Server and connection destination server switching control method

Abstract
By providing a load measuring unit measuring the load of a cache server, an overflown load determination unit determining whether the measured load is overflown, by comparing the measured load with a predetermined value, a connection destination retrieval request information transmitting unit transmitting connection destination retrieval request information for requesting to search for the connection destination of a load source cache server, to a contents server if it is determined that the load is overflown, a connection destination information receiving unit receiving connection destination information indicating the retrieved connection destination, from the contents server that has transmitted the connection destination retrieval request information and a switch request transmitting unit transmitting switch request information for requesting to switch the connection to the connection destination indicated by the connection destination information, based on the received connection destination information, the load of each cache server can be distributed.
Description

BRIEF DESCRIPTION OF THE DRAWINGS


FIG. 1 shows the problem of the prior art;



FIG. 2 shows the summary of the present invention;



FIG. 3 shows an example of the network configuration adopting the present invention;



FIG. 4 shows an example of the functional configuration of a contents sever;



FIG. 5 shows an example of the functional configuration of the cache server;



FIG. 6 shows a contents delivery network for showing an example of the operation of the present invention;



FIG. 7 shows an example of the operation of switching the connection destination of a two-order lower cache server to another cache server, due to the load increase of the highest-order cache server;



FIG. 8 shows an example of information included in a connection destination switch request message;



FIG. 9 shows an example of information included in a connection destination switch response message;



FIG. 10 shows an example of information included in a switch destination notice message;



FIG. 11 shows an example of information included in a switch destination response message;



FIG. 12 shows an example of information included in a connection request message;



FIG. 13 shows an example of information included in a connection response message;



FIG. 14 shows an example of the operation of switching the connection destination of a two-layer lower cache server to another two-layer lower cache server, due to the load increase of the highest-order cache server;



FIG. 15 shows an example of information included in a connection destination retrieval request message;



FIG. 16 shows an example of information included in a connection destination retrieval response message;



FIG. 17 shows another example of the operation of switching the connection destination of a two-layer lower cache server to another two-layer lower cache server, due to the load increase of the highest-order cache server;



FIG. 18 shows an example of the operation of switching the connection destination of a two-layer lower cache server to a contents sever, due to the load increase of the highest-order cache server;



FIG. 19 shows an example of the operation in the case where the connection is switched, due to the decrease of overlapped cache contents between a parent cache server and a child cache server;



FIG. 20 shows an example of the operation in the case where a request for switching a connection to a cache server in which overlapped contents to cache is large is received from a contents sever;



FIG. 21 shows an example of the connection destination switching operation in the case where the amount of contents requested by a child cache server relatively increases and the child cache server is directly connected to a contents sever;



FIG. 22 shows an example of the connection destination switching operation in the case where the amount of contents requested by a child cache server relatively increases and the connection of the child cache server is switched to another cache server;



FIG. 23 shows an example of the operation in the case where a failure occurs in a parent cache server and the connection destination of the cache server is modified;



FIG. 24 shows an example of the operation of switching the connection destination of the highest-order cache server to another cache server;



FIG. 25 shows an example of the operation of modifying cache update under the lead of a cache server to cache update under the lead of a contents sever;



FIG. 26 shows an example of the operation of modifying cache update under the lead of a contents sever to cache update under the lead of a cache server;



FIG. 27 shows an example of the operation of a cache server at the time of receiving a connection destination retrieval request;



FIG. 28 shows an example of the operation of a cache server at the time of receiving a connection switch request;



FIG. 29 shows an example of the operation of a cache server at the time of receiving a connection switch response;



FIG. 30 shows an example of the operation of the parent cache server at the time of receiving a switch destination cache server notice;



FIG. 31 shows an example of the operation of a child cache server at the time of receiving a switch destination cache server notice;



FIG. 32 shows an example of the operation of a cache server at the time of receiving a switch destination cache server notice response;



FIG. 33 shows an example of the operation of a cache server at the time of receiving a connect request;



FIG. 34 shows an example of the operation of a cache server at the time of receiving a connect response;



FIG. 35 shows an example of the operation of a cache server of transmitting a child cache server connection switch request to a higher-order server at the time of heavy load;



FIG. 36 shows an example of the operation of a cache server of transmitting a connection switch request to a child cache server at the time of heavy load;



FIG. 37 shows an example of the operation of a contents sever in the case where a connection destination is switched due to the load status of the contents server;



FIG. 38 shows an example of the operation of a contents sever at the time of receiving a connection destination retrieval request;



FIG. 39 shows an example of the operation of a contents sever at the time of receiving a connection destination switch request;



FIG. 40 shows an example of the operation of a contents sever at the time of receiving a connect request;



FIG. 41 shows an example of the operation of a contents sever at the time of receiving a connection destination retrieval response;



FIG. 42 shows an example of the operation of a contents sever at the time of receiving a connection destination switch response;



FIG. 43 shows the hardware configurations of a contents sever and cache server of the present invention; and



FIG. 44 shows how to load the connection destination server switching control program of the present invention onto a computer.


Claims
  • 1. A cache server for caching contents in a contents server and delivering the contents to a client according to a request of the client, comprising: a load measuring unit for measuring a load of a cache server, caused by a load source cache server subordinately connected to the cache server caching contents cached in the cache server;an overflown load determination unit for determining whether a load measured by the load measuring unit is overflown, by comparing the load with a predetermined value;a connection destination retrieval request information transmitting unit for transmitting a connection destination retrieval request for requesting the contents sever or another cache server to search for a connection destination of the load source cache server, which is its load source, if the overflown load determination unit determines that the load is overflown;a connection destination information receiving unit for receiving the connection destination information indicating a connection destination retrieved by the contents sever or the other cache server from the contents sever or the other cache server, which is a transmitting destination, to which the connection destination retrieval request information transmitting unit has transmitted the connection destination retrieval request information; anda switch request transmitting unit for transmitting a switch request information for requesting the load source cache server to switch a connection to the connection destination indicated in the connection destination information, based on the connection destination information received by the connection destination information receiving unit.
  • 2. The cache server according to claim 1, wherein the load of the cache server is measured based on a size of contents requested to the load source cache server.
  • 3. The cache server according to claim 1, wherein the load of the cache server is measured based on the number of clients requesting for access to the load source cache server.
  • 4. The cache server according to claim 1, wherein the load of the cache server is measured based on a frequency of access to the load source cache server.
  • 5. The cache server according to claim 1, wherein the load of the cache server is measured based on a degree of overlap between contents by cached by the cache server and contents of cached by the load source cache server.
  • 6. The cache server according to claim 1, wherein the connection destination retrieval request information transmitting unit transmits the connection destination retrieval request information to the contents server connected to the cache server or the other cache server in predetermined order.
  • 7. The cache server according to claim 6, wherein the connection destination retrieval request information transmitting unit sequentially transmits the connection destination retrieval request information to the contents server connected to the cache server or the other cache server highly ordered in a hierarchical contents delivery network of the contents server connected to the cache server or the other cache server.
  • 8. The cache server according to claim 1, wherein the connection destination retrieval request information transmitting unit transmits information about the load source cache server together with the connection destination retrieval request information.
  • 9. The contents server according to claim 1, comprising: a connection destination retrieval request information receiving unit for receiving a connection destination retrieval request for requesting to search for the connection destination of the load source cache server, which is the load source of the cache server, from the cache server according to claim 1;a connection destination retrieval request transfer unit for transferring the connection destination retrieval request information to another cache server subordinately connected to the contents sever received by the connection destination retrieval request information receiving unit;a connection destination possible/impossible determination result receiving unit for receiving a connection destination determination result indicating whether the server can be a connection destination of the load source cache server, from the other cache server which is a transfer destination to which the connection destination retrieval request information is transmitted;a connection destination determining unit for determining whether the server can be a connection destination of the load source cache server, based on the load of the contents server if all the connection destination possible/impossible determination results received by the connection destination possible/impossible determination result receiving unit cannot be a connection destination of the load source cache server; anda connection destination possible/impossible determination result transmitting unit for transmitting a connection destination possible/impossible determination result indicating whether the connection destination determined by the connection destination determination unit is possible.
  • 10. The other cache server according to claim 1, comprising: a connection destination retrieval request information receiving unit for receiving connection destination retrieval request information for requesting to search for the connection destination of a load source cache server, which is the load source of the cache server, from the contents server according to claim 9;a connection destination determination unit for determining whether the server can be the connection destination of the load source cache server, based on a load of the cache server, included in the connection destination retrieval request information received by the connection destination retrieval request information receiving unit;a connection destination retrieval request information transfer unit for transferring the connection destination retrieval request information to another cache server subordinately connected to the cache server if a connection destination possible/impossible determination result indicating whether the connection destination determined by the connection destination determination unit can be the connection destination of the load source cache server; anda connection destination possible/impossible determination result transmitting unit for transmitting the connection destination possible/impossible determination result indicating whether the connection destination determined by the connection destination determination unit can be the connection destination of the load source cache server, to the contents server or cache server which has transmitted the connection destination retrieval request information.
  • 11. The cache server according to claim 10, wherein the connection destination retrieval request information transfer unit transfers the connection destination retrieval request information in predetermined order.
  • 12. The other cache server according to claim 1, comprising: a connection destination retrieval request information receiving unit for receiving connection destination retrieval request information for requesting to search for the connection destination of a load source cache server, which is the load source of the cache server, from the contents server according to claim 1;a connection destination determination unit for determining whether the server can be the connection destination of the load source cache server, based on a load of the cache server, included in the connection destination retrieval request information received by the connection destination retrieval request information receiving unit;a connection destination retrieval request information transfer unit for transferring the connection destination retrieval request information to another cache server subordinately connected to the cache server if a connection destination possible/impossible determination result indicating whether the connection destination determined by the connection destination determination unit can be the connection destination of the load source cache server; anda connection destination possible/impossible determination result transmitting unit for transmitting the connection destination possible/impossible determination result indicating whether the connection destination determined by the connection destination determination unit can be the connection destination of the load source cache server, to the contents server or cache server which has transmitted the connection destination retrieval request information.
  • 13. The cache server according to claim 12, wherein the connection destination retrieval request information transfer unit transfers the connection destination retrieval request information in predetermined order.
  • 14. A contents delivery network for delivering contents in a contents sever according to a request from a client, which comprises the contents server and cache server according to claim 1.
  • 15. A connection destination server switching control method in a contents delivery network for delivering contents in a contents server, according to a request from a client, wherein a cache server for caching the contents in the contents servermeasures a load of the cache server, caused by a load source cache server subordinately connected to the cache server caching contents cached in the cache server andtransmits a connection destination retrieval request information for requesting the contents sever to search for a connection destination of the load source cache server, which is its load source, by comparing the measured load with a predetermined value if it is determined that the load is overflown,the contents serverreceives the connection destination retrieval request information transmitted from the cache server andtransfers the received connection destination retrieval request information to another cache server subordinately connected to the contents server,the other cache serverdetermines whether the server can be a connection destination of the load source cache server, based on a load of the other cache server, included in the connection destination retrieval request information transferred by the contents server,transmits connection destination possible/impossible determination result indicating whether the server can be the determined connection destination, to the contents server that has transmitted the connection destination retrieval request information,the contents serverreturns the received connection destination possible/impossible determination result to a load source cache server as the determined connection destination andthe load source cache server modifies the connection destination, based on the returned connection destination possible/impossible determination result.
  • 16. A cache server for caching contents in a contents server and delivering the contents to a client according to a request of the client, comprising: load measuring means for measuring a load of a cache server, caused by a load source cache server subordinately connected to the cache server caching contents cached in the cache server;overflown load determination means for determining whether a load measured by the load measuring means is overflown, by comparing the load with a predetermined value;connection destination retrieval request information transmitting means for transmitting a connection destination retrieval request for requesting the contents sever or another cache server to search for a connection destination of the load source cache server, which is its load source, if the overflown load determination means determines that the load is overflown;connection destination information receiving means for receiving the connection destination information indicating a connection destination retrieved by the contents sever or the other cache server from the contents sever or the other cache server, which is a transmitting destination, to which the connection destination retrieval request information transmitting means has transmitted the connection destination retrieval request information; andswitch request transmitting means for transmitting a switch request information for requesting the load source cache server to switch a connection to the connection destination indicated in the connection destination information, based on the connection destination information received by the connection destination information receiving means.
Priority Claims (1)
Number Date Country Kind
2006-081582 Mar 2006 JP national