JPH11313059A - Multicasting communication method/system and storage medium recording multicasting communication program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide push-type multicasting communication/system having real time property and scalability with respect to the increase of the number of reception hosts, and a storage medium recording a multicasting communication program. SOLUTION: Data whose destination is a channel from a transmission host 100 are distributed to a reception host 500 through one repeating server 200 or a plurality of repeating servers 200 having tree structures where repeating routes are defined for the channels. The reception host 500 transmits a channel entry request message or an entry separation message to the repeating server 200 for requesting entry/separation to/from the channel. Upon receiving the pertinent message, the repeating server 200 registers or deletes the address of the reception host 500 or the slave repeating server 200 in/from an address management table and repeats the pertinent message to the master repeating server 200.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information distribution method and an information distribution system on the Internet, and more particularly to a multicast communication method and system for performing push-type information distribution and a recording medium on which a multicast communication program is recorded. is there.

[0002]

2. Description of the Related Art Conventionally, as an information distribution method for simultaneously distributing information to a large number of reception hosts on the Internet, a pull type in which a transmission host individually distributes information based on a request from a reception host has been mainly used.

[0003]

In this pull-type information distribution method, the receiving host accesses the transmitting host at fixed intervals, so that the receiving host accesses the transmitting host and the transmitting host side Is not always synchronized with the information update. Therefore, the real-time property of information was low. Also, since the sending host sends data individually to the receiving host, the load on the sending host increases greatly when the number of receiving hosts increases, and as a result, when the number of receiving hosts increases. However, there was no scalability that the sending host could continue information distribution efficiently.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a push-type multicast communication method and system having a real-time property and scalability against an increase in the number of receiving hosts, a system thereof, and a multicast communication program. It is to provide a recorded recording medium.

[0005]

In order to achieve the above object, according to the present invention, there is provided a tree which uses the Internet, via one relay server, or a data relay path defined for a channel. In a multicast communication for distributing data from a sending host to one or more receiving hosts via a plurality of relay servers having a structure, the receiving host, when joining a channel, The relay server transmitting a channel join request message and receiving the channel join request message,
The channel joining request message is relayed to the relay server that is higher in the tree structure, and the address of the receiving host or the relay server that is the transmission source of the channel joining request message is registered in the address management table, and the transmitting host is The relay server that transmits the data addressed to the channel to the one relay server or the relay server that is the root of the tree structure defined for the channel, and receives the data addressed to the channel, performs address management. Relays data to a relay server or a receiving host below the tree structure registered in the table, the receiving host receives the data relayed by the relay server, and the receiving host leaves the channel In this case, a channel leaving request message is transmitted to the relay server, and the channel leaving request message is sent. The relay server receiving the address deletes the address of the receiving host or the relay server that is the transmission source of the channel leave request message from the address management table, and the number of the receiving host and the relay server registered in the address management table is zero. If it does, it relays the channel departure request message to the relay server that is higher in the tree structure.

According to the present invention, in order to transmit data destined for a channel from a transmitting host to a receiving host, the transmitting host must define data destined for the channel with respect to the one relay server or the channel. What is necessary is just to transmit to the relay server used as the root of the tree structure. Thereby, the data is distributed to the receiving host registered in the address management table of each relay server via the relay server.

When a receiving host requesting the start of data reception sends a channel join request message to the relay server, the address of the receiving host is registered in the address management table of the relay server. Further, the channel join request message is relayed to a relay server that is higher in the tree structure with respect to the relay server, and the address of the relay server of the relay source is registered in the address management table of each relay server of the relay destination. Thus, as described above, when data is transmitted from the transmission host, the data is distributed to the reception host based on the address management table.

[0008] Further, when the receiving host requesting suspension of data reception transmits a channel leaving request message to the relay server, the address of the receiving host registered in the address management table of the relay server is deleted. When the number of receiving hosts or relay servers registered in the address table becomes zero due to this deletion, the channel leave request message is relayed to a relay server that is higher in the tree structure for the relay server, and the The address of the relay server at the relay source registered in the address management table of the previous relay server is deleted. As a result, as described above, even if data is transmitted from the transmission host, the data is not distributed to the reception host.

FIG. 1 shows the operation principle of the present invention.
This will be described with reference to FIG. FIG. 1 is a sequence chart illustrating the operation principle of the present invention, and FIG. 2 is a configuration diagram illustrating the operation principle of the present invention.

As shown in FIG. 1, a receiving host 500 requesting to start receiving data transmits a message requesting to join a channel to relay server 200 (step S11). The relay server 200 relays the received channel join request message to the relay server 200 that is higher in the tree structure (step S12). Also,
Relay server 20 that has received the channel join request message
0 registers the address of the receiving host 500 of the message transmission source or the address of the relay server 200 in an address management table for managing the address of the receiving host 500 that receives data or the address of the relay server 200 that is lower in the tree structure ( Step S13).

The sending host 100 sends data addressed to the channel to the relay server 200 that is the root of the tree structure (step S21). The relay server 200 that has received the data relays the data to the relay server (relay server registered in the address management table) 200 or the receiving host 500 that has joined the channel identified by the channel identifier in the data. (Step S2
2).

Receiving host 5 for requesting suspension of data reception
00 transmits a message requesting withdrawal from the channel to the relay server 200 (step S31).
The relay server 200 is a relay server 2 that is higher in the tree structure.
With respect to 00, the received channel leaving request message is relayed (step S32). The relay server 200 that has received the channel leave request message is the receiving host 500 that receives the data or the relay server 2 that is lower in the tree structure.
00, the address of the message receiving host 500 or the address of the relay server 200 is deleted from the address management table. (Step S33).

As shown in FIG. 2, a multicast communication system according to the present invention provides a transmission host which transmits data to a relay server 200 which becomes a root of a tree structure defined for a channel as a destination of data. 100
The relay server 200 that relays the data transmitted from the transmission host 100 or the relay server 200 that is higher in the tree structure to the relay server 200 or the reception host 500 that is lower in the tree structure, And a receiving host 500 for receiving data relayed from the relay server 200 while requesting to join or leave the channel.

The transmission host 100 has data transmission means 110 for transmitting data to a relay server 200 which is a root of a tree structure defined for a channel as a data destination.

The relay server 200 is connected to the transmission host 10
0 or a data receiving means 210 for receiving data sent from the relay server 200 which is higher in the tree structure, and the transmission host 100 or the relay server 200 which is higher in the tree structure.
Data relay means 220 for relaying / transmitting data sent from the server to the relay server 200 or the receiving host 500 at the lower level of the tree structure, the channel identified by the channel identifier in the received data, and the lower level of the tree structure. An address management unit 230 that manages the correspondence with the address of the relay server 200 or the receiving host 500, and the channel joining request message or the channel leaving request message transmitted by the relay server 200 or the receiving host 500 that is lower in the tree structure. Message receiving means 250 for receiving
And a message relay unit 260 that relays a channel join request message or a channel leave request message received from the relay server 200 or the receiving host 500 that is lower in the tree structure to the relay server 200 that is higher in the tree structure.

The receiving host 500 is connected to the relay server 20
It has a message transmitting unit 510 for transmitting a message requesting to join or leave the channel to 0, and a data receiving unit 520 for receiving data relayed from the relay server.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A multicast communication system according to an embodiment of the present invention will be described. First, the configuration of the multicast communication system will be described with reference to FIG. FIG. 3 is a configuration diagram illustrating a multicast communication system. The configuration shown in the figure is one transmission host 100, three relay servers 200, three reception hosts 5
00.

The transmission host 100 sets a data transmission connection (TCP connection) with the relay server 200a in order to transmit data without error, and uses the connection to set a specific channel as a destination. Send data.

When the relay server 200 receives the channel join request message from the relay server 200 or the receiving host 500 at the lower level of the tree structure, the relay server 200
00 or a connection for data transmission (TCP connection) with the receiving host 500. In the following description, a relay server that is higher in the tree structure than a certain relay server is called a parent relay server, and a relay server that is lower in the tree structure is called a child relay server. The relay server that becomes the root of the tree structure is called a root relay server.

Relay server 200 searches the address management table using the channel identifier in the received data as a key,
The data is relayed to the relay server 200 or the receiving host 500 subscribed to the channel using the data transmission connection set when the channel subscription request message is received.

When joining the channel, the receiving host 500 sets a control connection (TCP connection) with the relay server 200, and transmits a channel joining request message using the connection. When leaving the channel, the receiving host 500 transmits a channel leaving request message using the connection set when the channel joining request message was transmitted.

Relay server 200 that has received the channel join request message or the channel leave request message sets up a control connection with parent relay server 200 and relays the received message to parent relay server 200. .

Next, the transmission host constituting the multicast communication system will be described with reference to FIGS. FIG. 4 is a diagram illustrating the structure of data transmitted by the transmission host, and FIG. 5 is a flowchart illustrating control of the transmission host.

As shown in FIG. 4, data D transmitted from the transmission host 100 includes a channel identifier D1 and a user data D2. The channel identifier D1 stores a channel identifier that is a destination of the user data D2. The user data section D2 is provided in the receiving host 50.
0 stores user data to be distributed.

The transmission host 100 operates based on the flowchart shown in FIG. 5, as described below.

First, when there is a data transmission request from the application, the transmission host 100 sets up a data transmission connection with the route relay server 200 defined for the channel (step S10).
1).

Next, using the connection set in step S101, the data D in which the channel identifier of the channel is set in the channel identifier D1 is transmitted to the relay server 200 (step S102). When the data transmission ends, the process proceeds to step S104 (step S104).
103).

Finally, the connection set with the relay server 200 is released (step S104). By the above operation, the data D is transmitted from the transmission host 100 to the route relay server 200.

Next, the relay server constituting the multicast communication system will be described with reference to FIGS. 6 illustrates the structure of a message relayed by the relay server, FIG. 7 illustrates the configuration of the relay server, FIG. 8 illustrates the configuration of the address management table, and FIGS. 9 to 11 illustrate the operation of the relay server. It is a flowchart explaining.

The structure of the message M exchanged between the relay server 200 and the receiving host 500 is, as shown in FIG.
1, a channel identifier section M2 for designating a channel identifier of a channel requesting to join or leave.

The relay server 200, as shown in FIG.
It comprises a data receiving unit 201, a data relay unit 202, an address management unit 203, and an address management table 204.

The data receiving unit 201 is a host
Alternatively, when data D is received from the parent relay server 200, the address management table 204 is searched using the channel identifier in the data D as a key. As a result of this search, if there is a receiving host 500 or a child relay server 200 subscribed to the channel, the data relay unit 202
Is the receiving host 500 or the child relay server 200
Relay the data to

The address management unit 203 is a sub relay server 2
00 or when a channel join request message is received from the receiving host 500, the address management table 204 is searched using the channel identifier in the message M as a key,
The list of the child relay server or the receiving host that is receiving the channel indicates the child relay server 20 of the message transmission source.
0 or the IP address of the receiving host 500 is added.

When receiving the channel leaving request message from the child relay server 200 or the receiving host 500, the address management unit 203 searches the address management table 204 using the channel identifier in the message M as a key. The IP address of the child relay server 200 or the receiving host 500 of the message transmission source is deleted from the list of the child relay servers or the receiving hosts that are receiving the channel.

As shown in FIG. 8, the address management table 204 includes a channel identifier 204a and one or more child relay servers 2 receiving data addressed to the channel.
00 or IP address list 20 of the receiving host 500
4b.

The relay server 200 operates based on the flowcharts shown in FIGS. 9 to 11, as described below. First, the operation when relay server 200 receives data D will be described with reference to FIG.

First, for the channel identified by the channel identifier of the received data D, if there is a child relay server 200 or a receiving host 500 that is receiving data with this channel as a destination, the processing is performed in step S20.
Move to 2. Otherwise, the process proceeds to step S2
03 (step S201).

In step S202, the received data D
Is relayed to the child relay server 200 or the receiving host 500, and the process ends (step S202).
At 203, the relay server 200 discards the received data D and ends the processing (step S203).

Next, the operation when the relay server 200 receives the channel join request message will be described with reference to FIG.

First, using the channel identifier in the received channel join request message as a key, the address management table 2
04 and the receiving host 50 receiving the channel.
0 and the source IP address of the channel join request message are added to the list of the child relay server 200 (step S301).

Next, a data relay connection is set with the source of the received channel join request message (step S302).

Next, if the relay server 200 is not the root of the tree structure defined for the channel indicated by the channel identifier in the received message, that is, if it is not the root relay server, the process proceeds to step S304.
Move to If the server is a route relay server, the process ends (step S303).

In step S304, regarding the channel identifier in the received message, if the channel join request message has been relayed to the parent relay server 200,
The process ends. If the channel join request message has not been relayed, the process proceeds to step S305 (step S304).

In step S305, the parent relay server 20
0 is set for the control connection (step S
305).

Finally, the channel relay request message is relayed to the parent relay server 200, and the process ends (step S206).

Next, the operation when the relay server 200 receives the channel leaving request message will be described with reference to FIG.

First, using the channel identifier in the received channel leave request message as a key, the address management table 2
04 and the receiving host 50 receiving the channel.
0 and the source IP address of the message from the list of the child relay servers 200 (step S40).
1).

Next, the connection for data relay set with the transmission source of the channel leaving request message is released (step S402).

As a result of the deletion in step S401, the number of receiving hosts 500 or child relay servers 200 receiving the channel becomes 0 for the channel identified by the channel identifier in the received channel leave request message.
If it becomes, the process moves to step S404. Otherwise, the process ends (step S
403) In step S404, if the relay server 200 is not the root of the tree structure defined for the channel indicated by the channel identifier in the received data, that is, if it is not the root relay server, the process proceeds to step S405. Transition. If it is the route relay server, the process ends (step S404).

In step S405, the parent relay server 20
It relays the channel leaving request message to 0 (step S405).

Finally, the control connection established with the parent relay server 200 is released (step S).
406).

Next, the receiving host constituting the multicast communication system will be described with reference to FIG. FIG. 12 is a flowchart illustrating the operation of the receiving host.

The receiving host 500 first sets a control connection with the relay server 200 (step S501).

Next, a channel join request message in which the channel identifier of the channel requested to start receiving is set in the channel identifier part is transmitted to relay server 200 (step S502).

As described above, the receiving host 500 can receive the data distributed from the transmitting host 100. If the data is relayed from the relay server 200, the receiving host 500 starts receiving the data (step S503).

Next, when requesting the termination of the reception of the channel, a channel leaving request message in which the channel identifier of the channel requesting the reception termination is set in the channel identifier part is transmitted to the relay server 200 (step S50).
4).

Finally, the control connection established with the relay server 200 is released (step S5).
05).

[0058]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to FIGS. FIG. 13 is a configuration diagram of a relay server according to one embodiment of the present invention, and FIG. 14 is a sequence chart in the multicast communication system of the present embodiment. Note that the same components as those in FIG. 2 will be described using the same reference numerals.

As shown in FIG. 13, the relay server 200 includes a data receiving unit 201, a data relay unit 202, an address management unit 203, an address management table 204, a message receiving unit 205, and a message relay unit 206.

The data receiving unit 201 is a host
Alternatively, when data is received from the parent relay server 200, the data is transferred to the address management unit 203.

The address management unit 203 searches the address management table 204 by using the channel identifier in the data as a key, and if there is the child relay server 200 or the receiving host 500 receiving the channel, the data is relayed to the data. Transfer to the unit 202.

The data relay unit 202 is provided with the address management unit 2
03 is relayed to the child relay server 200 or the receiving host 500 subscribed to the channel.

The message receiving section 205 receives the message from the receiving host 5
00 or the message is received from the child relay server 200, the message is transferred to the address management unit 203.

The address management unit 203 receives the
0 or when the message received from the child relay server 200 is a channel join request message, the address management table 204 is set using the channel identifier in the message as a key.
And adds the IP address of the transmission source of the message to the list of the receiving host 500 and the child relay server 200 that are receiving the channel, and transfers the message to the message relay unit 206.

The message relay unit 206 sets up a control connection with the parent relay server 200 and relays the channel join request message received from the address management unit 203 to the parent relay server 200.

However, if it is the root of the tree structure defined for the channel indicated by the channel identifier in the message, that is, if it is the root relay server, or if it is already the parent relay server 200 If the channel join request message has been relayed, the message is not relayed to the parent relay server 200.

The address management unit 203 is a
0 or the message received from the child relay server 200 is
In the case of the channel leave request message, the address management table 20 is set using the channel identifier in the message as a key.
4 is deleted, and the IP address of the child relay server 200 or the receiving host 500 of the message transmission source is deleted from the list of the child relay servers or the receiving hosts that are receiving the channel.

As a result of this deletion, the number of child relay servers 200 or receiving hosts 500 registered in the channel becomes 0
Is satisfied, and if it is not the root of the tree structure defined for the channel (if it is not the root relay server), the address management unit 203
The message is transferred to the message relay unit 206.

The message relay unit 206 that has received the channel leave request message from the address management unit 203 relays the message to the parent relay server 200.

Next, a series of operations of one embodiment in the multicast communication system of the present invention will be described with reference to FIG. Here, an example in which news is distributed using channel (2) will be described.

In the sequence chart shown in FIG. 14, data transmitted from one transmission host 100 is transmitted to three reception hosts 500a and 500a via three relay servers 200.
00b, 500c.

First, in step S601, the receiving host 500a sets a control connection with the relay server 200, sets a message to indicate that the request is a channel joining request, and requests the channel identifying unit to join. A channel join request message in which channel (2) is set is transmitted via the connection. Similarly, receiving hosts 500b and 500c also transmit a channel join request message to relay server 200.

At step S602, the relay server 200
When receiving the channel joining request message from the receiving host 500 or the child relay server 200, the message receiving unit 205 transfers the message to the address management unit 203. The address management unit 203 that has received the transfer of the channel join request message notifies the data relay unit 202 and the message relay unit 206 of the transfer. The address management unit 20 that has received the channel join request message
3 searches the address management table 204 by using the channel identifier in the message as a key, and adds a list of the receiving host 500 and the child relay server 200 receiving the channel to the receiving host 500 or the relay server 200 of the message source. Is registered.

In this example, 2a, 2b, and 2c are set in the channel identifier (2) shown in FIG. 8 as individual addresses of each receiving host 500 or the child relay server 200.

The data relay unit 202, which has received the notification from the address management unit 203, sets up a data relay connection with the child relay server 200 or the receiving host 500 as the message transmission source.

In step S603, the address management unit 2
03, the message relay unit 206 is defined not for the root of the tree structure defined for the channel (2) indicated by the channel identifier in the message but for the channel (2). If the channel joining request message has not been relayed to the parent relay server 200, the parent relay server 200
A control connection is set between the relay server and the parent relay server 200.

In step S604, the sending host 100
Sets a connection for data transmission with the route relay server 200 that is the root of the tree structure defined for the channel (2), sets the channel (2) in the channel identifier part, and sets the user data part. To send the data that set the news article.

In step S605, the relay server 200
When receiving the data from the transmission host 100 or the parent relay server 200, the data receiving unit 201 transfers the data to the address management unit 203. Address management unit 203
Searches the address management table 204 and determines whether there is a receiving host 500 or a relay server 200 that is receiving the channel (2) identified by the channel identifier in the data. To the data relay unit 2
02.

In step S606, the address management unit 2
The data relay unit 202 that has received the data from the data relay unit 03 relays the data to the child relay server 200 or the reception host 500 that is receiving the channel (2) using the data relay connection set in step S602.

In step S607, the receiving host 500
a, using the control connection set in step S601, sets the message type part to be a channel leave request, and relays the channel leave request message in which the channel (2) requesting the leave is set in the channel identifier part. It is transmitted to the server 200. Similarly, the receiving hosts 500b and 500c also transmit a channel leaving request message to the relay server 200. Also, the receiving host 500
a, 500b, and 500c release the control connection set in step S601 after transmitting the channel leave request message.

In step S608, the relay server 200
When the message receiving unit 201 receives a channel leave request message from the relay server 200 or the receiving host 500, the message receiving unit 201 transfers the message to the address management unit 203. The address management unit 203 searches the address management table 204 using the channel identifier in the message as a key, and from the list of the receiving host 500 and the child relay server 200 receiving the channel, the child relay server 200 or The IP address of the receiving host 500 is deleted.

In step S609, as a result of this deletion,
When the number of child relay servers 200 or receiving hosts 500 registered in the channel becomes 0, the fact is notified to the data relay unit 202 and the message relay unit 206.

The data relay unit 206, which has received a notification from the address management unit 203 that the number of child relay servers 200 or the number of receiving hosts 500 registered in the address management table 204 has become 0, returns the data set in step S602. Release the relay connection.

Further, the message relay unit 206, which has been notified from the address management unit 203 that the number of child relay servers 200 or the number of receiving hosts 500 registered in the address management table 204 has become 0, becomes the message relay unit 206 itself. If it is not the root of the tree structure defined for the channel (2) indicated by the channel identifier in the middle, the received channel leaving request message is relayed to the parent relay server 200 using the control connection set in step 603. After the transmission of the message, the control connection is released.

According to such a multicast communication system, the transmission host 100, the relay server 200, and the relay server 200
A connection for data transmission and data relay is set between the host and the receiving host 500. At the time of data update, the data is immediately transmitted from the transmitting host 100 to the relay server 200, and the data is sequentially copied and received at each relay server 200. To relay to the host 500, the sending host 10
0, if only one data is transmitted to the relay server 200, it becomes possible to transmit the data to all the receiving hosts 500 receiving the channel in real time. That is, the data distribution is excellent in real-time property.

Further, the load on the sending host 100 when the number of receiving hosts 500 increases is small, and even when the number of receiving hosts 500 increases as compared with the pull type data distribution, the traffic on the network increases. Since it is small, it has scalability that information distribution can be easily continued even when the scale of the network becomes large.

The setting and release of the data transmission connection, the data relay connection, and the control connection are not limited to those in the present embodiment, but may be, for example, in the following formats and combinations thereof.

The connection is set and released each time data is generated.

A request for joining / leaving a plurality of channels is transmitted using the initially set control connection.

[0090]

As described in detail above, according to the present invention,
In order to distribute data destined for a channel from a transmission host to a reception host, the transmission host transmits the data destined for the channel to the one relay server or a relay server that becomes a root of a tree structure defined for the channel. Should be sent to Thereby, the data is distributed to the receiving host registered in the address management table of each relay server via the relay server. In other words, if the sending host sends only one piece of data to the relay server, it becomes possible to send the data in real time to all the receiving hosts that are receiving the channel. That is, the data distribution is excellent in real-time property.

Further, the increase in the load on the transmitting host when the number of receiving hosts increases is small, and the increase in the network traffic is small even when the number of receiving hosts increases as compared with the pull-type data distribution. Even if the scale of the network becomes large, it has scalability that information distribution can be easily continued.

[Brief description of the drawings]

FIG. 1 is a sequence chart illustrating the operation principle of the present invention.

FIG. 2 is a configuration diagram illustrating the operation principle of the present invention.

FIG. 3 is a configuration diagram illustrating a multicast communication system of the present invention.

FIG. 4 is a view for explaining the structure of data transmitted by a transmission host according to the present invention;

FIG. 5 is a flowchart illustrating control of a transmission host according to the present invention.

FIG. 6 is a view for explaining the structure of a message relayed by the relay server of the present invention.

FIG. 7 is a configuration diagram of a relay server according to the present invention.

FIG. 8 is a view for explaining the configuration of an address management table according to the present invention;

FIG. 9 is a flowchart illustrating the operation of the relay server of the present invention.

FIG. 10 is a flowchart illustrating the operation of the relay server of the present invention.

FIG. 11 is a flowchart illustrating the operation of the relay server of the present invention.

FIG. 12 is a flowchart for explaining the operation of the receiving host according to the present invention;

FIG. 13 is a configuration diagram of a relay server according to an embodiment of the present invention;

FIG. 14 is a sequence chart of a multicast communication system according to one embodiment of the present invention;

[Explanation of symbols]

100: transmission host, 101: data transmission unit, 110:
Data transmission means, 200: relay server, 201: data reception unit, 210: data reception means, 202: data relay unit, 220: data relay means, 203: address management unit, 230: address management means, 204: address management table , 205: message receiving unit, 250: message receiving unit, 206: message receiving unit, 260: message relay unit, 500: receiving host, 501: message transmitting unit, 510: message transmitting unit, 502: data receiving unit, 520 ... Data receiving means

Claims (12)

[Claims] 1. A multicast communication method for distributing data from a transmission host to one or a plurality of reception hosts using the Internet, wherein the data is transmitted via one relay server or a data relay path. Is distributed via a plurality of relay servers having a tree structure defined for a channel, and the transmission host transmits data addressed to a channel to the one relay server or a tree structure defined for the channel. A multicast communication method, wherein the transmission is performed to a relay server that is a root of the multicast communication. 2. The relay server, when receiving a channel join request message from a receiving host or a relay server lower in the tree structure, relays the channel join request message to a relay server higher in the tree structure. 2. The multicast communication method according to claim 1, wherein 3. The relay server includes an address management table, and, when receiving a channel join request message from a receiving host or a relay server at a lower level of a tree structure, a receiving host that is a transmission source of the channel join request message. 3. The multicast communication method according to claim 1, wherein an address of the relay server is registered in an address management table. 4. When the relay server receives data addressed to a channel from a transmission host or a relay server higher in the tree structure, the relay server lower in the tree structure registered in the address management table. 4. The multicast communication method according to claim 1, wherein data is relayed to a receiving host. 5. The relay server, when receiving a channel leaving request message from a receiving host or a relay server below the tree structure, manages an address of the receiving host or the relay server that transmitted the channel leaving request message. When the number of receiving hosts and relay servers registered in the address management table becomes zero due to the deletion, the channel leaving request message is relayed to the relay server higher in the tree structure. The multicast communication method according to any one of claims 1 to 4, wherein: 6. The multicast communication method according to claim 1, wherein the receiving host transmits the channel joining request message or the channel leaving request message to the relay server. 7. The reception host according to claim 1, wherein the reception host receives data transmitted by the relay server.
The multicast communication method according to claim 1. 8. Using the Internet, one relay server or one relay host from a transmission host via a plurality of relay servers having a tree structure in which a data relay path is defined for a channel. Or, in a multicast communication method for distributing data to a plurality of receiving hosts, the receiving host transmits a channel subscription request message to the relay server when subscribing to a channel, and receives the channel subscription request message. The relay server relays the channel join request message to a relay server higher in the tree structure and registers the address of the receiving host or relay server that is the source of the channel join request message in an address management table, The transmission host transmits data destined for a channel to the one relay server or channel. The relay server that has transmitted data to the relay server that is the root of the tree structure defined for and received the data destined for the channel is a relay server that is lower in the tree structure registered in the address management table. Or relaying data to a receiving host, wherein the receiving host receives the data relayed by the relay server, and the receiving host sends a channel leave request message to the relay server when leaving the channel. The relay server that has transmitted and received the channel departure request message deletes the address of the receiving host or the relay server that is the source of the channel departure request message from the address management table, and receives the registered host registered in the address management table. If the number of relay servers becomes zero, the relay server A multicast communication method characterized by relaying a tunnel leaving request message. 9. Using the Internet, one relay server or one relay host from a transmission host via a plurality of relay servers having a tree structure in which a data relay path is defined for a channel. Or a multicast communication system that distributes data to a plurality of receiving hosts, wherein the transmitting host transmits data destined for a channel to the one relay server or a relay server that becomes a root of a tree structure defined for the channel When the relay server receives a channel join request message from a receiving host or a relay server below the tree structure, the relay server is a transmission source of the channel join request message. Register the address of the receiving host or relay server in the address management table, and set the receiving host or relay server When receiving the channel leave request message from the server, the address management means for deleting the address of the receiving host or the relay server that transmitted the channel leave request message from the address management table, and the receiving host or the relay lower in the tree structure. When a channel join request message is received from the server, and
If the channel join request message has not been relayed to the relay server higher in the tree structure, the channel join request message is relayed to the relay server higher in the tree structure. This is a case where a channel leaving request message is received from a relay server at a lower level in the structure, and the number of receiving hosts or relay servers registered in the address management table has become zero due to deletion of an address by the address management means. In this case, a message relay unit that relays the channel departure request message to a relay server at a higher level in the tree structure, and data addressed to a channel from the transmission host or the relay server at a higher level in the tree structure is received. In this case, the data is sent to the relay server or the receiving host registered in the address management table. Data receiving means for relaying data transmitted from the relay server, and the receiving host transmits a channel joining request message or a channel leaving request message to the relay server. A multicast communication system, comprising: 10. A method in which one transmission host uses an Internet or one relay server or a plurality of relay servers in which a data relay path has a tree structure defined with respect to a channel. Or in a recording medium recording a multicast communication program for distributing data to a plurality of receiving hosts, wherein the receiving host transmits a channel join request message to the relay server when joining a channel, A recording medium on which a multicast communication program is recorded, wherein when a data is transmitted from a server, the data is received, and when leaving the channel, a channel leaving request message is transmitted to the relay server. . 11. Using the Internet, a single relay server or one relay server from a transmission host via a plurality of relay servers in which a data relay path has a tree structure defined for a channel. Or, in a recording medium recording a multicast communication program for distributing data to a plurality of receiving hosts, the relay server, when receiving a channel join request message from the receiving host or a relay server below the tree structure, While relaying the channel join request message to the relay server at the top of the tree structure, registering the address of the receiving host or relay server that is the source of the channel join request message in the address management table, If data addressed to a channel is received from a relay server at the top of the structure, When relaying data to a lower relay server or receiving host registered in the dress management table, and receiving a channel leaving request message from the receiving host or a lower relay server in the tree structure, the channel leaving request is received. If the address of the receiving host or relay server that transmitted the message is deleted from the address management table, and the number of receiving hosts and relay servers registered in the address management table becomes zero due to the deletion, the address becomes higher in the tree structure. A recording medium on which a multicast communication program is recorded, which relays the channel leaving request message to a relay server. 12. Using the Internet, one relay server or one relay server from a transmission host via a plurality of relay servers having a tree structure in which a data relay path is defined for a channel. Or, in a recording medium recording a multicast communication program for distributing data to a plurality of receiving hosts, the transmitting host has a tree structure defined for the one relay server or the channel for data destined for a channel. A recording medium on which a multicast communication program is recorded, which is transmitted to a root relay server.