Abstract:
A group management assistance method includes a presence information receiving step (step S 142 ) of receiving presence information of a client in which presence information changes, a change occurrence group detecting step (step S 143 ) of determining whether a group to be generated by the presence information, a group in which constituent members are changed by the presence information, or a group in which constituent members are deleted by the presence information is present by comparing a policy of each group with the presence information, and a group information transmitting step (step S 144 ) of transmitting group information related to the group to be generated, the group in which the constituent members are changed, or the group in which the constituent members are deleted.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a group management assistance apparatus, a group management apparatus, a group management assistance method, and a group management method which manage members of a session group. 
         [0003]    2. Description of the Related Art 
         [0004]    A group management method according to a first conventional art will be described below with reference to  FIGS. 11 and 12 . 
         [0005]      FIG. 11  shows a configuration of a Push-To-Talk (to be referred to as PTT hereinafter) system  900 . 
         [0006]    In  FIG. 11 , a group management server  901  stores and manages group information  951  and provides the group information  951  when the group information  951  is requested from a PTT server  902 . In  FIG. 11 , the group information  951  includes a group ID (GID)  951 - 1  and a group member ID (UID)  951 - 2  included in the group. 
         [0007]    The PTT clients  903  communicate with the group management server  901  to perform addition, deletion, edition, and the like to the group information  951 . In order to perform session with another group information  951 , the PTT clients  903  communicates with the PTT server  902 . 
         [0008]    The PTT server  902  performs the start, management, and end of a session in which a plurality of PTT clients  903  participate. The management of the session also includes exchanges of various media exchanged between PTT clients  903 - 1  and  903 - 2 . 
         [0009]    In the PTT system  900 , a presence server  904  shown in  FIG. 11  is used. However, since a conventional group management method does not contribute to the presence server  904 , an explanation about the presence server  904  is omitted. 
         [0010]      FIG. 12  is a timing chart showing an operation of a PTT system. 
         [0011]    The PTT clients  903  edit the group information  951  to transmit the edited group information  951  to the group management server  901  (step S 801 ). In this case, it is assumed that new group information  951  is registered as GID:xxx4. 
         [0012]    The group management server  901  receives and registers group information from the PTT clients  903  (step S 802 ). 
         [0013]    Thereafter, when a session start request is issued by a group member of GID:xxx4 from the PTT clients  903  to the PTT server  902  (step S 803 ), the PTT server  902  inquires about group information for the group management server  901  by using the group ID  951 - 1  as a key to acquire the group member ID  951 - 2  of GID:xxx4 (step S 804 ). 
         [0014]    The group management server  901  which receives the inquiry reads the group information by using a GID as a key (step S 805 ), and the group management server  901  provides the group information  951  about GID:xxx4 (step S 806 ). 
         [0015]    The PTT server  902  refers to the received group information to execute a session establishing process with clients participating in a session (step S 807 ), and the PTT server  902  establishes a PTT session (step S 808 ). 
         [0016]    More specifically, when a session establishing request is issued from a certain PTT client, the PTT server  902  acquires a UID of a PTT client belonging to a group such that the PTT client inquires about the UID for the group management server  901  by using a GID belonging the PTT client as a key. The PTT server  902  establishes a PTT session with the PTT clients  903  having the acquired UID. 
         [0017]    As a second conventional art, a group management method in an ID telephone exchanger disclosed in JP-A-2002-359690 will be described below. 
         [0018]    This conventional art designates an IP telephone terminal participating in an IP telephone session on the basis of a participating terminal table held by the IP telephone exchanger. 
         [0019]      FIG. 13  is a block diagram of a group management process portion extracted from the invention described in JP-A-2002-359690. 
         [0020]    A telephone exchanger  961  has a voice receiving unit  961 - 1  which receives voice from a participating terminal, a voice exchanging unit  961 - 2  which transfers (exchanges) the received voice to the participating terminal, and a voice transmitting unit  961 - 3  which transmits the exchanged voice to another terminal. 
         [0021]    The voice exchanging unit  961 - 2  transmits a received voice received from a certain terminal to another participating terminal described in a participating terminal table  961 - 4  to realize group speech. 
         [0022]    The participating terminal table  961 - 4  is operated by a table operating process of a participating terminal table operating unit  961 - 5  which receives a designation (S 963 ) from a participating terminal table operation designating unit  962 - 1  of an IP telephone terminal  962 . More specifically, addition and deletion of a terminal to/from the participating terminal table  961 - 4 . The participating terminal table operation designating unit  962 - 1  addition and deletion of a terminal to/from the participating terminal table  961 - 4  by an operation designated by the input unit  962 - 4 . 
         [0023]    On the other hand, the telephone exchanger  961  causes a terminal state recognizing unit  961 - 6  to monitor a state of the terminal (step S 964 ), and the obtained information is held in a terminal state table  961 - 7 . 
         [0024]    The information of the terminal state table  961 - 7  is provided from a terminal state notifying unit  961 - 8  to a terminal depending on an inquiry request (step S 965 ) from a terminal state inquiring unit  962 - 2  of the IP telephone terminal  962  (S 966 ). 
         [0025]    When a user of the IP telephone terminal  962  will start an IP telephone session, the user visually checks a plurality of terminal states except for user&#39;s own terminal displayed on a display unit  962 - 3  and operates an input unit  962 - 4  such that another IP telephone terminal  962  in IP telephone terminals which are members which can participate in the session (members displayed on the display unit  962 - 3 ) is registered in the participating terminal table  961 - 4 . 
         [0026]    In this manner, the session between the IP telephone terminal  962  which issues a designation (step S 963 ) for registration and the IP telephone terminal  962  designated by the designation is started. 
         [0027]    However, in the group management method according to the first conventional art, the following problems are posed. 
         [0028]    It is a first problem that the method cannot cope with a dynamic change of a group because group members in group information are quasi-fixedly registered in advance. 
         [0029]    It is a second problem that a session participating member cannot be changed during a session because session establishment is executed by referring to group information only once when the session is established. 
         [0030]    It is a third problem that, when a session will be performed by members constituting clients for, i.e., a specific presence, a session cannot be easily established by desired members because a user operates a terminal to search for the members and must designate member IDs of the members. 
         [0031]    In the group management method according to the second conventional art, the following problems are posed. 
         [0032]    A first problem is as follows. That is, a user of a certain participating IP terminal  962  sees the IP telephone terminal  962  displayed on the display unit  962 - 3  which reflects a state of the terminal state table  961 - 7  to determine another IP telephone terminal  962  to be registered in the participating terminal table  961 - 4 , so that the corresponding IP telephone terminal  962  is registered in the participating terminal table  961 - 4 . Therefore, since a group constituting process is performed through determination and operation by a human being, the group constituting process is not automated, and the method cannot cope with a dynamic change of a group. More specifically, an automatic process to establish a session cannot be performed. 
         [0033]    A second problem is as follows. That is, since a user herself/himself to participate in a session monitors a state of the display unit  962 - 3  and then operates the IP telephone terminal  962  owned by the user, the user herself/himself must perform determination and operation to change session participating members during a session. More specifically, an automatic changing process cannot be performed during the session. 
         [0034]    A third problem is as follows. That is, when a session is to be performed by members constituted by only clients in which a value of a specific presence of a plurality of presences (presence states (for example, “position”, “presence”, “sitting”, “in conference”, “absence”, and the like)) is a predetermined value (for example, ““position” is “company” or the like), a user operates a terminal to search for a member being in such a presence state and must designate IDs of the respective members (“member IDs”). For this reason, a session by members in an arbitrary presence state cannot be easily established. 
       SUMMARY OF THE INVENTION 
       [0035]    It is an object of the present invention to provide a group management assistance apparatus, a group management apparatus, a group management assistance method, and a group management method which make it possible to dynamically change group members. 
         [0036]    According a first aspect of the present invention, there is provided a group management assistance apparatus comprising: a presence information receiving unit which receives presence information of a client in which presence information changes; a change occurrence group detecting unit which determines whether a group to be generated, a group in which constituent members are changed, or a group to be deleted is present by comparing a policy of each group with the presence information; and a group information transmitting unit which transmits group information related to the group to be generated, the group in which the constituent members are changed, or the group to be deleted. 
         [0037]    In the group management assistance apparatus, the policy may include information is in an apparatus except for the group management assistance apparatus or information input from an apparatus except for the group management assistance apparatus. 
         [0038]    Therefore, the group information can be changed automatically with the presence information of a client in which presence information changes. Thus, it can be changed dynamically a client who participate in a session. 
         [0039]    According to a second aspect of the present invention, there is provided a group management server comprising: a group information receiving unit which receives group information from a group management assistance apparatus; a session change detecting unit which determines whether a group which has been established a session and in which participating members must be changed by the group information is present; and a session participating member changing unit which, if a group which has been established a session and in which participating members must be changed by the group information is present, then changes members participating the group using the group information. 
         [0040]    Therefore, the session participating member can be changed dynamically depending on the received group information. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0041]      FIG. 1  is a block diagram showing a configuration of a system according to Embodiment 1 of the present invention; 
           [0042]      FIG. 2  is a sequence diagram showing main operations of the system shown in  FIG. 1 ; 
           [0043]      FIG. 3  is a block diagram showing a configuration of a system according to Embodiment 2 of the present invention; 
           [0044]      FIG. 4  is a sequence diagram showing main operations performed by Embodiment 2 of the present invention of the system shown in  FIG. 3 ; 
           [0045]      FIG. 5  is a diagram showing an example of a group policy held by the group management assistance apparatus shown in  FIG. 1  or  3 ; 
           [0046]      FIG. 6  is a diagram showing an example of presence information; 
           [0047]      FIG. 7  is a sequence diagram showing main operations performed by Embodiment 3 of the present invention of the system shown in  FIG. 3 ; 
           [0048]      FIG. 8  is a block diagram showing a configuration of a system according to Embodiment 4 of the present invention; 
           [0049]      FIG. 9  is a diagram showing an example of a group policy held by the group management assistance apparatus shown in  FIG. 8 ; 
           [0050]      FIG. 10  is a sequence diagram showing main operations of a system shown in  FIG. 8 ; 
           [0051]      FIG. 11  is a block diagram showing a configuration of a system according to a conventional art 1; 
           [0052]      FIG. 12  is a sequence diagram showing main operations of the system shown in  FIG. 11 ; and 
           [0053]      FIG. 13  is a block diagram showing a configuration of a system of a conventional art 2. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0054]    Best modes to carry out the present invention will be described below in detail with reference to the accompanying drawings. 
       Embodiment 1 
       [0055]    The present invention is characterized in that, in an electron conference system and a Push-To-Talk (PTT) system, a member constituting a group and a member participating a session (conversation or conference) is instantaneously an optimum constituent member. 
         [0056]      FIG. 1  is a constitution of an electronic conference system using a group management method according to the present invention. 
         [0057]    In  FIG. 1 , a group management assistance apparatus  103  refers to presence information  123  held by a presence server  105  and generates or re-constitutes group information  122  on the basis of a group policy  121  held in the group management assistance apparatus  103 . The group management assistance apparatus  103  registers the result in a group management server  107 . 
         [0058]    The group management server  107  manages group information related to a plurality of conference clients  109 - 1 ,  109 - 2 , and  109 -N, receives the group information  122  provided from the group management assistance apparatus  103 , and provides the group information  122  to a conference server  113 . 
         [0059]    The presence server  105  receives the presence information  123  from presence acquiring devices  111 - 1 ,  111 - 2 , and  111 -N and the conference clients  109 - 1 ,  109 - 2 , and  109 -N and manages the presence information  123 . The presence server  105  provides the presence information  123  to the conference clients  109 - 1 ,  109 - 2 , and  109 -N and the group management assistance apparatus  103 . 
         [0060]    The conference server  113  acquires the group information  122  from the group management server  107  and manages (establishes, maintains, and dissolves) a conference session to which the plurality of conference clients  109 - 1 ,  109 - 2 , and  109 -N serving as group members participate. 
         [0061]      FIG. 2  shows a sequence for explaining an operation of a conference system using the group management method according to the present invention. 
         [0062]    In  FIG. 2 , when the presence information  123  held by the presence server  105  changes (step S 121 ), then the presence server  105  notifies the group management assistance apparatus  103  of the changed presence information  123  (step S 123 ). 
         [0063]    When a group configuration changes due to the notified presence information  123 , the group management assistance apparatus  103  re-constitutes the group (step S 125 ), and the group information  122  expressing the re-constituted group is set and give to the group management server  107  (step S 127 ). 
         [0064]    When the group management server  107  receives the group information  122  (step S 129 ), the group management server  107  immediately registers the group information  122  (step S 131 ). 
         [0065]    In this manner, in this embodiment, the group information  122  is designed to be re-constituted immediately after the presence information  123  changes. 
         [0066]    Groups which reflect states of the conference clients  109  which change with time can be constituted. 
       Embodiment 2 
       [0067]    Referring to  FIG. 3 , a PTT system according an embodiment using the group management method of the present invention. 
         [0068]    In  FIG. 3 , the group management assistance apparatus  103  holds the group policy  121 , constitutes a group according to the group policy  121  on the basis of the presence information  123 , and notifies the group management server  107  of the group information  122  representing the group. 
         [0069]    In this case, the group policy  121  is constituted by information (GID)  121 - 1  specifying at least a group and condition information constituting the group. 
         [0070]    The group information  122  is constituted by information (GID)  122 - 1  constituting at least a group and constituent member information  122 - 2  of the group. 
         [0071]    The group management server  107  holds the group information  122 , receives group information  124  from the group management assistance apparatus  103  and a PTT client  115 , and returns group information  126  responding to a group information inquiry  125  from a PTT server  119 . 
         [0072]    The presence server  105  receives the presence information  123  from the PTT client  115  or a various presence information acquiring device  111 , manages these pieces of presence information  123 , and provides the pieces of presence information  123  to the PTT client  115  and the group management assistance apparatus  103 . 
         [0073]    The PTT server  119  manages a voice conference session in which the plurality of PTT clients  115  participate. 
         [0074]    The PTT client  115  performs a voice conference session with other plurality of PTT clients through the PTT server  119 . 
         [0075]    An operation of the PTT system shown in  FIG. 3  and using the group management method according to the present invention will be described by using a time chart shown in  FIG. 4 . 
         [0076]    In  FIG. 4 , when the presence information  123  managed by the presence server  105  changes (step S 141 ), the presence server  105  transmits the presence information  123  to the group management assistance apparatus  103  (step S 142 ). 
         [0077]    The group management assistance apparatus  103 , on the basis of the received presence information, searches a group using the presence information as a policy of a group configuration (step S 143 ). When the corresponding group policy is present, group information is edited according to the group policy and transmitted to the group management server  107  (step S 144 ). 
         [0078]    When the group management server  107  receives new group information from the group management assistance apparatus  103 , the group management server  107  registers the new group information as group information and subsequently manages the group information. 
         [0079]    An example of a group policy is shown in  FIG. 5 . In this case, it is designated that 
         [0000]    “A group indicated by Group ID: GID:xxx4 is a group constituted by clients in which “positions” which are one types of pieces of presence information in clients including six clients: 
         [0080]    UID:aaaa 
         [0081]    UID:bbbb 
         [0082]    UID:cccc 
         [0083]    UID:dddd 
         [0084]    UID:eeee 
         [0085]    UID:ffff 
         [0000]    are “companies””. 
         [0086]    For example, in step S 142 , when the presence information is transmitted from the presence server  105  to the group management assistance apparatus  103 , a “position” which is one type of presence information is shown in  FIG. 6  as a result of the transmission. In this case, the group of GID:xxx4 is a group constituted by three clients: 
         [0087]    UID:aaaa 
         [0088]    UID:bbbb 
         [0089]    UID:cccc 
         [0000]    in which “positions” are “companies” in six clients shown in  FIG. 5 . In such a case, in step S 144 , 
         [0090]    GID:xxx4 
         [0091]    UID:aaaa 
         [0092]    UID:bbbb 
         [0093]    UID:cccc 
         [0000]    are transmitted. 
         [0094]    When pieces of position information before transmission of the presence information in step S 142  are 
         [0095]    UID:aaaa:Shibuya 
         [0096]    UID:bbbb:Harajuku 
         [0097]    UID:cccc:Ebisu 
         [0098]    UID:dddd:Shibuya 
         [0099]    UID:eeee:Shinjuku 
         [0100]    UID:ffff:Shinagawa, 
         [0000]    a group is generated. 
         [0101]    When pieces of position information before transmission of the presence information in step S 142  are 
         [0102]    UID:aaaa:company 
         [0103]    UID:bbbb:company 
         [0104]    UID:cccc:Ebisu 
         [0105]    UID:dddd:Shibuya 
         [0106]    UID:eeee:Shinjuku 
         [0107]    UID:ffff:Shinagawa, 
         [0000]    group members increase in number. 
         [0108]    Furthermore, when pieces of position information before transmission of the presence information in step S 142  are 
         [0109]    UID:aaaa:company 
         [0110]    UID:bbbb:company 
         [0111]    UID:cccc:company 
         [0112]    UID:dddd:company 
         [0113]    UID:eeee:Shinjuku 
         [0114]    UID:ffff:Shinagawa, 
         [0000]    group members decrease in number. 
         [0115]    When pieces of position information serving as results of the presence information transmitted in step S 142  at one point of time are 
         [0116]    UID:aaaa:company 
         [0117]    UID:bbbb:Tamachi 
         [0118]    UID:cccc:Shinbashi 
         [0119]    UID:dddd:company 
         [0120]    UID:eeee:Shinjuku 
         [0121]    UID:ffff:Shinagawa, 
         [0000]    and when pieces of position information serving as results of presence information transmitted in step S 142  at the next point of time are 
         [0122]    UID:aaaa:Yurakucho 
         [0123]    UID:bbbb:Tamachi 
         [0124]    UID:cccc:Shinbashi 
         [0125]    UID:dddd:company 
         [0126]    UID:eeee:Shinjuku 
         [0127]    UID:ffff:Shinagawa, 
         [0000]    the group is deleted. In such a case, in step S 144 , only 
         [0128]    GID:xxx4, 
         [0129]    UID:NULL, 
         [0000]    or 
         [0130]    GID:xxx4 
         [0000]    is transmitted. 
         [0131]    For example, when the presence information is transmitted from the presence server  105  to the group management assistance apparatus  103 , “positions” serving as one types of the presence information are consequently shown in  FIG. 6 . In this case, the group of GID:xxx4 is a group constituted by three clients: 
         [0132]    UID:aaaa 
         [0133]    UID:bbbb 
         [0134]    UID:cccc 
         [0000]    in which “positions” are “companies” in the sixth clients shown in  FIG. 5 . In such a case, in step S 144 , 
         [0135]    GID:xxx4 
         [0136]    UID:aaaa 
         [0137]    UID:bbbb 
         [0138]    UID:cccc 
         [0000]    are transmitted. 
         [0139]    In this manner, at any time, the group management assistance apparatus  103  updates the group information the moment the presence information is notified by the presence server  105 . 
         [0140]    When a user starts a session by the PTT client  115 , the user requests the session start by a desired group ID. Processes including the request process performed until a PTT session is established are the same as those in a PTT system of the conventional art 1 (see  FIG. 12 ). The same reference symbols (S 803  to S 808 ) as in  FIG. 12  denote the same processes in  FIG. 4 . 
       Embodiment 3 
       [0141]    A basic configuration of Embodiment 3 of the present invention is the same as that in Embodiment 2. However, the point which makes it possible to change the members in the PTT session is devised.  FIG. 7  shows the timing chart showing the operation. 
         [0142]    In  FIG. 7 , the group management server  107  recognizes whether at least one piece of group information  122  sequentially managed by the group management server  107  includes group information the PTT group session of which is established (step S 146 ). 
         [0143]    When the group management server  107  receives the group information from the group management assistance apparatus  103  (step S 145 ), the group management server  107  determines whether the group the session of which is established at the present includes a group having the same GID as that of the group information (step S 147 ). When the group includes such a group (for example, the group of GID:xxx4), the group management server  107  provides the group information  122  received in step S 145  to the PTT server  119  (step S 148 ). 
         [0144]    When the PTT server  119  receives the group information in step S 148 , in a group in a session, the PTT server  119  updates group information of a group related to the group information on the basis of the group information. In this manner, a session member of the group is changed (step S 149 ). 
         [0145]    For example, in GID:xxx4 having the group policy shown in  FIG. 5 , it is assumed that a presence shown in  FIG. 6  at past time and that a session is started in this state. Thereafter, at one point of time, if “position” of UID:aaaa changes into a position except for company, although it is in the process of the session, session members are changed such that participating members in the session are only UID:bbbb and cccc. 
         [0146]    In this manner, according to this embodiment, a group is also changed during a session. For this reason, when secret information which can be spoken only in “company” is exchanged in conversation, the secret information can be advantageously prevented from leaking from a client moving from the company to out-of-company. 
         [0147]    For example, when the embodiment is applied to a game to set presence information set in a group policy as scenario information such as “stage” or “phase”, game contents having higher reality can be provided to a user. 
       Embodiment 4 
       [0148]    A basic configuration of Embodiment 4 of the present invention is the same as that in Embodiment 2. However, Embodiment 4 is different from Embodiments 2 and 3 in that a group policy includes information stored in an external device (for example, a directory as shown in  FIG. 8 ). 
         [0149]    A configuration of Embodiment 4 is shown in  FIG. 8 . At least one group policy is stored in a group management assistance apparatus  103 B shown in  FIG. 8 . A group policy as an example is shown in  FIG. 9 . As shown in  FIG. 9 , the group policy refers to a list in a directory server on the directory service device  301  serving as an external device. More specifically, in a policy of a group discriminated from another group by GID:xxx4, it is defined that “a client in which “position” serving as one type of presence information is a group member of members which are present in LIST:zzz1 of the directory service device  301 ”. As shown in  FIG. 8 , in the directory service device  301 , it is described that a member of a list discriminated from another member by LIST:zzz1 is a client of UID:xyz01 to xyz05. 
         [0150]    The group management assistance apparatus  103 B checks all group policies managed by the group management assistance apparatus  103 B when the group management assistance apparatus  103 B receives presence information from the presence server  105 . When the group policies include a group policy which refers to a list held by the directory service device  301 , the group management assistance apparatus  103 B acquires a member from the list (steps S 151  and S 152 ). When a member corresponding to a client related to the presence information received from the presence server  105  is included in members acquired from the directory service device  301 , the presence information of the client is compared with the group policy. When the presence information of the client affects addition and deletion of a member of the group, group information in a state after the addition or deletion is transmitted to the group management server  107 . 
         [0151]    A timing chart showing an operation unique to Embodiment 4 of the system shown in  FIG. 8  is shown in  FIG. 10 .  FIG. 4  of Embodiment 2 is different from  FIG. 10  of this embodiment in that group policy searching in step S 143  performed after the presence information is received in step S 142  in the operation shown in  FIG. 4  until the group information is transmitted in step S 144  includes directory information inquiry and directory information acquisition in steps S 151  and S 152 . 
         [0152]    In this manner, in this embodiment, the client information in the group policy is acquired with reference to the information stored in the external device. Therefore, for example, when a group constituted by members for organization in a company or an arbitrary business project is constituted, a management cost caused by registering (double registration) member information in both an in-company database and a group policy for a PTT system can be reduced. Furthermore, a communication means for a floating project in a company can be flexibly set. 
         [0153]    For example, a customer database is stored in a directory service device, a service which provides information to a customer group depending on presences can be realized. More specifically, when a group policy is given by “a PTT client in which “come-to-shop” serving as one of pieces of presence information is “true” in PTT clients having predetermined IDs is a group member”, a PTT client in which “come-to-shop” serving as one of pieces of presence information is actually “true” in PTT clients having predetermined IDs can be set as a group member. When a group policy is given by “a PTT client in which “purchased amount of certain merchandise” serving as one of pieces of presence information is “10000 yen or higher” in PTT clients having predetermined IDs is a group member”, a PTT client in which “purchased amount of certain merchandise” serving as one of pieces of presence information is actually “10000 yen or higher” in PTT clients having predetermined IDs can be set as a group member. When a group policy is given by “a PTT client in which “a PTT client in which the number of times of visiting to a certain shop” serving as one of pieces of presence information is “one or more” in PTT clients having predetermined IDs is a group member”, a PTT client in which the number of times of visiting to a certain shop” serving as one of pieces of presence information is actually “one or more” in PTT clients having predetermined IDs can be set as a group member. 
         [0154]    Furthermore, for example, when an inhabitant database is used as a directory service, a service which provides disaster information, evacuation instruction information, or the like to an inhabitant group depending on presences can be realized. 
         [0155]    In the timing chart in  FIG. 10 , it is set that the group management assistance apparatus performs information inquiry to the directory service. However, on the directory service side, corresponding information in the directory service may be written in a group policy managed by the group management assistance apparatus. 
         [0156]    The group management assistance apparatus  103  and  103 B shown in  FIG. 1  or the like, the presence server  105  shown in  FIG. 1  or the like, the group management server  107  shown in  FIG. 1  or the like, and the conference server shown in  FIG. 1  or the like can be realized by hardware, software, or a combination therebetween. The apparatus and the server are realized by a means including software, a program functioning as these apparatus and servers is loaded and executed by a computer. 
         [0157]    In the embodiments described above, the group management method according to the present invention is applied to a PTT system. However, the group management method can be generally applied to a system such as an electronic conference system or an electronic mail system except for a PTT system which is constituted by groups and exchanges information between the groups.