JP5011728B2 - System adopting hot standby method and synchronization method used therefor - Google Patents

Description

  The present invention relates to a system employing a hot standby system and a synchronization method used therefor, and more particularly to a system synchronization method employing a hot standby system comprising an active system and a standby system.

  The characteristics of message type communication are classified into order type communication and non-order type communication. The sequential communication is a method in which messages are exchanged between the user terminal and the system, but the next message is not transmitted unless a response message is received. On the other hand, unordered communication is a method in which the next message can be transmitted without confirming delivery of the transmitted message.

  In general, in the case of an information processing system that handles sequential messages, state management is performed on whether or not a message has been transmitted or received, and it is necessary to match the state between the user terminal and the system.

  If the system consists of both active and standby subsystems, the standby system can be used regardless of the active system failure, as long as the processing timing is completely the same between the active and standby systems. Therefore, there should be consistency between the user terminal and the information processing system.

  However, in practice, the timing at which messages arrive at both the active and standby systems is also different, and it is very difficult to match the processing timing between them.

  In addition, as shown in FIG. 11, when the control for adjusting the processing timing is not performed, the subsystem (standby system) 53 causes a difference in processing timing between the subsystem (active system) 52 and the subsystem (standby system) 53. Although processing is in progress, since the processing is completed in the subsystem (active system) 52, the response message 501 is returned first, and a synchronization shift occurs between the subsystem (active system) 52 and the subsystem (standby system) 53. there is a possibility.

  As shown in FIG. 12, when the user terminal 6 receives the response message 501 from the subsystem, it can transmit the next message 601. As shown in FIG. 13, when the subsystem (active system) 52 has completed the processing of the previous message, but the subsystem (standby system) 53 is still processing, the next sequential message 502, When 503 is distributed and sent by the duplicator 51, a state mismatch occurs between the user terminal 6 and the subsystem (standby system) 53, and the corresponding message 503 is discarded.

  Since the subsystem (standby system) 53 does not output a response to the outside, in the system 5 having a redundant configuration, if complete synchronization between the subsystems configuring the redundancy is not performed, the user terminal after the failure switching 6 and the system 5 may become inconsistent, and a disconnection may occur between the two.

In mission critical systems that are required to continue to operate for 24 hours, 365 days, in order to realize high availability, a redundant configuration employing the hot standby method as described above has been adopted. It is desired that the active system and the standby system constituting the redundancy are always in the same state, and it is desired that there is no problem even if they are switched at any timing. As this type of hot standby system, there is a technique disclosed in Patent Document 1 below.
JP-A-8-320800

  However, in the system employing the above-described conventional hot standby method, the processing capacity and processing timing of the active subsystem and the standby subsystem need to be completely the same, but the active subsystem It is very difficult to synchronize the processing timing between the active subsystem and the standby subsystem in a system where the standby subsystem is separated from the standby subsystem.

  Also, in a system that uses a conventional hot standby system, the timing of receiving messages in the active subsystem and standby subsystem is affected by the transmission path, so it is very important to control the reception timing of these messages. It is difficult to.

  Due to the above technical background, the active subsystem and the standby subsystem can be processed at asynchronous timing, and the synchronization with the user terminal is maintained regardless of the timing at which switching occurs. The technique to be done is desired.

  Therefore, an object of the present invention is to solve the above-described problems and maintain the state between the user terminal and the new active subsystem regardless of the timing at which a failure occurs in the active subsystem. Another object of the present invention is to provide a system adopting a hot standby method and a synchronization method used therefor.

The system adopting the hot standby system according to the present invention adopts a hot standby system composed of an active subsystem and a standby subsystem, and receives a sequential message for exchanging messages with a user terminal. , A system for transmitting a response message to the ordered message to the user terminal and receiving the next ordered message sent after receiving the response message at the user terminal,
The standby subsystem includes a means for creating a response message for the received ordered message simultaneously with the reception of the ordered message; a means for holding the response message without transmitting it to the user terminal; Message processing means for processing the received ordered message, and means for updating the held response message when the held response message is different from the processing result of the ordered message received from the message processing means; And a means for transmitting a response message held after the own subsystem is switched to the active system.

The synchronization method according to the present invention employs a hot standby system including an active subsystem and a standby subsystem, and receives an ordered message for exchanging messages with a user terminal. Is a synchronization method used in a system that transmits a response message to the user terminal and receives the next sequential message sent after receiving the response message at the user terminal,
A process in which the standby subsystem simultaneously creates the response message for the received ordered message simultaneously with the reception of the ordered message; a process for holding the response message without transmitting it to the user terminal; A message process for processing the received ordered message, a process for updating the stored response message when the held response message is different from the processing result of the ordered message received from the message process , And processing for transmitting a response message held after the subsystem is switched to the active system.

  In other words, a system employing the hot standby method of the present invention is a system having a hot standby type redundant configuration, in which an active subsystem is not required to perform timing processing between the active subsystem and the standby subsystem. It is characterized in that no state mismatch occurs between the user terminal and the system after switching from the system to the standby subsystem.

  More specifically, in the system employing the hot standby method of the present invention, when the user terminal and the system are connected and performing message type communication, the first subsystem and the second subsystem in the system are used. The system has a hot standby redundant configuration.

  The signal from the user terminal to the system should be the same in both subsystems because the message is duplicated by the duplicator and the first subsystem and the second subsystem receive the same signal. Strictly speaking, a slight state shift occurs at a certain moment between subsystems in which the first subsystem and the second subsystem are separated from each other, strictly speaking, due to processing timing and message transmission path delay.

  In order to absorb the deviation between the two subsystems, the second subsystem of the standby system eliminates the processing state of the sequential message, and always controls the state so that the next sequential message can be accepted. . In the second subsystem of the standby system, a response message is created at the same time as the message is received, and is held without being transmitted.

  The response held by the second subsystem when the user terminal is communicating with the first subsystem and a failure occurs in the first subsystem and the user subsystem is switched to the second subsystem that is in hot standby By starting from transmitting a message, the connection between the two is maintained so that a state mismatch does not occur between the user terminal and the second subsystem.

  As described above, in the system adopting the hot standby method of the present invention, in the hot standby type system, the processing timing is not synchronized between the subsystems having the hot standby type redundant configuration. Synchronization between the user terminal and both subsystems is performed only by subsystem state control. In addition, in the system adopting the hot standby method of the present invention, it is possible to provide a method that does not cause a state mismatch between the user terminal and the subsystem no matter what timing the failure occurs and the subsystem is switched. It becomes.

  As described above, in the system adopting the hot standby system of the present invention, the standby subsystem is absorbed in order to absorb the processing timing difference between the active subsystem and the standby subsystem mentioned above. In order to eliminate the state during the processing of the sequential message in, accept the next message.

  In the system adopting the hot standby system of the present invention, a response message is generated at the same time as the standby subsystem receives the message, and the response message is held without being transmitted. After switching between the active and standby systems, messages are exchanged in order without omission by starting processing from sending the response message held by the subsystem that became the active system from the standby system (A response message can always be sent because there is no state of being processed).

  As standby processing, processing may be performed in the order in which received order-type messages are received asynchronously with active processing timing, and complicated timing control is not required.

  As a result, in the system adopting the hot standby method of the present invention, it is possible to avoid a state mismatch with the user terminal by simply controlling the state of the standby system without performing processing timing synchronization between both subsystems. Even after the system switchover, the connection between user terminals is maintained, and it is possible to start from the next sequential message, and no message is lost.

  The present invention is configured and operated as described above to maintain the state between the user terminal and the new active subsystem regardless of when the switching occurs in the active subsystem. The effect of being able to be obtained.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a system employing a hot standby system according to an embodiment of the present invention. In FIG. 1, a system 1 that employs a hot standby system includes subsystems 12 and 13 and a duplicator 11 that duplicates a signal from the user terminal 2 and transfers it to both subsystems 12 and 13. .

  The user terminal 2 has a function of transmitting / receiving an unordered message and an ordered message. The unordered message has a function of transmitting to the system 1 at any timing. On the other hand, the sequential message has the following functions because the next message can be transmitted only when a response to the transmitted message is received.

  That is, the user terminal 2 increments and assigns a message number to an ordered message, transmits it, holds the message number of the transmitted ordered message, and whether the ordered message has been transmitted or received a response. A function that manages the status of messages, a function that discards a message number that is not waiting for a response, a function that discards a message number that is waiting for a response, and a function that discards it It has.

  The system 1 is a system in which the subsystems 12 and 13 and the duplicator 11 are integrated. The subsystem 12 is a subsystem in the system 1 and has a function of exchanging messages with the user terminal 2 and a function of processing received messages in order and returning the result to the user terminal 2. .

  Further, the subsystem 12 has a function of transmitting a response message to the user terminal 2 after processing the message without performing state management or the like for the unordered message. Furthermore, the subsystem 12 has the following functions regarding the handling of sequential messages.

  That is, the subsystem 12 has a function of holding the received message number of the ordered message, and a function of processing the ordered message of the received message number + 1 and discarding the ordered message to which other message numbers are assigned. And a function for managing the status of whether an ordered message is being processed or whether a response has been transmitted, and a function for assigning the received message number and transmitting the response message to the user terminal 2 after processing the message. Further, when the subsystem 12 becomes a standby system after system switching, the subsystem 12 realizes the contents listed below for the standby system function.

  The subsystem 13 has a hot standby type redundant configuration with the subsystem 12 and is completely synchronized with the subsystem 12. The subsystem 13 processes the same message as the subsystem 12 because the message from the user terminal 2 is distributed by the duplicator 11.

  Further, the subsystem 13 has the same function as the subsystem 12 described above for the unordered message. On the other hand, the subsystem 13 has the following functions for the sequential message.

  That is, the subsystem 13 processes the ordered message of the received message number + 1 and discards the ordered message to which other message numbers are assigned, and in the case of a correct message number, creates a response message. A function that holds the response message, a function that processes the message and updates the contents if the result is different from the held response message, and a function that determines that the system is a standby system and does not send a response message And a function of transmitting a retained response message when the system becomes active. Further, when the subsystem 13 becomes active after system switching, the subsystem 13 realizes the above-described contents for the active system.

  The duplicator 11 has a function of duplicating a signal from the user terminal 2 and transmitting the signal to the active subsystem 12 and the standby subsystem 13, and does not duplicate a response message from the subsystem 12. 2 to send.

  FIG. 2 is a diagram showing the contents of management information in the user terminal 2 of FIG. In FIG. 2, the management information A in the user terminal 2 is composed of a message number A1 and a status [sent / received] A2.

  FIG. 3 is a diagram showing a format of a message transmitted / received between the user terminal 2 and the system 1 of FIG. In FIG. 3, the message B includes a header B1, a message number B2, and a payload B3.

  FIG. 4 is a diagram showing the contents of management information in the active subsystem 12 of FIG. In FIG. 4, the management information C in the active subsystem 12 is composed of a message number C1 and a status [processing / responded] C2.

  FIG. 5 is a block diagram showing the configuration of the active subsystem 12 of FIG. In FIG. 5, the active subsystem 12 includes a message receiver 121, a message processor 122, and a response message transmitter 123.

  FIG. 6 is a diagram showing the contents of the management information in the standby subsystem 13 of FIG. In FIG. 6, the management information D in the standby subsystem 13 consists of a message number D1.

  FIG. 7 is a block diagram showing the configuration of the standby subsystem 13 of FIG. In FIG. 7, the standby subsystem 13 includes a message receiving unit 131, a message processing unit 132, and a response message holding unit 133.

  In FIG. 6, the subsystem 12 shows a configuration when operating as an active system, and in FIG. 7, the subsystem 13 shows a configuration when operating as a standby system. As the configuration of the systems 12 and 13, the configurations of FIGS. 6 and 7 are merged.

  That is, the subsystems 12 and 13 are configured by a message reception unit, a message processing unit, a response message transmission unit, a response message holding unit, and a control unit that controls transmission of a response message from the response message transmission unit. Become. In that case, the control unit controls transmission of the response message from the response message transmission unit when operating as an active system and controls transmission of the response message from the response message transmission unit when operating as a standby system.

  FIG. 8 is a diagram showing a state when a failure occurs during message processing in the active subsystem 12 of FIG. 1 and the system is switched. The operation of the system 1 employing the hot standby system according to one embodiment of the present invention, particularly the control operation in the standby subsystem 13 will be described with reference to FIGS.

  The user terminal 2 updates the information of the management information A shown in FIG. The message number A1 of the management information A indicates the message number assigned to the ordered message transmitted to the system 1. Further, the user terminal 2 manages transmission / reception of sequential messages in the state A2 of the management information A so that it can be determined whether the message has been transmitted or the response message has been received. When the user terminal 2 transmits an ordered message, the user terminal 2 acquires a number from the message number A1 and assigns it to the transmission message. Thereafter, the user terminal 2 shifts the state A2 to the transmitted state.

  On the other hand, when the user terminal 2 receives the response message from the system 1, the user terminal 2 compares the message number in the received response message with the message number A1 of the management information A, and if it matches, changes the state A2 to “received”. In this case, if the message number in the received response message and the message number A1 of the management information A do not match, the user terminal 2 discards the response message.

  As shown in FIG. 3, the transmission message from the user terminal 2 includes a header B <b> 1, a message number B <b> 2 managed by the user terminal 2 for waiting for a response, and a payload B <b> 3.

  When the active subsystem 12 of the system 1 receives the message from the user terminal 2, it determines whether or not the message number of the received message matches “message number C1” +1 shown in FIG. The state C2 of the management information C is changed to “processing”. The subsystem 12 completes the message processing, transmits a response message to the user terminal 2, and then changes the state C <b> 2 to “responded”.

  In this case, as shown in FIG. 5, when the active subsystem 12 receives a message at the message receiving unit 121, the message processing unit 122 processes the message, and then the response message transmitting unit 123 sends the message to the user terminal. 2 sends a response message.

  When the standby subsystem 13 of the system 1 receives the message distributed by the duplicator 11, it determines whether or not the message number of the received message matches the “message number D1” +1 of the management information D shown in FIG. .

  If the message numbers match, the subsystem 13 receives the message at the message receiving unit 131 and creates a response message as shown in FIG. 7, and holds the response message in the response message holding unit 133 without transmitting the response message. To do. If the processing result is different from the message created in advance after the actual message is processed, the subsystem 13 updates the content of the response message held in the response message holding unit 133.

  If a failure occurs during message processing in the subsystem 12, the user terminal 2 cannot transmit the next message until a response message is returned. When the above failure occurred, the subsystem 12 was processing a message, but the status of the subsystem 13 is (1) the message from the replicated user terminal 2 has not yet arrived, (2) There are two possible patterns: the message is considered processed and the response message is retained.

  Here, in the case of the pattern (1), the user terminal 2 can receive a response message when the subsystem 13 to be the new active system performs processing as usual after the failure switching.

  On the other hand, in the case of the pattern (2), the subsystem 13 assumes that the processing is complete and does not transmit the response message 101 but holds it in the response message holding unit 133. Therefore, after the failure switching, as shown in FIG. By transmitting the response message 101 held in the response message holding unit 133 to the user terminal 2, the user terminal 2 can receive the response message 101. The state with the active subsystem 13 can be maintained.

  In addition, when a failure switching occurs after the subsystem 12 has already returned a response, the subsystem 13 transmits a response message. The user terminal 2 receives the response message of the message number waiting for the response, but since it has already been received in the state A2, the response message is discarded, so there is no problem.

  As described above, in the present embodiment, in the system 1 having the hot standby redundant configuration, a method for synchronizing the subsystems 12 and 13 having the redundant configuration without performing the synchronization of the processing timing is provided. The following effects are exhibited.

  That is, in this embodiment, it is not necessary to synchronize complicated processing timing between the subsystems 12 and 13 having a hot standby type redundant configuration, and synchronization can be performed with simple state control.

  Further, in this embodiment, the state between the user terminal 2 and the new active subsystem 13 can be maintained regardless of the timing of the failure of the active subsystem 12. Furthermore, in this embodiment, no message is lost, and there is no need to re-synchronize after system switching.

  FIG. 9 is a block diagram showing the configuration of a system employing a hot standby system according to another embodiment of the present invention. In FIG. 9, the basic configuration of a system employing a hot standby system according to another embodiment of the present invention is the same as that of the system employing the hot standby system according to the above-described embodiment of the present invention. The case where the systems 14 and 15 are further comprised of a plurality of sub-subsystems is shown.

  In order to simplify the explanation, FIG. 9 shows a case where the subsystems 14 and 15 are configured by three subsystems 141 to 143 and 151 to 153. A system employing a hot standby system according to another embodiment of the present invention will be described with reference to FIG.

  In FIG. 9, the subsystems 14 and 15 are composed of a plurality of subsystems 141 to 143 and 151 to 153. At this time, it is assumed that the message from the user terminal 2 has a configuration in which a response message is returned to the user terminal 2 via the sub-subsystems 141 and 151 → the sub-subsystems 142 and 152 → the sub-subsystems 143 and 153.

  In the system 1 in which the response message is sent back through the plurality of sub-subsystems 141 to 143 and 151 to 153, by using the present invention, it operates as shown in FIG. It is possible to solve the conventional problems.

  In FIG. 10, when the sub-subsystem 151 receives a message at the message receiving unit 1511, it creates and sends a response message to the sub-subsystem 153, and instructs the sub-subsystem 153 to hold the response message. On the other hand, the sub-system 151 processes the received message with the message processing unit 1512 and requests another sub-system 152 to process it. Finally, in the sub-subsystem 153, if the processing result is different from the response message processed by the message processing unit 1531 and held in the response message (MSG) holding unit 1532, the response message is updated with the processing result. .

  As described above, in this embodiment, even in the system 1 divided into the plurality of sub-subsystems 141 to 143 and 151 to 153, the sub-subsystem 153 in the standby-system sub-system 15 that has received the message always receives the next message. Control to make it possible to receive the response, and makes a response creation request to the subsystem 153 that actually has a response function. In addition, the actual processing is performed later, and only the result is updated, so that synchronization between the active system and the standby system can be realized even when the processing is performed asynchronously with the active subsystem 14. Can do.

1 is a block diagram showing the configuration of a system that employs a hot standby system according to an embodiment of the present invention. It is a figure which shows the content of the management information in the user terminal of FIG. It is a figure which shows the format of the message transmitted / received between the user terminal of FIG. 1, and a system. FIG. 2 is a diagram showing the contents of management information in the active subsystem of FIG. 1. FIG. 2 is a block diagram illustrating a configuration of an active subsystem of FIG. 1. FIG. 3 is a diagram showing the contents of management information in the standby subsystem of FIG. 1. FIG. 2 is a block diagram illustrating a configuration of a standby subsystem in FIG. 1. FIG. 2 is a diagram showing a state when a failure occurs during message processing in the active subsystem of FIG. 1 and system switching is performed. It is a block diagram which shows the structure of the system which employ | adopted the hot standby system by the other Example of this invention. FIG. 10 is a block diagram illustrating a configuration of a standby subsystem in FIG. 9. It is a figure which shows operation | movement of the system which employ | adopted the conventional hot standby system. It is a figure which shows operation | movement of the user terminal of FIG. It is a figure which shows the problem at the time of the message transmission / reception of the system which employ | adopted the conventional hot standby system.

Explanation of symbols

1 system
2 User terminal
11 Duplicator
12 to 15 subsystems 121, 131, 1511 message receivers 122, 132, 1512,
1521, 1531 Message Processing Unit
123 Response message transmitter
133, 1532 Response message holding units 141-143
151-153 Sub-subsystem
A Management information at user terminal 2 A1, B2, C1, D1 Message number
A2, C2 state
B message
B1 header
B2 Message number
B3 payload
Management information in C subsystem 12
D Management information in subsystem 13

Claims (6)

When a hot standby method comprising an active subsystem and a standby subsystem is adopted and an ordered message for exchanging messages with a user terminal is received, a response message to the ordered message is sent to the user terminal And receiving the next sequential message sent after receiving the response message at the user terminal,
The standby subsystem includes a means for creating a response message for the received ordered message simultaneously with the reception of the ordered message; a means for holding the response message without transmitting it to the user terminal; Message processing means for processing the received ordered message, and means for updating the held response message when the held response message is different from the processing result of the ordered message received from the message processing means; And a means for transmitting a response message held after the sub-system is switched to the active system. A system employing a hot standby system.   The system adopting a hot standby system according to claim 1, further comprising: a duplicator that duplicates a message from the user terminal and distributes the message to the active subsystem and the standby subsystem.   3. The system adopting a hot standby system according to claim 1, wherein the active subsystem and the standby subsystem comprise a plurality of subsystems. When a hot standby method comprising an active subsystem and a standby subsystem is adopted and an ordered message for exchanging messages with a user terminal is received, a response message to the ordered message is sent to the user terminal A synchronization method used in a system for receiving a next sequential message sent after receiving the response message at the user terminal,
A process in which the standby subsystem simultaneously creates the response message for the received ordered message simultaneously with the reception of the ordered message; a process for holding the response message without transmitting it to the user terminal; A message process for processing the received ordered message, a process for updating the stored response message when the held response message is different from the processing result of the ordered message received from the message process , And a process of transmitting a response message held after the subsystem is switched to the active system.   5. The synchronization method according to claim 4, wherein the system includes a duplicator that duplicates a message from the user terminal and distributes the message to the active subsystem and the standby subsystem.   6. The synchronization method according to claim 4, wherein the active subsystem and the standby subsystem comprise a plurality of subsystems.

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