JP2002026950A - Method and system for building up server tree structure, server, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and system for building up a server tree structure that can prevent increase in a load in a specific server, realize a transmission form of service data with a small network load and realize a highly reliable high-speed information distribution service and to provide a server network system and a server. SOLUTION: Each server is provided with a means that autonomously configures a tree structure where a faulty server or a deleted server is avoided in the case that the server is stopped by a fault or a manager deletes the sever and where the transmission path of service data can continuously be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and system for constructing a server tree structure in which a plurality of servers are connected in a tree structure in a hierarchical parent-child relationship, a server, and a recording medium.

[0002]

2. Description of the Related Art If a service based on data provided on a network is defined as a data service, and data used for the data service is defined as service data, information retrieval services,
There are file distribution services and audio and video stream distribution services.

[0003] As one means of providing data services,
There is a method of providing a service by a plurality of servers installed in a distributed manner. As an example, a plurality of WEB servers are provided to provide an information distribution service by HTTP. The purpose of installing a plurality of servers is mainly for high reliability and high throughput. High reliability means that information necessary for providing a service is duplicated on another server (replication server) so that even if one server fails, the service is provided by another replication server. To be able to continue. Higher throughput means that requests from a plurality of users are processed by a plurality of servers, thereby increasing the amount of requests that can be processed per unit time.

[0004] There are the following technical points to consider when increasing the reliability and throughput of a data service by a plurality of servers. The first point is that when service data is updated or new data is generated as service data, it is desirable that the updated data or new service data be promptly transmitted to a service providing server. It is. This is because it is not preferable that the information provided by each server is different, in other words, it is not preferable that the service is lost due to the distribution. The second point is that it is necessary to efficiently transmit service data between the servers. This is because service data, such as a service for providing video and images, may have a large capacity.

[0005] As a conventional technique for realizing high reliability by a plurality of servers, a paper "Automatic Replication for High
ly Available Services ”(author Sanjay Ghemawat, NIT-
LCS-TR-473, Massachusetts Institute of Technology). FIG. 10 shows a conventional configuration of a server using this method.
Shown in

As shown in FIG. 11, the conventional server shown in FIG. 10 includes a parent server (primary server in the original text) that actually provides a service and a child server (original textbook) that holds a copy as a backup device for a failure. Then backup server)
The service providing device is configured by the above.

The server shown in FIG. 10 accepts a registration request message 101 from a child server when operating as a parent server and returns a registration response message 102 to the child server. A registration request means 106 for transmitting a registration request message 104 to the parent server and receiving a registration response message 105 from the parent server, and holding a list of identifiers of servers to which the own server has a connection relationship as server list information 107. And a parent determining unit 109 for determining a new parent server when a failure or the like occurs in the parent server of the own server.

The conventional server having such a configuration autonomously selects another server as a new parent server and continues the service when the parent server stops by the operation of the following means.

First, as shown in Table 1, the server list information of the state storage means 108 includes a server identifier and a time at which the server was last confirmed to be operating normally (final confirmation time). It is.

[0010]

[Table 1] Here, S1, S2, S3 are server identifiers, T1, T
2 and T3 are final confirmation times.

When the own server is operating as a parent server, the registration receiving means 103 receives the registration request message 101 from the child server and registers the identifier of the child server in the server list information 107 in the state storage means 108. Then, the last confirmation time of the child server is updated to the current time, and a registration response message 102 including the server list information is transmitted to the child server. FIG. 12 shows an example of a processing flow of the registration request processing. In this example, when a child server that is not the parent server receives the registration request message 101, it transmits a registration response message with a response code of “ParentMoved”.

In FIG. 12, when a registration request message 101 is received from a registration transmission request server, server list information 107 is obtained from the state storage means 108 (step 1201), and a parent server identifier is obtained from the obtained server list information 107. It is acquired (step 1202). Then, it is determined whether the parent server indicated by the acquired server list is the server itself (step 1203). If the parent server is not the server itself, the response code is set to “ParentMo
The server sends a registration response message “ved” to the server that transmitted the registration request message (step 1208). However, if the parent server is itself, the registration request message 101 is transmitted in the server list information 107. It is determined whether a server is included (step 120).
4) If it is not included, the identifier of the server that transmitted the registration request message 101 is stored in the server list information 1
07 is additionally registered (step 1205). However, if the server that transmitted the registration request message 101 is included in the server list information 107, the process proceeds to step 1206 without performing the registration processing of the server list information 107.

In step 1206, the last confirmation time of the server that transmitted the registration request message 101 in the server list information 107 is rewritten to the current time, and the server list information 107 in the state storage unit 108 is updated. Thereafter, the response code is set to “OK” and the registration response message 10
Reply 2.

FIG. 13 shows an example of a processing flow of the registration response processing of the child server. In this example, when the response code of the registration response is “ParentMoved”, the registration request message 1
04 is executed again. Child server registration request means 1
06 is a periodic registration request message 1 to the parent server.
04, and the parent server sends a registration response message 10
5 is received, and the server list information 107 of the state storage unit 108 is updated with the server list information included in the registration response message 105 (step 130).
1). If the response code is “ParentMoved” (step 1302), the registration request message 104 is transmitted to the parent server of the parent server identifier included in the registration response message 105 (step 1303). If the response code is "OK", the process ends.

As described above, the relationship between the parent and child servers is established. Thereafter, each time service data to be transmitted to the child server occurs, the parent server transmits the service data to the child server based on the list of child servers held in the state storage unit 108.

On the other hand, when the communication with the parent server is interrupted, the child server determines that the parent server has been stopped, and updates the parent server. That is, a new parent server is selected from the server identifiers of the server list information 107 stored in the state storage unit 108 in accordance with a predetermined priority. With this mechanism, the service is continued even when the parent server stops. An important point in describing the present invention in describing the present invention is that service data is transmitted from one parent server to all other child servers.

As a means widely used for improving the efficiency of information transfer, there is a method of transmitting information between servers in a tree-like manner, in other words, in a hierarchical manner. This concept is shown in FIG. Here, the transmitting side when transferring service data between servers is defined as a parent server, and the receiving side is defined as a child server. In this configuration, service data is transferred in multiple stages such that a server that is a parent server for one child server becomes a child server for another server.

Thus, the servers are connected in a tree shape by superposing the parent-child connections of the servers in multiple stages. Such a tree-like server connection is called a server tree. As shown in FIG. 14, a set of one parent server and servers connected to the parent server as children is called a branch. A branch to which a parent server of a certain branch A depends is defined as an upper branch of the branch A. For example, in FIG. 14, the branches of the area 110, the area 120, and the area 130 are subordinate to the branch of the area 100. In this case, the branch of the area 100 is expressed as an upper branch of the branches of the area 110, the area 120, and the area 130. In the example of FIG. 14, the area 110 includes the server S1.
11 to S113 are arranged, of which S111 is the parent server. The area 120 includes a server S1.
21 to S123 are arranged, of which S121 is the parent server. The area 130 includes a server S1.
31 to S133 are arranged, of which S131 is the parent server.

Further, in area 100, area 110
Server S111 becomes the parent server, and the areas 120, 1
Each of the 30 servers is a child server, the server S211 in the area 200 is a parent server in the entire network, and each of the servers in the areas 100, 200, and 300 is a child server. In FIG. 14, servers connected by double lines are the same device.

In this configuration, each server acquires service data from its own parent server. By configuring a tree-structured connection relationship in consideration of the perspective relationship between servers and the network topology, it is possible to reduce the number of times that the same service data is transferred on the same relay route and to streamline the service data.

[0021]

However, in the method described in the above article, service data is transmitted directly from the primary server to another backup server. Therefore, there are the following two problems. The first problem is that transmission of service data imposes a heavy load on the primary server. The second problem is that the load on the network may be increased by transferring the same service data over the same relay path many times.

On the other hand, the method of transmitting information hierarchically has the following problems. The problem is that the influence upon occurrence of a failure is large. When a certain server is stopped due to a failure, service data is not transmitted not only to the stopped server but also to a server connected to a branch lower than the server.

The present invention has been made in order to solve such a problem, and an object of the present invention is to prevent a load on a specific server from increasing and realize a service data transmission mode with a small network load. An object of the present invention is to provide a server tree structure construction method, a server network system, and a server capable of realizing a highly reliable and high-speed information distribution service.

[0024]

In order to achieve the above object, a feature of the present invention is to provide a tree structure that avoids a server when the server is stopped due to a failure or deleted by an administrator. The point is that each server is provided with means for autonomously configuring and maintaining and maintaining the service data transmission path.

More specifically, the server tree structure construction method of the present invention comprises a plurality of servers each having a set of a parent server and a child server of the parent server as a branch, and a branch to which a certain server belongs as a child as a dependent branch. State that stores server tree information including a list of server identifiers belonging to the dependent branch in a format that allows the priority in the parent server and the selection of the parent server to be determined, and a list of server identifiers in the upper branch of the dependent branch. A method for constructing a server tree structure in which a plurality of servers are connected in a tree structure in a hierarchical parent-child relationship with a storage means, wherein a server identifier and a dependent branch identifier are provided from a child server of a dependent branch to a parent server. And send a registration request message containing the Receiving a registration response message including a list of server identifiers at the lunch from the parent server, and a list of server identifiers of the branch held by the state storage means in the own server according to the list of server identifiers of the branch included in the registration response message Receiving the registration request message from the child server, and the server identifier list of the subordinate branch indicated by the registration request message among the server identifier lists held by the state storage means in the own server is the child step. A second step of updating the server to include the server, and further transmitting a registration response message including a server identifier list of the branch and a higher-level server identifier list of the branch to the child server; Stop is detected, and the status storage means in the own server is stored. Characterized in that it comprises a third step of selecting a new parent server in accordance server tree information.

In the third step, if the new parent server in the dependent branch is the own server, the upper branch of the branch indicated by the status storage means in the own server is set as the new dependent branch to the parent server. The method further comprises a fourth step of selecting

In the fourth step, if it is not possible to select a new parent server in the dependent branch, the server identifier of the upper-level branch of the dependent branch held by the state storage means in the own server is determined. A fifth step of selecting a parent server from the list is further provided.

In the server network system of the present invention, a plurality of servers having a parent server and a set of child servers of the parent server as branches and a branch to which a certain server belongs as a subordinate branch are arranged in a tree structure in a hierarchical parent-child relationship. A list of server identifiers belonging to a dependent branch in a format that allows each server to determine a parent server and a priority in selecting a parent server, and a server identifier in an upper branch of the dependent branch. State storage means for storing server tree information including: a list of server identifiers; transmitting a registration request message including a server identifier and a dependent branch identifier from the child server of the dependent branch to the parent server; List of server identifiers in the upper branch of the Receiving from the parent server a registration response message including the following, and updating the list of server identifiers of the branch held by the state storage means in the own server with the list of server identifiers of the branch included in the registration response message: Processing means for receiving the registration request message from the child server, so that the server identifier list of the dependent branch indicated by the registration request message in the server identifier list held by the status storage means in the own server includes the child server. A second processing unit for updating and transmitting a registration response message including a server identifier list of the branch and a server identifier list of a higher rank of the branch to the child server; and detecting a stop of the parent server in each branch. New according to the server tree information held by the status storage means in the own server. Characterized by comprising a third processing means for selecting a server.

Further, the third processing means, when the new parent server in the dependent branch is its own server,
Parent update processing means for selecting a parent server as a new subordinate branch of a branch indicated by the state storage means in the own server is further provided.

[0030] When it is impossible to select a new parent server in the dependent branch, the parent update processing means may determine a server identifier of a higher-level branch of the dependent branch held by the status storage means in the own server. A parent server is selected from a list.

Further, the server of the present invention comprises a plurality of servers having a parent server and a set of child servers of the parent server as branches, and a branch to which a certain server belongs as a subordinate branch in a tree structure in a hierarchical parent-child relationship. A list of server identifiers belonging to a dependent branch and a list of server identifiers in an upper branch of the dependent branch in a format in which the server in the connected server network system can determine the priority in selecting the parent server and the parent server. Status storage means for storing server tree information including:
A registration request message including a server identifier and a dependent branch identifier is transmitted from the child server of the dependent branch to the parent server, and a registration response including a list of server identifiers of the dependent branch and a list of server identifiers in a higher branch of the dependent branch First processing means for receiving a message from a parent server and updating a list of server identifiers of the branch held by the state storage means in the own server with a list of server identifiers of the branch contained in the registration response message; Receiving the registration request message from the server, and updating the server identifier list of the dependent branch indicated by the registration request message from the server identifier list held by the state storage means in the own server so as to include the child server; List of server identifiers for the branch and the top of the branch A second processing unit for transmitting a registration response message including a server identifier list to the child server, detecting a stop of the parent server in each branch, and according to server tree information held by the state storage unit in the own server. And a third processing means for selecting a new parent server.

Further, the third processing means, when the new parent server in the dependent branch is its own server,
Parent update processing means for selecting a parent server as a new subordinate branch of a branch indicated by the state storage means in the own server is further provided.

If the parent update processing means cannot select a new parent server in the dependent branch, the parent update processing means stores the server identifier in the upper branch of the dependent branch held by the state storage means in the own server. A parent server is selected from a list.

Further, the medium in which the program for constructing the server tree structure of the present invention is recorded includes a plurality of sets each having a parent server and a set of child servers of the parent server as branches, and a branch to which a certain server belongs as a child as a dependent branch. Each server includes a list of server identifiers belonging to the dependent branch in a format that allows the priority in the parent server and the selection of the parent server to be determined, and a list of server identifiers in the upper branch of the dependent branch. A medium for recording a program for constructing a server tree structure in which a plurality of servers are connected in a tree structure in a parent-child relationship in a hierarchical structure, comprising a state storage means for storing server tree information, the server being a child server of a dependent branch. Sends a registration request message including the server identifier and the dependent branch identifier to the parent server, A registration response message including a list of server identifiers of the subordinate branch and a list of server identifiers in the upper branch of the subordinate branch is received from the parent server, and the list of server identifiers of the branches included in the registration response message includes A first process of updating a list of server identifiers of a branch held by a state storage unit, and receiving a registration request message from a child server, and requesting a registration request from a server identifier list held by the state storage unit in the own server. The server identifier list of the dependent branch indicated by the message is updated so as to include the child server, and a registration response message including the server identifier list of the branch and the server identifier list of the upper branch of the branch is transmitted to the child server. The second processing and the parent server in each branch Detecting a stop, characterized by recording a server tree structure construction program and a third processing of selecting a new parent server in accordance server tree information in which the state storage means holds in the own server.

In the third process, if the new parent server in the dependent branch is the own server, the upper branch of the branch indicated by the status storage means in the own server is set as the new dependent branch. And a parent update process for selecting

In the parent update processing, if it is impossible to select a new parent server in the dependent branch, a list of server identifiers in the upper branch of the dependent branch held by the state storage means in the own server is provided. And a process of selecting a parent server from.

[0037]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram of a server according to an embodiment of the present invention. The server 10 of this embodiment returns a registration request receiving unit 13 for receiving a registration request message 11 from a child server, a registration request processing unit 14 for processing a registration request, and a registration response message 12 when operating as a parent server. A registration response transmission unit 15 is provided. Further, when operating as a child server, a registration request transmitting unit 17 for transmitting a registration request message 16 to the parent server, a registration response receiving unit 19 for receiving a registration response message 18 from the parent server, and processing the registration response message. Registration response processing means 20, state storage means 22 for holding a list of identifiers of servers to which the own server has a tree-structured connection relation as server tree information 21, and new parent when a failure or the like occurs in the parent server of the own server. A parent determining unit 23 for determining a server is provided. The server 10 is realized by a computer on which software for providing a service is activated. Also,
Each unit other than the state storage unit 22 of the present invention is also realized by software operating on a computer. Also,
The state storage means 22 is realized by a database on a computer.

Here, a set of one parent server and a server connected as a child to the parent server is a branch, a branch on which a parent server of a certain branch A is subordinate is a higher branch of the branch A, and a branch to which the server is a child Is defined as a dependent branch, the state storage means 22 stores server tree information including a server list 211 of the branch to which the own server belongs and a server list 212 of the upper branch of the dependent branch.

When the parent server of the dependent branch is stopped and the own server is determined to be the new parent server of the branch, the parent determining means 23 sets the upper branch of the branch as a new dependent branch and sets a new dependent branch. The parent server for the own server is determined from the server list of the dependent branch.

FIG. 2 is a diagram showing an embodiment of a server network system in which the servers having the configuration shown in FIG. 1 are connected in a tree structure. As in the case of FIG. 14, the area 110,
The branch of area 120 and area 130 is area 100
Subordinate to a branch. In this case, the branch of area 100 is divided into area 110, area 120, area 13
It is expressed as an upper branch of the 0 branch. In the example of FIG. 2, servers S111 to S113 are arranged in the area 110, and among them, S111 is stopped, and
12 indicates that it is a parent server. Also,
In the area 120, servers S121 to S123 are arranged, of which S121 is a parent server. Also,
Servers S131 to S133 are arranged in the area 130, of which S131 is the parent server. Further, in the area 100, the server S121 of the area 120
Is the parent server, each server in the areas 120 and 130 is a child server, and the server S211 in the area 200 is the parent server in the entire network, and the areas 100 and 20 are
Each of the servers 0 and 300 is a child server. In addition,
In FIG. 2, the servers connected by double lines are the same device.

When the parent server of the dependent branch is stopped and the own server is determined to be the new parent server of the branch, the parent determining means 23 in each server sets the upper branch of the branch to a new dependent branch. Then, the parent server for the own server is determined from the server list of the new subordinate branch.

Thus, when the parent server of a certain branch is stopped, a branch connected to the upper branch is newly formed by another server of the branch. By reconfiguring the branch, even if a certain server stops, it is possible to continue transmitting service data while avoiding the server. That is, it is possible to solve the problem of the method of transmitting service data hierarchically, that is, the point that the influence upon occurrence of a failure is large. This parent determination process is automatically executed periodically at a predetermined cycle.

For example, the server Slll in FIG.
As shown in FIG. 2, when the server is stopped for some reason, as shown in FIG. 2, the server S112 becomes the parent of the branch of the area 110, the S112 makes the branch of the area 100 a new subordinate branch, and S121 becomes the new parent server.

In order to perform such a parent determination process, the registration response message is configured to include a server list of a subordinate branch of the registration request transmission server and a server list of an upper branch of the subordinate branch. This makes it possible to update the server tree information 21 in the state storage unit 22.

If the parent server of the subordinate branch is stopped and it is impossible to select a new parent server from the server list of the subordinate branch, the parent determination means 23 adds a new parent server from the server list of the upper branch of the subordinate branch. A new parent server is selected, and a dependent branch is updated.

Thus, when the parent server of a branch including only one server having the ability to become a parent server is stopped, the other server of the branch registers with another branch. As a result, transmission of service data can be continued while avoiding a stopped server.

For example, as shown in FIG.
2. Assuming that the server S11 is stopped, assuming that the server S113 is not a server capable of being a parent server, the servers S112 and S113 may select a parent server from the server list of the branch to which the own server belongs. Since it is impossible, the branch 10 which is the upper branch
Select the parent server from the 0 server list. In the example of FIG. 3, the server S112 selects the server S121 in the area 120 as the parent server, and the server S113 selects the server S121 in the area 130.
In this example, the server S131 is selected as the parent server.

Next, a method of realizing the state storage means 22 will be described. The status storage means 22 of each server holds information as shown in Table 2.

[0049]

[Table 2] The example in Table 2 is an example of the server S112, and the branch 11
0 and a server list of the branch 100 are shown. Each server list indicates information on servers belonging to the branch in the order of priority in determining the parent server, with the parent server of the branch at the top. For example, for the branch 110, the parent server is Sll, and the server that becomes the parent server when Sll is stopped is S121. The tree information of the server includes the identifier of the server, the time at which the server was finally confirmed to be operating normally (final confirmation time) Tnnn (T111, T121,...), And the ability of the server to become a parent server. And information P indicating whether or not the information is included. In the example of Table 2, the server Sl
13 indicates that the final confirmation time is T113. “P” after T113 is the server Sl11.
3 has the ability to be a parent server. If the server does not have the ability to be the parent server, the character at that position is "C".
Becomes

By selecting a branch to which the server belongs as a child in the server tree information 21, a dependent branch can be obtained. From the example of Table 2, the server S112
Is a branch 110.
In Table 2, the ladder level 2 indicates a dependent branch, and the ladder level 1 indicates a higher branch thereof.

Next, the trigger of the activation of the parent determining means 23 will be described. Registration request transmitting means 17, registration request receiving means 1
3 transmits and receives a registration request message and a registration response message by TCP / IP. The format of the message and the processing of the message will be described later. Registration request transmission means 17
Acquires the dependent branch and the identifier of the parent server of the dependent branch from the state storage means 22, and periodically tries to transmit a registration request message to the parent server at a predetermined cycle. When the parent server is stopped for some reason and the TCP / IP connection with the parent server cannot be established, the registration request transmitting means 17 inputs the dependent branch and the identifier of the parent server to the parent determining means 23. Then, an update instruction is issued.

First, the parent determining means 23 deletes the identifier of the parent server from the server tree information 21 of the state storage means 22. Next, the server tree information 21 in the state storage unit 22
From the parent server of the subordinate branch. That is, the first element of the server list of the dependent branch is acquired as the identifier of the parent server. Then, when the selected parent server is itself, the upper branch of the dependent branch is set as a new dependent branch, and acquisition of the parent server is executed again.

For example, in the state shown in Table 2, that is, when the dependent branch is the branch 110 and the parent server is Sll,
If Sl11 has stopped, the parent determining means 23 of Sl12
Selects Sl12, that is, itself, as the parent server of the branch 110, makes the branch 100 a new subordinate branch, and selects S121 as the parent server. Through the above processing, the server tree is reconstructed as shown in FIG.

If it is not possible to update a new parent server from the dependent branch, the parent server is selected from the server list of the upper branch of the dependent branch, the selected server is set as the parent, and the lower server of the upper branch is selected. Is determined as a dependent branch. As a method of selecting a parent server at this time, a method of selecting a server randomly, a method of selecting a server having the shortest distance on the network from the server, and the like can be considered.

For example, if neither the server S112 nor the server S113 has the ability to be a parent server, the parent server determination means 23 of the server S112 sets the server S121 as the parent server.
Select Then, “Branch” is sent to the server S121.
A registration request message 16 with Id = BranchlOO / S121 "is sent out. The BranchlOO / S121 means a branch below the branch 100 and having the server S121 as a parent.
Upon receiving this, the server S121 registers the server S112 in the branch 120, and transmits a registration response message 12. By the above processing, the server tree is reconstructed as shown in FIG. As still another embodiment, a method of selecting the branch 100 as the dependent branch can be considered.

FIG. 4 shows a processing flow of the parent updating means summarizing the above. In FIG. 4, the parent determining means 23 determines that the parent server has been stopped for some
When the ID of the stopped parent server is input from the registration request transmitting means 17 when the / IP connection cannot be established, the following parent update processing is performed.

First, the status storage means 2 stores the identifier of the parent server.
2 is deleted from the server tree information 21 (step 40).
1). Next, the server tree information 21 in the state storage unit 22
To obtain a registered branch (step 40)
2). That is, the branch to which the own server belongs as a child is acquired as a registered branch. Next, the server list of the registered branch is obtained (step 403). Thereafter, the identifier of the server with the highest priority in the acquired server list is selected (step 404).

Next, it is determined whether or not the selected server has the ability to become a parent server (step 405). If it has the ability to be the parent server, the selected server is determined as the parent server (step 406). next,
It is determined whether or not the parent server is itself, and if not, the parent server update process ends.

If it is determined in step 405 that the server does not have the ability to become the parent server, the server is selected from the server list of the upper branch of the registered branch and determined as a new parent server (step 408). Then, a branch having the server belonging to the upper branch of the registered branch as a parent is set as a new registered branch (step 40).
9).

On the other hand, if the parent server is itself in step 407, it is determined whether or not the registered branch is the top-level “Top” (step 410).
If it is “Top”, there is no registered branch, and the process ends (step 411). However, "To
If it is not p ”, the registered branch is set to 1
After the upper-level branch is set as a new registered branch (step 412), the process returns to step 403 and the process is repeated. Through the above processing, the server tree is reconstructed.

Next, means for realizing the update of the state storage means 22 will be described. FIG. 5 shows the format of the registration request message 16. As shown in FIG. 5, the registration request message 11
Is a RegisterRequ indicating that it is a registration request message
est, server identifier ServerId = S112, dependent branch identifier
BranchId, ParentCapability indicating whether the sending server of the registration request message has the ability to be the parent server is 1
It is composed of information as a set. Where Parent
Capability = YES means that it has the ability to be a parent server.

FIG. 6 shows the format of the registration response message 11. As shown in FIG. 6, the registration response message 11 includes a response code Response = OK or Response = ParentMoved,
It is composed of information consisting of branches.
In the description starting with “Branch =”, the word after that indicates the identifier of the branch, and the portion enclosed by {} indicates server list information of the branch.

Upon receiving the registration request message 11 as shown in FIG. 5, the registration request processing means 14 first obtains the server list of the subordinate branch of the registration request message 11 from the state storage means 22. If the parent server of the dependent branch is another server, the response code is “ParentMoved”; otherwise, the response code is “OK”. If the response code is "OK" and the acquired server list does not include the identifier of the server that transmitted the registration request message, the server identifier is added to the server list. Then, the last confirmation time of the server in the server list is rewritten to the current time, and the server tree information 21 of the state storage unit 22 is updated. FIG. 7 shows the above processing flow.

In FIG. 7, the registration request processing means 14
When the registration request message 11 as shown in FIG. 5 is received, first, the server list of the dependent branch (registered branch) of the registration request message 11 is obtained from the state storage unit 22 (step 701). Next, the identifier of the parent server is acquired from the acquired server list (step 702). Next, it is determined whether or not the parent server indicated by the acquired server list is itself (step 703). If it is, the server sends a registration request message to the server list held by itself. It is determined whether or not the server is included (step 704). If not, the identifier of the server that transmitted the registration request message is additionally registered as a server list of the server tree information 21 of the state storage unit 22. (Step 705).

However, if it is included, the last confirmation time of the server which transmitted the registration request message in the server list is rewritten to the current time, and the server list in the state storage means 22 is updated (step 706). Thereafter, the response code is set to "OK" (step 707), and the server list of the registered branch held in the state storage means 22
The server list of the upper branch of the registered branch is set as server tree information to be included in the registration response message (step 709), and the registration response message including the response code and the server tree information is transmitted. On the other hand, in step 703, if the parent server is not the server itself, but the server itself is a child server, the response code is set to “ParentMoved” (step 708), and the process proceeds to step 709.

When the registration response processing means 20 receives the registration response message 18, the registration response processing means 20 changes the server list of the branch whose server list is included in the registration response message among the server lists included in the server tree information 21 in the state storage means 22. Is rewritten by the server list included in the registration response message. If the response code is “ParentMoved”, a registration request message is transmitted to the new parent server. FIG. 8 shows the above processing flow.

In FIG. 8, the registration response processing means 20
When the registration response message 18 is received, the server tree of the state storage unit 22 is updated with the server tree included in the registration response message 18 (Step 801). That is, of the server list included in the server tree information 21 in the state storage means 22, the server list of the branch whose server list is included in the registration response message is rewritten with the server list included in the registration response message. Next, if the response code is "ParentMoved"
It is determined whether it is “OK” (step 802), and “Parent
If the response code is "Moved", a registration request message is transmitted to the new parent server having the parent server identifier included in the registration response message 18 (step 803). Ends the processing.

FIG. 9 shows an embodiment of a server network in which the servers of the present invention are arranged for each region. In FIG.
The rectangle of R represents the relay device, the character string starting with S represents the identifier of the server, and the rectangle surrounding this represents the server.
Here, the area 120 is divided into areas 121, 122, and 123, and the server 121 is assigned to these areas 121 to 123.
~ S123 is arranged, and the area 130 is further changed to the area 131,
132, 133, and these areas 131-133
Servers S131 to S133 are located in
0 is divided into regions 111, 112, and 113, and servers S111 to S113 are arranged in these regions 111 to 113. The servers between the regions generate a parent-child relationship via the relay device R. A connection structure having a tree structure as shown in FIG. The numbers “5”, “10”, “2” added to the line connecting the server
"0" and the like represent the line capacity. With this configuration, even when a server in a certain area is stopped due to a failure, the tree-structured connection relationship is reconstructed so as to avoid the failure, and data service can be performed smoothly.

The tree-structured connection relationship construction process performed by the server can be recorded on a recording medium such as a CD-ROM and provided to a computer user. Further, in the above description, the case where a new connection relationship is reconstructed when the server is stopped for some reason has been described. However, even when a new server is added to any branch, the addition is performed. By activating the process of determining a parent server in a new server, the server can be automatically incorporated into the server tree structure.

[0070]

As is apparent from the above description, according to the present invention, when service data is transferred in a hierarchical manner for efficiency, even if a certain server is stopped due to a failure, the stopped server can be used. It is possible to continue the transfer of service data while avoiding it, and to improve the reliability of the system. Even if there is no other server that can be the parent of the branch where the parent server has stopped, the transfer of service data to another server belonging to the branch can be continued. As a result, it is possible to distribute servers while providing efficient service data transfer, and to provide a highly reliable and high throughput data service.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of a server according to the present invention.

FIG. 2 is a diagram illustrating an example of a connection relationship of a tree structure of a server and a method of restructuring.

FIG. 3 is an explanatory diagram when a parent server of another branch is selected.

FIG. 4 is a flowchart illustrating a procedure of a parent update process in a parent determination unit.

FIG. 5 is a diagram showing an example of the content of a registration request message.

FIG. 6 is a diagram showing an example of the content of a registration response message.

FIG. 7 is a flowchart showing processing when a registration request message is received.

FIG. 8 is a flowchart showing processing when a registration response message is received.

FIG. 9 is a diagram showing an embodiment in which the present invention is applied to servers arranged in regions.

FIG. 10 is a configuration diagram of a conventional server used for a data distribution service.

FIG. 11 is an explanatory diagram when a parent server is switched in a conventional server configuration.

FIG. 12 is a flowchart showing processing when a registration request message is received in a conventional server configuration.

FIG. 13 is a flowchart showing processing when a registration response message is received in a conventional server configuration.

FIG. 14 is a diagram showing an example of a tree structure connection relationship in a conventional server configuration.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kimihiko Fukami 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation F-term (reference) 5B045 BB11 GG06 JJ46 5K033 CB17 DA01 DA16 DB12

Claims (12)

[Claims] 1. A server comprising a plurality of servers each having, as a branch, a set of a parent server and child servers of the parent server, and a subordinate branch having a branch to which a certain server belongs as a child.
State storage means for storing server tree information including a list of server identifiers belonging to the dependent branch and a list of server identifiers in an upper branch of the dependent branch in such a manner that the priority in the selection of the parent server and the parent server can be determined; A method for constructing a server tree structure in which a plurality of servers are connected in a tree structure in a hierarchical parent-child relationship, wherein a registration including a server identifier and a dependent branch identifier is provided from a child server of a dependent branch to a parent server. A request message is transmitted, and a registration response message including a list of server identifiers of the dependent branch and a list of server identifiers in a higher branch of the dependent branch is received from the parent server, and a list of server identifiers of the branches included in the registration response message And the brass stored in the status storage means in the server. A first step of updating a list of server identifiers of a plurality of sub-branches indicated by the registration request message in the server identifier list received by the status storage means in the own server; A second step of updating the server identifier list to include the child server, and further transmitting a registration response message including the server identifier list of the branch and the server identifier list of the upper branch to the child server; A third step of detecting a stop of the parent server in each branch and selecting a new parent server in accordance with server tree information held by the state storage means in the own server;
A method of constructing a server tree structure in which a plurality of servers are connected in a tree in a hierarchical parent-child relationship by executing the first to third steps. 2. In the third step, when the new parent server in the dependent branch is the own server, the parent server of the branch indicated by the status storage means in the own server is set as a new dependent branch. The method according to claim 1, further comprising a fourth step of selecting a server tree structure. 3. In the fourth step, when it is impossible to select a new parent server in the dependent branch, the server identifier of the upper-level branch of the dependent branch held by the state storage means in the own server is set. The method according to claim 2, further comprising a fifth step of selecting a parent server from a list. 4. A server network system in which a set of a parent server and child servers of the parent server is connected as a branch, and a plurality of servers having a branch to which a certain server belongs as a subordinate branch are connected in a tree structure in a hierarchical parent-child relationship. Server tree information including a list of server identifiers belonging to a dependent branch and a list of server identifiers in a higher-order branch of the dependent branch in such a manner that each server can determine the parent server and the priority in the selection of the parent server. A registration request message including a server identifier and a dependent branch identifier from the child server of the dependent branch to the parent server, and a list of server identifiers of the dependent branch and a server in the upper branch of the dependent branch. A registration response message containing a list of identifiers from the parent server First processing means for receiving and updating a list of server identifiers of the branches held by the status storage means in the server according to the list of server identifiers of the branches included in the registration response message; Receiving the message, updating the server identifier list of the dependent branch indicated by the registration request message in the server identifier list held by the status storage means in the own server so as to include the child server, and further updating the server identifier list of the branch Second processing means for transmitting a registration response message including a list of server identifiers higher than the branch to the child server; detecting the stop of the parent server in each branch; Third processing means for selecting a new parent server according to the server tree information held Server network system according to claim Rukoto. 5. The third processing means, when the new parent server in the dependent branch is the own server, sets the upper branch of the branch indicated by the status storage means in the own server as a new dependent branch. The server network system according to claim 4, further comprising a parent update processing means for selecting a server. 6. When the parent update processing means cannot select a new parent server in the dependent branch, the parent update processing means stores a server identifier of a higher-level branch of the dependent branch held by the state storage means in the own server. The server network system according to claim 5, wherein a parent server is selected from a list. 7. A server network system in which a set of a parent server and a child server of the parent server is connected as a branch, and a plurality of servers having a branch to which a certain server belongs as a subordinate branch are connected in a tree structure in a hierarchical parent-child relationship. The server stores server tree information including a list of server identifiers belonging to a dependent branch and a list of server identifiers in a higher-order branch of the dependent branch in such a manner that the priority order in selecting the parent server and the parent server can be determined. Transmitting a registration request message including a server identifier and a dependent branch identifier from the child server of the dependent branch to the parent server, and a list of server identifiers of the dependent branch and a server identifier of a higher order branch of the dependent branch. Registration response message containing list and parent server First processing means for receiving and updating a list of server identifiers of the branches held by the status storage means in the server according to the list of server identifiers of the branches included in the registration response message; Receiving the message, updating the server identifier list of the dependent branch indicated by the registration request message in the server identifier list held by the status storage means in the own server so as to include the child server, and further updating the server identifier list of the branch Second processing means for transmitting a registration response message including a list of server identifiers higher than the branch to the child server; detecting the stop of the parent server in each branch; Third processing means for selecting a new parent server according to the server tree information held Server. 8. The third processing means, when the new parent server in the dependent branch is the own server, sets the upper branch of the branch indicated by the status storage means in the own server as a new dependent branch. The server according to claim 7, further comprising a parent update processing unit for selecting a server. 9. When the parent update processing unit cannot select a new parent server in the dependent branch, the parent update processing unit may determine a server identifier of a higher-level branch of the dependent branch held by the state storage unit in the own server. The server according to claim 8, wherein a parent server is selected from a list. 10. A server comprising a plurality of servers each having a set of a parent server and a child server of the parent server as a branch and a branch to which a certain server belongs as a child as a dependent branch, wherein each server has a priority in selecting the parent server and the parent server. State storage means for storing server tree information including a list of server identifiers belonging to the dependent branch in a format in which the order can be determined, and a list of server identifiers in an upper branch of the dependent branch; Recording a program for constructing a server tree structure connected in a tree in a parent-child relationship, wherein a registration request message including a server identifier and a dependent branch identifier from a child server of a dependent branch to a parent server In the list of server identifiers of the subordinate branch and the upper branch of the subordinate branch. A registration response message including the list of server identifiers from the parent server, and a list of the server identifiers of the branches held by the state storage means in the own server according to the list of the server identifiers of the branches included in the registration response message. A first process for updating; receiving the registration request message from the child server; and a server identifier list of a subordinate branch indicated by the registration request message in the server identifier list held by the state storage means in the own server is the child server. And transmitting a registration response message including a server identifier list of the branch and a higher-level server identifier list of the branch to the child server, and stopping the parent server in each branch Is detected, and the server tree information held by the state storage means in the own server is Third processing and recording medium recording server tree structure construction program including to elect a new parent server are. 11. In the third process, when the new parent server in the dependent branch is the own server,
11. The system according to claim 10, further comprising a parent update process of selecting a parent server as a new subordinate branch of a branch indicated by the status storage means in the own server.
A recording medium according to claim 1. 12. In the parent update processing, when it is impossible to select a new parent server in a dependent branch, a list of server identifiers in an upper branch of the dependent branch held by the state storage means in the own server. 12. The recording medium according to claim 11, further comprising: a process of selecting a parent server from.