JP2012138864A - Communication terminal, communication system, communication method and communication program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication terminal, a communication system, a communication method and a communication program that can reliably disconnect sessions between communication terminals establishing P2P communication.SOLUTION: When receiving a first request signal from a management terminal managing session establishment states out of the other communication terminals with established sessions, the communication terminal transmits second request signals requesting session disconnection to the communication terminals other than the management terminal (S53). When receiving first response signals from the other communication terminals to which the second request signals have been transmitted (S55: YES), the communication terminal disconnects the sessions with the other terminal apparatuses that have transmitted the first response signals (S59). When disconnecting the sessions with all the communication terminals other than the management terminal, the communication terminal transmits a second response signal to the management terminal (S61) and disconnects the session with the management terminal (S63).

Description

  The present invention relates to a communication terminal, a communication system, a communication method, and a communication program that perform Peer to Peer (P2P) communication with another communication terminal.

  Communication terminals capable of performing multipoint communication with a plurality of other communication terminals by performing Peer to Peer (P2P) type communication instead of conventional server-client type communication are known. In the server-client type communication, the communication load may be concentrated on the server, whereas in the P2P type communication, there is an advantage that the communication load is distributed and it is difficult to concentrate the communication load on a specific communication terminal. For this reason, for example, a P2P communication method is used as a communication method when a video conference is performed between a plurality of communication terminals, instead of a conventional server-client communication method using an MCU (Multi point control Unit). Being started.

  When terminating a P2P communication by disconnecting a session between communication terminals, the server disconnects all sessions by sending a disconnect request to the client in a lump as in the case of server-client communication. Can not do it. For this reason, various communication methods for disconnecting sessions between communication terminals in which P2P type communication is performed have been proposed. For example, in the communication terminal described in Patent Document 1, communication for disconnecting a session is performed according to the following procedure.

  It is assumed that a session is established between the communication terminals X and Y and between the communication terminals Y and Z, and a session between the communication terminals X and Z is not established. The communication terminal X transmits a disconnection request to the communication terminal Y. The communication terminal Y receives the disconnection request, and the session between the communication terminals X and Y is disconnected. Next, the communication terminal Y transmits a disconnection request to the communication terminal Z. The communication terminal Z receives the disconnection request, and the session between the communication terminals Y and Z is disconnected. In this way, all sessions between the communication terminals X, Y, and Z are disconnected.

JP-A-9-186785

  However, in the above-described method, for example, it is assumed that the communication state of the communication line between the communication terminals Y and Z is bad and the communication due to the disconnect request between the communication terminals Y and Z fails. In this case, although the session between the communication terminals X and Y is disconnected, the session between the communication terminals Y and Z is maintained in an established state. As described above, in the above-described method, a session that is not disconnected may occur among sessions between communication terminals, and there is a problem in that P2P communication cannot be reliably terminated.

  An object of the present invention is to provide a communication terminal, a communication system, a communication method, and a communication program capable of reliably disconnecting a session between communication terminals performing P2P type communication.

  The communication terminal according to the first aspect of the present invention is a communication terminal that performs Peer to Peer (P2P) type communication with a plurality of other communication terminals with which a session has been established. A first receiving means for receiving a first request signal for requesting disconnection of the session from the terminal; and the other receiving the first request signal when receiving the first request signal in the first receiving means. After transmitting the second request signal in the first transmission means, the first transmission means for transmitting a second request signal for requesting disconnection of the session, to the other communication terminals other than the communication terminal, Second receiving means for receiving a first response signal in response to a request for disconnecting the session from the other communication terminal that has received the second request signal; and receiving the first response signal in the second receiving means. In case, The first disconnection unit for disconnecting the session with the other communication terminal that has transmitted the first response signal, and the first disconnection unit with all the other communication terminals that have transmitted the second request signal. A second transmission unit configured to transmit a second response signal corresponding to the session disconnection request to the other communication terminal that has transmitted the first request signal when the session is disconnected; And a second disconnecting means for disconnecting the session with the other communication terminal that has transmitted the first request signal when the second response signal is transmitted.

  According to the first aspect, when the communication terminal receives the first request signal, the communication terminal performs communication of the second request signal / first response signal to remove other communication terminals that transmitted the first request signal. The session with the other communication terminal can be reliably disconnected. The communication terminal disconnects a session with another communication terminal that has transmitted the first request signal after the termination of the session by performing communication of the second request signal / first response signal. When communication of the second request signal / first response signal fails, the communication terminal does not disconnect the session with the other communication terminal that has transmitted the first request signal. Another communication terminal that has transmitted the first request signal can perform communication for disconnecting the session that has not been disconnected, using the session that has been maintained. Therefore, the communication terminal prevents a part of the session from being maintained without being disconnected, and can reliably disconnect all the sessions.

  In the first aspect, the first transmission unit is a management in which the other communication terminal that has transmitted the first request signal received by the first reception unit manages an established state of the session between the communication terminals. In the case of a terminal, the second request signal may be transmitted to the other communication terminal excluding the management terminal. The communication terminal transmits the second request signal when the other communication terminal that transmitted the first request signal is a management terminal. The communication terminal can prevent the session from being disconnected when an unspecified communication terminal that is not the management terminal transmits the first request signal. As a result, the communication terminal can stabilize the session and increase the reliability of the P2P communication.

  In the first aspect, the first receiving means receives identification information for identifying the other communication terminal that has transmitted the first request signal together with the first request signal, and the first transmitting means The identification information received by the first reception means is transmitted together with the second request signal, and the identification information transmitted by the first transmission means and the other communication terminal that has received the second request signal receive the identification information. The second receiving means for receiving the information and the second request information, the identification information received by the first receiving means, and the identification information received by the third receiving means match the second information You may provide the 3rd cutting | disconnection means to cut | disconnect the said session with said other communication terminal which transmitted the request signal. The communication terminal compares the identification information received together with the first request signal with the identification information received together with the second request signal. When the identification information matches, the session can be disconnected according to the second request signal. The plurality of communication terminals that have received the first request signal respectively transmit the second request signal to other communication terminals that have established a session. Therefore, the second request signal is received from the destination communication terminal that has transmitted the second request signal. In such a case, the communication terminal confirms that the received second request signal is transmitted from another communication terminal based on an instruction from the communication terminal that transmitted the first request signal to itself. Recognize and disconnect sessions. As a result, the communication terminal can accurately disconnect the session being established in accordance with the instruction of the communication terminal that has transmitted the first request signal.

  A communication terminal according to the second aspect of the present invention is a communication terminal that performs Peer to Peer (P2P) type communication with a plurality of other communication terminals with which a session has been established. On the other hand, at least one of the first transmission unit that transmits a request signal for requesting disconnection of the session and the plurality of other communication terminals that has received the request signal transmitted by the first transmission unit is being established. When the response signal corresponding to the session disconnection request is transmitted after disconnecting all the sessions, the reception unit that receives the response signal, and the reception unit that receives the response signal, First disconnecting means for disconnecting the session with the other communication terminal that has transmitted the response signal.

  According to the second aspect, the communication terminal transmits a request signal to a plurality of other communication terminals with which a session has been established, so that not only a session with another communication terminal but also between other communication terminals The session can also be disconnected. When receiving a response signal, the communication terminal disconnects a session with another communication terminal. If the communication terminal cannot receive the response signal, the communication terminal determines that a session that has not been disconnected remains, and does not disconnect the session with another communication terminal. As a result, the communication terminal can reliably disconnect all sessions by communicating with other communication terminals using the maintained session. The communication terminal can prevent a part of the session between other communication terminals from being maintained without being disconnected.

  In the second aspect, the receiving means may continue to receive the response signal until the total number of the received response signals is equal to or more than the number obtained by subtracting 1 from the total number of the plurality of other communication terminals. Good. Even if the communication terminal is in a poor communication state with other communication terminals and cannot receive response signals from all other communication terminals, the total number of received response signals is other than those in which P2P communication is performed. When the number is equal to or greater than the number obtained by subtracting 1 from the total number of the plurality of communication terminals, it can be determined that all the sessions between the other communication terminals are disconnected. Therefore, the communication terminal can easily recognize that all sessions have been disconnected by monitoring the total number of response signals. In addition, since the communication terminal does not need to receive response signals from all other communication terminals, the session can be reliably and efficiently terminated in a short time.

  Further, in the second aspect, when the response signal of the number obtained by subtracting 1 from the total number of the plurality of other communication terminals cannot be received even after a predetermined time has elapsed in the receiving means, transmission of the response signal that has not been received yet You may provide the 2nd transmission means to resend the said request signal with respect to the said other said communication terminal. When a predetermined number of response signals cannot be received after a predetermined time has elapsed, the communication terminal determines that the session between the other communication terminals has failed to disconnect, and other communication terminals that have failed to disconnect the session Thus, the request signal can be retransmitted. As a result, the communication terminal can reliably disconnect the session even when the session between the plurality of other communication terminals is not disconnected due to temporary deterioration of the communication state or the like.

  Further, in the second aspect, when the response signal of the number obtained by subtracting 1 from the total number of the plurality of other communication terminals cannot be received even after a predetermined time has elapsed in the receiving means, transmission of the response signal that has not been received yet Third transmission means for transmitting a third request signal for forcibly disconnecting the session to the other communication terminal, and after transmitting the third request signal in the third transmission means, And a second disconnection unit that disconnects the session with the other communication terminal that has transmitted the three request signals. A communication terminal can immediately disconnect a session with another communication terminal when the communication state between the other communication terminals is poor and the session cannot be disconnected. Accordingly, the communication terminal can avoid a state in which a session with a good communication state is not disconnected for a long time due to the presence of a session with a bad communication state.

  A communication system according to a third aspect of the present invention is a communication system that establishes a session between a communication terminal and a plurality of other communication terminals, and performs Peer to Peer (P2P) type communication. Are a first transmission unit that transmits a first request signal for requesting disconnection of the session to the plurality of other communication terminals, and a plurality of units that have received the first request signal transmitted by the first transmission unit. The second response signal is received when at least one of the other communication terminals transmits a second response signal corresponding to the session disconnection request after disconnecting all the established sessions. First receiving means; and first disconnecting means for disconnecting the session with the other communication terminal that has transmitted the second response signal when the first receiving means receives the second response signal. The other communication terminal receives the first request signal from the communication terminal, and the second communication unit except for the other communication terminal when receiving the first request signal in the second reception unit. From a second transmission means for transmitting a second request signal for requesting disconnection of the session to the terminal, and from the other communication terminal except for itself after transmitting the second request signal in the second transmission means , Third receiving means for receiving a first response signal in response to a request for disconnecting the session, fourth receiving means for receiving the second request signal from the other communication terminal other than itself, and the fourth receiving A third transmission means for transmitting the first response signal to the other communication terminal that has transmitted the second request signal when the second request signal is received by the means; Other communication end When the first response signal is received from or the first response signal is transmitted to the other communication terminal in the third transmission means, the session with the other communication terminal is disconnected. When the second disconnecting unit and the second disconnecting unit disconnect the session with all the other communication terminals that have transmitted the second request signal, the second response signal is sent to the communication terminal. Fourth transmission means for transmitting, and third disconnection means for disconnecting the session with the communication terminal when the fourth response means transmits the second response signal.

  According to the third aspect of the present invention, the communication terminal transmits a first request signal to a plurality of other communication terminals with which a session has been established, so that not only a session with another communication terminal, Sessions between other communication terminals can also be disconnected. When the other communication terminal receives the first request signal, it can reliably disconnect the session with the other communication terminal by performing communication of the second request signal / first response signal. The other communication terminal disconnects the session with the communication terminal that has transmitted the first request signal after termination of the session disconnection by performing communication of the second request signal / first response signal. When the communication of the second request signal / first response signal fails, the other communication terminal does not disconnect the session with the communication terminal that transmitted the first request signal. The communication terminal can perform communication for disconnecting a session that has not been disconnected, using the maintained session. Therefore, the communication terminal prevents a part of the session from being maintained without being disconnected, and can reliably disconnect all the sessions.

  The communication method according to the fourth aspect of the present invention is the communication method according to any one of the other communication terminals among a plurality of other communication terminals that establish a session and perform Peer to Peer (P2P) type communication. A first receiving step for receiving a first request signal for requesting disconnection of a session; and the other communication terminal that has transmitted the first request signal when the first request signal is received in the first receiving step. A first transmission step of transmitting a second request signal for requesting disconnection of the session to the other communication terminals except for the second request signal after transmitting the second request signal in the first transmission step. A second receiving step of receiving a first response signal in response to the session disconnection request from the other communication terminal that has received the signal; and receiving the first response signal in the second receiving step. A first disconnection step of disconnecting the session with the other communication terminal that has transmitted the first response signal, and all the other communication that transmitted the second request signal in the first disconnection step. A second transmission step of transmitting a second response signal in response to the session disconnection request to the other communication terminal that has transmitted the first request signal when the session with the terminal is disconnected; A second disconnecting step of disconnecting the session with the other communication terminal that has transmitted the first request signal when the second response signal is transmitted in the second transmitting step.

  According to the fourth aspect, when the first request signal is received, the communication of the second request signal / first response signal is performed, so that other communication except the other communication terminal that has transmitted the first request signal is performed. The session with the terminal is securely disconnected. After termination of the session by performing communication of the second request signal / first response signal, the session with the other communication terminal that has transmitted the first request signal is disconnected. If communication of the second request signal / first response signal fails, the session with the other communication terminal that has transmitted the first request signal is not disconnected. Another communication terminal that has transmitted the first request signal can perform communication for disconnecting the session that has not been disconnected, using the session that has been maintained. Therefore, it is possible to prevent a part of the session from being disconnected and maintained, and to reliably disconnect all sessions.

  The communication program according to the fifth aspect of the present invention provides a communication program from any one of the other communication terminals among a plurality of other communication terminals that establish a session and perform Peer to Peer (P2P) communication. A first receiving step for receiving a first request signal for requesting disconnection of a session; and the other communication terminal that has transmitted the first request signal when the first request signal is received in the first receiving step. A first transmission step of transmitting a second request signal for requesting disconnection of the session to the other communication terminals except for the second request signal after transmitting the second request signal in the first transmission step. A second receiving step of receiving a first response signal in response to the session disconnection request from the other communication terminal that has received the signal; and receiving the first response signal in the second receiving step. In the first disconnection step of disconnecting the session with the other communication terminal that has transmitted the first response signal, and in the first disconnection step, all of the other other having transmitted the second request signal A second transmission step of transmitting a second response signal in response to a request for disconnection of the session to the other communication terminal that has transmitted the first request signal when the session with the communication terminal is disconnected; When the second response signal is transmitted in the second transmission step, the computer is caused to execute a second disconnection step of disconnecting the session with the other communication terminal that has transmitted the first request signal.

  According to the fifth aspect, when the first request signal is received, the communication of the second request signal / first response signal is performed, so that other communication except the other communication terminal that has transmitted the first request signal is performed. The session with the terminal is securely disconnected. After termination of the session by performing communication of the second request signal / first response signal, the session with the other communication terminal that has transmitted the first request signal is disconnected. If communication of the second request signal / first response signal fails, the session with the other communication terminal that has transmitted the first request signal is not disconnected. Another communication terminal that has transmitted the first request signal can perform communication for disconnecting the session that has not been disconnected, using the session that has been maintained. Therefore, it is possible to prevent a part of the session from being disconnected and maintained, and to reliably disconnect all sessions.

1 is a diagram illustrating an overview of a communication system 1 and an electrical configuration of a communication terminal 10. It is a schematic diagram for demonstrating a communication procedure. It is a schematic diagram for demonstrating a communication procedure. It is a schematic diagram for demonstrating a communication procedure. It is a schematic diagram for demonstrating a communication procedure. It is a flowchart which shows a main process. It is a flowchart which shows a transmission side process. It is a flowchart which shows a receiving side process. It is a schematic diagram for demonstrating a communication procedure. It is a schematic diagram for demonstrating a communication procedure.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. These drawings are used to explain technical features that can be adopted by the present invention. The configuration of the apparatus, the flowcharts of various processes, and the like that are described are not intended to be limited to only that, but are merely illustrative examples.

  The communication system 1 will be described with reference to FIG. The communication system 1 includes communication terminals 11, 12, 13, 14, and 15 (hereinafter referred to as “communication terminal 10” when they are not distinguished from each other). The communication terminal 10 can perform a video conference with another communication terminal 10 by performing P2P communication via the network 2. The communication terminal 10 is, for example, a known PC or a dedicated terminal for video conference. In addition, the code | symbol (11, 12, 13, 14, and 15) attached | subjected to the communication terminal 10 in FIG. 1 shall also show ID of each communication terminal 10. FIG. A dotted line given between the communication terminals 10 in FIG. 1 indicates that a session for performing P2P communication is established between the communication terminals 10.

  The electrical configuration of the communication terminal 10 will be described. The communication terminal 10 includes a CPU 20 that controls the communication terminal 10. The CPU 20 is electrically connected to the ROM 21, RAM 22, hard disk drive (HDD) 23, input unit 24, display 25, camera 26, speaker 27, microphone 28, communication I / F 29, and drive device 30. The ROM 21 stores a boot program, BIOS, OS, and the like. The RAM 22 stores a timer, a counter, and temporary data. The HDD 23 stores a communication program for the CPU 20. The input unit 24 is a keyboard or a mouse that receives input from the user. The communication I / F 29 performs timing control when communicating with another communication terminal 10 via the network 2. The drive device 30 can read information stored in the storage medium 301. For example, when setting up the communication terminal 10, the communication program stored in the storage medium 301 is read by the drive device 30 and stored in the HDD 23.

  With reference to FIGS. 2 to 5, an outline of a communication procedure when a session between communication terminals 10 is disconnected will be described. It is assumed that a session is established between the communication terminals 10 by a well-known method and P2P type communication is executed. It is assumed that the communication terminal 11 is selected in advance as a terminal that manages communication for disconnecting a session between the communication terminals 10. Hereinafter, a terminal that manages communication for disconnecting a session is referred to as a “management terminal”. The communication terminals 12, 13, 14, and 15 recognize in advance that the communication terminal 11 is a management terminal.

  In addition, the selection method of a management terminal is not specifically limited. For example, the communication terminal 10 having the smallest ID or the communication terminal 10 having the largest ID among the communication terminals 10 performing P2P type communication may be determined as the management terminal. Further, for example, the communication terminal 10 that first transmitted a packet for starting P2P communication may be defined as a management terminal.

  As shown in FIG. 2, first, the communication terminal 11 disconnects the sessions 41, 42, 43, and 44 with the communication terminals 12, 13, 14, and 15. And 15, a first request signal requesting session disconnection is transmitted. The communication terminals 12, 13, 14, and 15 receive the first request signal. At this time, the session between the communication terminal 11 and the communication terminals 12, 13, 14, and 15 is not disconnected.

  Each of the communication terminals 12, 13, 14, and 15 that has received the first request signal requests to disconnect the session in order to disconnect all other sessions except the session with the communication terminal 11. Two request signals are transmitted. For example, the communication terminal 12 is connected to the communication terminals 13, 14, and 15 to disconnect sessions 45, 46, and 47 with the communication terminals 13, 14, and 15, as shown in FIG. Two request signals are transmitted. The communication terminals 13, 14, and 15 receive the second request signal. As illustrated in FIG. 4, the communication terminals 13, 14, and 15 that have received the second request signal from the communication terminal 12 transmit a first response signal to the communication terminal 12 in order to respond to a session disconnection request. To do. The communication terminal 12 receives the first response signal.

  Note that the communication of the procedure described in FIG. 3 and FIG. 4 is executed similarly in the other communication terminals 13, 14, and 15 that have received the first request signal from the communication terminal 11. Therefore, for example, the communication terminal 12 receives the first response signal from the communication terminals 13, 14, and 15 according to the second request signal transmitted by itself (see FIG. 4), and from the communication terminals 13, 14, and 15 The second request signal is received, and the first response signal is returned according to the received second request signal. The communication terminal 12 (1) receives the first response signal from the communication terminals 13, 14, and 15 according to the second request signal transmitted by itself, or (2) the communication terminals 13, 14, and 15 When the first response signal is transmitted in response to the second request signal received from, the sessions 45, 46, and 47 with the communication terminals 13, 14, and 15 are disconnected.

  As a result of communication using the second request signal / first response signal, it is assumed that the communication terminals 12, 13, 14, and 15 have disconnected all other sessions except for the session with the communication terminal 11. As illustrated in FIG. 5, the communication terminals 12, 13, 14, and 15 transmit a second response signal to the communication terminal 11 in order to respond to a session disconnection request. The communication terminal 11 receives the second response signal. Sessions 41, 42, 43, and 44 between the communication terminal 11 and the communication terminals 12, 13, 14, and 15 are disconnected. Through the above procedure, all sessions between the communication terminals 10 are disconnected.

  It is assumed that the communication state between the communication terminal 12 and the communication terminal 13 deteriorates and the communication of the second request signal / first response signal performed between the communication terminal 12 and the communication terminal 13 fails. The communication terminal 12 does not transmit a second response signal to the communication terminal 11 when the session 45 with the communication terminal 13 cannot be disconnected. The communication terminal 13 does not transmit a second response signal to the communication terminal 11 when the session 45 with the communication terminal 12 cannot be disconnected. Since the second response signal corresponding to the first request signal transmitted from the communication terminal 11 is not transmitted from the communication terminals 12 and 13, the session 41 between the communication terminal 11 and the communication terminal 12, And the session 42 between the communication terminal 11 and the communication terminal 13 is not disconnected. The communication terminal 11 can instruct to resend the first request signal using the maintained sessions 41 and 42 and end the session between the communication terminal 12 and the communication terminal 13 again. In this way, the communication terminal 11 prevents a part of the established sessions from remaining without being disconnected. The communication terminal 11 can reliably end all sessions.

  A main process executed by the CPU 20 of the communication terminal 10 will be described with reference to FIGS. The main process is started and executed in a state where a session is established between the communication terminals 10 and P2P type communication is performed.

  As shown in FIG. 6, it is determined whether an instruction to disconnect the established session and end the P2P communication is input by the user via the input unit 24 (S11). Further, it is determined whether a notification packet (S16, which will be described later) transmitted from another communication terminal 10 has been received (S11). When an instruction to end the P2P communication is input, or when a notification packet is received from another communication terminal 10 (S11: YES), it is determined whether or not it is a management terminal (S12). . If the terminal itself is not a management terminal (S12: NO), a notification packet notifying that an instruction to end P2P communication has been input is transmitted to the management terminal (S16). The process returns to S11.

  On the other hand, when it is determined in S12 that it is a management terminal (S12: YES), identification information for identifying the communication terminal 10 is acquired (S13). For example, ID is used as the identification information. The first request signal for requesting session disconnection and the identification information acquired in S13 are transmitted to all other communication terminals 10 with which the session has been established (S14). Processing for managing communication for disconnecting the session (transmission side processing (see FIG. 7)) is executed (S15). After the transmission side process ends, the process returns to S11.

  The transmission side process will be described with reference to FIG. In response to the first request signal transmitted in S14 (see FIG. 6), it is determined whether or not a second response signal has been received from another communication terminal 10 (S31). When the second response signal is received (S31), the session with the other communication terminal that has transmitted the second response signal is disconnected (S32).

  The total number “M” of received second response signals is identified. Further, the number of other communication terminals 10 having a session with itself, that is, the total number “N” of the first request signals transmitted in S14 (see FIG. 6) is specified. By comparing “M” with “N−1”, it is determined whether all the established sessions are disconnected (S33). The reason why “M” and “N-1” are compared is as follows.

  For example, as illustrated in FIG. 2, it is assumed that the first request signal is transmitted from the communication terminal 11 to the communication terminals 12, 13, 14, and 15. The communication terminals 12, 13, 14, and 15 communicate all the sessions between the communication terminals 12, 13, 14, and 15 by communication of the second request signal / first response signal (see, for example, FIGS. 3 and 4). Is disconnected. Here, as shown in FIG. 9, it is assumed that the communication state between the communication terminal 11 and the communication terminal 13 deteriorates and the second response signal transmitted from the communication terminal 13 cannot be received by the communication terminal 11. The second response signal transmitted from the communication terminals 12, 14, and 15 is received by the communication terminal 11. In this case, since all the sessions between the communication terminals 12, 13, 14, and 15 are disconnected, there is a problem even if the communication terminal 11 disconnects the session with the communication terminal 13 that has not received the second response signal. Absent.

  Therefore, even when the communication terminal 11 cannot receive the second response signal from all of the communication terminals 12, 13, 14, and 15 that have transmitted the first request signal, the total number “M” of the received second response signals is If the number is “N−1” or more obtained by subtracting 1 from the total number “N” of the communication terminals 12, 13, 14, and 15 that have transmitted one request signal, the session between the communication terminals 12, 13, 14, and 15 is Judge all disconnected. In the above example, since the communication terminal 11 has received the second response signal from the communication terminals 12, 14, and 15, “M” is 3. In addition, since the communication terminal 11 transmits the first request signal to the communication terminals 12, 13, 14, and 15, “N” is 4. Therefore, “M” (= 3) satisfies the condition of “N−1” (= 3) or more. Therefore, even if the communication terminal 11 determines that all the sessions between the communication terminals 12, 13, 14, and 15 have been disconnected and has not received the second response signal from the communication terminal 13, the communication terminal 13 Disconnect the session between. As a result, the sessions 41, 42, 43, and 44 between the communication terminal 11 and the communication terminals 12, 13, 14, and 15 are all disconnected. In this way, the communication terminal 11 can disconnect all the sessions in a short time by efficiently determining whether or not all the sessions between the communication terminals 12, 13, 14, and 15 have been disconnected. it can.

  As shown in FIG. 7, when the total number “M” of the received second response signals is equal to or greater than the number “N−1” obtained by subtracting 1 from the total number “N” of the transmitted first request signals (S33: YES), it is determined that the session between the other communication terminals 10 has been disconnected. The session with the other communication terminal that has not received the second response signal is disconnected (S35). The transmission side process ends, and the process returns to the main process (see FIG. 6). On the other hand, when the total number “M” of the received second response signals is less than the number “N−1” obtained by subtracting 1 from the total number “N” of the transmitted first request signals (S33: NO), There is a possibility that a session that has not been disconnected still remains among the sessions between the communication terminals. In order to continuously monitor reception of the second response signal, the process returns to S31.

  If the second response signal has not been received from the other communication terminal 10 (S31: NO), it is determined whether the elapsed time since the transmission of the first request signal has reached a predetermined time or more (S37). When the elapsed time is less than the predetermined time (S37: NO), there is a possibility that the second response signal is received from the other communication terminal 10 that has transmitted the first request signal, so the process returns to S31. On the other hand, when the elapsed time after transmitting the first request signal is equal to or longer than the predetermined time (S37: YES), the session between the other communication terminals 10 cannot be disconnected due to the deterioration of the communication state or the like. There is a possibility. Therefore, the first request signal and the identification information are retransmitted to other communication terminals 10 that have not received the second response signal (S39). As a result, the communication terminal 10 can reliably disconnect the session by retransmitting the first request signal even when the session is not disconnected due to a temporary deterioration of the communication state or the like.

  It is determined whether the number of retransmissions of the first request signal to the other communication terminal 10 has reached a predetermined number or more (S41). When the number of retransmissions of the first request signal is less than the predetermined number (S41: NO), the process returns to S31. If the number of retransmissions of the first request signal is equal to or greater than the predetermined number (S41: YES), there is a possibility that the session with another communication terminal 10 cannot be disconnected due to disconnection of the network 2 or the like. There is. In this case, the third request signal requesting forcible disconnection of the session with the other communication terminal 10 is transmitted to the other communication terminal 10 that has not received the second response signal (S43). .

  Reception of the third response signal transmitted from the other communication terminal 10 in response to the third request signal is monitored (S45). When the third response signal is not received (S45: NO), the process returns to S45. When the third response signal is received (S45: YES), the session with the other communication terminal 10 that has transmitted the third response signal is disconnected (S35). Thus, the communication terminal 10 forcibly disconnects the session with the other communication terminal 10 when the communication state between the other communication terminals 10 is very poor and the session cannot be disconnected. be able to. Accordingly, the communication terminal can avoid a state in which a session with a good communication state is not disconnected for a long time due to the presence of a session with a very bad communication state. In addition, the communication terminal can avoid taking a long time for communication for session disconnection. The transmission side process ends, and the process returns to the main process (see FIG. 6).

  In the above description, after the third request signal is transmitted to the other communication terminal 10 (S43), the reception of the third response signal is monitored (S45). The present invention is not limited to this. The communication terminal 10 may disconnect the session with the other communication terminal 10 immediately after transmitting the third request signal to the other communication terminal 10. Since the session can be disconnected regardless of the response from the other communication terminal 10, even if the communication state between the communication terminal 10 and the other communication terminal 10 is very bad and communication is impossible, it is sure. In addition, the session can be quickly disconnected.

  In the above description, the third request signal is transmitted to the other communication terminal 10 when the number of retransmissions of the first request signal and the identification information is equal to or greater than a predetermined number. However, the present invention is not limited to this. . For example, the third request signal may be transmitted based on the elapsed time since the first request signal was transmitted. Specifically, in S37 of FIG. 7, it is determined whether or not the elapsed time since the transmission of the first request signal is equal to or longer than the first predetermined time. One request signal and identification information may be retransmitted. In S41, the elapsed time after transmitting the first request signal may be monitored. When the elapsed time since the transmission of the first request signal is equal to or longer than the second predetermined time (first predetermined time <second predetermined time) (S41: YES), the third request signal is transmitted. Also good.

  In S11 of the main process in FIG. 6, when an instruction to disconnect the established session and end the P2P communication is not input (S11: NO), the first request signal and the identification information are transmitted to the other communication terminals 10. Is received (S17). When the first request signal and the identification information are received (S17: YES), a process for performing communication for disconnecting the session (reception side process (see FIG. 8)) is executed based on an instruction from the management terminal. (S18). Details of the processing on the receiving side will be described later. After the reception side process is completed, the process returns to S11.

  On the other hand, when the first request signal and the identification information are not received (S17: NO), it is determined whether the first request signal and the identification information retransmitted from another communication terminal 10 are received (S19). When the retransmitted first request signal and identification information are received (S19: YES), the process proceeds to S18, and the receiving side process (see FIG. 8) is executed (S18). After the reception side process is completed, the process returns to S11. When the retransmitted first request signal and identification information are not received (S19: NO), the process returns to S11.

  The receiving side process will be described with reference to FIG. It is determined whether the other communication terminal 10 that has transmitted the first request signal and the identification information received in S17 (see FIG. 6) is a management terminal (S51). If the other communication terminal 10 that is the transmission source of the first request signal and the identification information is not a management terminal (S51: NO), it is determined that the received first request signal and the identification information are invalid, and the receiving-side process ends. The process returns to the main process (see FIG. 6). In this way, the communication terminal 10 prevents the session from being disconnected when an unspecified communication terminal 10 different from the management terminal transmits the first request signal. As a result, the session is stabilized and the reliability of P2P communication is improved.

  When the other communication terminal 10 that is the transmission source of the first request signal and the identification information is the management terminal (S51: YES), request disconnection of the session other than the session with the management terminal among the established sessions The second request signal to be transmitted is transmitted to the other communication terminals 10 excluding the management terminal. Further, the identification information received in S17 (see FIG. 6) is acquired and transmitted together with the second request signal (S53).

  After the transmission of the second request signal and the identification information, it is determined whether a first response signal transmitted from another communication terminal 10 is received according to the transmitted second request signal (S55). If the first response signal has been received (S55: YES), it is determined whether or not it has become possible to disconnect all sessions with the other communication terminals 10 except the management terminal (S57). ). A first response signal is received from another communication terminal 10 (see S55), or a second request signal is received from another communication terminal 10 (see S65, described later), and a first response signal is returned (S71). In the case of reference (described later), a session with another communication terminal 10 can be disconnected. On the other hand, when the first response signal is not received from the other communication terminal 10 and the first response signal is not transmitted to the other communication terminal 10, a session with the other communication terminal 10 is performed. Is determined not to be cut. If there remains a session that cannot be disconnected (S57: NO), the process returns to S55.

  If the session with all other communication terminals 10 excluding the management terminal can be disconnected (S57: YES), the session with all other communication terminals 10 other than the management terminal is disconnected (S59). A second response signal is transmitted to the management terminal that has transmitted the first request signal (S61). The session with the management terminal is disconnected (S63). The receiving side process is terminated, and the process returns to the main process (see FIG. 6).

  On the other hand, when the first response signal is not received in S55 (S55: NO), it is determined whether the second request signal and the identification information are received from the other communication terminals 10 excluding the management terminal (S65). When the second request signal and the identification information are received (S65: YES), the received identification information is compared with the identification information received together with the first request signal in S17 (see FIG. 6) (S69). Based on the comparison result, it is determined whether or not the received second request signal is valid. Hereinafter, a specific example will be described.

  For example, as illustrated in FIG. 10, it is assumed that the first request signal and identification information 101 and 102 transmitted from the communication terminal 11 that is a management terminal are received by the communication terminal 12 and the communication terminal 15. The communication terminal 12 transmits the identification information 101 received from the communication terminal 11 to the communication terminal 15 together with the second request signal. The communication terminal 15 receives the second request signal and the identification information 101. The identification information 101 transmitted from the communication terminal 11 to the communication terminal 12 and the identification information 102 transmitted from the communication terminal 11 to the communication terminal 15 are the same. Therefore, the identification information 102 received from the communication terminal 11 by the communication terminal 15 matches the identification information 101 received from the communication terminal 12. In this case, the communication terminal 15 determines that the second request signal received from the communication terminal 12 is transmitted from the communication terminal 12 based on an instruction from the communication terminal 11, and the received second request signal is valid. It is judged that. Then, the communication terminal 15 transmits the first response signal 103 to the communication terminal 12 and disconnects the session 47 with the communication terminal 12.

  On the other hand, it is assumed that the identification information received by the communication terminal 15 from the management terminal is different from the identification information received by the communication terminal 15 from the communication terminal 12. In this case, the communication terminal 15 determines that the second request signal received from the communication terminal 12 is transmitted from the communication terminal 12 based on an instruction from another management device different from the communication terminal 11. It is determined that the received second request signal is invalid. In this case, the communication terminal 15 does not transmit the first response signal to the communication terminal 12 and does not disconnect the session with the communication terminal 12. In this way, the communication terminal 10 accurately grasps whether or not the received second request signal is based on an instruction from the management terminal that has transmitted the first request signal to itself, and performs common management. Only the session instructed from the terminal can be reliably disconnected.

  The determination based on the identification information described above is performed when, for example, a specific communication terminal 10 belongs to a plurality of P2P communication groups (for example, when participating in a plurality of different video conferences). It is particularly effective. This is because when there is a session disconnection instruction from the management terminal in one group, it is possible to prevent the session in the other group from being disconnected accidentally.

  As shown in FIG. 8, when the identification information received in S17 (see FIG. 6) matches the identification information received in S65 (S69: YES), the other communication terminal 10 that has transmitted the second request signal is notified. On the other hand, a first response signal is transmitted (S71). It is determined whether or not it has become possible to disconnect all sessions with other communication terminals 10 other than the management terminal (S75). If there remains a session that cannot be disconnected (S75: NO), the process returns to S55. If the session with all other communication terminals 10 other than the management terminal can be disconnected (S75: YES), the process proceeds to S59. Sessions with all other communication terminals 10 excluding the management terminal are disconnected (S59). A second response signal is transmitted to the management terminal that has transmitted the first request signal (S61). The session with the management terminal is disconnected (S63). The receiving side process is terminated, and the process returns to the main process (see FIG. 6).

  When the second request signal and the identification information are not received in S65 (S65: NO), it is determined whether the third request signal is received from the management terminal (S77). When the third request signal is received (S77: YES), the third response signal is transmitted to the management terminal (S79). The session with the management terminal is disconnected (S81). The receiving side process is terminated, and the process returns to the main process (see FIG. 6). If the third request signal has not been received (S77: NO), the process returns to S55.

  As described above, when the communication terminal 10 receives the first request signal from the management terminal, the communication terminal 10 communicates with the other communication terminals 10 other than the management terminal by communicating the second request signal / first response signal. The session can be disconnected. The communication terminal 10 can disconnect the session with the management terminal after termination of the session disconnection by performing communication of the second request signal / first response signal. When the communication of the second request signal / first response signal fails, the communication terminal 10 does not disconnect the session with the management terminal, so the session with the management terminal is maintained. By using the maintained session and transmitting the first request signal from the management terminal, the communication terminal 10 can reliably disconnect all the sessions. The communication terminal 10 can prevent a part of a session in which P2P type communication is performed from being disconnected and maintained.

  In addition, the management terminal transmits a first request signal to a plurality of other communication terminals 10 with which a session has been established, so that not only a session with another communication terminal 10 but also between other communication terminals 10 Sessions can also be disconnected. When the management terminal receives the second response signal, the management terminal disconnects the session with the other communication terminal 10. When the management terminal cannot receive the second response signal, the management terminal determines that an undisconnected session remains, and does not disconnect a session with another communication terminal 10. Accordingly, the management terminal can reliably disconnect all sessions by communicating with other communication terminals 10 using the maintained session. The management terminal can prevent a part of a session between other communication terminals from being maintained without being disconnected.

  In the communication terminal of the present invention, the CPU 20 that performs the process of S17 corresponds to the “first receiving means” of the present invention. The CPU 20 that performs the process of S53 corresponds to the “first transmission unit” of the present invention. The CPU 20 that performs the process of S55 corresponds to the “second receiving means” of the present invention. The CPU 20 that performs the process of S59 corresponds to the “first cutting means” of the present invention. The CPU 20 that performs the process of S61 corresponds to the “second transmission unit” of the present invention. The CPU 20 performing the process of S63 corresponds to “second cutting means” and “third cutting means” of the present invention. The CPU 20 that performs the process of S65 corresponds to the “third receiving means” of the present invention. The CPU 20 of the management terminal that performs the process of S14 corresponds to the “first transmission means” of the present invention. The CPU 20 of the management terminal that performs the process of S31 corresponds to the “reception unit” of the present invention. The CPU 20 of the management terminal that performs the process of S32 corresponds to the “first cutting means” of the present invention. The CPU 20 of the management terminal that performs the process of S39 corresponds to the “second transmission means” of the present invention. The CPU 20 of the management terminal that performs the process of S43 corresponds to the “third transmission unit” of the present invention. The CPU 20 of the management terminal that performs the process of S35 corresponds to the “second cutting means” of the present invention.

  In the communication system of the present invention, the CPU 20 of the management terminal that performs the process of S14 corresponds to the “first transmission means” of the present invention. The CPU 20 of the management terminal that performs the process of S31 corresponds to the “first receiving means” of the present invention. The CPU 20 of the management terminal that performs the process of S32 corresponds to the “first cutting means” of the present invention. The CPU 20 that performs the process of S17 corresponds to the “second receiving means” of the present invention. The CPU 20 that performs the process of S53 corresponds to the “second transmission unit” of the present invention. The CPU 20 that performs the process of S55 corresponds to the “third receiving means” of the present invention. The CPU 20 that performs the process of S65 corresponds to the “fourth receiving means” of the present invention. The CPU 20 that performs the process of S71 corresponds to the “third transmission unit” of the present invention. The CPU 20 that performs the process of S59 corresponds to the “second cutting means” of the present invention. The CPU 20 that performs the process of S61 corresponds to the “fourth transmission unit” of the present invention. The CPU 20 that performs the process of S63 corresponds to the “third cutting unit” of the present invention.

  In the communication method and communication program of the present invention, the process of S17 corresponds to the “first reception step” of the present invention. The process of S53 corresponds to the “first transmission step” of the present invention. The process of S55 corresponds to the “second reception step” of the present invention. The process of S59 corresponds to the “first cutting step” of the present invention. The process of S61 corresponds to the “second transmission step” of the present invention. The process of S63 corresponds to the “second cutting step” of the present invention.

  In addition, this invention is not limited to the above-mentioned embodiment, A various deformation | transformation is possible. In the above description, one of the plurality of communication terminals 10 that perform P2P communication is selected as the management terminal. Here, for example, the function of the management device described above may be implemented in a server among communication terminals that perform server-client type communication. That is, the present invention can also be used as a communication method for disconnecting a session in server-client type communication.

  In the above-described embodiment, all the communication terminals 10 that have received the first request signal from the management terminal have transmitted the second request signal. The present invention is not limited to this. For example, when the second request signal is received from another communication terminal 10 that is scheduled to transmit the second request signal before transmitting the second request signal, the first response signal is returned to the communication terminal 10. Therefore, the second request signal need not be transmitted. Thereby, since the communication amount between the communication terminals 10 can be suppressed, the communication load of the network 2 can be reduced.

  The time from when the first request signal is transmitted until the second request signal is transmitted is randomly determined so that the timing at which the second request signal is transmitted from the communication terminal 10 does not coincide with the other communication terminals 10. May be. As a result, it is possible to prevent the transmission timing of the second request signal from being matched and the signals from colliding with each other to cause communication failure.

  In the above-described main process (see FIG. 6), when the user inputs an instruction to end the P2P communication, the transmission side process (see FIG. 7) is called and executed in the CPU 20 of the management terminal. The receiving side process (see FIG. 8) is called and executed in the CPU 20 of the communication terminal 10 of FIG. Therefore, while the transmission-side process or the reception-side process is being executed, a new first request signal transmitted from another communication terminal 10 cannot be received and processed. On the other hand, for example, the transmission side process and the reception side process may be started at the execution timing described above and executed in parallel with the main process. Thereby, in the main process, it is possible to always receive a new first request signal transmitted from another communication terminal 10 (S17, see FIG. 6). Thereby, even when the first request signal is transmitted from a plurality of management terminals at the same time, each first request signal is received and the corresponding second request signal is transmitted to the other communication terminal 10. It becomes possible.

  The management terminal may be changeable during P2P communication. For example, when the communication terminal 11 as the management terminal leaves the video conference, the authority of the management terminal may be transferred to any one of the communication terminals 12, 13, 14, and 15. Specifically, the communication terminal 11 transmits a notification packet indicating that any one of the communication terminals 12, 13, 14, and 15 becomes a management terminal to the communication terminals 12, 13, 14, and 15. May be.

1 Communication system 10, 11, 12, 13, 14, 15 Communication terminal 20 CPU

Claims (10)

A communication terminal that performs Peer to Peer (P2P) type communication with a plurality of other communication terminals that have established sessions,
First receiving means for receiving a first request signal for requesting disconnection of the session from any one of the other communication terminals;
A second request for disconnecting the session from the other communication terminal excluding the other communication terminal that has transmitted the first request signal when the first request signal is received by the first receiving means; First transmission means for transmitting a request signal;
Second receiving means for receiving a first response signal in response to a request for disconnecting the session from the other communication terminal that has received the second request signal after transmitting the second request signal in the first transmitting means. When,
First disconnecting means for disconnecting the session with the other communication terminal that has transmitted the first response signal when the second response means receives the first response signal;
In the first disconnecting means, when the session with all the other communication terminals that transmitted the second request signal is disconnected, the other communication terminal that transmitted the first request signal, Second transmission means for transmitting a second response signal in response to a session disconnection request;
A second disconnecting unit configured to disconnect the session with the other communication terminal that has transmitted the first request signal when the second transmission unit transmits the second response signal. Communication terminal. The first transmission means includes
When the other communication terminal that has transmitted the first request signal received by the first receiving means is a management terminal that manages the state of establishment of the session between the communication terminals, the other except the management terminal The communication terminal according to claim 1, wherein the second request signal is transmitted to the communication terminal. The first receiving means includes
Receiving identification information for identifying the other communication terminal that has transmitted the first request signal together with the first request signal;
The first transmission means includes
Transmitting the identification information received by the first receiving means together with the second request signal;
Third receiving means for receiving the identification information and the second request information from the other communication terminal that is the destination of the identification information and the second request signal transmitted in the first transmission means;
When the identification information received by the first receiving unit matches the identification information received by the third receiving unit, the session with the other communication terminal that has transmitted the second request signal is disconnected. The communication terminal according to claim 1, further comprising a third cutting unit configured to perform the cutting. A communication terminal that performs Peer to Peer (P2P) type communication with a plurality of other communication terminals that have established sessions,
First transmission means for transmitting a request signal for requesting disconnection of the session to the plurality of other communication terminals;
After at least one of the plurality of other communication terminals that have received the request signal transmitted by the first transmission means disconnects all the established sessions, a response signal that responds to the request for disconnecting the session is generated. Receiving means for receiving the response signal when transmitted,
A communication terminal comprising: a first disconnecting unit that disconnects the session with the other communication terminal that has transmitted the response signal when the receiving unit receives the response signal. The receiving means includes
5. The response signal is continuously received until the total number of the received response signals is equal to or greater than the number obtained by subtracting 1 from the total number of the plurality of other communication terminals. Communication terminal.   If the response signal obtained by subtracting 1 from the total number of the plurality of other communication terminals cannot be received even after a predetermined time has elapsed in the receiving means, the other communication as the transmission source of the response signal that has not been received yet The communication terminal according to claim 4, further comprising second transmission means for retransmitting the request signal to the terminal. If the response signal obtained by subtracting 1 from the total number of the plurality of other communication terminals cannot be received even after a predetermined time has elapsed in the receiving means, the other communication as the transmission source of the response signal that has not been received yet Third transmission means for transmitting a third request signal for forcibly disconnecting the session to the terminal;
A second disconnecting unit that disconnects the session with the other communication terminal that has transmitted the third request signal after transmitting the third request signal in the third transmitting unit. Item 6. The communication terminal according to Item 4 or 5. A communication system that establishes a session between a communication terminal and a plurality of other communication terminals, and performs Peer to Peer (P2P) type communication,
The communication terminal is
First transmission means for transmitting a first request signal for requesting disconnection of the session to the plurality of other communication terminals;
The at least one of the plurality of other communication terminals that have received the first request signal transmitted by the first transmission means disconnects all the established sessions, and then responds to the session disconnection request. A first receiving means for receiving the second response signal when transmitting a second response signal;
A first disconnecting unit that disconnects the session with the other communication terminal that has transmitted the second response signal when the second response signal is received by the first receiving unit;
The other communication terminal is:
Second receiving means for receiving the first request signal from the communication terminal;
A second transmission means for transmitting a second request signal for requesting disconnection of the session to the other communication terminals other than itself when the second reception means receives the first request signal;
After receiving the second request signal in the second transmission means, third receiving means for receiving a first response signal in response to a request for disconnection of the session from the other communication terminal other than itself,
A fourth receiving means for receiving the second request signal from the other communication terminals other than itself;
Third transmission means for transmitting the first response signal to the other communication terminal that has transmitted the second request signal when the second request signal is received by the fourth reception means;
When receiving the first response signal from the other communication terminal in the third receiving means, or when transmitting the first response signal to the other communication terminal in the third transmitting means, Second disconnection means for disconnecting the session with another communication terminal;
Fourth transmission for transmitting the second response signal to the communication terminal when the second disconnection unit disconnects the session with all the other communication terminals that transmitted the second request signal. Means,
A communication system comprising: a third disconnecting unit that disconnects the session with the communication terminal when the fourth response unit transmits the second response signal. A first request signal for requesting disconnection of the session is received from any one of a plurality of other communication terminals that have established a session and perform peer-to-peer (P2P) type communication. A first receiving step,
When receiving the first request signal in the first reception step, a second request for disconnecting the session from the other communication terminals other than the other communication terminal that has transmitted the first request signal. A first transmission step of transmitting a request signal;
A second receiving step of receiving a first response signal in response to a request for disconnecting the session from the other communication terminal that has received the second request signal after transmitting the second request signal in the first transmitting step; When,
A first disconnecting step of disconnecting the session with the other communication terminal that has transmitted the first response signal when the first response signal is received in the second receiving step;
In the first disconnecting step, when the session with all the other communication terminals that transmitted the second request signal is disconnected, the other communication terminal that transmitted the first request signal, A second transmission step of transmitting a second response signal in response to the session disconnection request;
A second disconnecting step of disconnecting the session with the other communication terminal that has transmitted the first request signal when the second response signal is transmitted in the second transmitting step. Communication method. A first request signal for requesting disconnection of the session is received from any one of a plurality of other communication terminals that perform peer-to-peer (P2P) type communication when a session is established. A first receiving step,
When receiving the first request signal in the first reception step, a second request for disconnecting the session from the other communication terminals other than the other communication terminal that has transmitted the first request signal. A first transmission step of transmitting a request signal;
A second receiving step of receiving a first response signal in response to a request for disconnecting the session from the other communication terminal that has received the second request signal after transmitting the second request signal in the first transmitting step; When,
A first disconnecting step of disconnecting the session with the other communication terminal that has transmitted the first response signal when the first response signal is received in the second receiving step;
In the first disconnecting step, when the session with all the other communication terminals that transmitted the second request signal is disconnected, the other communication terminal that transmitted the first request signal, A second transmission step of transmitting a second response signal in response to the session disconnection request;
To cause the computer to execute a second disconnection step of disconnecting the session with the other communication terminal that has transmitted the first request signal when the second response signal is transmitted in the second transmission step. Communication program.

Images