A content resource distribution system, method and computing device cluster

Abstract

The present application discloses a content resource distribution system, method and computing device cluster, wherein each edge node group in the system includes a first-class edge node and a second-class edge node, the second-class edge node is responsible for traversing the source of all edge nodes in the edge node group, and the second edge node belongs to the second-class edge node; the first edge node is used to receive a first access request from a client, and when the first content resource is not cached locally, send a first redirection indication to the client; the second edge node is used to receive a first access request from a client, and when the first content resource is already cached locally, send the first content resource to the client, or, when the first content resource is not cached locally, traverse the source of the first content resource through a central node, cache the first content resource locally at the second edge node, and send the first content resource to the client, thereby reducing traversal traffic and bandwidth costs.

Description

Technical Field

[0001] The present application relates to the field of computer technology, and in particular to a content resource distribution system, method, and computing device cluster. Background Art

[0002] A content distribution network (CDN) is used to distribute content resources from source servers to edge nodes located in different regions, allowing users to obtain the required content resources through the nearest edge node. A CDN can adopt a two-tier deployment architecture, where the CDN includes edge nodes and central nodes, with the central node being the direct superior node of the edge node. Alternatively, a CDN can adopt a three-tier deployment architecture, where the CDN includes edge nodes, regional central nodes, and central nodes, where the regional central nodes are the direct superior nodes of the edge nodes and the central nodes are the indirect superior nodes of the edge nodes.

[0003] When an edge node receives an access request for a content resource, and the edge node and its upper-level nodes (including direct and indirect upper-level nodes, such as the central node in a two-level deployment architecture, and the regional central node and central node in a three-level deployment architecture) do not store the content resource, the access request can be returned to the source. The so-called return to the source means forwarding the access request to the origin server, which responds to the access request. Because multiple edge nodes may return to the source for access requests to the same content resource, that is, repeated return to the source, it leads to increased return to the source traffic and increased bandwidth costs. Summary of the Invention

[0004] Embodiments of the present application provide a content resource distribution system, method, and computing device cluster to reduce back-to-source traffic and lower bandwidth costs.

[0005] In a first aspect, the present application provides a content resource distribution system, the content resource distribution system including at least one edge node group and a central node; each edge node group includes a first type of edge node and a second type of edge node, the first type of edge node is not responsible for the back-to-source of all edge nodes in the edge node group, the second type of edge node is responsible for the back-to-source of all edge nodes in the edge node group, a first edge node belongs to the first type of edge node, and a second edge node belongs to the second type of edge node; the first edge node can: receive a first access request from a client, the first access request is used to request a first content resource; when the first edge node does not locally cache the first content resource, send first redirection indication information to the client, The first redirection indication information is used to instruct the client to send the first access request to the second edge node; the second edge node can: receive the first access request from the client; when the second edge node has cached the first content resource locally, send the first content resource to the client; or, when the second edge node has not cached the first content resource locally, return the first content resource through the central node, cache the first content resource locally to the second edge node, and send the first content resource to the client; the central node can: assist any one edge node in the at least one edge node group to return the first content resource from the source server used to provide the first content resource.

[0006] Based on the above system, different edge nodes in the same edge node group are divided into two categories. The first type of edge nodes are not responsible for the back-to-source of all edge nodes in the edge node group, and the second type of edge nodes are responsible for the back-to-source of all edge nodes in the edge node group, so that an edge node belonging to the first type of edge nodes can instruct the client to redirect to an edge node belonging to the second type of edge nodes when it does not cache the content resources accessed by the client locally. An edge node belonging to the second type of edge nodes can directly feed back the content resources to the client when it has cached the content resources accessed by the client locally, and when it does not cache the content resources accessed by the client locally, it can return to the source content resources and feed back the returned content resources to the client, and store the returned content resources. In this way, when other clients request the content resources, the corresponding edge nodes in the second type of edge nodes can directly provide the cached content resources, thereby avoiding multiple edge nodes from repeatedly returning the same content resources to the central node, reducing the back-to-source traffic and reducing bandwidth costs.

[0007] In a possible design, the first edge node may also determine that the status of the second edge node is normal before sending the first redirection indication information to the client.

[0008] Through this design, the first edge node can instruct the client to redirect to the second edge node only when the first edge node does not cache the content resources accessed by the client locally and the status of the second edge node is normal. This can avoid instructing the client to redirect to the second edge node in an abnormal status, thereby improving the response speed and response success rate of the client accessing content resources.

[0009] In a possible design, the first edge node may also return the first content resource through the central node, cache the first content resource locally to the first edge node, and send the first content resource to the client when the first edge node does not cache the first content resource locally and the status of any second-type edge node of the second edge node is abnormal.

[0010] Through this design, when the first edge node does not cache the content resources accessed by the client locally and the status of any second edge node in the second type of edge nodes is abnormal, the first edge node can return to the source through itself instead of the second edge node. In this way, the content resources accessed by the client can be provided while avoiding instructing the client to be redirected to the second edge node with an abnormal status, thereby improving the response success rate of the client accessing the content resources.

[0011] In a possible design, the first edge node may further: send the first access request response to the client when the first content resource has been cached locally.

[0012] With this design, the first edge node can directly feed back the content resources to the client when the content resources accessed by the client have been cached locally, thereby improving the response speed of the client accessing the content resources.

[0013] In one possible design, when assisting any one edge node in the at least one edge node group to return the first content resource from the source station server used to provide the first content resource, the central node can specifically: receive the first access request from any one edge node in the at least one edge node group; when the central node has cached the first content resource locally, send the first content resource to the any one edge node; or, when the central node has not cached the first content resource locally, send the first access request to the source station server, receive the first content resource from the source station server, cache the first content resource locally to the central node, and send the first content resource to the any one edge node.

[0014] In one possible design, the at least one edge node group can be formed based on the location and / or operator of multiple edge nodes. This design allows for different edge node groups to be formed based on their location and / or operator, with those more suitable for back-to-source processing and those not suitable for back-to-source processing.

[0015] In one possible design, the first type of edge node and the second type of edge node can be determined according to the back-to-source policy corresponding to the edge node group, and the back-to-source policy is used to indicate the edge node responsible for the back-to-source of all edge nodes in the edge node group in different time periods.

[0016] Through this design, according to the back-to-source policy corresponding to the edge node group, the edge node responsible for the back-to-source of all edge nodes in the edge node group in different time periods is determined, that is, the back-to-source aggregation node of all edge nodes in the edge node group in different time periods is determined, so that different edge node groups that are more suitable for back-to-source processing and those that are not suitable for back-to-source processing can be obtained.

[0017] In the second aspect, the present application also provides a content resource distribution method, which is applied to a first edge node, the first edge node belongs to the first type of edge node in the edge node group, and the first type of edge node is not responsible for the back-to-source of all edge nodes in the edge node group. The method includes: the first edge node can receive a first access request from a client, and the first access request is used to request a first content resource; the first edge node can send a first redirection indication information to the client when the first edge node does not cache the first content resource locally, and the first redirection indication information is used to instruct the client to send the first access request to a second edge node, the second edge node belongs to the second type of edge node in the edge node group, and the second type of edge node is responsible for the back-to-source of all edge nodes in the edge node group.

[0018] In a possible design, before sending the first redirection indication information to the client, the first edge node may also determine that the status of the second edge node is normal.

[0019] In a possible design, the first edge node may also send the first access request to the central node, receive the first content resource from the central node, cache the first content resource locally on the first edge node, and send the first content resource to the client when the first edge node does not cache the first content resource locally and the status of any second edge node in the second type of edge node is abnormal.

[0020] In a possible design, the first edge node may further send the first content resource to the client when the first edge node has locally cached the first content resource.

[0021] In a third aspect, the present application also provides a content resource distribution method, which is applied to a second edge node, the second edge node belongs to a second type of edge node in an edge node group, and the second type of edge node is responsible for the back-to-source of all edge nodes in the edge node group. The method includes: the second edge node can receive a first access request from a client, the first access request is used to request a first content resource, and the first access request is sent by the client to the second edge node when the client has not requested the first content resource from the first edge node. The first edge node belongs to the first type of edge node in the edge node group, and the first type of edge node is not responsible for the back-to-source of all edge nodes in the edge node group; the second edge node can send the first content resource to the client when the second edge node has cached the first content resource locally; or, when the second edge node has not cached the first content resource locally, send the first access request to the central node, receive the first content resource from the central node, cache the first content resource locally to the second edge node, and send the first content resource to the client.

[0022] In a fourth aspect, the present application further provides a first edge node, the first edge node belonging to the first type of edge node in the edge node group in the first aspect above, the first edge node having the function of implementing the method described in the second aspect or any possible design of the second aspect above, the function can be implemented by hardware, or can be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions, such as a communication module and a processing module.

[0023] In a fifth aspect, the present application further provides a second edge node, which belongs to the second type of edge node in the edge node group in the first aspect above, and has the function of implementing the method described in the third aspect or any possible design of the third aspect above, and the function can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions, such as a communication module and a processing module.

[0024] In the sixth aspect, an embodiment of the present application also provides a computing device, including a processor and a memory, wherein the memory is used to store computer program instructions. When the processor executes the computer program instructions, any possible design scheme in the above-mentioned second aspect and / or third aspect is executed.

[0025] In a seventh aspect, the present application also provides a computing device, comprising the computing apparatus described in the sixth aspect above.

[0026] In an eighth aspect, the present application further provides a computing device cluster comprising at least one computing device, wherein the structure of each computing device includes a processor and a memory. The processor is configured to support the first edge node to execute the method of the second aspect or any possible design of the second aspect, or the processor is configured to support the second edge node to execute the method of the third aspect or any possible design of the third aspect. The memory is coupled to the processor and stores the necessary program instructions and data for the communication device. The structure of the communication device also includes a communication interface for communicating with other devices.

[0027] In the ninth aspect, the present application also provides a computer-readable storage medium, which includes computer program instructions. When the computer program instructions are executed by a computing device, the computing device executes the method of the second aspect or any possible design of the second aspect, or the computing device executes the method of the third aspect or any possible design of the third aspect.

[0028] In the tenth aspect, the present application also provides a computer program product comprising instructions, which, when executed by a computing device, enables the computing device to execute the method of the second aspect or any possible design of the second aspect, or enables the computing device to execute the method of the third aspect or any possible design of the third aspect.

[0029] In the eleventh aspect, the present application also provides a chip, which can be coupled to a memory, and is used to call a computer program stored in the memory and execute the above-mentioned second aspect or any possible design method of the above-mentioned second aspect, or, and execute the above-mentioned third aspect or any possible design method of the above-mentioned third aspect.

[0030] The beneficial effects of the above-mentioned second to eleventh aspects and their possible designs can refer to the description of the beneficial effects of the method described in the above-mentioned first aspect and any possible design thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of an existing CDN;

[0032] Figure 2a A schematic diagram of an existing content resource distribution scenario;

[0033] Figure 2b A schematic diagram of another existing content resource distribution scenario;

[0034] Figure 3 A schematic diagram of the structure of a content resource distribution system provided in an embodiment of the present application;

[0035] Figure 4 A flowchart of a content resource distribution method provided in an embodiment of the present application;

[0036] Figure 5 A schematic diagram of a content resource distribution scenario provided in an embodiment of the present application;

[0037] Figure 6 A schematic diagram of the structure of a first edge node provided in an embodiment of the present application;

[0038] Figure 7 A schematic diagram of the structure of a second edge node provided in an embodiment of the present application;

[0039] Figure 8 A schematic diagram of the structure of a computing device provided in an embodiment of the present application;

[0040] Figure 9 A schematic diagram of the structure of a computing device cluster provided in an embodiment of the present application;

[0041] Figure 10 A schematic diagram of a connection method between computing device clusters provided in an embodiment of the present application. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0043] Some of the terms involved in the embodiments of the present application are explained below to facilitate understanding of the embodiments of the present application.

[0044] (1) At least one of the embodiments of the present application includes one or more; wherein, more means greater than or equal to two. In addition, in the description of this specification, words such as "first" and "second" are only used for the purpose of distinguishing descriptions, and cannot be understood as expressing or implying relative importance, nor can they be understood as expressing or implying order. For example, the first object and the second object do not represent the importance of the two or the order of the two, but are only for distinguishing descriptions. In the embodiments of the present application, "and / or" is only a description of the association relationship, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the previous and next associated objects are in an "or" relationship.

[0045] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a direct connection or an indirect connection through an intermediate medium.

[0046] References to "one embodiment" or "some embodiments" in this document mean that one or more embodiments provided herein include a particular feature, structure, or characteristic described in conjunction with that embodiment. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in yet other embodiments" appearing in various places herein do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0047] (2) Content distribution network (CDN), which is used to distribute content resources from the source server to edge nodes located in different regions, so that users can obtain the required content resources through the nearest edge node. For example, Figure 1 A schematic diagram of an existing CDN is shown in FIG. Figure 1 As shown, CDN can include edge nodes (EN), regional center nodes (RCN) and central nodes (CN). Among them, edge nodes can be deployed in provincial and municipal locations of each operator network to serve users. For example, edge nodes 11, 12, 13 and 14 are deployed in region 1; edge nodes 21, 22, 23 and 24 are deployed in region 2. Regional central nodes can be deployed in the central location of each region of each operator network to serve edge nodes and serve as regional aggregation nodes back to the source. For example, regional central node 1 is deployed in the central location of region 1; regional central node 2 is deployed in the central location of region 2. Central nodes can be deployed in the central location of each operator network to serve edge nodes and regional central nodes and serve as the total exit node back to the source. For example, central nodes are deployed in the central locations of regions 1 and 2.

[0048] (3) Back-to-source refers to when an edge node receives an access request for a content resource, and the edge node and its upper-level node (such as a regional center node or a center node) do not store the content resource, the access request can be forwarded to the origin server through the regional center node or the center node. The origin server responds to the access request and feeds it back to the corresponding edge node with the back-to-source request through the regional center node or the center node.

[0049] (4) Secondary deployment architecture

[0050] CDN can adopt a two-level deployment architecture, that is, CDN includes edge nodes and central nodes, where the central node is the direct superior node of the edge node. Edge nodes can be deployed to the provincial and municipal locations of each operator network to provide content resources to users nearby, and central nodes can be deployed to the central location of each operator network to be responsible for the back-to-source of edge nodes. Under this two-level deployment architecture, each edge node or central node first determines whether the content resource requested by the user has been cached locally. If the content resource has been cached locally, the content resource will be directly fed back to its subordinate node. If the content resource is not cached locally, the content resource will be fed back to its superior node, and the content resource will be fed back to its subordinate node while returning to the source, and the content resource will be cached locally. Therefore, for repeated content resources, the central node will only back-source the content resource from the source server once.

[0051] For example, Figure 2a This is a schematic diagram of an existing content resource distribution scenario, such as Figure 2aAs shown, the CDN adopts a two-level deployment architecture, including first-level nodes (edge ​​nodes) and second-level nodes (central nodes). When client A requests content resource A, the domain name system (DNS) can return the Internet Protocol (IP) address of edge node A based on the principle of proximity. Client A initiates a hypertext transfer protocol (HTTP) request to edge node A to obtain content resource A. After receiving the HTTP request from client A, edge node A checks the local cache of edge node A. If edge node A has already cached content resource A locally, it directly feeds content resource A back to client A. If edge node A does not have local cache of content resource A, it requests the upper-level node (such as the central node) to return to the source content resource A, and feeds content resource A back to client A while returning to the source, while caching content resource A locally on edge node A. After receiving the HTTP request from edge node A, the central node checks its local cache. If the central node has already cached content resource A locally, it directly feeds content resource A back to edge node A. If the central node does not have content resource A cached locally, it requests the upper-level node (such as the origin server) to return content resource A to the source, feeding content resource A back to edge node A while returning to the source, and simultaneously caching content resource A locally on the central node. Therefore, when both edge node A and edge node B return to the source for content resource A, although the central node will receive two access requests for content resource A, it will only return content resource A once from the origin server, and then return it to edge node A and edge node B respectively.

[0052] It can be seen that when CDN adopts a two-level deployment architecture, although repeated back-to-origin traffic can be avoided between the central node and the origin server, repeated back-to-origin traffic still occurs between each edge node and the central node. The number of repetitions is equal to the number of edge nodes that receive access requests for the same content resource, resulting in increased CDN back-to-origin traffic and increased bandwidth costs.

[0053] (5) Three-level deployment architecture

[0054] CDNs can also adopt a three-tiered deployment architecture, consisting of edge nodes, regional center nodes, and central nodes. Regional center nodes are the direct superiors of edge nodes, while central nodes are the indirect superiors of edge nodes. Compared to the two-tiered deployment architecture, the three-tiered deployment architecture introduces regional center nodes. This allows edge nodes in each region to first return to the regional center node, which then returns to the central node. This achieves regional convergence and ensures that the central node only receives a single access request for the same content resource in each region, reducing the back-to-source traffic from each region to the central node.

[0055] For example, Figure 2b This is a schematic diagram of another existing content resource distribution scenario, such as Figure 2b As shown, the CDN adopts a three-level deployment architecture, including first-level nodes (edge ​​nodes), second-level nodes (regional center nodes) and third-level nodes (center nodes). When client A requests content resource A, DNS can return the IP address of edge node A based on the principle of proximity. Client A initiates an HTTP request to edge node A to obtain content resource A. After edge node A receives the HTTP request from client A, it checks the local cache of edge node A. If edge node A has cached content resource A locally, it directly feeds back content resource A to client A. If edge node A does not cache content resource A locally, it requests the superior node (such as regional center node A) to return to the source content resource A, and feeds back content resource A to client A while returning to the source, and at the same time caches content resource A locally on edge node A. After receiving the HTTP request from edge node A, regional center node A checks the local cache of regional center node A. If regional center node A has already cached content resource A locally, it directly feeds content resource A back to edge node A. If regional center node A does not have content resource A cached locally, it requests the superior node (such as the central node) to return to the source content resource A. While returning to the source, it feeds content resource A back to edge node A, and caches content resource A locally in regional center node A. After receiving the HTTP request from regional center node A, the central node checks the local cache of the central node. If the central node has already cached content resource A locally, it directly feeds content resource A back to regional center node A. If the central node does not have content resource A cached locally, it requests the superior node (such as the origin server) to return to the source content resource A. While returning to the source, it feeds content resource A back to regional center node A, and caches content resource A locally in the central node. Therefore, when both edge node A and edge node B in region A return to the source of content resource A, although the regional center node A in region A will receive two access requests for content resource A, it will only return to the source of content resource A once from the central node. Furthermore, for the central node, the central node will only receive one access request for content resource A from region A, and will only return to the source of content resource A once from the source server.

[0056] As can be seen, when a CDN adopts a three-tier deployment architecture, while the central node can avoid repeated back-to-origin calls and only receives a single access request for the same content resource in each region, each edge node in each region still experiences repeated back-to-origin calls. The number of repetitions is equal to the number of edge nodes receiving access requests for the same content resource, resulting in increased back-to-origin traffic and bandwidth costs within each CDN region. Furthermore, the addition of regional central nodes increases the difficulty and cost of CDN deployment.

[0057] In view of this, the technical solution of the embodiment of the present application is provided. The embodiment of the present application can be applied to Figure 1 、 Figure 2a or Figure 2b In any of the architecture systems shown. The embodiments of the present application are described in detail below.

[0058] The content resource distribution method provided in the embodiment of the present application can be applied to a content resource distribution system. The content resource distribution system may include one or more clients; it may also include one or more edge node groups, wherein one edge node group may include two types of edge nodes, namely, first-type edge nodes and second-type edge nodes, the first-type edge nodes are not responsible for the return to the source of all edge nodes in the edge node group, the first-type edge nodes may include one or more edge nodes, the second-type edge nodes are responsible for the return to the source of all edge nodes in the edge node group, the second-type edge nodes may include one or more edge nodes; the content resource distribution system may also include one or more central nodes; it may also include one or more source station servers.

[0059] For example, Figure 3 A structural diagram of a content resource distribution system provided in an embodiment of the present application. Figure 3 A structural example is given, which includes a client 100, three edge node groups 110, 120, and 130, a central node 140, and an origin server 150. It should be understood that in actual applications, the number of clients, edge node groups, central nodes, and origin servers included in the content resource distribution system is not limited to this. Edge node group 110 includes three edge nodes, namely edge node 111, edge node 112, and edge node 113, wherein edge node 111 belongs to the first type of edge node, and edge node 112 and edge node 113 belong to the second type of edge node. Edge node group 120 includes three edge nodes, namely edge node 121, edge node 122, and edge node 123, wherein edge node 121 and edge node 122 belong to the first type of edge node, and edge node 123 belongs to the second type of edge node. Edge node group 130 includes three edge nodes: edge node 131, edge node 132, and edge node 133. Edge node 131 is a first-category edge node, and edge nodes 132 and 133 are second-category edge nodes. It should be understood that in practical applications, the number of first-category edge nodes and second-category edge nodes included in the edge node group is not limited to this.

[0060] based on Figure 3 The specific architecture of the content resource distribution system shown in FIG2 is shown in FIG3 , and the content resource distribution method provided by the embodiment of the present application is described in conjunction with the accompanying drawings. It should be understood that the content resource distribution method of the present application can also be applied to Figure 3As shown or with Figure 3 The content resource distribution system with similar functional structure is not specifically limited in the embodiments of the present application.

[0061] Figure 4 A flow chart of a content resource distribution method provided in an embodiment of the present application is provided. In the following introduction, the method is applied to Figure 3 For example, the client described below may be Figure 3 In the client 100 of the system shown, the edge node group described below can be Figure 3 In the illustrated system, the first edge node 110 may be Figure 3 The edge node 111 in the system shown in FIG. 1 may be a second edge node as described below. Figure 3 The edge node 112 or edge node 113 in the system shown, the central node described below can be Figure 3 The central node 140 in the system shown in FIG. 1 may be a source server described below. Figure 3 The source server 150 in the system shown. The method may include the following steps:

[0062] S401: A client sends a first access request to a first edge node. Correspondingly, the first edge node receives the first access request from the client.

[0063] In some embodiments, when a client requests a first content resource, the DNS may select a first edge node from multiple edge nodes based on the proximity principle as the edge node serving the client, and send the IP address of the first edge node to the client. After receiving the IP address of the first edge node, the client may send a first access request (such as an HTTP request) to the first edge node. Accordingly, the first edge node may receive the first access request from the client. The first access request is used to request the first content resource.

[0064] In a specific implementation, the first edge node may belong to a first type of edge node or a second type of edge node in the first edge node group. Among them, the first type of edge node is an edge node that is not responsible for the return to the source of all edge nodes in the first edge node group. The first type of edge node in the first edge node group may include one or more edge nodes. The second type of edge node is an edge node that is responsible for the return to the source of all edge nodes in the first edge node group. The second type of edge node is equivalent to the return to the source aggregation node of all edge nodes in the first edge node group. The second type of edge node in the first edge node group may include one or more edge nodes. For ease of explanation, in the embodiment of the present application, it is taken as an example that the first edge node belongs to the first type of edge node in the first edge node group.

[0065] The first edge node group can be obtained by dividing the plurality of edge nodes according to their locations and / or operators. Specifically, edge nodes located in different cities or the same city in the same province can be grouped together; or edge nodes belonging to the same operator can be grouped together; or edge nodes belonging to the same operator and located in different cities or the same province can be grouped together; or edge nodes belonging to the same operator and located in different cities in different provinces can be grouped together; or edge nodes belonging to different operators and located in different cities or the same province can be grouped together; or edge nodes belonging to different operators and located in different cities in different provinces can be grouped together. For example, if edge node A, edge node B, and edge node C are located in city A, city B, and city C in province 1, respectively; or, the operators of edge node A, edge node B, and edge node C are all operator A; or, the operators of edge node A, edge node B, and edge node C are all operator A, and they are located in city A, city B, and city C in province 1, respectively; or, the operators of edge node A, edge node B, and edge node C are all operator A, and they are located in city A, city B, and city C in province 1, respectively; or, the operators of edge node A, edge node B, and edge node C are operator A, operator B, and operator C, and they are located in city A, city B, and city C in province 1, respectively; or, the operators of edge node A, edge node B, and edge node C are operator A, operator B, and operator C, and they are located in city A in province 1, city B in province 2, and city C in province 3, respectively. In this case, edge node A, edge node B, and edge node C can all be classified into edge node group A.

[0066] The first type of edge nodes and the second type of edge nodes are determined according to a back-to-source policy corresponding to the first edge node group. The back-to-source policy is used to indicate the edge nodes responsible for back-to-source of all edge nodes in the first edge node group in different time periods. For example, edge node group A includes edge node A, edge node B, and edge node C. The back-to-source policy corresponding to edge node group A can indicate that the edge nodes responsible for the back-to-source of all edge nodes in edge node group A are polled on a daily basis. That is, on the first day, edge node A is responsible for the back-to-source of edge nodes A, edge node B, and edge node C. At this time, edge node B and edge node C belong to the first type of edge nodes in the first edge node group, and edge node A belongs to the second type of edge node in the first edge node group; on the second day, edge node B is responsible for the back-to-source of edge nodes A, edge node B, and edge node C. At this time, edge node A and edge node C belong to the first type of edge nodes in the first edge node group, and edge node B belongs to the second type of edge node in the first edge node group; on the third day, edge node C is responsible for the back-to-source of edge nodes A, edge node B, and edge node C. At this time, edge node A and edge node B belong to the first type of edge nodes in the first edge node group, and edge node C belongs to the second type of edge node in the first edge node group; and so on. On the fourth day, edge node A is again responsible for the back-to-source of edge nodes A, edge node B, and edge node C.

[0067] S402: When the first edge node does not cache the first content resource locally, the first edge node sends first redirection indication information to the client. Correspondingly, the client receives the first redirection indication information from the first edge node.

[0068] In some embodiments, after the first edge node receives the first access request from the client, it can determine whether the first edge node has cached the first content resource locally. If the first edge node has cached the first content resource locally, the first edge node can send the first content resource to the client. Accordingly, the client can receive the first content resource from the first edge node. If the first edge node does not cache the first content resource locally, the first edge node can send a first redirection indication message (such as HTTP302 redirection message) to the client. Accordingly, the client can receive the first redirection indication message from the first edge node. The first redirection indication message can be used to instruct the client to send the first access request to the second edge node, and the second edge node can belong to the second type of edge node in the first edge node group.

[0069] In a specific implementation, if the first edge node has locally cached the first content resource, the first edge node may send the first content resource to the client, and accordingly, the client may receive the first content resource from the first edge node.

[0070] If the first edge node does not locally cache the first content resource, the first edge node may determine whether the status of the second edge node is normal. For example, the first edge node may periodically send a probe request to the second edge node. If the first edge node receives a probe request response from the second edge node, the first edge node may determine that the status of the second edge node is normal. If the first edge node does not receive a probe request response from the second edge node, the first edge node may determine that the status of the second edge node is abnormal.

[0071] If the first edge node determines that the second edge node is in a normal state, the first edge node may send a first redirection instruction message to the client. Correspondingly, the client may receive the first redirection instruction message from the first edge node. The first redirection instruction message carries the IP address of the second edge node.

[0072] If the first edge node determines that the status of the second edge node is abnormal, the first edge node may determine whether there are other edge nodes (eg, third edge nodes) in the second type of edge nodes except the second edge node, and whether the status of the third edge node is normal.

[0073] If the first edge node determines that a third edge node exists among the second-category edge nodes and that the third edge node is in a normal state, the first edge node may send a second redirection instruction to the client. Accordingly, the client may receive the second redirection instruction from the first edge node. The second redirection instruction instructs the client to send the first access request to the third edge node, and the second redirection instruction carries the IP address of the third edge node.

[0074] If the first edge node determines that there is no third edge node in the second type of edge node or that there is a third edge node but the status of the third edge node is abnormal, the first edge node can return the first content resource to the source through the central node, cache the first content resource locally to the first edge node, and send the first content resource to the client. For example, the first edge node can send a first access request to the central node. Accordingly, the central node can receive the first access request from the first edge node, and when the central node has cached the first content resource locally, send the first content resource to the first edge node, or, when the central node has not cached the first content resource locally, send the first access request to the source server, receive the first content resource from the source server, cache the first content resource locally to the central node, and send the first content resource to the first edge node.

[0075] S403: The client sends a first access request to the second edge node. Correspondingly, the second edge node receives the first access request from the client.

[0076] In some embodiments, after receiving the first redirection instruction information from the first edge node, the client may send a first access request to the second edge node. Correspondingly, the second edge node may receive the first access request from the client.

[0077] Similarly, after receiving the second redirection instruction information from the first edge node, the client may also send the first access request to the third edge node. Correspondingly, the third edge node may receive the first access request from the client.

[0078] S404: When the second edge node has cached the first content resource locally, the second edge node sends the first content resource to the client. Alternatively, when the second edge node has not cached the first content resource locally, the second edge node sources the first content resource through the central node, caches the first content resource locally on the second edge node, and sends the first content resource to the client.

[0079] In some embodiments, after the second edge node receives the first access request from the client, it can determine whether the second edge node has cached the first content resource locally. If the second edge node has cached the first content resource locally, the second edge node can send the first content resource to the client. Accordingly, the client can receive the first content resource from the second edge node. If the second edge node does not cache the first content resource locally, the second edge node can source the first content resource back through the central node, cache the first content resource locally at the second edge node, and send the first content resource to the client. For example, the second edge node can send a first access request to the central node. Accordingly, the central node can receive the first access request from the second edge node, and when the central node has cached the first content resource locally, send the first content resource to the second edge node, or, when the central node does not cache the first content resource locally, send the first access request to the source server, receive the first content resource from the source server, cache the first content resource locally at the central node, and send the first content resource to the second edge node.

[0080] For example, Figure 5 A schematic diagram of a content resource distribution scenario provided in an embodiment of the present application is shown as follows: Figure 5As shown, the content resource distribution system adopts a two-level deployment architecture, including first-level nodes (edge ​​nodes) and second-level nodes (center nodes). Among them, edge node A1, edge node B1 and edge node C1 are divided into the same edge node group (for example, called edge node group 1), and the back-to-source policy corresponding to edge node group 1 indicates that the edge nodes responsible for the back-to-source of all edge nodes in edge node group 1 are polled in sequence on a daily basis, that is, the first day is edge node A1, the second day is edge node B1, and the third day is edge node C1. By analogy, edge node AN, edge node BN and edge node CN are divided into the same edge node group (for example, called edge node group N), and the back-to-source policy corresponding to edge node group N indicates that the edge nodes responsible for the back-to-source of all edge nodes in edge node group N are polled in sequence on a daily basis, that is, the first day is edge node AN, the second day is edge node BN, and the third day is edge node CN. The content resource distribution system can be achieved through Figure 5 Steps 1 to 10 shown below are used to distribute content resources:

[0081] Step 1: The edge nodes in each edge node group receive the back-to-origin policy issued for that edge node group. For example, edge nodes A1, B1, and C1 in edge node group 1 receive the back-to-origin policy issued for edge node group 1. Edge nodes AN, BN, and CN in edge node group N receive the back-to-origin policy issued for edge node group N.

[0082] Step 2: Client A sends an access request for content resource 1 to edge node A1. Correspondingly, edge node A1 receives the access request for content resource 1 from client A.

[0083] Step 3: If edge node A1 does not cache content resource 1 locally, it determines, based on the origin-back policy issued for edge node group 1, that edge node B1 is currently responsible for origin-back for all edge nodes in edge node group 1 and sends a redirection instruction to client A. The redirection instruction instructs client A to send the access request for content resource 1 to edge node B1, and the redirection instruction carries the IP address of edge node B1.

[0084] Step 4: Client A sends an access request for content resource 1 to edge node B1. Correspondingly, edge node B1 receives the access request for content resource 1 from client A.

[0085] Step 5: When edge node B1 does not cache content resource 1 locally, it determines the back-to-source of all edge nodes in edge node group 1 that it is currently responsible for according to the back-to-source policy corresponding to edge node group 1, and sends an access request for content resource 1 to the central node.

[0086] Step 6: When the central node does not cache the content resource 1 locally, the central node sends an access request for the content resource 1 to the origin server, and receives an access request response for the content resource 1 from the origin server.

[0087] Step 7: The central node sends a response to the access request for content resource 1 to edge node B1. Accordingly, edge node B1 receives the response to the access request for content resource 1 from the central node. The central node can serve client B1 while returning to the source, while caching content resource 1 locally on the central node.

[0088] Step 8: Edge node B1 sends a response to client A's access request for content resource 1. In return, client A receives the response from edge node B1. Edge node B1 can serve client A while returning to the source, while also caching content resource 1 locally on edge node B1.

[0089] Step 9: Client B sends an access request for content resource 1 to edge node B1. Correspondingly, edge node B1 receives the access request for content resource 1 from client B.

[0090] Step 10: When the edge node B1 has cached the content resource 1 locally, the edge node B1 directly feeds the content resource back to the client B.

[0091] Based on the above solution, after a first edge node belonging to the first type of edge node in the first edge node group receives a client's request to access a first content resource, because the first edge node does not locally cache the first content resource, the first edge node can instruct the client to redirect to a second edge node belonging to the second type of edge node in the first edge node group. After receiving the client's request to access the first content resource, the second edge node can directly feed back the first content resource to the client if the second edge node has locally cached the first content resource. If the second edge node does not locally cache the first content resource, it can return to the source of the first content resource and feed back the returned first content resource to the client, and store the returned first content resource. In this way, when other clients request the first content resource, the second edge node can directly provide the cached first content resource, thereby avoiding multiple edge nodes repeatedly returning the same content resource to the central node, reducing the return-to-source traffic and bandwidth costs. The reduced return-to-source traffic and bandwidth costs can be 1 / N, where N is equal to the number of first type edge nodes in the edge node group.

[0092] Similarly, after receiving the first access request from the client, the third edge node can perform the same operation as the second edge node performs after receiving the first access request from the client, that is, determine whether the third edge node has cached the first content resource locally, and when the third edge node has cached the first content resource locally, send the first content resource to the client, or, when the third edge node has not cached the first content resource locally, send the first access request to the central node, receive the first content resource from the central node, cache the first content resource locally on the third edge node, and send the first content resource to the client. Based on the above scheme, after the first edge node of the first type of edge node in the first edge node group receives the client's access request for the first content resource, since the first edge node does not cache the first content resource locally, the first edge node can instruct the client to redirect to the third edge node of the second type of edge node in the first edge node group. After receiving the client's access request for the first content resource, the third edge node can directly feed back the first content resource to the client if the third edge node has cached the first content resource locally. If the third edge node does not cache the first content resource locally, it can return to the source of the first content resource and feed back the returned first content resource to the client, and store the returned first content resource. In this way, when other clients request the first content resource, the third edge node can directly provide the cached first content resource, thereby avoiding multiple edge nodes repeatedly returning the same content resource to the central node, reducing the return-to-source traffic and reducing bandwidth costs.

[0093] Based on the above embodiments, the present application also provides a content resource distribution method, which is applied to the first edge node in the above content resource distribution system embodiment. The specific implementation process can refer to the above Figure 4 The process in the illustrated flow is handled by the first edge node. The repeated parts are not discussed here.

[0094] Based on the above embodiments, the present application also provides a content resource distribution method, which is applied to the second edge node in the above content resource distribution system embodiment. The specific implementation process can refer to the above Figure 4 The process in the illustrated flow is handled by the second edge node. The repeated parts are not discussed here.

[0095] Based on the above embodiments, the present application also provides a first edge node, such as Figure 6 FIG. 1 is a schematic diagram of a first edge node structure provided in an embodiment of the present application, wherein the first edge node is used to implement the above Figure 4-Figure 5 The content resource distribution method shown. Figure 6The first edge node 600 belongs to the first type of edge node in the edge node group. The first type of edge node is not responsible for the back-to-source of all edge nodes in the edge node group. The first edge node 600 may include a processing module 601 and a communication module 602.

[0096] The communication module 602 is used to receive a first access request from a client, where the first access request is used to request a first content resource. The communication module 602 is also used to send a first redirection indication message to the client when the first edge node does not cache the first content resource locally, where the first redirection indication message is used to instruct the client to send the first access request to a second edge node, where the second edge node belongs to a second type of edge node in the edge node group, and the second type of edge node is responsible for the back-to-source of all edge nodes in the edge node group.

[0097] In one possible design, the processing module 601 is used to determine whether the status of the second edge node is normal before sending the first redirection indication information to the client.

[0098] In one possible design, the communication module 602 is further used to send the first access request to the central node and receive the first content resource from the central node when the first edge node does not cache the first content resource locally and the status of any second edge node in the second type of edge node is abnormal; the processing module 601 is further used to cache the received first content resource locally to the first edge node and send the first content resource to the client.

[0099] In a possible design, the communication module 602 is further configured to send the first content resource to the client when the first edge node has locally cached the first content resource.

[0100] Based on the above embodiments, the present application also provides a second edge node, such as Figure 7 FIG. 1 is a schematic diagram of a second edge node structure provided in an embodiment of the present application, wherein the second edge node is used to implement the above Figure 4-Figure 5 The content resource distribution method shown. Figure 7 The second edge node 700 belongs to the second type of edge node in the edge node group. The second type of edge node is responsible for returning to the source of all edge nodes in the edge node group. The second edge node 700 may include a processing module 701 and a communication module 702.

[0101] The communication module 702 is used to receive a first access request from a client, where the first access request is used to request a first content resource. The first access request is sent by the client to the second edge node when the client has not requested the first content resource from the first edge node. The first edge node belongs to the first type of edge node in the edge node group, and the first type of edge node is not responsible for the back-to-source of all edge nodes in the edge node group; when the second edge node has locally cached the first content resource, the first content resource is sent to the client; or, when the second edge node has not locally cached the first content resource, the first access request is sent to the central node to receive the first content resource from the central node; the processing module 701 is used to cache the received first content resource locally at the second edge node and send the first content resource to the client.

[0102] Based on the above embodiments, the present application also provides a computing device, such as Figure 8 FIG. 8 is a schematic diagram of the structure of a computing device provided in an embodiment of the present application. The computing device 800 includes a bus 802, a processor 804, a memory 806, and a communication interface 808. The processor 804, the memory 806, and the communication interface 808 communicate with each other via the bus 802. The computing device 800 can be a first edge node or a second edge node. It should be understood that the present application does not limit the number of processors and memories in the computing device 800.

[0103] The bus 802 may be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 8 The bus 802 may include a path for transmitting information between various components of the computing device 800 (eg, memory 806, processor 804, communication interface 808).

[0104] The processor 804 may include any one or more processors such as a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor (MP), or a digital signal processor (DSP).

[0105] The memory 806 may include a volatile memory, such as a random access memory (RAM).

[0106] The processor 804 may also include a non-volatile memory, such as a read-only memory (ROM), a flash memory, a hard disk drive (HDD), or a solid state drive (SSD).

[0107] The memory 806 stores executable program codes, and the processor 804 executes the executable program codes to implement the functions of the communication module and the processing module respectively, thereby achieving the following: Figure 4-Figure 5 That is, the memory 806 stores the method for executing Figure 4-Figure 5 Instructions for the method shown.

[0108] The communication interface 808 uses a transceiver module such as, but not limited to, a network interface card or a transceiver to implement communication between the computing device 800 and other devices or a communication network.

[0109] Based on the above embodiments, the present application also provides a computing device cluster. The computing device cluster includes at least one computing device. The computing device can be a first edge node or a second edge node.

[0110] like Figure 9 As shown, the computing device cluster includes at least one computing device 800. The memory 806 in one or more computing devices 800 in the computing device cluster may store the same Figure 4-Figure 5 Instructions for the method shown.

[0111] In some possible implementations, the memory 806 of one or more computing devices 800 in the computing device cluster may also store a program for executing the following steps: Figure 4-Figure 5 In other words, the combination of one or more computing devices 800 can jointly execute instructions for performing the method shown in FIG. Figure 4-Figure 5 Instructions for the method shown.

[0112] It should be noted that the memory 806 in different computing devices 800 in the computing device cluster can store different instructions, each for executing part of the functions of the first edge node or the second edge node. In other words, the instructions stored in the memory 806 in different computing devices 800 can implement the functions of one or more modules of the communication module and the processing module.

[0113] In some possible implementations, one or more computing devices in a computing device cluster may be connected via a network, which may be a wide area network or a local area network. Figure 10 A possible implementation is shown. Figure 10 As shown, two computing devices 800A and 800B are connected via a network. Specifically, each computing device is connected to the network via a communication interface within the computing device. In this possible implementation, the memory 806 within computing device 800A stores instructions for executing the functions of a communication module. Simultaneously, the memory 806 within computing device 800B stores instructions for executing the functions of a processing module.

[0114] It should be understood that Figure 10 The functionality of the computing device 800A shown in FIG. 8 may also be implemented by multiple computing devices 800. Similarly, the functionality of the computing device 800B may also be implemented by multiple computing devices 800.

[0115] Based on the above embodiments, the embodiments of the present application further provide a computer-readable storage medium, which can be any available medium that a computing device can store or a data storage device such as a data center that contains one or more available media. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive). The computer-readable storage medium includes instructions that instruct the computing device to execute the following: Figure 4-Figure 5 The method shown.

[0116] Based on the above embodiments, the present application also provides a computer program product including instructions. The computer program product may be software or a program product including instructions that can be run on a computing device or stored in any available medium. When the computer program product is run on at least one computing device, the at least one computing device is enabled to execute the following command: Figure 4-Figure 5 The method shown.

[0117] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0118] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0119] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0120] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0121] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A content resource distribution system, characterized in that: The content resource distribution system includes at least one edge node group and a central node; Each edge node group includes a first type of edge node and a second type of edge node, wherein the first type of edge node is not responsible for traversal of all edge nodes in the edge node group, and the second type of edge node is responsible for traversal of all edge nodes in the edge node group, the first edge node belongs to the first type of edge node, and the second edge node belongs to the second type of edge node; The first edge node is configured to receive a first access request from a client, the first access request being for a first content resource; and when the first edge node does not locally cache the first content resource, send first redirection instruction information to the client, the first redirection instruction information being for instructing the client to send the first access request to the second edge node; The second edge node is configured to receive the first access request from the client; When the second edge node has locally cached the first content resource, sending the first content resource to the client; or, when the second edge node has not locally cached the first content resource, returning the first content resource through the central node, caching the first content resource locally on the second edge node, and sending the first content resource to the client; The central node is used to assist any edge node in the at least one edge node group to source the first content resource from an origin server that is used to provide the first content resource.

2. The system according to claim 1, wherein The first edge node is further configured to: Before sending the first redirection indication information to the client, it is determined that the status of the second edge node is normal.

3. The system according to claim 1, wherein: The first edge node is further configured to: When the first edge node does not cache the first content resource locally and the status of any second-type edge node of the second edge node is abnormal, the first content resource is returned to the source through the central node, the first content resource is cached locally on the first edge node, and the first content resource is sent to the client.

4. The system according to claim 1, wherein: The first edge node is further configured to: When the first edge node has locally cached the first content resource, the first content resource is sent to the client.

5. The system according to any one of claims 1 to 4, characterized in that: The central node is specifically used to: receiving the first access request from any one edge node in the at least one edge node group; When the central node has cached the first content resource locally, the first content resource is sent to any one of the edge nodes; or, when the central node has not cached the first content resource locally, the first access request is sent to the source server, the first content resource is received from the source server, and the first content resource is cached locally on the central node, and the first content resource is sent to any one of the edge nodes.

6. The system according to any one of claims 1 to 4, characterized in that: The at least one edge node group is obtained by dividing the plurality of edge nodes according to locations and / or operators to which they belong.

7. The system according to any one of claims 1 to 4, characterized in that: The first type of edge nodes and the second type of edge nodes are determined according to a back-to-source policy corresponding to the edge node group, where the back-to-source policy is used to indicate edge nodes responsible for back-to-source of all edge nodes in the edge node group in different time periods.

8. A content resource distribution method, characterized in that: Applied to a first edge node, the first edge node belongs to a first type of edge node in an edge node group, and the first type of edge node is not responsible for back-to-source for all edge nodes in the edge node group. The method includes: receiving a first access request from a client, where the first access request is for requesting a first content resource; When the first edge node does not cache the first content resource locally, a first redirection indication message is sent to the client, where the first redirection indication message is used to instruct the client to send the first access request to a second edge node, where the second edge node belongs to a second type of edge node in the edge node group, and the second type of edge node is responsible for traversing the source of all edge nodes in the edge node group.

9. The method according to claim 8, wherein Before sending the first redirection instruction information to the client, the method further includes: Determine that the status of the second edge node is normal.

10. The method according to claim 8, wherein The method further comprises: When the first edge node does not cache the first content resource locally and the status of any second edge node in the second type of edge node is abnormal, the first access request is sent to the central node, the first content resource is received from the central node, the first content resource is cached locally on the first edge node, and the first content resource is sent to the client.

11. The method according to claim 8, wherein The method further comprises: When the first edge node has locally cached the first content resource, the first content resource is sent to the client.

12. A content resource distribution method, characterized in that: Applied to a second edge node, the second edge node belongs to a second type of edge node in an edge node group, and the second type of edge node is responsible for traversing all edge nodes in the edge node group. The method includes: receiving a first access request from a client, the first access request being used to request a first content resource, the first access request being sent by the client to the second edge node when the client fails to request the first content resource from the first edge node, the first edge node being a first type of edge node in the edge node group, and the first type of edge node being not responsible for back-to-source communication for all edge nodes in the edge node group; When the second edge node has locally cached the first content resource, the first content resource is sent to the client; or, when the second edge node has not locally cached the first content resource, the first access request is sent to the central node, the first content resource is received from the central node, the first content resource is cached locally on the second edge node, and the first content resource is sent to the client.

13. A computing device, characterized in that: The method comprises a processor and a memory, wherein the memory is used to store computer program instructions. When the processor executes the computer program instructions, the method according to any one of claims 8 to 11 is executed.

14. A computing device, characterized in that: The method comprises a processor and a memory, wherein the memory is used to store computer program instructions, and when the processor executes the computer program instructions, the method according to claim 12 is performed.

15. A computing device, characterized in that Comprising a computing device as claimed in claim 13 or 14.

16. A computing device cluster, characterized in that: comprising at least one computing device as claimed in claim 15.

17. A computer-readable storage medium, characterized in that The method comprises computer program instructions, which, when executed by a computing device, cause the computing device to perform the method according to any one of claims 8 to 11 or 12.

18. A computer program product comprising instructions, characterized in that When the instructions are executed by a computing device, the computing device is caused to perform the method according to any one of claims 8 to 11 or 12.

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