JP2006209465A - Load distribution system, load distribution device, server, load distribution program and load distribution method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To distribute the load of a server in server processing in which the server side starts to communicate with a client and performs processing with respect to response from the client. <P>SOLUTION: This load distribution system has two or more servers 20 provided with a load information storing means for storing self-load information and a client list storing means for storing designation information of a client to which a server itself has to communicate, a load distribution device 10 provided with a whole client list storing means for storing the whole clients and a load monitoring means for receiving load information from the load information storing means of a server, monitoring the load information, preparing client designation information for distributing the whole clients to make loads among servers equal on the basis of the load information and allocating the clients to each server, and transmitting the designation information to corresponding servers, and two or more clients 30 for transmitting response to a server for a request received from the server. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention manages a list of clients to be communicated by a load balancer in server processing (device polling, etc.) in which communication is started from the server side to a client and a response from the client is processed. A load balancing system, a load balancing device, a server, and the like that monitor the load of a plurality of servers and distribute the server load by designating clients to communicate with each server so that the load is even among the servers. The present invention relates to a load distribution program and a load distribution method.

In a conventional server load distribution system, communication is generally started from the client side to a server, and load distribution processing is performed so that the processing load on the server is equal among a plurality of servers.
FIG. 7 shows the configuration of such a conventional server load distribution system. For example, requests d3001c1 to d300nc1 such as HTTP (Hyper Text Transfer Protocol) from the clients 300-1 to 300-n are sent to the servers 200a to 200c. It is assumed that the load is distributed and distributed.

In the figure, a load monitoring unit 101 of the load distribution apparatus 100 monitors load information d2001a to d2001c of each server 200a to 200c, and requests d3001c1 to clients 300-1 to 300-n addressed to virtual representative server addresses. When d300nc1 arrives, the destination addresses of the requests d3001c1 to d300nc1 are converted to the servers 200a to 200c so that the requests are distributed so that the loads on the servers 200a to 200c are equalized, and the requests d3001c2 to d300nc2 are respectively supported. Are transferred to the servers 200a to 200c.
In addition, responses d3001s1 to d300ns1 returned from the servers 200a to 200c are also converted from the servers 200a to 200c to virtual representative server addresses, so that the responses d3001s2 to d300ns2 are returned to the clients.

  However, since this conventional server load distribution system realizes server load distribution by distributing the request to the server when a request is transmitted from the client side, the present invention assumes that It could not be applied to server processing that starts communication from the server side and processes the response returned from the client.

Here, as a conventional server load distribution system, for example, a server load distribution system described in Patent Document 1, a wide area load distribution apparatus described in Patent Document 2, and the like can be cited.
According to the server load balancing system described in Patent Document 1, it is possible to avoid that each of the server load balancers becomes a bottleneck of packet processing speed and to perform high-speed communication between the server and the client. Yes.
Further, according to the wide area load distribution apparatus described in Patent Literature 2, it is impossible to cope with the case where all the servers to be distributed become a heavy load or the like, and as the network scale increases, As the number of servers increases, the load measurement accuracy of servers belonging to another network far from the load balancer decreases, and the load balancer itself may become a bottleneck and prevent proper load balancing. It is possible to solve the problem and appropriately perform load balancing and fault concealment among servers belonging to different networks.

JP 2003-174473 A JP 2000-132524 A

  However, even in these conventional technologies, load distribution processing is performed by starting communication from the client side to the server and distributing the processing load of the server to a plurality of servers. It has not been possible to realize server load distribution in server processing in which communication is started from the server side, which is the subject of the invention, to the client, and the response from the client is processed.

  The present invention has been considered in view of the above circumstances. In the server processing in which communication is started from the server side to the client and the response from the client is processed, the client to be communicated by the load balancer Load that can distribute the server load by managing the list of servers, monitoring the load on multiple servers, and specifying the clients that should communicate with each server so that the load is even among the servers An object is to provide a distributed system, a load distribution apparatus, a server, a load distribution program, and a load distribution method.

  In order to achieve the above object, a load distribution system of the present invention is a load distribution system that starts communication with a client from a server side and distributes a load of a server that performs processing for a response from the client, The server communicates with two or more servers provided with load information storage means for storing its own load information and client list storage means for storing specification information of clients to be communicated transmitted from the load balancer. Load information is received from all client list storage means for storing all clients and load information storage means in the server, the load information is monitored, and the load between servers is equalized based on the load information. Allocate all clients to the server and create client specification information to be assigned to each server. A load balancer having a load monitoring means for transmitting the specified information to the corresponding server, to request that is transmitted from the server, it is constituted with the two or more client sending the response to the server.

With such a configuration of the load distribution system, even in a system in which communication is started from the server side to the client, and the server processes in response to the response from the client, the load is evenly distributed among a plurality of servers. can do.
Also, the load balancer refers to the load of each server and distributes the client to be processed to each server. Therefore, it is possible to distribute the load without having to grasp the load of each client, which is larger than the number of servers. It is also possible to reduce the amount of information.
Note that “so that the load between servers is equal” means that the load is close to the most equal, and does not mean that the load on all servers should be strictly equal. .

  Further, in the load distribution system of the present invention, the load distribution apparatus receives a request from the server to the client, converts the request source address from the server address to the virtual representative server address, The correspondence information between the address of the client and the address of the client is stored in the address conversion table, the response from the client to the server is received and received, the address conversion table is searched based on the client address, and the server address is acquired. The address conversion means for converting the destination address of the response from the address of the virtual representative server to the address of the server, and the address conversion table for storing the association information between the server address and the client address are provided.

With such a configuration of the load balancing system, even if the allocation of the server that communicates with the client changes, the source address of the packet that reaches the client is always the address of the virtual representative server.
Therefore, the present invention can be applied even when a response is allowed only for communication from a specific server address (virtual representative server address).

  Further, in the load distribution system of the present invention, instead of the load distribution device, one of the servers is configured as a load distribution device, and the one server includes all client list storage means in the load distribution device, and The load monitoring means is provided.

  The load distribution system according to the present invention is a load distribution system that distributes a load of a server that starts communication from a server side to a client and processes a response from the client. Load information storage means for storing, client list storage means for storing designation information of clients to communicate with itself, load information from load information storage means in other servers other than the self, and load information of other servers and self When the load difference is equal to or greater than a predetermined value, the client list of the server with the low load is changed from the client list storage unit in the server with the high load so that the load between these servers becomes equal. Two or more servers provided with load monitoring means for moving a part of the specified information of the client to the storage means; The request that has been transmitted from, it is constituted with the two or more client sending the response to the server.

  If the load balancing system is configured as described above, in a system in which communication is started from the server side to the client and the server performs processing according to the response from the client without separately preparing a load balancing device, The load can be evenly distributed among the servers.

  Also, the load distribution apparatus of the present invention starts load communication from the server side to the client, and distributes the load of the server that processes the response from one or more clients to two or more servers. All client list storage means for storing all client information that the server communicates with, and receiving load information from the server to monitor the load information, and load between servers based on the load information All the clients are distributed so as to be even, and the designation information of the client to be assigned to each server is created, and load monitoring means for transmitting this designation information to the corresponding server is provided.

  The load distribution apparatus of the present invention mediates and receives a request from the server to the client, converts the transmission source address of the request from the server address to the virtual representative server address, Address correspondence information is stored in the address conversion table, and the response from the client to the server is received and received. The address conversion table is searched based on the client address to obtain the server address, and the response destination address Is converted from the address of the virtual representative server to the address of the server, and an address conversion table for storing association information between the server address and the client address.

  The server of the present invention is a server that starts communication with a client, and a processing load performed on responses from one or more clients is distributed between the two or more servers. Load information storage means for storing load information and client list storage means for storing specification information of clients to be communicated with by itself, load information is acquired from the load information storage means by the load balancer, and the load information is monitored Then, based on the load information, the client is distributed so that the load between the servers becomes equal, and the client designation information created by allocating each server is received from the load balancer.

  The server of the present invention is a server that starts communication with a client, and a processing load performed on responses from one or more clients is distributed between the two or more servers. Load information storage means for storing load information, client list storage means for storing client designation information to be communicated with, and load information from load information storage means in other servers other than the self, and other servers When the load difference is equal to or greater than a predetermined value, the load information from the client list storage means in the high load server is equalized. Load monitoring means for moving part of the client designation information to the client list storage means of the low server is provided.

  In addition, the load distribution program of the present invention starts communication with a client from the server side, and loads two or more servers using a load distribution device to load a server that processes a response from one or more clients. A load distribution program that distributes the load distribution device to all client list storage means for storing all client information that the server communicates with, receives load information from the server, monitors the load information, and Based on the information, all clients are allocated so that the load between servers is equalized, and client designation information to be assigned to each server is created, and this function is used as a load monitoring means for transmitting this designation information to the corresponding server. As a configuration.

  The load distribution program of the present invention receives a load distribution apparatus through a request from a server to a client, converts the transmission source address of the request from the server address to the virtual representative server address, The correspondence information between the address of the client and the address of the client is stored in the address conversion table, the response from the client to the server is received and received, the address conversion table is searched based on the client address, and the server address is acquired. It is configured to function as an address conversion unit that converts the destination address of the response from the address of the virtual representative server to the address of the server, and an address conversion table that stores association information between the server address and the client address.

  The load distribution program of the present invention is a load distribution program that starts communication with clients and distributes the processing load performed on responses from one or more clients to two or more servers. The server functions as load information storage means for storing its own load information, and client list storage means for storing designation information of clients to which the server should communicate, and the server is operated by the load balancer from the load information storage means. Receive load information and monitor the load information, load the client specification information created by allocating clients and allocating each server so that the load among servers is equal based on the load information It is configured to receive from the distributed device.

  The load distribution program of the present invention is a load distribution program that starts communication with clients and distributes the processing load performed on responses from one or more clients to two or more servers. The server receives load information from load information storage means for storing its own load information, client list storage means for storing designation information of clients to which it should communicate, and load information storage means in other servers other than itself When the load information of other servers is compared with its own load information and the load difference is greater than or equal to a predetermined value, the client list storage in the server with a high load is made so that the load between these servers becomes equal. Load monitoring means for moving a part of the client designation information from the means to the client list storage means of the server with low load; There is a structure in which to function Te.

  In addition, the load distribution method of the present invention is a load distribution that starts communication with a client from the server side and distributes the load of a server that processes a response from one or more clients to two or more servers. The server stores its own load information in the load information storage means, and the load balancer receives the load information from the server and monitors the load information. Based on the load information, the server Allocate clients so that the load is evenly distributed, create client designation information to be assigned to each server, send this designation information to the corresponding server, and the server sent from the load balancer The client designation information stored in the client list storage means is stored in the client list storage means. The client sends a request to the client, and the client sends a response to the server in response to the request sent from the server, and the server executes a process corresponding to the response sent from the client, This is a method of storing own load information in a load balancer.

  Further, according to the load distribution method of the present invention, the load distribution apparatus receives the request from the server to the client, converts the transmission source address of the request from the server address to the virtual representative server address, The request is sent to the client, the server address and the client address correspondence information are stored in the address conversion table, the client sends a response to the server in response to the request sent from the server, and the load The distribution device receives the response from the client to the server and receives it, searches the address conversion table based on the client address, obtains the server address, and sends the response destination address from the virtual representative server address to the server address. Convert it to an address There as a way to send a Nsu to the server.

  In addition, the load distribution method of the present invention is a load distribution that starts communication with a client from the server side and distributes the load of a server that processes a response from one or more clients to two or more servers. A method in which a server stores its own load information in load information storage means, and stores client designation information to be communicated in client list storage means, and stores load information in a server other than itself Load information is received from the means, and the load information of other servers is compared with its own load information. A part of the client's specified information is moved from the client list storage means of the server with high load to the client list storage means of the server with low load The client transmits a request to the client related to the designation information stored in the client list storage means, the client transmits a response to the server in response to the request transmitted from the server, and the server is transmitted from the client. This is a method of executing processing corresponding to the response and storing the load information of the own device in the load balancer.

If the load balancer, the server, and the load balance program are configured as described above, and the load balance method is such a method, communication is started from the server side to the client, and the server responds to the response from the client. In a system that performs processing, a load can be evenly distributed among a plurality of servers.
Further, the present invention can be applied even when a client only allows a response to communication from a specific server address.
Furthermore, it is possible to realize such load distribution among a plurality of servers without separately preparing a load distribution device.

  According to the present invention, in the server processing that starts communication from the server side to the client and processes the response from the client, the load balancer manages a list of clients to be communicated, and a plurality of By monitoring the server load and designating clients to communicate with each server so that the load is even among the servers, it is possible to distribute the server load.

Hereinafter, a preferred embodiment of a load distribution system according to the present invention will be described with reference to the drawings.
Note that the load distribution system of the present invention shown in the following embodiments is configured to operate by a computer controlled by a load distribution program. The CPU of the computer as the load balancer and server sends a command to each component of the computer based on the load balance program and performs predetermined processing required for the operation of the load balancer and server, for example, load monitoring process, client Distribution and designation processing, address conversion processing, and the like. Thus, each process and operation in the load distribution system of the present invention can be realized by specific means in which the program and the computer cooperate.

The program is stored in advance in a recording medium such as a ROM and a RAM, and is executed by causing the computer to read the program from a recording medium mounted on the computer. For example, the program may be read by the computer via a communication line.
Further, the recording medium for storing the program can be constituted by, for example, a semiconductor memory, a magnetic disk, an optical disk, or any other recording means that can be read by any computer.

[First embodiment]
First, the configuration of the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the load distribution system of this embodiment.
As shown in FIG. 1, the load distribution system of this embodiment includes a load distribution device 10, a server 20 (20a, 20b, 20c), and a client 30 (30-1, 30-2, 30-3,... 30-n).

The load distribution apparatus 10 is an information processing apparatus that distributes the load of two or more servers 20, and includes an all client list storage unit 11 and a load monitoring unit 12.
The all client list storage unit 11 stores all clients with which the server 20 communicates. That is, in the example of FIG. 1, the all client list storage unit 11 stores the identification information of all the clients 30-1 to 30-n.

The load monitoring unit 12 monitors the load information by receiving the load information from the load information storage unit 21 (21a, 21b, 21c) in the server 20. The monitoring process may be a conventionally known process, for example, a process that periodically receives load information.
Also, the load monitoring unit 12 creates client designation information to be communicated by each server 20 based on the received load information from each server 20 so that these loads are equalized. In other words, reduce the number of clients to be processed for high-load servers, and increase the number of clients to be processed for low-load servers so that the load between each server approaches evenly. Create client specification information.

Specifically, various methods can be used for the load equalization processing. For example, when the load of the server 20a is 70, the load of the server 20b is 30, and the load of the server 20c is 50, The load monitoring unit 12 is configured to reduce the number of clients of the server 20a having a higher load than 50, which is the average value of the load information, and increase the number of clients of the server 20b having a lower load than 50, which is the average value of the load information. Can be.
Therefore, in this case, the load monitoring unit 12 creates client designation information so that the server 20b can communicate with either the client 30-1 or the client 30-2 with which the server 20a is communicating.

At this time, which of the client 30-1 and the client 30-2 with which the server 20a is communicating can be selected to be communicated with the server 20b, for example, can be randomly performed.
When the client 30-2 is selected to be communicated with the server 20b, the load monitoring unit 12 sends the designation information of the client 30-1 to the server 20b as the designation information of the client to the server 20a. The designation information of the client 30-2 and the client 30-3 is created as the designation information of the client, and the designation information of the client 30-n is created as the designation information of the client to the server 20c, and transmitted to the corresponding server 20.

  Further, when load information for each client 30 is stored in the load information storage unit 21 in the server 20, for example, the load information of the server 20a is 20 for the client 30-1, 50 for the client 30-2, When the client 30-3 is 30 as the load information of the server 20b and the client 30-n is 50 as the load information of the server 20c, the load monitoring unit 12 includes the client 30-1 with which the server 20a communicates and In selecting which of the clients 30-2 to communicate with the server 20b, the client 30- suitable as a client having a load closer to the difference between the load information of the server 20b having a low load and the average value of the load information. 1 can be selected.

  In addition, any method may be used as long as the load monitoring unit 12 can distribute the clients to be communicated with each server 20 so that the load on each server 20 is equalized.

The server 20 transmits a request to the client 30 to start communication, and executes processing corresponding to the content of this response based on the response from the client 30.
As shown in FIG. 1, each server 20 includes load information storage means 21 (21a, 21b, 21c) and client list storage means 22 (22a, 22b, 22c).

The load information storage unit 21 stores the load of the server 20 as quantitative information. For example, the CPU load rate in the server 20 or the memory usage ratio with respect to all the memories can be used as the load information.
The client list storage unit 22 stores a partner client to which the server 20 should communicate. In this embodiment, the communication partner client is transmitted from the load balancer 10 to the server 20 as the client designation information d202 and stored in the client list storage unit 22.

  The client 30 is an information processing apparatus that returns a response to the server 20 in response to a request transmitted from the server 20. It is assumed that the content of this response may differ from client to client depending on whether the client 30 has data to be processed by the server. Therefore, when such communication between the server 20 and the client 30 is performed, the load between the servers 20 starts to be biased depending on which client 30 the server 20 is communicating with.

  Next, a processing procedure in the load distribution system of this embodiment will be described with reference to FIGS. FIG. 2 is an operation procedure diagram showing a processing procedure in the load distribution system of this embodiment.

First, the load distribution apparatus 10 monitors the load information storage unit 21 of each server 20 by the load monitoring unit 12, and the load of each server 20 is equalized based on the load information d201 (d201a, d201b, d201c). As described above, a list of all clients to be communicated and processed by the server is input from the all client list storage means 11, and the servers to be communicated and processed by each server 20 are distributed and specified (step 10). At this time, the load monitoring unit 12 creates client designation information d202 (d202a, d202b, d202c) and transmits it to the corresponding server 20 respectively.
Since the load on each server 20 is equal in the initial state, clients to be communicated and processed by each server 20 are specified equally.

In response to this, the server 20 stores the received client designation information d202 in the client list storage means 22 (step 11).
Then, communication is started by transmitting a request to the client based on the client designation information d202 stored in the client list storage means 22 (step 12).

The client 30 responds to the received request by returning a response to the server 20 (step 13).
The server 20 executes processing according to the received response (step 14). The processing of step 12 to step 14 can be repeatedly executed.

With these operations, the load among the servers 20 starts to be biased depending on the processing contents of each server 20 (whether the client has data to be processed by the server or not).
On the other hand, the load monitoring unit 12 in the load distribution apparatus 10 periodically monitors the load information d201 of each server 20, and each server 20 should communicate and process so that the load on the server 20 is equalized. The client designation is changed (step 15).
That is, as described above, the number of clients to be processed by a server with a high load is reduced, the number of clients to be processed by a server with a low load is increased, and new client designation information d202 is created, 20 to send.

  On the other hand, the server 20 performs the same operations as in steps 11 to 14 (steps 16 to 19), and the load balancer 10 again monitors the load information d201 of the server 20 and changes the client designation. (Step 20), the server 20 stores the client designation information d202 (Step 21). Thereafter, the operations from step 17 to step 21 are repeatedly executed.

  As described above, according to the load distribution system of the present embodiment, even in a system in which communication is started from a server side to a client and processing is performed by a server in response to the response from the client, a plurality of servers The load can be evenly distributed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the load distribution system of this embodiment.
In the present embodiment, it is assumed that the client 30 is limited so as to permit a response only to communication from a specific server, and the load balancer 10 receives and receives the communication between the server 20 and the client 30. This is different from the first embodiment in that the address is converted. About another point, it is the same as that of 1st embodiment.

As shown in FIG. 3, the load distribution apparatus 10 of this embodiment includes an address conversion unit 13 and an address conversion table 14 in addition to the configuration in the first embodiment.
In the present embodiment, it is assumed that the client 30 allows a response only for communication from a specific server address (virtual representative server address).
For this reason, the address conversion unit 13 receives the packet of the request transmitted from the server 20 once, and converts the transmission source address of this packet from the address of the server 20 to the virtual representative server address. Send.

At this time, in order to return the transmission destination address (destination address) of the response packet from the client 30 to the address of the original communication partner server 20, the address from which server 20 the packet is addressed to which client 30 is addressed. It is stored in the conversion table 14.
That is, the address conversion unit 13 stores association information between the address of the server 20 that is the transmission source of the received packet and the address of the client 30 that is the transmission destination in the address conversion table 14.

  As a result, when the address conversion unit 13 receives the response packet transmitted from the client 30 via the mediation, the address conversion unit 13 searches the address conversion table 14 using the address of the client 30 of the transmission source of the packet as a key, and the corresponding server. Get 20 addresses. Then, the virtual representative server address of the transmission destination of the response packet is converted into the acquired address of the server 20 and transmitted to the server 20.

  Of course, at this time, the correspondence information between the address of the client 30 and the address of the server 20 is stored in the address conversion table 14 for each packet, and the address of the server 20 can be acquired from the address conversion table 14 for each packet. it can.

  The address conversion table 14 is a storage unit that stores the address of the server 20 for each address of the client 30. It is also possible to hold the association information between the address of the client 30 and the address of the server 20 for each packet.

  Next, a processing procedure in the load distribution system of this embodiment will be described with reference to FIGS. FIG. 4 is an operation procedure diagram showing a processing procedure in the load distribution system of this embodiment.

  First, the load distribution device 10 monitors the load of each server 20 by the load monitoring unit 12 and distributes and designates the client 30 so that the load of each server 20 is equal. The operation until the notification is started (step 30 to step 32) is the same as the operation (step 10 to step 12) in the first embodiment.

  Next, in the present embodiment, the request packet transmitted from the server 20 to the client 30 is not directly transmitted to the client 30 but is temporarily received by the load balancer 10. Then, the source address of the request packet is converted from the address of the server 20 to the virtual representative server address by the address conversion means 13 in the load balancer 10 (step 33) and transmitted to the client 30 (step 34). .

On the other hand, when a response packet is transmitted to the server 20 by the response of the client 30 (step 35), the address translation unit 13 in the load distribution apparatus 10 receives the packet through this.
The address translation unit 13 searches the address translation table 14 based on the address of the client 30 that is the source of the response packet, acquires the address of the corresponding server 20, and the virtual representative server that is the destination of the response packet The address is converted into the acquired address of the server 20 (step 36), and the response packet is transmitted to the server 20 (step 37).

The server 20 executes processing according to the received response (step 38). These processes of step 32 to step 38 can be repeatedly executed.
Next, the load of each server 20 is monitored by the load balancer 10 and the designation of the client 30 is changed (step 39), and the client designation information d202 is stored in the server 20 (step 40). Is the same as the operation (steps 15 and 16) in the first embodiment.
Thereafter, the operations from step 32 to step 40 are repeatedly executed.

As described above, according to the load distribution system of this embodiment, even if the allocation of the server that communicates with the client changes, the source address of the packet that reaches the client is always the address of the virtual representative server.
Therefore, the present invention can be applied even when a response is allowed only for communication from a specific server address (virtual representative server address).

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the load distribution system of this embodiment.
This embodiment is different from the first embodiment in that the function of the load distribution apparatus 10 in the first embodiment is mounted on one server 20a among the plurality of servers 20. About another point, it is the same as that of 1st embodiment.

As shown in FIG. 5, the server 20a in the present embodiment includes an all client list storage unit 23a and a load monitoring unit 24a in addition to the configuration in the first embodiment.
Accordingly, the server 20a functions as a load distribution apparatus in addition to the operation in the first embodiment.

That is, the load monitoring unit 24a in the server 20a receives and monitors the load information d201 (d201a) from the load information storage unit 21a in the server 20a, and loads from the load information storage units 21b and 21c in the servers 20b and 20c. Information d201 (d201b, d201c) is received and monitored.
Then, the load monitoring means 24a distributes and designates the clients 30 so that the loads on the servers 20a are equal, as in the load distribution apparatus 10 of the first embodiment, and stores the client list in the servers 20a. The created client designation information d202a is stored in the means 22a, and the client designation information d202b and d202c is transmitted to the servers 20b and 20c, respectively, and stored in the client list storage means 22b and 22c in each server 20.
In addition, the point that the request is transmitted from the server 20 to the client 30, the response is returned from the client 30 to the server 20, and the corresponding processing is executed in the server 20 is the same as in the first embodiment. It is.

  As described above, according to the load distribution system of the present embodiment, communication is started from the server side to the client without preparing a separate load distribution apparatus, and the server performs processing according to the response from the client. In the system, the load can be evenly distributed among a plurality of servers.

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the load distribution system of this embodiment.
This embodiment is different from the first embodiment in that the functions of the load distribution apparatus 10 in the first embodiment are distributed and held in each server 20. About another point, it is the same as that of 1st embodiment.

As shown in FIG. 6, each server 20 (20a, 20b, 20c) in the present embodiment includes load monitoring means 25 (25a, 25b, 25c) in addition to the configuration in the first embodiment.
As a result, each server 20 functions as a load balancer in addition to the operation in the first embodiment.

That is, by the load monitoring means 25, each server 20 exchanges the load information stored in each other's load information storage means 21 (d1ab, d1bc, d1ca), and two servers having a load difference of a certain value or more. If there is, a part of the client to be processed is moved from the high load server to the low load server (d2ab, d2bc, d2ca).
In this case, since there is no master client list information such as the client list in the all client list storage unit 11 in the load distribution apparatus 10 of the first embodiment, in the initial state, manually in each server 20 in advance. Clients are appropriately distributed and set in the client list storage unit 22.

  As described above, even with the load distribution system of the present embodiment, a system in which communication is started from the server side to the client without using a separate load distribution device, and the server performs processing according to a response from the client Therefore, the load can be evenly distributed among a plurality of servers.

It goes without saying that the present invention is not limited to the above embodiment, and that various modifications can be made within the scope of the present invention.
For example, by combining the second embodiment and the third embodiment, the server 20a shown in FIG. 5 includes the address conversion unit 13 and the address conversion table 14, and the client only communicates with a specific server. The present invention can be configured as various combinations of the above-described embodiments, such as being applicable to cases where a response is permitted.
In addition, for example, the load distribution device, the server, and the client can be appropriately changed, such as a configuration in which the communication lines such as the Internet are connected to each other.

  The present invention can be suitably used for a system in which communication is started from a server side to a client, and a server performs processing (for example, device polling) in response to a response from the client.

It is a block diagram which shows the structure of the load distribution system of 1st embodiment of this invention. It is an operation | movement procedure figure which shows the process sequence in the load distribution system of 1st embodiment of this invention. It is a block diagram which shows the structure of the load distribution system of 2nd embodiment of this invention. It is an operation | movement procedure figure which shows the process sequence in the load distribution system of 2nd embodiment of this invention. It is a block diagram which shows the structure of the load distribution system of 3rd embodiment of this invention. It is a block diagram which shows the structure of the load distribution system of 4th embodiment of this invention. It is a block diagram which shows the structure of the conventional load distribution system.

Explanation of symbols

10 Load balancer
11 All client list storage means
12 Load monitoring means
13 Address conversion means
14 Address conversion table
20 (20a, 20b, 20c) servers
21 (21a, 21b, 21c) Load information storage means
22 (22a, 22b, 22c) Client list storage means
23a All client list storage means
24a Load monitoring means
25 (25a, 25b, 25c) Load monitoring means
30 (30-1 to 30-n) clients
d201 (d201a, d201b, d201c) Load information
d202 (d202a, d202b, d202c) Client specification information
d301s to d303s Request information from server to client
d301s1 to d30ns1 Request information from server to client (before conversion)
d301s2 to d30ns2 Request information from server to client (after conversion)
d301c to d30nc Response information from client to server
d301c1 to d30nc1 Response information from client to server (before conversion)
d301c2 to d30nc2 Response information from client to server (after conversion)
100 load balancer
101 Load monitoring means
102 Address conversion means
103 Address conversion table
200 (200a, 200b, 200c) server
201 (201a, 201b, 201c) Load information storage means
300 (300-1 to 300-n) clients

Claims (15)

A load distribution system that distributes the load of a server that starts communication from a server side to a client and processes a response from the client,
Two or more servers provided with load information storage means for storing own load information, and client list storage means for storing client designation information transmitted from the load balancer to which the self should communicate;
Receiving the load information from all client list storage means for storing all clients with which the server communicates, and the load information storage means in the server, and monitoring the load information, and based on the load information, The load distribution comprising load monitoring means for distributing all the clients so that the load among the servers is equal and creating client designation information to be assigned to each server and transmitting the designation information to the corresponding server Equipment,
A load distribution system comprising: two or more clients that transmit a response to the server in response to a request transmitted from the server. The load balancer is
Receiving the request from the server to the client, converting the request source address from the server address to the virtual representative server address, and associating the server address with the client address Information is stored in an address conversion table, and the response from the client to the server is received and received. The address conversion table is searched based on the address of the client to obtain the address of the server. An address conversion unit that converts a destination address from the address of the virtual representative server to an address of the server, and the address conversion table that stores association information between the address of the server and the address of the client. Contract The load distribution system according to claim 1. Instead of the load balancer, one of the servers is configured as the load balancer, and the one server includes the all client list storage unit and the load monitor unit in the load balancer. The load distribution system according to claim 1 or 2, further comprising: A load distribution system that distributes the load of a server that starts communication from a server side to a client and processes a response from the client,
Load information storage means for storing own load information, client list storage means for storing designation information of clients to which the self should communicate, receiving load information from load information storage means in a server other than the self, When the load information of the server is compared with the load information of the self and the load difference is greater than or equal to a predetermined value, the load from the client list storage means in the high load server is equalized so that the load between these servers is equalized Two or more servers provided with load monitoring means for moving a part of the designation information of the client to the client list storage means of the server with low load;
A load distribution system comprising: two or more clients that transmit a response to a request transmitted from the server. A load balancer that starts communication with a client from the server side and distributes the load of a server that processes a response from one or more clients to two or more servers,
All client list storage means for storing all client information with which the server communicates;
The client receives load information from the server, monitors the load information, and distributes all the clients so that the load among the servers is equal based on the load information. A load balancer comprising load monitoring means for creating designated information and transmitting the designated information to a corresponding server. Receives a request from the server to the client, converts the request source address from the server address to the virtual representative server address, and associates the server address with the client address. Is stored in an address conversion table, and the response from the client to the server is received and received, the address conversion table is searched based on the address of the client, the address of the server is acquired, and the response is transmitted. Address conversion means for converting the destination address from the address of the virtual representative server to the address of the server;
The load distribution apparatus according to claim 5, further comprising: the address conversion table that stores association information between the address of the server and the address of the client. A server that starts communication with a client and distributes the processing load performed on responses from one or more clients between two or more servers,
Load information storage means for storing own load information;
Client list storage means for storing designation information of clients to be communicated with;
The load information is acquired from the load information storage means by the load balancer and the load information is monitored. Based on the load information, the clients are distributed so that the load between the servers is equalized, The server characterized by receiving the designation information of the client created by assignment from the load balancer. A server that starts communication with a client and distributes the processing load performed on responses from one or more clients between two or more servers,
Load information storage means for storing own load information;
Client list storage means for storing designation information of clients to be communicated with;
When load information is received from load information storage means in a server other than the self, the load information of the other server is compared with the load information of the self, and when the load difference is a predetermined value or more, these Load monitoring means for moving a part of the specified information of the client from the client list storage means in the high load server to the client list storage means in the low load server so that the load between the servers is equalized A server characterized by that. A load distribution program that starts communication with a client from the server side, and distributes the load of the server that processes the response from one or more clients to two or more servers by a load distribution device,
The load balancer;
All client list storage means for storing all client information with which the server communicates;
The client receives load information from the server, monitors the load information, and distributes all the clients so that the load among the servers is equal based on the load information. A load balancing program that creates specified information and functions as a load monitoring means to send this specified information to the corresponding server. The load balancer;
Receives a request from the server to the client, converts the request source address from the server address to the virtual representative server address, and associates the server address with the client address. Is stored in an address conversion table, and the response from the client to the server is received and received, the address conversion table is searched based on the address of the client, the address of the server is acquired, and the response is transmitted. Address conversion means for converting the destination address from the address of the virtual representative server to the address of the server;
The load distribution program according to claim 9, wherein the load distribution program functions as the address conversion table that stores association information between the server address and the client address. A load distribution program that starts communication with a client and distributes the processing load performed on responses from one or more clients to two or more servers.
The server,
Load information storage means for storing own load information;
While functioning as a client list storage means for storing designation information of clients to be communicated with,
The server is caused to receive the load information from the load information storage means by the load balancer and to monitor the load information, and based on the load information, the client is arranged so that the load between the servers is equalized. A load distribution program characterized by causing the client distribution information to be received and distributed from the load distribution apparatus. A load distribution program that starts communication with a client and distributes the processing load performed on responses from one or more clients to two or more servers.
The server,
Load information storage means for storing own load information;
Client list storage means for storing designation information of clients to which the self should communicate;
When load information is received from load information storage means in a server other than the self, the load information of the other server is compared with the load information of the self, and when the load difference is a predetermined value or more, these Load distribution that functions as a load monitoring unit that moves part of the client's specified information from the client list storage unit in the high load server to the client list storage unit in the low load server so that the load between servers is equal program. A load balancing method for starting communication with a client from a server side and distributing a load of a server that performs processing on a response from one or more clients to two or more servers,
The server stores its own load information in the load information storage means,
A load balancer receives the load information from the server, monitors the load information, and distributes the clients to equalize the load among the servers based on the load information. Create the specified information of the client to be assigned to, send this specified information to the corresponding server,
The server stores in the client list storage means the designation information of the client to be communicated by the server transmitted from the load balancer, and requests the client according to the designation information stored in the client list storage means. Send
In response to the request sent from the server, the client sends a response to the server,
The load distribution method, wherein the server executes processing corresponding to a response transmitted from the client, and stores its own load information in the load distribution apparatus. The load balancer receives the request from the server to the client as an intermediary, converts the source address of the request from the server address to the virtual representative server address, and sends the request to the client. And sending the address conversion table to store the address information of the server and the client address,
In response to the request sent from the server, the client sends a response to the server,
The load balancer receives the response from the client to the server as an intermediary, searches the address conversion table based on the address of the client to obtain the address of the server, and sends the response destination address The load distribution method according to claim 13, wherein the address is converted from the address of the virtual representative server to the address of the server, and the response is transmitted to the server. A load balancing method for starting communication with a client from a server side and distributing a load of a server that performs processing on a response from one or more clients to two or more servers,
The server stores its own load information in the load information storage means, and also stores client designation information to be communicated in the client list storage means, and loads the load information from the load information storage means in another server other than itself. The load information of the other servers and the load information of the self are compared, and when the load difference is greater than or equal to a predetermined value, the load is high so that the load between these servers is equalized. Move a part of the client designation information from the client list storage means in the server to the client list storage means in the low load server, and send a request to the client related to the designation information stored in the client list storage means,
In response to the request sent from the server, the client sends a response to the server,
The load distribution method, wherein the server executes processing corresponding to a response transmitted from the client, and stores its own load information in the load distribution apparatus.

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