JP3326672B2 - Message retransmission method and system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a message retransmission method and system, and more particularly, to a message retransmission method for transmitting a message from a server to a client, and retransmitting the message from the server when the client cannot completely receive the message. And systems.

More specifically, the present invention relates to a message retransmission method and system for effectively continuing or terminating retransmission according to the reception status of a client in a communication system in which a large number of clients on the receiving side are connected to a communication network.

[0003]

2. Description of the Related Art Generally, in resending a message in an information communication system, if a client on the transmitting side does not completely receive the message after the server on the transmitting side has transmitted the message, an unreceived portion of the message is received. Is transmitted to the server with the information included in the response, and the server composes a retransmission message based on the response, and retransmits the message to a client that has not successfully received the message.

Further, in the prior art, there is a method in which a retransmission limit is set in a server before communication is started, and retransmission is stopped when the retransmission limit is reached. If the number of times of limitation is not set or is set to infinity, there is a method of continuing retransmission until a message is completely received.

FIG. 12 is a sequence chart showing an example of conventional message retransmission. In the following message retransmission, it is assumed that the number of retransmissions is set in advance. Step 10) The server sends messages to clients A, B, and C, respectively.

Step 11) The client A notifies the server that the message has been normally received. Step 12) The client B notifies the server that the message reception has not been normally completed.

Step 13) The client C notifies the server that the message has been normally received. Step 14) The server determines whether or not retransmission has been performed to the client B a predetermined number of times. If the number of times has not been reached, the server transmits a message to the client B again. If the number has exceeded the predetermined number, the retransmission of the message is stopped.

[0008]

However, in the above-mentioned conventional technique, the number of retransmissions is fixedly set, so that it is possible to successfully transmit a message to a terminal that requires retransmission more than the number of times. There is a problem that can not be.

Further, even when the client becomes unreceivable, useless retransmission is repeated. In particular, in a system in which retransmission is repeated indefinitely without determining a predetermined number of retransmissions, there is a problem that transmission costs and traffic increase.

[0010] Particularly, when a server transmits and retransmits a message to a large number of clients at the same time, clients (terminals) in various reception situations coexist, and the above-mentioned problem appears remarkably, Cannot be retransmitted, or the amount of useless retransmission communication increases.

[0011] The present invention has been made in view of the above points, and the quality of each line and the reception status of the client are various as in the case of simultaneous transmission / retransmission to a large number of clients. Even if it is difficult to anticipate before communication, retransmission can be performed as long as there is a retransmission effect, and as a result, the message completion rate of the client can be improved without increasing unnecessary communication volume A retransmission method and a message retransmission server are provided.

[0012]

FIG. 1 is a diagram for explaining the principle of the present invention. The present invention, in the transmission and reception of messages constituting a message between a plurality of clients and servers connected via a communication network,
In the message retransmission method of retransmitting a message again when the client cannot receive all of the messages, when the reception of the message transmitted from the server from each client is not completed, the server notifies the server that reception has not been completed. (Step 1), the server sends a message from the server for each client for each message reception and retransmission.
Complete the client's reception based on the identification information of the transmitted packet.
Using the retransmission management table that manages the number of
Indicates the completion of reception in the retransmission management table for each message retransmission
If the information has increased by more than a predetermined number and
Check if the number of clients with
Judgment (steps 2 and 3) and information indicating the completion of reception
Information has increased by more than the specified number, and
If there are more than a certain number of clients,
If any of them,
On the other hand, retransmission is continued (step 4).

[0013]

FIG. 2 is a diagram showing the principle of the present invention. The present invention relates to a plurality of clients connected via a communication network 200, a message retransmission for passing a message through the network with the client , and retransmitting the message again when the client cannot receive all of the messages. a system, server 100
Is a communication unit 120 for transmitting a message or receiving a response from the client 301,
1 and the client identification information for each message sent to
Packet identification information of the packet transmitted from the server
A retransmission management table 140 that updates and manages the number of response records indicating completion of reception at any time, and a retransmission management table 140
Refers to the reception status of the
The retransmission condition determining means 160 and the retransmission condition determining means 160
In the case where the number of response records has increased
Has retransmission control means 110 for continuing retransmission to the client , and the client 301
It has a reception status notifying unit 311 for notifying the server of the reception status of the message sent from 00.

The retransmission condition determination means 160
Referring to the response record in the retransmission management table 140,
The number of response records has increased by more than
If there are clients that have unreceived packets
If the number is equal to or greater than the predetermined number, or
Means to determine that continuation of retransmission is to be performed when the

[0016]

[0017]

Thus, according to the present invention, based on the response after the message is transmitted, the retransmission table of the server is referred to and the reception status of the client (how much part of one message is normally received each time a message is received / re-received) is received. Has been grasped). By comparing the retransmission condition with the retransmission condition, the next retransmission is executed for the client in which the effect of the retransmission continues based on the situation, and the retransmission is ended when the effect of the retransmission stops. As a result, the retransmission is not terminated when the effect of the retransmission is continued, and the retransmission is not repeated unnecessarily despite the ineffectiveness of the retransmission. Message retransmission can be performed according to the number of retransmissions.

[0019]

FIG. 3 shows the configuration of the entire system to which the present invention is applied. The present invention, as shown in FIG.
, 30n (n is an arbitrary natural number). The server 100 communicates with a plurality of clients 301, 302,
.., 30n. In this example, simultaneous information distribution is shown, and the server 100
, 30n, and the clients 301, 302,..., 30n return the server 100 with the reception status (information of the unreceived portion of the message) included in the response to the server 100. Constructing a retransmission message based on the information,
, 30n are retransmitted all at once.

For example, if a 2 Mbyte message is 1K
When distributing information simultaneously to 5000 clients using packets capable of storing byte information, the number of packets to be transmitted to all clients is 2000 × 5000, so it is necessary to set an effective number of retransmissions without waste. .

FIG. 4 shows the configuration of the server of the present invention. In the figure, a server 100 includes a communication network 200
Communication control unit 1 for sending and receiving messages by connecting to
20, a retransmission table management unit 140 that grasps and manages the reception status of the client from the response, and a retransmission table management unit 140
Message generating unit 150 for generating a message to be transmitted / retransmitted based on the information
Retransmission control unit 11 for instructing retransmission and controlling the entire retransmission
0, a retransmission condition management unit 160 for managing retransmission conditions necessary for realizing the present invention, and an application management unit 130 for generating a message and requesting the retransmission control unit 110 to transmit the message.

The retransmission condition management section 160 will be described. FIG. 5 shows the configuration of the retransmission condition management unit of the server of the present invention. The retransmission condition management unit 160 registers the reception status register 153 that records the increase in the number of received packets in the transmission management table in the retransmission table management unit 140, and registers the increase number or ratio of the number of received packets as a retransmission determination condition. A retransmission condition register 162 and a retransmission determination unit 161 that compares the reception status register 153 with the retransmission condition register 162 to determine whether to continue retransmission or end retransmission.

FIG. 6 shows the structure of a message and a packet transmitted in the server of the present invention. The figure shows the server 1
10 shows a configuration of a message 404 requested to be transmitted by the application management unit 130 and a transmission packet 400 when the message is divided and transmitted. The transmission packet 400 includes a client destination 401 of a transmission destination, a packet ID 402 which is a packet sequence number, and transmission information 403 for dividing and storing a message. For the client destination 401, for example, in the Internet protocol, an IP address can be used, and particularly when transmitting to a group of clients, an IP class D address can be used.

FIG. 7 shows the structure of a response packet returned from the client to the server according to the present invention. The response packet shown in the figure includes a server destination 501 of a return destination, a client ID 502 of a client that has returned the response packet, and an ID string of a plurality of packets that have not been received due to packet loss or transmission information error in each client. 50
3 is included. For example, in the Internet protocol, the server destination 501 can use the IP address of the server 100, and the client ID can use the IP address of the client.

FIG. 8 shows the configuration of the transmission management table stored in the retransmission table management section of the present invention. In the figure, in the matrix (n × m) of the number of packets (m) required for divided transmission of “the number of clients (n) × message”, each client has received (○) and not received (×) each packet. Is shown. In implementation, (○)
Is a bit-on “1”, and (×) is a bit-off “0”.
Should be assigned.

In the transmission management table, all non-received (x) are set at the time of the first message transmission, and are checked for each response packet (if not included in the packet ID column, received is set (o)). The latest client reception status is managed. After receiving all the responses after each transmission / retransmission, the message composing unit 150 composes a message to be retransmitted next time based on the reception / non-reception status. For example, the message composing unit 150 performs an OR (logical sum) of the packet IDs to which “x” is added (if there is even one x in the column, it is included in the retransmission message).
A retransmission message to be retransmitted all at once can be configured.

Next, a description will be given of a processing procedure when retransmission processing is performed using the above configuration. FIG. 9 is a flowchart showing the procedure of the retransmission processing of the present invention. Step 101) The message 404 is passed from the application management unit 130 to the retransmission control unit 110. The retransmission control unit 110 divides the message into transmission packets 400 in units of transmission information 403, stores the transmission information 400 in the message composition unit 150, and stores the retransmission table management unit 14
At 0, a transmission management table as shown in FIG. 8 is set. In the initial state before this message transmission, all the packets have not been received yet, so "x" is set in the retransmission management table.

Step 102) The retransmission control section 110 instructs the communication control section 120 to transmit the message stored in the message composing section 150, and the first message is divided and stored in a required number of transmission packets and transmitted. Step 103) The packet ID of the packet that has not been received due to a packet loss or information error from the client is the packet ID column 503 of the response packet 500.
Is returned to the server 100. When the client can receive all the packets and reconstruct the message, it returns a response packet 500 that does not include the packet ID sequence to the server 100. In the server 100, the client ID 502 and the packet ID column 50 of the response packet 500
3 to update the transmission management table. Server 10
0 means step 1 until all clients return a response
Repeat 03.

Step 104) After all the response packets are returned in one transmission and retransmission, in the reception information register 163 of the retransmission condition management unit 160, the increased number of received (）) in the transmission management table is retransmitted. It is reported from the table management unit 140. Step 105) The retransmission determination unit 161 compares the number recorded in the reception status register 163 with the condition recorded in the retransmission condition register 162, and executes the next retransmission, or retransmits the message without performing retransmission. Is determined.

In the retransmission condition register 162, before the message transmission request (step 101), a retransmission termination determination condition (criterion for retransmission termination due to no retransmission effect or reduced effect) is set. deep. The following are examples of termination conditions for retransmission termination.

(1) When the received increase number becomes 0 successively twice, (2) When the received increase number becomes 3 or less and becomes a fixed number or less (for example, 5); (3) Not yet A certain number of successful clients (eg 3)
(4) In the case of the above (3) and (1); etc. Step 106) When it is determined in step 105 that retransmission has been completed, the retransmission condition management unit 160 instructs the retransmission control unit 110 to end retransmission. The retransmission control unit 110 reports the transmission result (success or failure of the message of each client) to the application management unit 130 by looking at the transmission management table of the retransmission table management unit 140.

Step 107) If it is determined in step 105 that the transmission is to be continued, retransmission condition management section 160 notifies retransmission control section 110 of that fact, and retransmission control section 110 instructs message composition section 150 to generate a retransmission message. The message composition unit 150 issues an instruction.
A retransmission message is generated with reference to the transmission management table of “0”.

When the retransmission message is formed, the retransmission control unit 110 transmits the generated message to the communication control unit 12.
0 and transmission of the retransmission message to the client is started. The above steps 102, 103, 10
The retransmission is continued as long as there is an effect that the number of successfully received packets is increasing in the client by repeating steps 4, 105, and 107. The effect of resending is gone,
Alternatively, when it becomes smaller, the retransmission is terminated under the conditions shown in step 107, for example, (1) to (4), and the amount of unnecessary retransmission communication can be saved.

Step 1 in the above flow chart
Steps 04 and 105 are core procedures for realizing the present invention, and are procedures for dynamically determining the continuation / end of retransmission during communication based on the reception status of the client.

[0035]

An embodiment of the present invention will be described below. In the retransmission processing described below, the retransmission end condition set in the retransmission condition register 162 is when the received increase number becomes 2 or less, or when the number of unsuccessfully received clients becomes 1 or less. In the following example, there are three clients A, B, and C. FIG. 10 is a sequence chart of a retransmission process according to one embodiment of the present invention, and FIG. 11 shows a state transition of the transmission management table according to one embodiment of the present invention.

First, the application management unit 13
0 passes the message 400 to the retransmission control unit 110, and the retransmission control unit 110 divides the message 400 into units of transmission information 403 of a transmission packet. In the present embodiment, the packet is divided into four, and a packet ID 402 is assigned to each of the divided messages. The packet ID 402 of the divided first message is “ID-A”, the packet ID 402 of the second message is “ID-B”, the packet ID 402 of the third message is “ID-C”, and the fourth message The packet ID 402 is “ID-D”. As shown in FIG. 11A, “×” is set in the transmission management table before message transmission. Here, retransmission control section 110 instructs communication control section 120 to transmit the first message (message ID = ID-A).

As a result, the communication control unit 120 transmits the first divided message (message ID = ID-
A) is transmitted to the clients A, B, and C. Next, the communication control unit 120 similarly transmits the next divided message (message ID = ID-B) to the clients A, B, and C. This process is repeated until transmission of the message ID = ID-D.

By this processing, the message divided into four is divided into four packets, and each of the clients A, B,
C has been transmitted. Next, the reception status of the transmitted message is notified from each client. Since client A has received all messages, the response packet
A response packet not including the packet ID is returned. The client B determines that only ID-B has not been received and displays “ID-B” in the packet ID column 503 of the response packet 500.
B ”is set and transmitted to the server 100. The client C determines that ID-B and ID-C have not been received and enters“ ID-B ”in the packet ID column 503 of the response packet 500.
B "and" ID-C "are set and transmitted to the server 100.

Each retransmission table management unit 140 of the server 100 updates the transmission management table based on the reception status of each of the clients A, B, and C. FIG. 11B shows the status updated at this time. Thereby, retransmission table management section 140 notifies retransmission condition management section 160 of the number of “○” in the transmission management table. At this time, the number of "○"
9 In this example, since the number of unsuccessful clients has not become 1 or less, the retransmission determination unit 161 determines to continue retransmission.

The retransmission condition management unit 160 notifies the retransmission control unit 110 that retransmission is to be continued.
Notifies the message composition unit 150 of the generation of the retransmission message. The message composing section 150 may generate a message divided into four in the same manner as described above, or may acquire information on which packet ID should be assembled from the retransmission table managing section 140, and determine that the message has not been received. It is also possible to assemble only those packets.

The communication control unit 120 is configured to
And sends the assembled packet. The reception status of the message transmitted from the server 100 is notified from each client. Since all the messages have been received, the client A returns a response packet 500 that does not include the packet ID in the response packet. Since the client B has also received all the packets, the response packet 500 that does not include the packet ID is returned as the response packet 500. Client C has ID-
Assuming that only C has not been received, “ID-C” is set in the packet ID column 503 of the response packet 500 and transmitted to the server 100.

The retransmission table management unit 1 of the server 100
Upon receiving the response packet 500 from each client, the 40 updates the transmission management table based on the reception status of the clients A, B, and C. The situation updated at this time is shown in FIG. Thereby, retransmission table management section 140 notifies retransmission condition management section 160 of the number of “○” in the transmission management table. At this time, the number of “○” is 11
It is. Therefore, the increase number of the reception status register 163 is 2
Thus, the retransmission determination unit 161 determines that the retransmission processing is to be ended in order to correspond to the condition “end the transmission if the increase number is 2 or less” in the retransmission condition register 162. Also,
At the same time, since the unsuccessful client is only the client C, the number of unsuccessful clients has become 1 or less, so the retransmission determination unit 161 determines to end the retransmission.

In this embodiment, the retransmission condition register 1
The retransmission condition set to 62 is set when the increase number becomes 2 or less, or the number of unsuccessful clients is set to 1 or less, but various conditions can be set without being limited to this example. It is. Further, in the present embodiment, a message is broadcast to each client. However, the present invention is not limited to broadcast communication, and can be applied to retransmission in various message transmission modes.

Further, when the client cannot temporarily respond during communication, a response inquiry packet may be transmitted from the server to prompt a response. In addition, by notifying the server that the server cannot respond (busy) from the client, the server may postpone the client, and after the recovery of the client, the server may retransmit to the client separately. Can be

Therefore, the present invention is not limited to the above-described embodiments, but can be variously modified and applied within the scope of the claims.

[0046]

As described above, according to the message retransmission method and the message retransmission server of the present invention, the server dynamically determines whether or not to continue retransmission according to the reception status of the communicating client. As a result, the quality of each line and the reception status of the client are diverse, such as when transmitting and retransmitting to many clients at the same time, and the retransmission effect is effective even when the required number of retransmissions is difficult to predict before communication. During a certain period, retransmission can be performed. As a result, there is an effect that the completion rate of message reception by the client is improved without increasing useless communication amount.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of the present invention.

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

FIG. 3 is a configuration diagram of an entire system to which the present invention is applied.

FIG. 4 is a configuration diagram of a server of the present invention.

FIG. 5 is a configuration diagram of a retransmission condition management unit of the server of the present invention.

FIG. 6 is a configuration diagram of a message and a transmission packet according to the present invention.

FIG. 7 is a configuration diagram of a response packet according to the present invention.

FIG. 8 is a diagram showing a configuration of a transmission management table of the present invention.

FIG. 9 is a flowchart showing a procedure of a retransmission process according to the present invention.

FIG. 10 is a sequence chart of a retransmission process according to an embodiment of the present invention.

FIG. 11 is a diagram illustrating a state transition of a transmission management table according to an embodiment of the present invention.

FIG. 12 is a sequence chart showing an example of conventional message retransmission.

[Explanation of symbols]

 Reference Signs List 100 server 110 retransmission control unit, retransmission control unit 120 communication control unit, communication unit 130 application management unit 140 retransmission table management unit, retransmission management table 150 message composition unit 160 retransmission condition management unit, retransmission condition determination unit 161 retransmission determination unit 162 retransmission Condition register 163 Reception status register 200 Communication network 301, 302, 30n Client 311 Reception status notification means 400 Message 401 Client destination 402 Packet ID 403 Transmission information 500 Response packet 501 Server destination 502 Client ID 503 Packet ID column

Continuation of front page (56) References JP-A-5-219056 (JP, A) JP-A-7-87087 (JP, A) JP-A-7-212359 (JP, A) JP-A-62-299139 (JP) JP-A-6-177878 (JP, A) JP-A-6-141028 (JP, A) JP-A-4-7937 (JP, A) JP-A-56-2765 (JP, A) , “Highly Reliable Simultaneous Distribution System Adaptable to the Internet”, Information Processing Society of Japan Research Report, Information Processing Society of Japan, December 7, 1995, Vol. 95, No. 117, pp. 9-14, 95- AVM-11-2 (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/56 H04L 12/18 H04L 1/16 H04L 29/08 G06F 13/00

Claims (3)

(57) [Claims] 1. A communication system connected via a communication network.
Number of clientsAnd saServerWhenCompose a message between
When sending or receiving messages, the client
If all messages cannot be received,
In the message retransmission method for performing retransmission, each of the clients transmitted from the server
Receiving messagesButIf not completed, the server
The server notifies the client that reception has not been completed.
EveryFrom the identification information of the packet transmitted from the server
Resend pipe that manages the number of received completion response records
Retransmission management for each message retransmission using the
The information indicating reception completion in the table has increased by a predetermined number or more.
Client that has a packet that has not yet been received
Determine whether the number is more than a predetermined number, The information indicating the reception completion has increased by a predetermined number or more,
And the number of clients with unreceived packets
Or if any of them,
Continuing retransmission to the client;
Message retransmission method. 2. A communication system connected via a communication network.
Number of clients and their clientsWhenThe network
Pass the message through the
If all messages cannot be received, resend the message again
Message resending systemAnd  The server sends the message or receives a message from the client.
Communication means for receiving a response; and the client for each message transmitted to the client.
AntIdentification information and the packet transmitted from the server
Indicates the reception completion according to the packet identification information of the packet.
Response recordsA retransmission management table for updating and managing at any time; and the reception status of the retransmission management tableSee the message
The number of response records of the client is a predetermined number every time a message is retransmitted
Judge whether it is increasingRetransmission condition determination means,In the retransmission condition determination means, the number of response records is a predetermined number.
If the number has increased by more than
Continue sending Retransmission control means, wherein the client checks the reception status of a message sent from the server by the server.
Server has a receiving status notifying means for notifying the server.
Message resending system. 3. The retransmission condition determining means refers to a response record in the retransmission management table, and
The number of response records has increased by more than
And the number of clients with unreceived packets
Is more than a predetermined number, or one of them
3. A method according to claim 2, further comprising: means for determining that retransmission is to be continued.
A message retransmission system as described.