ID included in the apparatus-ID notification packet to a validity period included in the apparatus-ID notification packet. 
       FIG. 12  is a flowchart of service-start-time broadcast packet transmission processing performed by the service-start notifying unit  242 . 
     As illustrated in  FIG. 12 , when a new UPnP service is started by the service providing unit  141  (Yes at Step S 301 ), the service-start notifying unit  242  sends a service-start notification packet to the other information processing apparatuses (Step S 302 ). 
     When a service list request is received from another information processing apparatus that receives the transmitted service-start notification packet (Yes at Step S 303 ), the service-start notifying unit  242  acquires, from the provided-service storage area  131 , all service IDs each corresponding to operation state indicating that a UPnP service is in operation is stored (Step S 304 ). 
     The service-start notifying unit  242  sends only the information processing apparatus, which has sent the service list request, a service-start-time broadcast packet including information concerning all UPnP services indicated by the service IDs acquired from the provided-service storage area  131  and a validity period common to all the UPnP services (Step S 305 ). 
       FIG. 13  is a flowchart of apparatus-ID notification packet transmission processing performed by the existence-confirmation notifying unit  243 . 
     As illustrated in  FIG. 13 , when predetermined notification timing comes (Yes at Step S 401 ), the existence-confirmation notifying unit  243  acquires, from the provided-service storage area  131 , the number of records each corresponding to operation state indicating that a UPnP service is in operation (Step S 402 ). 
     When the number of records acquired from the provided-service storage area  131  is equal to or larger than “1”, i.e., a UPnP service in operation is present in the information processing apparatus  200  (Yes at Step S 403 ), the existence-confirmation notifying unit  243  generates an apparatus-ID notification packet including the apparatus ID of the information processing apparatus  200  and a validity period, and sends the apparatus-ID notification packet to the other information processing apparatuses in the UPnP network (Step S 404 ). 
     On the other hand, when the number of records acquired from the provided-service storage area  131  is “0”, i.e., a UPnP service in operation is not present in the information processing apparatus  200  (No at Step S 403 ), the existence-confirmation notifying unit  243  ends the processing. 
     As explained above, in the information processing apparatus  200  according to the second embodiment, when a new UPnP service is started, the service-start notifying unit  242  sends a service-start notification packet to other information processing apparatuses. When a service list request responding to the service-start notification packet is received, the service-start notifying unit  242  sends a service-start-time broadcast packet to the information processing apparatus, which has sent the service list request. When the predetermined notification time comes, the existence-confirmation notifying unit  243  issues an apparatus ID notification packet. Therefore, even when a complex UPnP service is provided, it is possible to set validity periods for sub-UPnP services included in the complex UPnP service to expire at the same timing and to reduce the number of broadcast packets. Moreover, the service using apparatus can control reception timing for the service-start notification packet. Consequently, when the service using apparatus is in a high load state, it is possible to prevent the service providing apparatus from sending the service-start notification packet to the service using apparatus. 
     In the first and second embodiment, the service using apparatus does not recognize which sub-UPnP services are included in a complex UPnP service. However, the service using apparatus can be configured to recognize which sub-UPnP services are included in a complex UPnP service. In a third embodiment, the service using apparatus recognizes relation among sub-UPnP services included in a complex UPnP service. 
       FIG. 14  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses according to the third embodiment. Information processing apparatuses  300   a  and  300   b  according to the third embodiment in  FIG. 14  correspond to the information processing apparatuses  1   a  to  1   d  in  FIG. 1 . In  Fig. 14 , for simplification of explanation, a flow of processing by the two information processing apparatus  300   a  and the information processing apparatus  300   b  is explained. However, the information processing apparatus  300   a  applies the same processing as is applied to the information processing apparatus  300   b  to other information processing apparatuses (not shown). The other information processing apparatuses performs the same processing as is performed by the information processing apparatus  300   b.    
     As illustrated in  FIG. 14 , the information processing apparatus  300   a  starts the UPnP service  10   a  (Step S 1301 ). In the same manner as the conventional information processing apparatus  900   a , the information processing apparatus  300   a  sends the information processing apparatus  300   b  a broadcast packet of the UPnP service  10   a  (Step S 1302 ). The information processing apparatus  300   b  receives the broadcast packet of the UPnP service  10   a  and performs predetermined setting work for using the UPnP service  10   a  (Step S 1303 ). 
     Subsequently, the information processing apparatus  300   a  starts the UPnP service  10   b  (Step S 1304 ). The information processing apparatus  300   a  sends the information processing apparatus  300   b  a packet indicating that the UPnP service  10   a  and the UPnP service  10   b  are related (hereinafter, “related service broadcast packet”) (Step S 1305 ). “The UPnP service  10   a  and the UPnP service  10   b  are related” means that the UPnP service  10   a  and the UPnP service  10   b  are elements of an identical complex UPnP service. Having received the related service broadcast packet, the information processing apparatus  300   b  recognizes that the UPnP service  10   a  and the UPnP service  10   b  are related. 
     Subsequently, the information processing apparatus  300   a  sends the information processing apparatus  300   b  a broadcast packet of the UPnP service  10   b  (Step S 1306 ). Upon receipt of the broadcast packet of the UPnP service  10   b , the information processing apparatus  300   b  performs predetermined setting work for using the UPnP service  10   b  and updates a validity period of the UPnP service  10   a  stored in the predetermined storage unit to a validity period included in the broadcast packet (Step S 1307 ). Since the information processing apparatus  300   b  has been notified that the UPnP service  10   a  and the UPnP service  10   b  are related, when receiving the broadcast packet of the UPnP service  10   b , it updates the validity period of the UPnP service  10   a . This makes it possible to set validity periods for the UPnP services  10   a  and  10   b  to expire at the same time. 
     In the example of  FIG. 14 , the information processing apparatus  300   a  issues the broadcast packet of the UPnP service  10   b  after the related service broadcast packet. However, the information processing apparatus  300   a  may issue the related service broadcast packet after the broadcast packet of the UPnP service  10   b . 
     Thereafter, the information processing apparatus  300   a  sends the information processing apparatus  300   b  a broadcast packet of the UPnP service  10   a  before a validity period included in the last broadcast packet expires (Step S 1308 ). Upon receipt of the broadcast packet, the information processing apparatus  300   b  updates validity periods of the UPnP service  10   a  and the UPnP service  10   b  related to the UPnP service  10   a  (Step S 1309 ). 
     The information processing apparatus  300   a  sends the broadcast packet of the UPnP service  10   b  to the information processing apparatus  300   b  before a validity period included in the last broadcast packet expires (Step S 1310 ). Upon receipt of the broadcast packet of the UPnP service  10   b , the information processing apparatus  300   b  discards the broadcast packet (Step S 1311 ). This is because, when the information processing apparatus  300   b  receives one of the UPnP services  10   a  or  10   b , the information processing apparatus  300   b  can update the validity period of the UPnP service  10   a  or  10   b . The information processing apparatus  300   b  determines in advance which of the broadcast packets of the UPnP services  10   a  and  10   b  is discarded. For example, when a service ID is information that can be compared like a numerical value, the information processing apparatus  300   b  determines in advance that the broadcast packet with a smaller service ID is discarded. 
       FIG. 15  is a block diagram of an information processing apparatus  300  according to the third embodiment. The information processing apparatus  300  in  FIG. 15  corresponds to the information processing apparatuses  300   a  and  300   b  explained above.  FIG. 15  depicts only components related to the UPnP. Like reference numerals refer to corresponding components having the same functions as those of  FIGS. 4 and 10 , and detailed explanation thereof is omitted. 
     A provided-service storage area  331  of a storage unit  330  stores information indicating whether UPnP services that can be provided by the information processing apparatus  300  are in operation and information indicating relation of the UPnP services.  FIG. 16  illustrates an example of contents of the provided-service storage area  331 . As illustrated in  FIG. 16 , the contents of the provided-service storage area  331  includes items such as relation ID, service ID, and operation state. The relation ID is an identification number for uniquely identifying relation of the UPnP services. A first row of the provided-service storage area  331  indicates that the UPnP service  10   a  with the service ID “ 10   a ” and a UPnP service  10   b  with the service ID “ 10   b ” are related. A second row of the provided-service storage area  331  indicates that a UPnP service  20   a  with the service ID “ 20   a ”, a UPnP service  20   b  with the service ID “ 20   b ”, and a UPnP service  20   c  with the service ID “ 20   c ” are related. 
     A received-service storage area  332  of the storage unit  330  stores information concerning UPnP services provided by the other information processing apparatuses in the UPnP network.  FIG. 17  illustrates an example of contents of the received-service storage area  332 . As illustrated in  FIG. 17 , the contents of the received-service storage area  332  includes items such as relation ID, service ID, and validity period. The relation ID is the same item as the relation ID of the provided-service storage area  331  in  FIG. 16 . 
     A service-start notifying unit  342  of a UPnP control unit  340  sends, when a new UPnP service is started by the service providing unit  141 , other information processing apparatuses a broadcast packet of the UPnP service and also a related-service broadcast packet. 
     Specifically, when a new UPnP service is started, the service-start notifying unit  342  retrieves a UPnP service that is related to the UPnP service started anew and is in operation from the provided-service storage area  331 . The service-start notifying unit  342  generates a related-service broadcast packet indicating that the retrieved UPnP service and the UPnP service started anew are related. The service-start notifying unit  342  sends the generated related-service broadcast packet to the other information processing apparatuses. 
     For example, when the UPnP service  10   b  is started anew and the provided-service storage area  331  changes to a state illustrated in  FIG. 16 , the service-start notifying unit  342  acquires the relation ID “ 001 ” corresponding to the service ID “ 10   b ” from the provided-service storage area  331 . The service-start notifying unit  342  acquires the service IDs “ 10   a ” and “ 10   b ” with the relation ID “ 001 ” and operation state “in operation”. Consequently, the service-start notifying unit  342  judges that the UPnP service  10   a  and the UPnP service  10   b  are related and generates a related-service broadcast packet indicating that the UPnP service  10   a  and the UPnP service  10   b  are related. 
     An existence-confirmation notifying unit  343  of the UPnP control unit  340  has the same function as that of the conventional information processing apparatus  900   a . The existence-confirmation notifying unit  343  sends the other information processing apparatuses a broadcast packet for each of UPnP services before a validity period included in the last broadcast packet expires. 
     A broadcast receiving unit  344  of the UPnP control unit  340  updates, when receiving a related-service broadcast packet, the received-service storage area  332  to make relation IDs of UPnP services included in the related-service broadcast packet identical. For example, when information indicating that service IDs “ 30   a ” and “ 30   b ” are related is included in the related-service broadcast packet, the broadcast receiving unit  344  updates the received-service storage area  332  to make relation IDs of the UPnP services  30   a  and  30   b  identical as indicated by an example of the received-service storage area  332  illustrated in  FIG. 17 . 
     When a broadcast packet is received, the broadcast receiving unit  344  retrieves a UPnP service related to a UPnP service indicated by the broadcast packet from the received-service storage area  332 . When the UPnP service related to the UPnP service indicated by the broadcast packet is present, the broadcast receiving unit  344  judges whether the received broadcast packet is not processed. For example, as described above, when a broadcast packet with a smaller service ID is discarded, a broadcast receiving unit  314  discards the received broadcast packet when a service ID of the UPnP service indicated by the received broadcast packet is smaller than a service ID of the UPnP service related to the UPnP service. When the received broadcast packet is not discarded, the broadcast receiving unit  344  updates validity periods in the received-service storage area  332  of the UPnP service indicated by the broadcast packet and the UPnP service related to the UPnP service to a validity period included in the broadcast packet. 
       FIG. 18  is a flowchart of broadcast packet transmission processing and related-service-broadcast-packet transmission processing performed by the service-start notifying unit  342 . 
     As illustrated in  FIG. 18 , when a new UPnP service is started by the service providing unit  141  (Yes at Step S 501 ), the service-start notifying unit  342  retrieves a UPnP service that is related to the UPnP service started anew and is in operation from the provided-service storage area  331  (Step S 502 ). 
     When the UPnP service that is related to the UPnP service started anew and is in operation is retrieved (Yes at Step S 503 ), the service-start notifying unit  342  generates a related-service broadcast packet indicating that the retrieved UPnP service and the UPnP service started anew are related, and sends the generated related service broadcast packet to the other information processing apparatuses (Step S 504 ). The service-start notifying unit  342  sends the other information processing apparatuses a broadcast packet of the UPnP service started anew (Step S 505 ). 
     On the other hand, when the UPnP service that is related to the UPnP service started anew and is in operation is not retrieved (No at Step S 503 ), the service-start notifying unit  342  sends the other information processing apparatuses a broadcast packet of the UPnP service started anew (Step S 505 ). 
     As explained above, in the information processing apparatus  300  according to the third embodiment, when a new UPnP service is started, the service-start notifying unit  342  sends other information processing apparatuses a broadcast packet of the UPnP service started anew. The service-start notifying unit  342  retrieves a UPnP service that is related to the UPnP service started anew and is in operation from the provided-service storage area  331 . The service-start notifying unit  342  sends the other information processing apparatuses a related-service broadcast packet indicating that the retrieved UPnP service and the UPnP service started anew are related. Therefore, even when a complex UPnP service is provided, it is possible to set validity periods for sub-UPnP services included in the complex UPnP service to expire at the same time and to reduce the number of broadcast packets. Moreover, as existence confirmation notification after the start of a UPnP service, it is possible to use a broadcast packet according to the conventional standards. 
     The configuration of the information processing apparatus  100  explained in the first embodiment can be combined with others. For example, the configuration of the information processing apparatus  100  can be combined with the configuration disclosed in Japanese Patent Application No. 2007-013626 filed by the applicant. In a fourth embodiment, an example of a combination of the configuration of the information processing apparatus  100  explained in the first embodiment and the configuration disclosed in Japanese Patent Application No. 2007-013626 is explained. 
       FIG. 19  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses  1100   a  and  1100   b  according to the fourth embodiment. The information processing apparatuses  1100   a  and  1100   b  according to the fourth embodiment in  FIG. 19  correspond to the information processing apparatuses la to Id of  FIG. 1 . The information processing apparatuses  1100   a  and  1100   b  are assumed to be mobile devices such as portable terminals. Explanation of a processing procedure (Steps S 1401  to S 1408 ), the same processing as previously described in connection with  FIG. 3 , is omitted. 
     As illustrated in  FIG. 19 , the information processing apparatus  1100   a  detects a change in radio wave intensity (Step S 1409 ). The information processing apparatus  1100   a  changes a value of a validity period set in a service-time broadcast packet (Step S 1410 ). 
     Specifically, the information processing apparatus  1100   a  judges that a communication state of the information processing apparatus  1100   a  is more stable as the radio wave intensity is higher and sets a validity period longer. This is because, when the radio wave intensity is high and the communication state is stable, it is unlikely that the information processing apparatus  1100   a  immediately leaves or is immediately disconnected from the network  2 . Consequently, when the radio wave intensity is high, the validity period is long, and it is possible to reduce the number of service-time broadcast packets. As a result, it is possible to reduce network load. 
     The information processing apparatus  1100   a  judges that a communication state of the information processing apparatus  1100   a  is more unstable as radio wave intensity is lower and sets a validity period short. This is because, when the radio wave intensity is low and the communication state is unstable, it is likely that the information processing apparatus  1100   a  leaves or is disconnected from the network  2 . Consequently, when the radio wave intensity is low, the validity period is short. Therefore, when the information processing apparatus  1100   a  leaves the network  2 , the other information processing apparatus  1100   b  can quickly recognize that the information processing apparatus  1100   a  leaves the network  2 . 
     The information processing apparatus  1100   a  sends the information processing apparatus  1100   b  a service-time broadcast packet including the validity period with the changed value (Step S 1411 ). Upon receipt of the service-time broadcast packet, the information processing apparatus  1100   b  updates validity periods of the UPnP services  10   a  and  10   b  to the validity period included in the service-time broadcast packet (Step S 1412 ). 
     As explained above, in addition to the configuration of the first embodiment, each of the information processing apparatuses  1100   a  and  1100   b  according to the fourth embodiment is configured to change, based on a change in a radio wave state, a value of a validity period set in a service-time broadcast packet. Therefore, even when a complex UPnP service is provided, it is possible to set validity periods for sub-UPnP services included in the complex UPnP service to expire at the same time and to reduce the number of broadcast packets. Moreover, when radio wave intensity is high, it is possible to reduce network load and, when radio wave intensity is low, other information processing apparatuses can quickly recognize that the information processing apparatus leaves the network  2 . 
     In the fourth embodiment, the information processing apparatus  1100   a  changes a set value of a validity period based on a change in radio wave intensity. However, the information processing apparatus  1100   a  can change the set value of the validity period based on a change in an apparatus state such as a communication band, a residual band, a residual power supply capacity, moving speed, or load. 
     In the fourth embodiment, a set value of a validity period set in a service-time broadcast packet is changed. However, the information processing apparatus  1100   a  can change, based on radio wave intensity, a validity period set in a service-start-time broadcast packet as well. 
     As in the fourth embodiment, the configuration of the information processing apparatus  200  explained in the second embodiment can be combined with the configuration disclosed in Japanese Patent Application No. 2007-013626 filed by the applicant. In a fifth embodiment, an example of a combination of the configuration of the information processing apparatus  200  explained in the second embodiment and the configuration disclosed in Japanese Patent Application No. 2007-013626 is explained. 
       FIG. 20  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses  1200   a  and  1200   b  according to the fifth embodiment. The information processing apparatuses  1200   a  and  1200   b  according to the fifth embodiment in  FIG. 20  correspond to the information processing apparatuses  1   a  to  1   d  of  FIG. 1 . The information processing apparatuses  1200   a  and  1200   b  are assumed to be mobile devices such as portable terminals. Explanation of a processing procedure (Steps S 1501  to S 1512 ), the same processing as previously described in connection with  FIG. 9 , is omitted. 
     As illustrated in  FIG. 20 , the information processing apparatus  1200   a  detects a change in radio wave intensity (Step S 1513 ). The information processing apparatus  1200   a  changes a value of a validity period set in an apparatus-ID notification packet (Step S 1514 ). The information processing apparatus  1200   a  sends the information processing apparatus  1200   b  an apparatus-ID notification packet including the validity period with the changed value (Step S 1515 ). When receiving the apparatus-ID notification packet, the information processing apparatus  1200   b  updates a validity period in the received-service storage area  232  corresponding to an apparatus ID included in the apparatus-ID notification packet to the validity period included in the apparatus-ID notification packet (Step S 1516 ). 
     As explained above, in addition to the configuration of the second embodiment, each of the information processing apparatuses  1200   a  and  1200   b  according to the fifth embodiment is configured to change a value of a validity period set in an apparatus-ID notification packet. Therefore, even when a complex UPnP service is provided, it is possible to set validity periods for sub-UPnP services included in the complex UPnP service to expire at the same time and to reduce the number of broadcast packets. Moreover, when radio wave intensity is high, it is possible to reduce network load and, when radio wave intensity is low, other information processing apparatuses can quickly recognize that the information processing apparatus leaves the network  2 . 
     As in the fourth and fifth embodiments, the configuration of the information processing apparatus  300  explained in the third embodiment can be combined with the configuration disclosed in Japanese Patent Application No.  2007 - 013626  filed by the applicant. In a sixth embodiment, an example of a combination of the configuration of the information processing apparatus  300  explained in the third embodiment and the configuration disclosed in Japanese Patent Application No. 2007-013626 is explained. 
       FIG. 21  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses  1300   a  and  1300   b  according to the sixth embodiment. The information processing apparatuses  1300   a  and  1300   b  according to the sixth embodiment in  FIG. 21  correspond to the information processing apparatuses  1   a  to  1   d  of  FIG. 1 . The information processing apparatuses  1300   a  and  1300   b  are assumed to be mobile terminals such as portable terminals. Explanation of a processing procedure (Steps S 1601  to S 1607 ), the same processing as previously described in connection with  FIG. 14 , is omitted. 
     As illustrated in  FIG. 21 , the information processing apparatus  1300   a  detects a change in radio wave intensity (Step S 1608 ). The information processing apparatus  1300   a  changes a value of a validity period set in a broadcast packet (Step S 1609 ). The information processing apparatus  1300   a  sends the information processing apparatus  1300   b  a broadcast packet of the UPnP service  10   a  including the validity period with the changed value (Step S 1610 ). Upon receipt of the broadcast packet, the information processing apparatus  1300   b  updates validity periods of the UPnP service  10   a  and the UPnP service  10   b  related to the UPnP service  10   a  (Step S 1611 ). 
     The information processing apparatus  1300   a  sends the information processing apparatus  1300   b  a broadcast packet of the UPnP service  10   b  including the validity period with the changed value (Step S 1612 ). The information processing apparatus  1300   b  discards the broadcast packet (Step S 1613 ). 
     As explained above, in addition to the configuration of the third embodiment, each of the information processing apparatuses  1300   a  and  1300   b  according to the sixth embodiment is configured to change a value of a validity period set in a broadcast packet based on a change in a radio wave state. Therefore, even when a complex UPnP service is provided, it is possible to set validity periods for sub-UPnP services included in the complex UPnP service to expire at the same time and to reduce the number of broadcast packets. Moreover, when radio wave intensity is high, it is possible to reduce network load and, when radio wave intensity is low, other information processing apparatuses can quickly recognize that the information processing apparatus leaves the network  2 . 
     The configuration of the information processing apparatus  100  explained in the first embodiment can be combined with the configuration disclosed in Japanese Patent Application No. 2007-047339 filed by the applicant. In a seventh embodiment, an example of a combination of the configuration of the information processing apparatus  100  explained in the first embodiment and the configuration disclosed in Japanese Patent Application No. 2007-047339 is explained. 
       FIG. 22  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses  1400   a  to  1400   c  according to the seventh embodiment. The information processing apparatuses  1400   a  to  1400   c  according to the seventh embodiment in  FIG. 22  correspond to the information processing apparatuses la to Id of  FIG. 1 . The information processing apparatuses  1400   a  and  1400   c  are assumed to be mobile devices such as portable terminals and the information processing apparatus  1400   b  is assumed to be a non-mobile device such as a server. Explanation of a processing procedure (Steps S 1701  to S 1708 ), the same processing as previously described in connection with  FIG. 3 , is omitted. 
     As illustrated in  FIG. 22 , the information processing apparatus  1400   a  detects a fall in radio wave intensity (Step S 1709 ) and judges whether monitoring is necessary. When the information processing apparatus  1400   a  is likely to leave the network  2  because a communication state is unstable, it sends the information processing apparatuses  1400   b  and  1400   c  a monitoring request (Step S 1710 ). It is assumed that, because the information processing apparatus  1400   b  as a non-mobile device is more stable than the information processing apparatus  1400   c  as a mobile device, the information processing apparatus  1400   b  monitors the information processing apparatus  1400   a.    
     The information processing apparatus  1400   b  sends existence confirmation notification for confirming at predetermined intervals that the information processing apparatus  1400   a  does not leave the network  2  to the information processing apparatus  1400   a  (Step S 1711 ). When the information processing apparatus  1400   a  that receives the existence confirmation notification is connected to the network  2  and can perform communication, the information processing apparatus  1400   a  sends an existence response to the information processing apparatus  1400   b  (Step S 1712 ). 
     The information processing apparatus  1400   b  sends a service-start-time broadcast packet to the information processing apparatus  1400   c  instead of the information processing apparatus  1400   a  (Step S 1713 ). Upon receipt of the service-start-time broadcast packet, the information processing apparatus  1400   c  updates validity periods of the UPnP services  10   a  and  10   b  (Step S 1714 ). 
     When the information processing apparatus  1400   a  leaves the network  2  (Step S 1715 ), i.e., when the existence response is not received from the information processing apparatus  1400   a , the information processing apparatus  1400   b  detects that the information processing apparatus  1400   a  leaves the network  2  (Step S 1716 ). The information processing apparatus  1400   b  sends the information processing apparatus  1400   c  a message indicating that the UPnP services  10   a  and  10   b  are not available (Step S 1717 ). In this message, information concerning a plurality of UPnP services can be set in a BYEBYE message in the UPnP. 
     As explained above, in addition to the configuration of the first embodiment, each of the information processing apparatuses  1400   a  to  1400   c  according to the seventh embodiment is configured to send, when it is judged based on a change in a radio wave state that a communication state is unstable, a monitoring request for the apparatus to the other information processing apparatuses. The other information processing apparatuses with stable communication state perform monitoring. Therefore, even when a complex UPnP service is provided, it is possible to set validity periods for sub-UPnP services included in the complex UPnP service to expire at the same time and to reduce the number of broadcast packets. Moreover, the other information processing apparatuses can quickly recognize that the information processing apparatus leaves the network  2 . 
     As in the seventh embodiment, the configuration of the information processing apparatus  200  explained in the second embodiment can be combined with the configuration disclosed in Japanese Patent Application No. 2007-047339 filed by the applicant. In an eighth embodiment, an example of a combination of the configuration of the information processing apparatus  200  explained in the second embodiment and the configuration disclosed in Japanese Patent Application No. 2007-047339 is explained. 
       FIG. 23  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses  1500   a  to  1500   c  according to the eighth embodiment. The information processing apparatuses  1500   a  to  1500   c  according to the eighth embodiment in  FIG. 23  correspond to the information processing apparatuses  1   a  to  1   d  of  FIG. 1 . The information processing apparatuses  1500   a  and  1500   c  are assumed to be mobile devices such as portable terminals and the information processing apparatus  1500   b  is assumed to be a non-mobile device such as a server. Explanation of a processing procedure (Steps S 1801  to S 1820 ), the same processing as previously described in connection with  FIGS. 9 and 22 , is omitted. 
     As illustrated in  FIG. 23 , when the information processing apparatus  1500   a  leaves the network  2  (Step S 1821 ), i.e., when the existence response is not sent from the information processing apparatus  1500   a , the information processing apparatus  1500   b  detects that the information processing apparatus  1500   a  leaves the network  2  (Step S 1822 ). The information processing apparatus  1500   b  sends the information processing apparatus  1500   c  an apparatus-ID notification packet including an apparatus ID of the information processing apparatus  1500   a  and a validity period “0” (Step S 1823 ). Upon receipt of the apparatus-ID notification packet, the information processing apparatus  1500   c  recognizes that the UPnP services  10   a  and  10   b  provided by the information processing apparatus  1500   a  are not available. 
     As explained above, in addition to the configuration of the second embodiment, each of the information processing apparatuses  1500   a  to  1500   c  according to the eighth embodiment is configured to send, when it is judged based on a change in a radio wave state that a communication state is unstable, a monitoring request for the apparatus to the other information processing apparatuses. The other information processing apparatuses with stable communication state perform monitoring. Therefore, even when a complex UPnP service is provided, it is possible to set validity periods for sub-UPnP services included in the complex UPnP service to expire at the same time and to reduce the number of broadcast packets. Moreover, the other information processing apparatuses can quickly recognize that the information processing apparatus leaves the network  2 . 
     As in the seventh and eighth embodiments, the configuration of the information processing apparatus  300  explained in the third embodiment can be combined with the configuration disclosed in Japanese Patent Application No. 2007-047339 filed by the applicant. In a ninth embodiment, an example of a combination of the configuration of the information processing apparatus  300  explained in the third embodiment and the configuration disclosed in Japanese Patent Application No. 2007-047339 is explained. 
       FIG. 24  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including information processing apparatuses  1600   a  to  1600   c  according to the ninth embodiment. The information processing apparatuses  1600   a  to  1600   c  according to the ninth embodiment in  FIG. 24  correspond to the information processing apparatuses  1   a  to  1   d  of  FIG. 1 . The information processing apparatuses  1600   a  and  1600   c  are assumed to be mobile devices such as portable terminals and the information processing apparatus  1600   b  is assumed to be a non-mobile device such as a server. Explanation of a processing procedure (Steps S 1901  to S 1917 ), the same processing as previously described in connection with  FIGS. 14 and 22 , is omitted. 
     As illustrated in  FIG. 24 , when the information processing apparatus  1600   a  leaves the network  2  (Step S 1918 ), i.e., when the existence response is not sent from the information processing apparatus  1600   a , the information processing apparatus  1600   b  detects that the information processing apparatus  1600   a  leaves the network  2  (Step S 1919 ). 
     The information processing apparatus  1600   b  sends the information processing apparatus  1600   c  a BYEBYE message (stop notification) for the UPnP service  10   a  (Step S 1920 ). Upon receipt of the BYEBYE message, the information processing apparatus  1600   c  recognizes that the UPnP service  10   a  is stopped and that the UPnP service  10   b  related to the UPnP service  10   a  is also stopped (Step S 1921 ). 
     The information processing apparatus  1600   b  sends the information processing apparatus  1600   c  a BYEBYE message for the UPnP service  10   b  (Step S 1922 ). The information processing apparatus  1600   c  discards the BYEBYE message (Step S 1923 ). 
     As explained above, in addition to the configuration of the third embodiment, each of the information processing apparatuses  1600   a  to  1600   c  according to the ninth embodiment is configured to send, when it is judged based on a change in a radio wave state that a communication state is unstable, a monitoring request for the apparatus to the other information processing apparatuses. The other information processing apparatuses with stable communication state perform monitoring. Therefore, even when a complex UPnP service is provided, it is possible to set validity periods for sub-UPnP services included in the complex UPnP service to expire at the same time and to reduce the number of broadcast packets. Moreover, the other information processing apparatuses can quickly recognize that the information processing apparatus leaves the network  2 . 
     The configuration of the information processing apparatus  100  explained in the first embodiment can be combined with the configuration disclosed in Japanese Patent Application No. 2007-047338 filed by the applicant. In a tenth embodiment, an example of a combination of the configuration of the information processing apparatus  100  explained in the first embodiment and the configuration disclosed in Japanese Patent Application No. 2007-047338 is explained. 
       FIG. 25  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including a monitoring apparatus  400  according to the tenth embodiment. An information processing apparatus  1700   a  in  FIG. 25  corresponds to the information processing apparatus  1   a  of  FIG. 1 . An information processing apparatus  1700   b  in  FIG. 25  corresponds to the information processing apparatus  1   b  in  FIG. 1 . The monitoring apparatus  400  corresponds to the information processing apparatus  1   c  in  FIG. 1 . The information processing apparatus  1700   a  is assumed to be a mobile device such as a portable terminal and connected to an access point  3 . The monitoring apparatus  400  is assumed to be an information processing apparatus that monitors the information processing apparatus  1700   a . The information processing apparatus  1700   b  is assumed to be a non-mobile device such as a personal computer. 
     As illustrated in  FIG. 25 , the information processing apparatus  1700   a  starts the UPnP service  10   a  (Step S 2001 ). The information processing apparatus  1700   a  sends the monitoring apparatus  400  and the information processing apparatus  1700   b  a service-start-time broadcast packet of the UPnP service  10   a  (Step S 2002 ). The monitoring apparatus  400  and the information processing apparatus  1700   b  perform predetermined setting work for using the UPnP service  10   a  (Steps S 2003  and S 2004 ). 
     The monitoring apparatus  400  sends the access point  3  an acquisition request for terminal connection information (Step S 2005 ). In response to the acquisition request, the access point  3  sends the terminal connection information to the monitoring apparatus  400  (Step S 2006 ). 
     In the terminal connection information stored by the access point  3 , information concerning a radio apparatus connected to the access point  3  by radio is stored. The monitoring apparatus  400  can judge, based on the terminal connection information, whether the information processing apparatus  1700   a  leaves the network  2 . The monitoring apparatus  400  periodically acquires the terminal connection information from the access point  3  and checks whether the information processing apparatus  1700   a  leaves the network  2 . It is assumed that the monitoring apparatus  400  confirms that the information processing apparatus  1700   a  is connected to the network  2 . 
     Subsequently, the information processing apparatus  1700   a  starts the UPnP service  10   b  (Step S 2007 ). The information processing apparatus  1700   a  sends the monitoring apparatus  400  and the information processing apparatus  1700   b  service-start-time broadcast packets of the UPnP services  10   a  and  10   b  (Step S 2008 ). The monitoring apparatus  400  and the information processing apparatus  1700   b  perform predetermined setting work for using the UPnP service  10   b  and updates a validity period of the UPnP service  10   a  (Steps S 2009  and S 2010 ). 
     The monitoring apparatus  400  sends a request for terminal connection information to the access point  3  (Step S 2011 ). The access point  3  notifies the monitoring apparatus  400  of the terminal connection information (Step S 2012 ). 
     The information processing apparatus  1700   a  leaves the network  2  (Step S 2013 ). Thereafter, the monitoring apparatus  400  acquires the terminal connection information from the access point  3  (Steps S 2014  and S 2015 ) and checks whether the information processing apparatus  1700   a  leaves the network  2 . 
     The monitoring apparatus  400  confirms that the information processing apparatus  1700   a  leaves the network  2  (Step S 2016 ). The monitoring apparatus  400  sends the information processing apparatus  1700   b  a message indicating that the UPnP services  10   a  and  10   b  are not available (Step S 2017 ). In the message, information concerning a plurality of UPnP services can be set in a BYEBYE message in the UPnP. Information concerning the UPnP services  10   a  and  10   b  is set in the message. 
     As explained above, in addition to the configuration of the first embodiment, the monitoring apparatus  400  according to the tenth embodiment is configured to monitor, based on the terminal connection information stored in the access point  3  connected via radio to the monitoring-object information processing apparatus  1700   a , whether the information processing apparatus  1700   a  leaves the network  2 . Therefore, even when a complex UPnP service is provided, it is possible to set validity periods for sub-UPnP services included in the complex UPnP service to expire at the same time and to reduce the number of broadcast packets. Moreover, other information processing apparatuses can quickly recognize that the information processing apparatus leaves the network  2 . 
     As in the tenth embodiment, the configuration of the information processing apparatus  200  explained in the second embodiment can be combined with the configuration disclosed in Japanese Patent Application No. 2007-047338 filed by the applicant. In an eleventh embodiment, an example of a combination of the configuration of the information processing apparatus  200  explained in the second embodiment and the configuration disclosed in Japanese Patent Application No. 2007-047338 is explained. 
       FIG. 26  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including a monitoring apparatus  500  according to the eleventh embodiment. An information processing apparatus  1800   a  in  FIG. 26  corresponds to the information processing apparatus  1   a  in  FIG. 1 . An information processing apparatus  1800   b  in  FIG. 26  corresponds to the information processing apparatus  1   b  in  FIG. 1 . The monitoring apparatus  500  corresponds to the information processing apparatus  1   c  in  FIG. 1 . The information processing apparatus  1800   a  is assumed to be a mobile device such as a portable terminal and connected to the access point  3 . The monitoring apparatus  500  is assumed to be an information processing apparatus that monitors the information processing apparatus  1800   a . The information processing apparatus  1800   b  is assumed to be a non-mobile device such as a personal computer. Explanation of a processing procedure (Steps S 2101  to S 2118 ), the same processing as previously described in connection with  FIGS. 9 and 25 , is omitted. 
     As illustrated in  FIG. 26 , the information processing apparatus  1800   a  leaves the network  2  (Step S 2119 ). The monitoring apparatus  500  acquires terminal connection information from the access point  3  (Steps S 2120  and S 2121 ) and checks whether the information processing apparatus  1800   a  leaves the network  2 . 
     The monitoring apparatus  500  confirms that the information processing apparatus  1800   a  leaves the network  2  (Step S 2122 ). The monitoring apparatus  500  sends the information processing apparatus  1800   c  an apparatus-ID notification packet including an apparatus ID and a validity period “0” of the information processing apparatus  1800   a  (Step S 2123 ). 
     As explained above, in addition to the configuration of the second embodiment, the monitoring apparatus  500  according to the eleventh embodiment is configured to monitor, based on the terminal connection information stored in the access point  3  connected via radio to the monitoring-object information processing apparatus  1800   a , whether the information processing apparatus  1800   a  leaves the network  2 . Therefore, even when a complex UPnP service is provided, it is possible to set validity periods for sub-UPnP services included in the complex UPnP service to expire at the same time and to reduce the number of broadcast packets. Moreover, the other information processing apparatuses can quickly recognize that the information processing apparatus leaves the network  2 . 
     As in the tenth and eleventh embodiments, the configuration of the information processing apparatus  300  explained in the third embodiment can be combined with the configuration disclosed in Japanese Patent Application No. 2007-047338 filed by the applicant. In a twelfth embodiment, an example of a combination of the configuration of the information processing apparatus  300  explained in the third embodiment and the configuration disclosed in Japanese Patent Application No. 2007-047338 is explained. 
       FIG. 27  is a sequence chart of a processing flow in a UPnP service provision system in a UPnP network including a monitoring apparatus  600  according to the twelfth embodiment. An information processing apparatus  1900   a  in  FIG. 27  corresponds to the information processing apparatus  1   a  in  FIG. 1 . An information processing apparatus  1900   b  in  FIG. 27  corresponds to the information processing apparatus  1   b  in  FIG. 1 . The monitoring apparatus  600  corresponds to the information processing apparatus  1   c  in  FIG. 1 . The information processing apparatus  1900   a  is assumed to be a mobile device such as a portable terminal and connected to the access point  3 . The monitoring apparatus  600  is assumed to be an information processing apparatus that monitors the information processing apparatus  1900   a . The information processing apparatus  1900   b  is assumed to be a non-mobile device such as a personal computer. Explanation of a processing procedure (Steps S 2201  to S 2213 ), the same processing as previously described in connection with  FIGS. 14 and 25 , is omitted. 
     The information processing apparatus  1900   a  leaves the network  2  (Step S 2214 ). The monitoring apparatus  600  acquires terminal connection information from the access point  3  (Steps S 2215  and S 2216 ) and checks whether the information processing apparatus  1900   a  leaves the network  2 . 
     The monitoring apparatus  600  confirms that the information processing apparatus  1900   a  leaves the network  2  (Step S 2217 ). The monitoring apparatus  600  sends the information processing apparatus  1900   b  a BYEBYE message (stop notification) for the UPnP service  10   a  (Step S 2218 ). Upon receipt of the BYEBYE message, the information processing apparatus  1900   b  recognizes that the UPnP service  10   a  is stopped and that the UPnP service  10   b  related to the UPnP service  10   a  is also stopped (Step S 2219 ). 
     The monitoring apparatus  600  sends the information processing apparatus  1900   b  a BYEBYE message for the UPnP service  10   b  (Step S 2220 ). The information processing apparatus  1900   b  discards the BYEBYE message (Step S 2221 ). 
     As explained above, in addition to the configuration of the third embodiment, the monitoring apparatus  600  according to the twelfth embodiment is configured to monitor, based on the terminal connection information stored in the access point  3  connected via radio to the monitoring-object information processing apparatus  1900   a , whether the information processing apparatus  1900   a  leaves the network  2 . Therefore, even when a complex UPnP service is provided, it is possible to set validity periods for sub-UPnP services included in the complex UPnP service to expire at the same time and to reduce the number of broadcast packets. Moreover, other information processing apparatuses can quickly recognize that the information processing apparatus leaves the network  2 . Furthermore, broadcast packet transmission processing for existence confirmation notification after the start of a UPnP service can be realized according to the conventional standards. 
     The information processing apparatus  100  according to the first embodiment illustrated in  FIG. 4 , the information processing apparatus  200  according to the second embodiment illustrated in  FIG. 10 , and the information processing apparatus  300  according to the third embodiment illustrated in  FIG. 15  are explained above as hardware; however, they can be implemented as software. For example, a computer program (hereinafter, “information processing apparatus control program”) can be executed on a computer to implement the same function as the UPnP control unit  140  of the information processing apparatus  100  to thereby realize the same function as the information processing apparatus  100 . Described below is an example of such a computer that executes an information processing apparatus control program  1071 . 
       FIG. 28  is a block diagram of a computer  1000  that executes the information processing apparatus control program  1071 . The computer  1000  is configured by connecting, via a bus  1080 , a central processing unit (CPU)  1010  that executes various kinds of arithmetic processing, an input device  1020  that receives input of data from a user, a monitor  1030  that displays various kinds of information, a media reading device  1040  that reads a program and the like from a recording medium, a network I/F  1050  that performs exchange of data between the computer  1000  and other computers via a network, a random access memory (RAM)  1060  that temporarily stores various kinds of information, and a hard disk drive (HDD)  1070 . 
     In the HDD  1070 , the information processing apparatus control program  1071  having functions same as those of the UPnP control unit  140  and information processing apparatus control data  1072  corresponding to the various data stored in the storage unit  130  are stored. The information processing apparatus control data  1072  can be distributed as appropriate and stored in other computers connected to the computer  1000  via the network. 
     The CPU  1010  loads the information processing apparatus control program  1071  from the HDD  1070  into the RAM  1060  to perform an information processing apparatus control process  1061 . In the information processing apparatus control process  1061 , information and the like read from the information processing apparatus control data  1072  are loaded into an area allocated to the process on the RAM  1060  as appropriate and various kinds of data processing are performed based on the data and the like. 
     The information processing apparatus control program  1071  need not necessarily be stored in the HDD  1070 . The computer  1000  can read and execute the program stored in a storage medium such as a compact disk-read only memory (CD-ROM). The program may be stored in another computer (or a server) or the like connected to the computer  1000  via a public line, the Internet, a local area network (LAN), a wide area network (WAN), or the like, and downloaded therefrom by the computer  1000  and executed. 
     When the elements of the information processing apparatus, the representations, or the arbitrary combinations of the elements disclosed herein are applied to methods, apparatuses, systems, computer programs, recording media, data structures, and the like, such methods, apparatuses, systems, computer programs, recording media, data structures, and the like are also effective as other forms of the present invention. 
     As set forth hereinabove, according to an embodiment of the present invention, even when the complex UPnP service is provided, it is possible to set validity periods for the sub-UPnP services included in the complex UPnP service to expire at the same time and to reduce the number of broadcast packets. 
     Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.