JP2003085070A - Content delivery system, content copying method and multicast method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a content delivery system that can quickly register contents in each of a plurality of distributed delivery servers and can reduce network cost thereof. SOLUTION: The content delivery system is so designed that the plurality of distributed delivery servers register and hold contents from content holder terminals and that any delivery server delivers contents to a player device. Each delivery server has a content accumulating part for registering and holding external contents and a content distributing part for copying and registering the contents registered and held therein in another delivery server. The content holder terminals have a content registering part for initially registering contents in a proximate delivery server. The content holder terminals initially register contents in a proximate delivery server, and with the delivery server as a direct or indirect starting point, the contents are copied and registered in each of the other delivery servers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a content distribution system, a content copy method, and a multicast method, which can be applied, for example, when a plurality of distribution servers distribute and distribute the content.

[0002]

2. Description of the Related Art Conventionally, as a technique for distributing multimedia digital contents on the Internet, there is a technique for distributing by a streaming system.

In the streaming system, the player device for reproducing the content does not have to wait for all the multimedia content files to be downloaded,
Playback is performed while receiving the video data and audio data delivered from the delivery server as a stream.

In the case of distributing contents via the Internet, if there is only one distribution server, access from a large number of player devices concentrates, which causes an increase in network traffic and an increase in load on the distribution server. This will lead to a decline in the performance of the distribution service.

Therefore, conventionally, a technique of preparing a plurality of distribution servers and mirroring them to distribute the load is used.

This distributed technology is called content routing, content caching, etc. For example, as shown in FIG. 2, the distribution server is divided into a center server 1 and a cache server 2, and the same content as the center server 1 is registered. By preparing a plurality of cache servers 2 at the edge of the core network (for example, the Internet) 3 and allowing the player device 4 to receive the content distribution from the cache server 2 (or the center server 1) closest to the player device 4, network traffic and distribution are achieved. This is a technology that distributes the load on the server.

Normally, the network (core network) 3 between the center server 1 and the cache server 2 is
Since the network 5 between the cache server 2 and the player device 4 is a dedicated line or backbone network and is an access network, the cost related to distribution is lower than that of the core network 3. Therefore, the cost is kept low by distributing the network traffic by content caching.

[0008]

However, in the method described above, the content holder who creates and / or owns the content to be stream-distributed needs to register the content in the original distribution server (center server 1).

Since the terminal 6 of the content holder is also usually connected to the access network, in order to register the content in the center server 1, the content has to pass through the core network (for example, the Internet) 3.

At this time, since the core network 3 between the center server 1 and the content holder terminal 6 generally has a high communication cost, enormous network cost and time are required to register the content. In particular, if the content holder needs to perform content registration work many times in order to confirm the content distribution, the cost of the core network becomes high each time. In practice, even if the created content is registered in the distribution server (center server 1), since the distribution is stream distribution, the reproduced content (image or sound) is often slightly different from what the content holder intended. , Re-registration after modification will also occur.

It is also conceivable that each content holder owns the distribution server and confirms with the distribution server, but (1) the cost of the distribution server is borne by the content holder, and (2) the actual core. Since it is confirmed in a local network environment that does not pass through a network or an access network, there is a problem that it is not sufficient for confirmation of actual content distribution, and therefore it cannot be adopted.

Further, conventionally, the content holder (or the content holder terminal) does not know which cache server 2 is the closest, and the content holder (or the content holder terminal) independently writes the content to the cache server 2. There is also no function to register and deliver. Therefore, the content holder (or the content holder terminal) registers the content in the center server 1 and then streams and confirms the content from the center server 1, or after registering the content in the center server 1,
Wait for the content to be copied from the center server 1 to the cache server 2 near the content holder terminal,
The content distribution from the cache server 2 must be confirmed.

Furthermore, when copying the content from the center server 1 in which the content from the content holder terminal is first registered to a plurality of cache servers 2, when there are a large number of cache servers 2 or at a distance from the center server 1. When there is the cache server 2, there is a problem that it takes a long time before the content is copied and registered in all the cache servers 2.

Therefore, even when a plurality of content distribution servers are distributed, there is a demand for a content distribution system that can quickly register the content to each distribution server and can suppress the network cost at that time. .

There is also a demand for a content copy method suitable for registering the same content in a plurality of distribution servers. In other words, a multicast method suitable for copying and transmitting data from a copy source node to a plurality of copy destination nodes is required.

[0016]

In order to solve such a problem, according to the first aspect of the present invention, a plurality of distribution servers distributed in a network register and hold the content transmitted from a content holder terminal. In the content distribution system in which the distribution server distributes the content to the player device that receives and reproduces the content, (1)
Each of the distribution servers has (1-1) a content storage unit that registers and holds content provided from an external device, and (1)
-2) It has a content distribution section for copying and registering the content registered and held by itself to another distribution server, and
(2) The content holder terminal has a content registration unit for initially registering the content in the adjacent distribution server, and (3) the content holder terminal initially registers the content in the adjacent distribution server, It is characterized in that the initially registered distribution server is used as a direct or indirect starting point, and the content is copied and registered in each of the other distribution servers.

In addition, the second aspect of the present invention determines how to copy-register the content of the distribution server in which the content from the content holder terminal is initially registered, in each of the other distribution servers to which the content is registered for copying. (1) When the content is transferred to each of the other distribution servers whose copy registration source has not been determined, with (1) the above-mentioned distribution server whose copy registration source has been determined at that time. Based on the network cost, the distribution registration source distribution server is determined for each of the other distribution servers for which the replication registration source has not been determined, and (2) this determination processing is performed for the distribution registration source distribution server not determined. It is characterized in that the replication registration procedure for all the distribution servers is determined repeatedly until there are no more servers.

Furthermore, the third aspect of the present invention determines how to duplicately transfer the data of any one of the above nodes to each of the other nodes to which the data is to be duplicated and transferred in a network having a plurality of nodes. (1) The network cost at the time of data transfer to each of the other nodes whose replication transfer source is not determined, with the above-mentioned nodes for which the replication transfer source has been determined at that time as the replication transfer source. Based on this, determine the replication transfer source node for each of the other nodes above where the replication transfer source has not been determined,
(2) The determination processing is repeated until there is no above-mentioned node for which a copy-transfer source node has not been determined, and a copy-transfer procedure to all the above-mentioned nodes is defined.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION (A) First Embodiment Hereinafter, a first embodiment of a content distribution system according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of the First Embodiment FIG. 1 is a block diagram showing the configuration of the content distribution system of the first embodiment.

In FIG. 1, a plurality of access networks (two shown in FIG. 1) 10 and 20 are connected to a core network (eg, the Internet) 30.

The access networks 10 and 20 are, for example, broadband networks capable of supporting multimedia digital contents such as MPEG4 (although they may be narrow band networks), and the distribution servers 11 and 21 and the content holder terminals 12 and 22.
Alternatively, the player devices 13 and 23 are appropriately used as network elements.

It should be noted that one access network (1
0, 20) may include a plurality of distribution servers (11, 21), and a certain access network may not have distribution servers. Similarly, one access network (10, 20) may include a plurality of content holder terminals (12, 22), and a certain access network may not be provided with a content holder. The same applies to the player device, but in the situation where the number of subscribers of the content distribution system is large, the player device will exist in any access network.

In the example shown in FIG. 1, the management server 31
Is an end node of the core network 30.
It should be noted that the management server 31 does not need to be in a specific network, and each access network 10, 20
All you need is a suitable network that can be accessed from.
Also, it may be in any access network.

Each of the distribution servers 11 and 21 is a so-called server class information processing device in terms of hardware.
In the case of the first embodiment, the distribution servers 11 and 21 are equivalent to each other, and the distribution servers 11 and 21 are to be servers (corresponding to conventional center servers) in which contents are registered first. In some cases, the content may be a server (corresponding to a conventional cache server) that is distributed from another distribution server and registered. That is, a certain distribution server is in a relationship in which it is the original, the other distribution server is the mirror server, and one of the other distribution servers is the original and itself is the mirror server.

The distribution servers 11 and 21 are functionally
As described in detail about the distribution server 11, it has a content distribution unit 111, a content storage unit 112, and a content distribution unit 113.

Each content storage unit 112 registers (stores) content given from the content holder terminal 12 or another distribution server. The content storage unit 112 stores the identification information of the content holders that can register the content, and when the content for registration (including the identification information of the content holders) is given, the content storage unit 112 can register the content holders. It is to confirm whether or not to register.

Further, each content distribution unit 111 distributes (transmits) the corresponding content stored in the content storage unit 112 as stream data in response to a content distribution request from the player device (13, 23).
To do. The content distribution unit 111 stores the identification information of the user (or the player device) that can distribute the content. When the content distribution request (including the user's identification information) is given, the content distribution unit 111 distributes the content. The distribution is performed after confirming that the user is the one who obtains it.

Further, each content distribution unit 113 has a function of registering the content given from one content holder terminal and registered in all other distribution servers in cooperation with the management server 31.

Each of the content holder terminals 12 and 22 is an information processing device such as a personal computer in terms of hardware,
Functionally, as described in detail regarding the content holder terminal 12, it has a content production section 121, a content registration section 122, and a content reproduction section 123.

Each content production section 121 has a function of producing and accumulating the content to be distributed. here,
The content production unit 121 may be one that directly produces the content (production software or the like), or may be one that produces an external device via a recording medium. It should be noted that, in relation to the content correction function, it is preferable to have something that directly produces the content (production software or the like).

Further, each content registration section 122 transmits the content by the content production section 121 to a distribution server near the content holder terminal 12 to register the content. The transmission of the content to be registered in the distribution server does not have to be the transmission of the stream data, but rather the transmission as the file data which can be expected to have a high communication quality.

Here, the content registration unit 122 and the content reproduction unit 123 together with the content holder terminal 1
The distribution server information 122A that is closer to 2 is shared and stored, and the distribution server that transmits the content for registration is recognized according to the distribution server information 122A. The distribution server information 122A may describe one distribution server or may describe a predetermined number of distribution servers. In the latter case, the content registration unit 122 registers the distribution server at the next closest position when the distribution server to be registered cannot be registered due to the distribution server to be registered or the network condition of the server. Switch to the target.

The distribution server information 122A is, for example, from the content distribution system administrator when the content holder concludes a contract as the content holder with the manager (or the operator or the provider) of the content distribution system. It is given and preset in the content registration unit 122.

The content registration unit 122 also informs the management server 31 when the content registration in any of the distribution servers is confirmed.

Each content reproducing unit 123 has a function of receiving the content distribution from the distribution server immediately after the content is registered and reproducing the content. The content reproduction unit 123 is similar to the content reproduction unit (131) of the player device described later. The content reproducing unit 123 is used to confirm what happens when the registered content is distributed.

Each of the player devices 13 and 23 is an information processing device such as a personal computer in terms of hardware, and functionally has a content reproducing section 131 as shown for the player device 13 in FIG.

Each content reproducing unit 131 gives a content distribution request to a distribution server close to the player device 13, 23 to transmit the desired content and reproduce the content.

Here, the content reproducing section 131 has the information 13 of the distribution server close to the player devices 13 and 23.
1A is stored, and the distribution server that distributes the content is recognized according to the distribution server information 131A. The distribution server information 131A may also describe one distribution server, or may describe a predetermined number of distribution servers. In the latter case, the content reproduction unit 131, when the distribution server cannot distribute due to the distribution server attempting distribution, the network condition with the server, etc., distributes from the distribution server at the next closest position. Switch to.

The distribution server information 131A is provided, for example, when the user makes a contract as a user with the administrator (or the operator or the provider) of the content distribution system.
It is given by the content distribution system administrator and preset in the content reproducing unit 131.

For example, one management server 31 is provided in the content distribution system, and is a so-called server-class information processing device in terms of hardware. The management server 31 is functionally equivalent to the distribution notification unit 31.
Has 1.

The distribution notifying unit 311 is used for all distribution servers 1.
The positions 0 and 20 are stored, and when a notification is given from a content holder terminal that content registration to a distribution server is completed, the content is recorded in the registered distribution server. It notifies other distribution servers to register (distribute) the content.

As described above, with respect to the distribution server in which the content holder terminals 12 and 22 register the content by the content registration unit 122 and receive the content distribution by the content reproduction unit 123, the distribution server closer to the system administrator in advance. Is specified in. In addition, the player devices 13 and 23 are connected to the content reproduction unit 13
The distribution server that receives the content distribution according to 1 is also designated in advance as a distribution server closer to the system administrator.

Here, the close distribution server may be a distribution server having a short physical distance or a distribution server having a short communication time, and distribution with low communication cost at the time of content registration and content distribution. It could be a server,
Further, it may be a distribution server indicating that the evaluation values considering a plurality of parameters as described above are close. When a plurality of delivery servers close to each other are designated, a predetermined number of delivery servers are designated from the one having the closest determination parameter.

The distribution server located near the content holder terminal is not limited to the one located in the same access network. Similarly, the distribution server located near the player device is also located in the same access network. Not limited.

(A-2) Operation of First Embodiment Next, the operation of the content distribution system of the first embodiment will be described with reference to FIGS. 3 and 4.

Here, FIG. 3 is an explanatory diagram showing a flow of data and the like of the content distribution system of the first embodiment, and FIG. 4 is an operation flowchart of the content distribution system of the first embodiment.

In FIG. 3, the same parts as those in FIG. 1 are designated by the same reference numerals. It is also assumed that the distribution server closest to the content holder terminal 22 and the player device 23 is the distribution server 21, and the distribution server closest to the player device 13 is the distribution server 11. Below,
The case where the content holder terminal 22 is the terminal of the content registration source will be described.

The content holder uses the content holder terminal 22 of its own to produce the content to be distributed, and causes the content holder terminal 22 to hold the content. Then, from the content holder terminal 22, the nearest distribution server 21 in the ready state to receive the produced content based on the stored distribution server information.
The file is transferred to and registered (S1).

After the registration of such contents, the contents holder determines the distribution server 21 which has registered the contents.
Content is distributed to the content holder terminal 22 and reproduced, and it is confirmed whether or not the content is correctly distributed (S2, S3).

When the content is not properly delivered, the content holder corrects or recreates the content, or without modifying the content, the content holder terminal 22.
Is used to re-register in the distribution server 21 (S1A). In this case as well, the distribution server 21 that has registered the content causes the content holder terminal 22 to distribute the content and confirms whether or not the content is correctly distributed.

In the content distribution after the initial registration or the re-registration, if it is confirmed that the content is correctly distributed, the content holder is closest to the management server 31 from the content holder terminal 22. Notify the distribution server 21 that the content registration is completed (S
4).

When the management server 31 receives the content registration completion information from the content holder terminal 22, the management server 31 sends the registered content to all the other distribution servers (to the distribution server 21 closest to the content holder terminal 22). In the following, the distribution server 11 will be described) to request copying (S5). At this time, the management server 31 causes the distribution server 21 to replace all other distribution servers 11
Notify the position of.

The distribution server 21 notified of the positions of all the other distribution servers 11 copies and transmits (distributes) the content to all the other distribution servers 11 notified from the management server 31, and the other distribution servers 11 are notified. Registers the received content (S6).

The player devices (users) 13 and 23 are
If necessary, the distribution server 11 or 21 that is closest to the specified self-communicable distribution server is requested to distribute the desired content, and the requested distribution server 11 or
21 is a player device 13 or 2 that requests the content.
3, and the player devices 13 and 23 receive and reproduce the distributed content (S7). Note that the player devices (users) 13 and 23 are the distribution servers 11 that are closest to themselves.
21, set periodic content distribution,
The distribution servers 11 and 21 may manage the time and autonomously distribute the content at a predetermined date and time.

(A-3) Effect of First Embodiment As described above, according to the first embodiment, the content holder (content holder terminal) that produces / owns the content to be distributed is designated with the content. There is no need to register a lot of network traffic and time to register the content to the distribution server, since it is enough to register with the distribution server (though it may be the second closest depending on the communication status etc.). The effect is obtained.

When confirming the distribution of the content registered by the content holder terminal, the content distribution can be confirmed from the distribution server closest to the content holder terminal, so that the content distribution can be confirmed regardless of other networks. The effect is that it does not require much network traffic and time.

As an example, FIG. 5 shows an average value obtained by measuring the time required to register contents. In addition,
FIG. 5 shows a case where the Internet, which is the core network 30, is connected at 10 Mbps.

As is apparent from FIG. 5, when the content holder terminal in Tokyo registers with the distribution server in Tokyo, it is about one-third of that in the case where it registers with the distribution server in Fukuoka.
You can register at the time of. That is, the effect of the first embodiment can be confirmed.

(A-4) Modified Embodiment of First Embodiment Although various modified embodiments have been mentioned in the description of the first embodiment, the first embodiment as exemplified below is further described. Modifications to the form may be mentioned.

In the above, the case where the number of the management server 31 is one is shown, but a plurality of management servers 31 may be provided. The content holder terminal may register the content in a nearby distribution server and, when giving a notification of registration completion, notify the management server 31 near the content holder terminal of itself.

In the above description, the management server 31 is provided, but the distribution servers 11 and 21 may also function as the management server 31. That is, each of the distribution servers 11 and 21 stores the position information of all the other distribution servers, and when the registration is completed as the registration server of the original content, all other stored contents are stored. The registered content may be distributed and transmitted based on the position information (for example, address information) of the distribution server.

Further, in the above, the content is distributed without considering the difference in the attributes of the access network, but the distribution server of the distribution source or the distribution destination is the access network to which the distribution server of the distribution destination belongs. The content (data) may be modified (for example, the number of frames may be changed or the number of vertical and horizontal dots in one frame may be changed) in consideration of the attributes and the like. When the distribution source distribution server modifies the distribution destination distribution server, the correction information may be transmitted from the management server 31 together with its position information.

Furthermore, in the above description, the distribution server in which the content is first registered causes all other distribution servers to distribute and register the content. May be a distribution server. For example, an access network having a plurality of distribution servers may be registered in any one distribution server.

Also, in the above description, the distribution server in which the content is first registered causes all other distribution servers to distribute and register the content. However, the distribution registration of the content (including copy processing) is dedicated. The responsible server may be provided in the system. For example, the management server 3
1 may be used as a server dedicated to the distribution registration process. In this case, the distribution server in which the content is registered first gives the registered content to the management server 31, and the management server 31 causes all other distribution servers to distribute and register the content.

(B) Second Embodiment Next, a second embodiment of the content distribution system according to the present invention will be described in detail with reference to the drawings.

(B-1) Configuration of the Second Embodiment FIG. 6 is a block diagram showing the configuration of the content distribution system of the second embodiment, and FIG. 1 according to the first embodiment described above. The same or corresponding parts are designated by the same reference numerals.

As is clear from the comparison between FIG. 6 and FIG.
In terms of functional blocks, the content distribution system of the second embodiment has the following functional parts added to the content distribution system of the first embodiment.

That is, each content holder terminal 12,
22 includes a content production unit 1 similar to that of the first embodiment.
21, content registration unit 122 and content reproduction unit 1
In addition to 23, a proximity delivery server detection unit 124 is provided. Further, each of the player devices 13 and 23 is also provided with a proximity distribution server detection unit 132 in addition to the content reproduction unit 131 similar to that of the first embodiment. Furthermore, the management server 31 includes the distribution notification unit 3 similar to that of the first embodiment.
In addition to 11, the request routing unit 312 is provided.

In each of the content holder terminals 12 and 22, the proximity delivery server detection unit 124 added in the second embodiment is a communication for recognizing (detecting) the delivery server closest to the content holder terminals 12 and 22. The processing is performed. The proximity delivery server detection unit 124 issues a ping to all delivery servers notified from the management server 31, and sends a packet round trip time (RTT: R).
It measures the out trip time and detects the delivery server with the shortest round trip time. The detected distribution server serves as a distribution server for the content holder terminals 12 and 22 to register the content, and serves as a distribution server for distributing the content for confirming the distribution of the content.

In each player device 13, 23, the second
Proximity distribution server detection unit 132 added in the embodiment of
Is for performing a communication process for recognizing (detecting) the distribution server closest to the player device 13, 23.
The proximity delivery server detection unit 132 is, for example, the management server 3
The ping is issued to all the distribution servers notified from 1, and the round trip time (RTT) of the packet is measured to detect the distribution server having the shortest round trip time. The detected distribution server becomes the distribution server to which the player devices 13 and 23 receive the content distribution.

In the management server 31, the request routing unit 312 added in the second embodiment has the content holder terminals 12 and 22 and the player devices 13 and 23.
The location information (for example, the address on the network) of all the distribution servers is notified to the request from.

Although not shown as a functional block in FIG. 6, the management server 31 records the position information of all the distribution servers, so that the distribution notification unit 311 distributes the content first registered. It is possible to notify the server of the position information of all other distribution servers, and by the request routing unit 312,
The content holder terminals 12, 22 and the player device 13,
It is possible to notify 23 of the position information of all distribution servers.

(B-2) Operation of Second Embodiment Next, the operation of the content distribution system of the second embodiment will be described with reference to FIGS. 7 and 8.

Here, FIG. 7 is an explanatory diagram showing the flow of data and the like in the content distribution system of the second embodiment, and FIG. 8 is an operation flowchart of the content distribution system of the second embodiment.

In FIG. 7, the same parts as those in FIG. 6 are designated by the same reference numerals. Below, the case where the content holder terminal 22 is the terminal of the content registration source will be described.

The content holder uses its own content holder terminal 22 to create the content to be distributed, and causes the content holder terminal 22 to hold the content. Note that the notation of such processing is omitted in FIGS. 7 and 8.

The content holder sends a content registration request to the management server 31 using the content holder terminal 22 (S11A in FIG. 7), and the management server 3
1 is a response to the content registration request,
Return the location information of all distribution servers (S11B in FIG. 7),
Upon receiving the reply, the content holder terminal 22 issues a network ping to all distribution servers, compares the round trip times of the packets obtained as a result, and distributes the distribution server with the shortest round trip time to the closest distribution. The server is determined (S11 in FIG. 8). In the following description, it is assumed that the distribution server 21 is determined as the closest distribution server.

Then, the content holder transfers the created content from the content holder terminal 22 to the decided distribution server 21 by file transfer (S1).
2).

After registering such content, the content holder determines the distribution server 21 which has registered the content.
Content is distributed to the content holder terminal 22 and reproduced, and it is confirmed whether or not the content is correctly distributed (S13, S14).

When the content is not properly delivered, the content holder corrects or recreates the content, or without modifying the content holder terminal 22.
Is used to re-register in the distribution server 21 (S12A). In this case as well, the distribution server 21 that has registered the content causes the content holder terminal 22 to distribute the content and confirms whether or not the content is correctly distributed.

In the content distribution after the initial registration or the re-registration, if it is confirmed that the content is correctly distributed, the content holder is closest to the management server 31 from the content holder terminal 22. Notify the distribution server 21 that the content registration is completed (S
15).

When the management server 31 receives the content registration completion information from the content holder terminal 22, the management server 31 sends the registered content to all the other distribution servers (to the distribution server 21 closest to the content holder terminal 22). In the following description, the distribution server 11 will be referred to) (S16). In addition, in this case, the management server 31 adds the distribution server 21 to all other distribution servers 1.
The position information of 1 is notified.

The distribution server 21 to which the position information of all other distribution servers 11 has been notified copies and transmits (distributes) the content to all of the other distribution servers 11 notified from the management server 31, and the other distributions. The server 11 registers the received content (S17).

The player devices (users) 13 and 23 are
When receiving content distribution, a content reception request is sent to the management server 31 (S18 in FIG. 7).
A), when the management server 31 receives the content reception request, as a response to the request, the management server 31 returns the position information of all distribution servers to the player devices 13 and 23 (S18B in FIG. 7), and the player devices 13 and 23 A network ping is issued to all the delivery servers returned as a response, and the server with the shortest round trip time of the resulting packet is determined as the closest delivery server (S18).

Then, each player device (user) 13,
23 requests the determined nearest distribution server to distribute the desired content, and the requested distribution server distributes the content to the requesting player device 13, 23,
The player devices 13 and 23 receive and reproduce the distributed content (S19).

In the above description of the operation, the content holder (content holder terminals 12 and 22) decides (detects) the closest distribution server each time it tries to register content. The closest distribution server may be determined (detected) at a timing unrelated to the registration operation. For example, when the number of distribution servers in the content distribution system changes due to expansion or removal, the detection operation may be activated by the notification from the management center 31. Further, the content holder terminals 12 and 22 may periodically and autonomously activate the detection operation.

Similarly, each player device (user) 13,
23 may also determine (detect) the closest distribution server at a timing unrelated to the content distribution request operation.

(B-3) Effects of the Second Embodiment The same effects as those of the first embodiment can also be obtained by the second embodiment.

According to the second embodiment, the content holder terminal itself can determine the closest distribution server, so that the content holder terminal hides the system or network configuration and transparently registers the content. Therefore, it is possible to obtain the effect that the content holder terminal is not affected even when the system is changed such as the number of distribution servers being increased or decreased or the network being changed.

Further, according to the second embodiment, the player device itself can determine the closest distribution server, so that the player device also knows the closest distribution server from itself in advance like the content holder terminal. It is no longer necessary to hide the system and network configuration from the player device and transparently deliver contents.
It is possible to obtain the effect that the player device is not affected when the system is changed, such as the number of distribution servers is increased or the network is changed.

(B-4) Modified Embodiment of Second Embodiment Although various modified embodiments have been mentioned in the description of the second embodiment described above, the second embodiment as exemplified below is further described. Modifications to the form may be mentioned.

In the modified embodiment of the first embodiment,
Reference will be omitted for those that are directly modified embodiments of the second embodiment.

In the above description, the content holder terminal or the player device has shown that all the distribution servers are the distribution servers to be detected when the nearest distribution server is detected. The distribution server may be a part of the distribution server. For example, the management center 31
When the position information of the distribution server is obtained for detection, the detection range is limited based on the position of the content holder terminal or the player device that obtained the position information, and the positions of the plurality of distribution servers within the limited range are determined. Information may be returned.

In the above description, the content holder terminal detects only the closest distribution server, but a predetermined number (or all) of distribution servers may be detected from the closest one. In this case, the distribution server that is the target of content registration is the closest distribution server, and if the distribution server cannot register due to the free storage capacity, the next closest distribution server will be the registration target. In the case where the distribution server cannot be registered and the distribution server cannot be registered, the distribution server closest to the next is selected as the distribution server to be registered. The same applies hereinafter. Similarly, the player device may detect a predetermined number (or all) of distribution servers from the closest one.

Further, in the above description, the management server 31 uses the distribution notification unit 311 and the request routing unit 312.
However, similar to the modified embodiment of the first embodiment, each distribution server may have only the function of the distribution notification unit 311. In addition, the distribution notification unit 31
1 and a request routing unit 3
The management server having 12 may be a separate server.

(C) Third Embodiment Next, a third embodiment of the content distribution system according to the present invention will be described in detail with reference to the drawings. Note that the embodiment of the content copy method according to the present invention is applied to the content distribution system of the third embodiment.

(C-1) Configuration of the Third Embodiment FIG. 9 is a block diagram showing the configuration of the content distribution system of the third embodiment, which differs from FIG. 6 according to the above-described second embodiment. The same reference numerals are given to the same corresponding parts.

As is clear from the comparison between FIG. 9 and FIG.
In terms of functional blocks, the content distribution system of the third embodiment has the following functional parts added to the content distribution system of the second embodiment.

In other words, each distribution server 11, 21 has
In addition to the content distribution unit 111, the content storage unit 112, and the content distribution unit 113 similar to those in the second embodiment, a cost measurement unit 114 between other servers is provided.

The other-server cost measuring unit 114 measures the network cost at the time of transferring the content from the distribution server to another distribution server for all the other distribution servers. Here, the network cost is
It represents an evaluation value indicating the ease of transfer, and may be transfer time, transfer cost, or a combination thereof. The other-server cost measuring unit 114 is, for example, the management server 31.
A large-sized packet is sent to all the distribution servers notified from the outgoing path, and a small-sized packet that is negligible compared to the outgoing path is sent backward from the outgoing distribution server to the backward path. Pin with extension to
g is issued, the round trip time (RTT) of the packet is measured, and that time or half the time is detected as the network cost.

In the case of the third embodiment, the functional block added to the second embodiment is the cost measurement unit 114 between other servers, but the distribution notification unit 311 in the management server 31 and each distribution server. Functions and the like of the content distribution unit 113 in 11 and 21 are slightly different from those of the second embodiment.

The distribution notifying unit 311 of the third embodiment has the same function as that of the second embodiment, and further, each distribution server is arranged so that the contents are distributed to all distribution servers at the minimum network cost. It has a function of deciding the registration order of the contents to and the transfer route for the registration and notifying each distribution server of the decision contents.

That is, in the case of the third embodiment, the content is not transferred from the distribution server in which the content is initially registered to all the other distribution servers and registered (in such a case). However, in the determination of the transfer content in consideration of the network cost, the content may be transferred from another distribution server and the registered distribution server may cause the other distribution server to transfer the content for registration.

Therefore, in the case of the third embodiment, the content distribution unit 113 of each distribution server 11, 21 can function even if the distribution server 11, 21 is not the distribution server in which the content is initially registered. There is something.

(C-2) Operation of Third Embodiment Next, the operation of the content distribution system of the third embodiment will be described with reference to FIGS. 10 and 11.

Here, FIG. 10 is an explanatory diagram showing a flow of data and the like of the content distribution system of the third embodiment, and FIG. 11 is an operation flowchart of the content distribution system of the third embodiment.

In FIG. 10, the same parts as those in FIG. 9 are designated by the same reference numerals. Below, the case where the content holder terminal 22 is the terminal of the content registration source will be described.

Also in the third embodiment, the contents holder terminal 22 to the management server 3 in step S15.
The operation up to the notification of the completion of content registration to the nearest distribution server 21 is the same as the above-mentioned second operation.
It is similar to the embodiment. Also, steps S18 and S
The operation of each player device 13, 23 of 19 receiving the distribution of the content from the distribution servers 11, 21 adjacent to
This is similar to the second embodiment described above.

That is, in the third embodiment, the management server 31 registers the content in all the distribution servers after receiving the notification from the content holder terminal 22 that the registration of the content is completed in the distribution server 21 closest to the content holder terminal 22. The operation up to this is different from that of the second embodiment. The operation of this different part will be described below.

When the management server 22 receives the content registration completion information from the content holder terminal 22, the registration order and registration of the content in each distribution server are performed so that the content is distributed to all distribution servers at the minimum network cost. And determines the content of the transfer (content copy request) to each distribution server sequentially or simultaneously (S16A). Each distribution server that has received the notification from the management server 22 copies (transfers and registers the content to the designated distribution server; S17).
A). This content copy request and registration are repeated until the content is registered in all distribution servers.

Hereinafter, such steps S16A and S16
An example of the operation part composed of 17A will be described in detail.

Here, a case where the content holder terminal registers the content in the distribution server Sx (1 ≦ x ≦ n) and distributes the content to the other (n−1) distribution servers will be described with reference to FIG. The procedure will be described with reference to the flowchart.

Note that the management server 31 records the locations (position information) of the n distribution servers S1, S2, ..., Sn as an all-server list All List.

(Procedure 1) The management server 31 sets the distribution server Sx to the content registered server list Source.
Put in List.

(Procedure 2) The management server 31 controls each distribution server Si (1≤i≤n, iεSource in the content registered server list SourceList).
List), the distribution server in which the content is not registered (that is, all server list All List
The distribution path P from Si to Sj (1 ≤ j ≤ n, j ≠ i) which is each distribution server after the content registration server list Source List is excluded from the content described in i, j) network cost C
Notify to measure (i, j). Distribution server Si
After measuring the network cost C (i, j), notifies the management server 31 and the management server 31 records the notified network cost C (i, j).

Here, the network cost C (i, j)
As described above, for example, the registered distribution server Si
To the unregistered distribution server Sj, issue a ping with an extended function to send a large size packet to the outgoing path and to send a small size packet to the reverse path, which is small enough to be ignored compared to the outgoing path. Then, the round trip time (RTT) of the packet is measured.

(Procedure 3) The management server 31 uses the route P
Of (i, j), the network cost C (i,
j) small path P (k, l) (1 ≦ k ≦ n, 1 ≦ l ≦
n and Sk are content registered server list Source
e List element, Sl is a content registered server list Source List unselected element),
The distribution server Sl is the content registered server list So
urce List. At this time, the selected route P (k, l) is put in the route list Path List.

(Procedure 4) Procedures 2 and 3 are repeated (n-1) times until all distribution servers S1 to Sn are included in the content registered server list Source List to obtain the minimum cost route list Path List.

(Procedure 5) The management server 31 notifies all distribution servers S1 to Sn of the route list Path List obtained as described above.

(Procedure 6) Each distribution server Si waits for the content to be registered. Each distribution server Si (including the initially registered one) is notified of the notified route list Path.
When there is a route P (i, j) starting from the self in List, if the content is registered in the self,
The content is duplicated and registered in the distribution server Sj at the end point of the route P (i, j). In the route list, P (i, j), P
When there are a plurality of registration destinations such as (i, k), duplicate registration is performed according to the order in the route list P (i, j).

As described above, the content distribution registration is scheduled by the management server 31, so that all the distribution servers S1 to S1 can be operated at the minimum network cost.
Content can be copied and registered in Sn.

The above operation will be described in a concrete example with reference to FIGS. 13 to 15 show the case where there are five distribution servers S1 to S5, and the distribution server S1 is the distribution server in which the content is registered first.

The network cost C (i, j) between the distribution servers S1, ..., S5 is as shown in FIG.

In the procedure 1, the management server 31 sets the distribution server S1 to the content registered server list Sou.
Put in rce List.

Therefore, in the procedure 2, the management server 31 causes the distribution server S1 to route P (1,2) to the distribution servers S2 to S5 in which the content is not registered.
~ P (1,5) network cost C (1,2) ~ C
Notify to measure (1, 5), and the distribution server S1
Measures network costs C (1,2) to C (1,5). The management server 31 uses the network costs C (1,2) to C (1,5) notified by the distribution server S1.
To record.

Here, the network cost C (1,3)
Is smallest among the notified notifications, the management server 31 uses the route P in step 3 as shown in FIG.
Select (1, 3) to select the distribution server S3 that is the end point of the route.
List of registered content server Source Li
Add to st and put the selected route P (1,3) in the route list Path List.

At this point, the distribution servers S1 and S are added to the content registered server list Source List.
Since step 3 is described, step 4 returns to step 2.

In the procedure 2 returned in this way,
The management server 31 sends the distribution server S1 and S3 to the distribution server S in which the content is not registered.
2, routes P (1,2), P (1,4) to S4, S5,
P (1,5) or P (3,2), P (3,4), P
Network cost C (1,2), C of (3,5)
(1,4), C (1,5) or C (3,2), C
(3, 4), C (3, 5) are notified to be measured, and each distribution server S1, S3 notifies the network cost C (1,
2), C (1,4), C (1,5) or C (3,3
2), C (3,4) and C (3,5) are measured. The management server 31 uses the network costs C (1,2), C (1,4), C notified from the distribution servers S1, S3.
(1,5), C (3,2), C (3,4) and C (3,3
Record 5).

Here, the network cost C (3,4)
Is smallest among the notified notifications, the management server 31 uses the route P in step 3 as shown in FIG.
Select (3, 4) to select the distribution server S4, which is the end point of the route.
List of registered content server Source Li
Add to st and put the selected route P (3,4) in the route list Path List.

Even at this point, the distribution servers S1 and S3 are added to the content registered server list Source List.
And S4 are described (because not all are described), the procedure 4 returns to the procedure 2.

In procedure 2 returned in this way,
The management server 31 respectively routes P (1,2), P (1,5) or P (3,2) to the distribution servers S2, S5 whose contents are not registered for the distribution servers S1, S3 and S4. ), P (3,5) or P (4,
2), network cost of P (4,5) C (1,
2), C (1,5) or C (3,2), C (3,
5) or C (4,2) and C (4,5) are notified to be measured, and each distribution server S1, S3, S4 has a network cost C (1,2), C (1,5) or C
(3,2), C (3,5) or C (4,2), C
Measure (4,5). The management server 31 notifies the network costs C (1,2), C (1,5), C (3,2), C (3,3) notified from the distribution servers S1, S3, S4.
5), C (4,2) and C (4,5) are recorded.

Here, the network cost C (1,2)
14C, the management server 31 determines in step 3 that route P, as shown in FIG. 14C.
Select (1, 2) to select the distribution server S2 that is the end point of the route.
List of registered content server Source Li
Add to st and put the selected route P (1,2) in the route list Path List.

Even at this point, the distribution servers S1 and S are added to the content registered server list Source List.
Since S2, S3, and S4 are described (because all are not described), the procedure 4 returns to the procedure 2.

In procedure 2 returned in this way,
The management server 31 includes distribution servers S1, S2, S3 and S.
4 to the distribution server S5 in which the content is not registered, P (1, 5) or P (2,
5) or P (3,5) or P (4,5) network cost C (1,5) or C (2,5) or C (3,5) or C (4,5) should be measured And each distribution server S1, S2, S3, S4 measures the network cost C (1,5) or C (2,5) or C (3,5) or C (4,5).
The management server 31 uses the distribution servers S1, S2, S3, S
Network cost C (1,5), C notified from 4
Record (2,5), C (3,5) and C (4,5).

Here, the network cost C (4,5)
If it is the smallest among those notified, the management server 31 uses the route P in the procedure 3 as shown in FIG.
Select (4,5) to select the distribution server S5 which is the end point of the route.
List of registered content server Source Li
Add to st and put the selected route P (4,5) in the route list Path List.

At this point, all distribution servers S1 are included in the content registered server list Source List.
Since ~ S5 is described, the procedure moves to step 5.

In step 5, the management server 31 notifies all the distribution servers S1 to S5 of the route list Path List obtained as described above. Route list P at this time
The contents of the ath List are P (1,3) -P (3,
4) -P (1,2) -P (4,5).

In procedure 6, each distribution server S1, ... S
5 is waiting for the content to be registered. Each distribution server S1, ..., S5 (including those initially registered)
When a route P (i, j) having its own origin is present in the notified route list Path List,
When the content is registered by itself, the content is duplicated and registered in the distribution server Sj at the end point of the route P (i, j).

In the state immediately after the route list Path List is notified to each distribution server S1, ..., S5, the content is registered only in the distribution server S1, and the distribution server S1 is used as the starting point. The two unprocessed routes P (1,3) and P (1,2) to be processed are described in the route list Path List.
Since 3) is described first, the distribution server S1 copies and registers the content in the distribution server S3, as shown in FIG.

After such registration, the contents are registered in the distribution servers S1 and S3. With respect to these distribution servers S1 and S3, the routes P (1,2) and P (3,3) are unregistered processing routes. 4) is the route list Pa
Since it is included in the th List, as shown in FIG. 15B, the duplicate registration of the content from the distribution server S1 to the distribution server S2 and the distribution server S3 to the distribution server S are performed.
The registration of the copy of the content in the file 4 is executed almost at the same time.

After such registration, contents are registered in the distribution servers S1 to S4, and the distribution server S1 to S4 has a path P as an unregistered processing path.
Since (4,5) is included in the route list Path List, as shown in FIG.
The content is registered in the distribution server S5 for replication.

As a result, all distribution servers S1 to S5
The contents are registered in.

(C-3) Effects of Third Embodiment The third embodiment can also achieve the same effects as those of the first and second embodiments.

Further, according to the third embodiment, each distribution server measures each network cost when the content holder terminal distributes and registers the content from one distribution server to all other distribution servers. Since the management server schedules and distributes the lowest network cost so that it can be selected,
The effect that the network traffic and the cost can be suppressed can be expected more than the above embodiment.

(C-4) Modified Embodiment of Third Embodiment Although various modified embodiments have been referred to in the description of the third embodiment described above, a third embodiment as exemplified below is further provided. Modifications to the form may be mentioned.

It is to be noted that the description of the modified embodiments of the first and second embodiments, which are the modified embodiments of the third embodiment as they are, is omitted.

In the above description, the network cost is measured for each content registration operation, but the network cost may be measured at a timing unrelated to the content registration operation. For example, if the distribution server is added or removed, the management server 31
Let each distribution server measure the network cost for all other distribution servers, collect and hold the measured contents, and use the held network cost for each content registration operation to The order of registration with each distribution server may be determined. Further, for example, the management server 31 periodically causes each distribution server to measure the network cost of all other distribution servers, collects and holds the measured content, and performs the registration operation of the content each time. Use the network cost you have,
The order of registration of the contents in each distribution server may be determined.

In the above description, the registration order of the contents to each distribution server is determined for each content registration operation. However, for each distribution server, the distribution server first registers the contents. In such a case, the registration order is determined in advance by the method as described above and held by the management server 31, and when the initial registration completion from a certain content holder terminal to a certain distribution server is notified, the management server The registration order of the initially registered distribution server may be taken out from the registered registration order and given to all distribution servers. The above-described pre-determination of the registration order is also performed, for example, when the distribution server is additionally installed or removed, or periodically.

As described above, if the registration order of the contents in each distribution server is determined in advance, the determined registration order may be held in each distribution server instead of the management server 31. good. For example, let each distribution server hold the registration order when the distribution server is the initially registered distribution server, and when the initial registration is completed,
Instead of waiting for the notification from the management server 31, the distribution server may perform copy registration with another distribution server. In this case, together with the content to be transferred, information defining the registration order (for example, the above-mentioned route list Path
List) also needs to be transferred.

Even when the management server 31 determines the registration order or holds the registration order,
The management server 31 stores information about the registration order only in the initially registered distribution server (for example, the route list Path described above).
List), and the information defining the registration order may be transferred to another distribution server together with the content to be transferred.

In the third embodiment, the distribution server is not classified into a center server and a cache server.
Even when the distribution server is classified into a center server and a cache server, the method of determining the registration order of the content to each distribution server as described above can be applied. For example, although the initial registration of content is performed by the center server, the above-described determination method can be applied when determining how to register content in all cache servers, and in particular, the distribution server (cache server) It is effective when the number of additional facilities is increased.

The other distribution servers that register the contents of the initially registered distribution server do not have to be all the other distribution servers, and may be some distribution servers. However, even if only a part of the distribution servers is registered, the plurality of distribution servers may be regarded as all the distribution servers and the process of the procedure shown in FIG. 12 may be executed. .

In the above description, one route is added to the route list Path List in the procedure 3 once, but two or more routes are added to the route list Path List.
to be added to the route list Path List
The relationship may be accelerated.

For example, in the procedure 2 in which the distribution servers S1 and S3 are described in the content registered server list Source List and the process returns (see FIG. 14B),
The management server 31 notifies the network costs C (1,2), C (1,4) of the distribution servers S1, S3,
C (1,5), C (3,2), C (3,4) and C
When (3, 5) is obtained, the minimum network cost C
Not only is the route P (3,4) of (3,4) added to the content registered server list Source List, but it is different from the route P (3,4) of the minimum network cost C (3,4). The route P (1,2) having the lowest network cost C (1,2) among the routes of the starting point may be added to the content registered server list Source List. Such plural additions may be performed for all routes having different starting points.

In such a case, there are many cases in which a plurality of distribution servers execute copy registration almost at the same time, and it can be expected that registration to all distribution servers will be performed quickly.

(D) Other Embodiments The above third embodiment is an application of the embodiment of the content copy method according to the present invention. The technical idea of the content copy method of registering content in all other distribution servers can also be applied to the multicast method.

It is possible to apply the multicast method in which the data possessed by one node of the network is duplicated and supplied to all or some of the other nodes.

[0159]

According to the first aspect of the present invention, even when a plurality of content distribution servers are distributed, it is possible to quickly register the content to each distribution server and reduce the network cost at that time. It is possible to provide a possible content distribution system.

Also, according to the second aspect of the present invention, it is possible to provide a content copy method suitable for registering the same content in a plurality of distribution servers.

Furthermore, according to the third aspect of the present invention, it is possible to provide a multicast method suitable for copying and transmitting data from a copy source node to a plurality of copy destination nodes.

[Brief description of drawings]

FIG. 1 is a block diagram showing a functional configuration of a content distribution system according to a first embodiment.

FIG. 2 is a block diagram showing a configuration of a conventional content distribution system.

FIG. 3 is an explanatory diagram showing a flow of data and the like of the content distribution system of the first embodiment.

FIG. 4 is an operation flowchart of the content distribution system according to the first embodiment.

FIG. 5 is an explanatory diagram of effects of the content distribution system according to the first embodiment.

FIG. 6 is a block diagram showing a functional configuration of a content distribution system according to a second embodiment.

FIG. 7 is an explanatory diagram showing a flow of data and the like of the content distribution system of the second exemplary embodiment.

FIG. 8 is an operation flowchart of the content distribution system according to the second embodiment.

FIG. 9 is a block diagram showing a functional configuration of a content distribution system according to a third embodiment.

FIG. 10 is an explanatory diagram showing a flow of data and the like of the content distribution system of the third exemplary embodiment.

FIG. 11 is an operation flowchart of the content distribution system according to the third embodiment.

FIG. 12 is a flowchart showing a procedure for determining the order of distribution servers for registering contents in the content distribution system according to the third embodiment.

FIG. 13 is a specific explanatory diagram (1) of a method of determining the order of distribution servers for registering content in the content distribution system of the third embodiment.

FIG. 14 is a specific explanatory diagram (2) such as a method of determining the order of distribution servers for registering content in the content distribution system of the third embodiment.

FIG. 15 is a specific explanatory diagram (3) of a method of deciding the order of distribution servers for registering contents in the content distribution system of the third embodiment.

[Explanation of symbols]

10, 20 ... Access network, 11, 21 ... Delivery server, 111 ... Content distribution section, 112 ... Content storage section, 113 ... Content distribution unit, 114 ... Cost measurement unit between other servers, 12, 22 ... Content holder terminal, 121 ... Content Production Department, 122 ... Content registration unit, 123 ... the content reproduction section, 124 ... Proximity distribution server detection unit, 13, 23 ... Player device, 131 ... a content reproducing section, 132 ... Proximity distribution server detection unit, 30 ... Core network (for example, Internet), 31 ... Management server, 311 ... Distribution notification unit, 312 ... Request routing unit.

Claims (8)

[Claims] 1. A plurality of distribution servers distributed in a network register and hold the content transmitted from a content holder terminal, and one of the distribution servers distributes the content to a player device that receives and reproduces the content. In the content distribution system, each of the distribution servers has a content storage unit that registers and holds the content given from the external device, and a content distribution unit that causes the other registered distribution server to copy and register the content registered and held by itself. The content holder terminal has a content registration unit that initially registers the content to the distribution server that is close to the content holder terminal, and the content holder terminal initially registers the content to the distribution server that is close to the distribution server. The server is a direct or indirect origin, and each of the above A content distribution system characterized by duplicating and registering content in a communication server. 2. The content distribution system according to claim 1, wherein the content holder terminal stores and holds information on the distribution server in proximity to which the content holder terminal initially registers content. 3. The content holder terminal includes a proximity delivery server detection unit that obtains a proximity evaluation value with each of the delivery servers and detects the delivery server in proximity to perform initial registration of content. The content distribution system according to claim 1. 4. Providing the information of each of the other distribution servers that duplicate-registers the content to the distribution server in which the content is initially registered, and the content is duplicated in the other distribution server from the distribution server in which the content is initially registered. It has the other server information provision apparatus which makes it register.
3. The content distribution system according to any one of 3 above. 5. Copying based on a network cost at the time of content transfer between two distribution servers in a plurality of distribution servers including the distribution servers to which content is registered for duplication and the distribution server in which the content is initially registered. A content distribution method decision notifying device that constructs a route relationship between a distribution source distribution server and a distribution registration destination distribution server so that it can be registered in all of the distribution servers that require content registration, and notifies each distribution server The content distribution system according to any one of claims 1 to 3, characterized by having. 6. Each of the distribution servers has an inter-server cost measuring unit that measures the network cost of a route from the self to another distribution server and notifies the content distribution method decision notification device of the network cost. The content distribution system according to claim 5, characterized in that 7. A content copy method for determining how to copy-register the content of a distribution server in which the content from the content holder terminal is initially registered, to each of the other distribution servers to which the content is registered for copy. , The replication registration source is determined at each point, and the replication registration source is determined based on the network cost when transferring the content to each of the other distribution servers whose replication registration source is not determined. The replication registration source distribution server for each of the other distribution servers that are not registered is determined, and this determination process is repeated until all the distribution servers for which the replication registration source distribution server has not been determined are exhausted. Content copy method, characterized by defining a copy registration procedure of. 8. A multicast method for determining, in a network having a plurality of nodes, how to replicate and transfer the data of any one of the nodes to each of the other nodes to which the data is to be replicated and transferred. Based on the network cost at the time of data transfer to each of the above-mentioned other nodes for which the copy-transfer source has been set, the above-mentioned nodes for which the copy-transfer source has been set are set as the copy-transfer source.
Determine the node that is the source of the copy transfer to each of the other nodes where the copy transfer source has not been determined, and repeat this determination process until all the above nodes for which the copy transfer source node has not been determined disappear. A multicast method characterized by defining a copy transfer procedure.