A multi-level cdn caching method, system, storage medium, and electronic device

Abstract

The application relates to a multi-layer CDN cache method, system, storage medium and electronic equipment. The method comprises the following steps: S1, an initial CDN node uses a first layer acl in an acl multi-layer configuration file to process a request, and sends the processed request to an Ats of the initial CDN node; the Ats accesses a next CDN node according to a pre-configured load balancing strategy, and sends the processed request to the next CDN node; S2, a current CDN node uses a next layer acl in the acl multi-layer configuration file to process a request, and sends the processed request to an Ats of the current CDN node; the Ats accesses a next CDN node according to a pre-configured load balancing strategy, and sends the processed request to the next CDN node; the next CDN node is in the same layer or adjacent layers with the previous CDN node; S3, the step S2 is repeated until the Ats accesses a source station according to the pre-configured load balancing strategy; the source station sends data and caches the data to the CDN nodes passed in the previous access route. The CDN nodes can play the roles of different cache layers, and high availability of the nodes is guaranteed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of CDN cache, and particularly relates to a multi-level CDN cache method, system, storage medium and electronic device. BACKGROUND

[0002] As a service for caching static files, CDN can provide the fastest and most stable service closest to users. Edge computing can distribute CDN nodes to edge nodes, so that CDN is truly close to the user side. Multi-level cache is the most commonly used way of CDN at present, and nodes with similar resource quantities are divided into nodes of the same level, and the load capacity of CDN is improved through the multi-level way. However, this limits a node to only play the role of a cache of a certain level, that is, the resources are planned at the beginning, and the configuration of the corresponding level is issued. However, in the edge scenario, the resources of the edge nodes are not all uniform, and the most can reach more than 10, and the least can be 1-3 machines. If a node can only play the role of a cache of a certain level, this leads to that the resource load of a large edge node is not full, and the load of a small edge node is very busy. SUMMARY

[0003] In view of the above problems in the prior art, the application provides a multi-level CDN cache method, system, storage medium and electronic device. In the application, a CDN node can access CDN nodes in the same level or adjacent levels, so the same CDN node can play the role of a cache of different levels, ensures high availability of each CDN node, and greatly improves the load efficiency of the CDN node.

[0004] The application adopts the following technical scheme:

[0005] The first aspect of the embodiment of the application provides a multi-level CDN cache method, including the following steps:

[0006] S1, an initial CDN node receives a data request, the initial CDN node processes the request using the first layer acl in the acl multi-level configuration file, and sends the processed request to the Ats of the initial CDN node, the Ats accesses the next CDN node according to a pre-configured load balancing strategy, so as to send the processed request to the next CDN node, and the next CDN node is in the same level or adjacent level with the initial CDN node;

[0007] S2, the current CDN node processes the request using the next layer acl in the acl multi-level configuration file, and sends the processed request to the Ats of the current CDN node, the Ats accesses the next CDN node according to a pre-configured load balancing strategy, so as to send the processed request to the next CDN node, and the next CDN node is in the same level or adjacent level with the previous CDN node.

[0008] S3, repeating step S2 until Ats accesses to the source station according to the pre-configured load balancing strategy, the source station down-loads data and caches to the cdn nodes passed in the previous access route.

[0009] As a preferred solution, step S1 includes the following steps before:

[0010] setting acl multi-level configuration file, load balancing strategy configuration file of each cdn node, and down-loading acl multi-level configuration file and corresponding load balancing strategy configuration file to each cdn node, the load balancing strategy configuration file includes inquiry strategy of cdn node and accessible cdn node;

[0011] Ats selects a cdn node as the next cdn node for access according to the pre-configured inquiry strategy in the accessible cdn node.

[0012] As a preferred solution, the top-level cdn nodes closest to the source station all adopt the master-backup inquiry strategy.

[0013] As a preferred solution, the master-backup inquiry strategy is that all top-level cdn nodes can directly access the source station, but only when all top-level cdn nodes accessible by the top-level cdn node all fail or when the top-level cdn node has no configured accessible cdn node, the top-level cdn node directly accesses the source station.

[0014] As a preferred solution, the rest of the level cdn nodes except the top-level cdn nodes all adopt the polling inquiry strategy.

[0015] As a preferred solution, the polling inquiry strategy is that the cdn node randomly selects a cdn node of the same level or an upper cdn node of the adjacent level in its accessible cdn nodes for access.

[0016] As a preferred solution, the accessible cdn nodes of the cdn node are configured according to the cache capacity of each cdn node.

[0017] The second aspect of the embodiment of the application provides a multi-level cdn cache system based on the above multi-level cdn cache method, including a center configuration module, a cdn node group and a source station.

[0018] The center configuration module is used for setting acl multi-level configuration file, load balancing strategy configuration file of each cdn node, and down-loading acl multi-level configuration file and corresponding load balancing strategy configuration file to each cdn node.

[0019] cdn nodes, configured to receive data requests and access and cache data according to the configured ACL multi-level configuration file and load balancing strategy configuration file;

[0020] a source station, configured to send the requested data to the corresponding cdn node.

[0021] The third aspect of the embodiment of the present application provides a computer readable storage medium, which stores computer instructions, and the computer instructions are used to make the computer execute the multi-level cdn caching method according to the first aspect of the embodiment of the present application and any one of the first aspect.

[0022] The fourth aspect of the embodiment of the present application provides an electronic device, which comprises a memory and a processor, the memory and the processor are connected to each other in communication, the memory stores computer instructions, and the processor executes the computer instructions to execute the multi-level cdn caching method according to the first aspect of the embodiment of the present application and any one of the first aspect.

[0023] The present application has the following beneficial effects:

[0024] In the present application, the cdn nodes can access the cdn nodes in the same level or adjacent level, so that the same cdn node can play the role of different cache levels, ensure the high availability of each cdn node, and greatly improve the load efficiency of the cdn node.

[0025] Each cdn node can use the same set of ACL multi-level configuration files, and only needs to process the request according to the order of using different layers of acl in the ACL multi-level configuration, without the need to issue different configurations for each level, reducing the complexity of operation and configuration management, and facilitating the central configuration system to issue configurations.

[0026] The master-backup inquiry strategy and the polling inquiry strategy are adopted to ensure that when a node fails, other normal nodes can be used for access, ensuring the normal operation of the cache, and the master-backup inquiry strategy also ensures the high availability of the node while the data is only sourced once. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0028] Figure 1 is a data access flowchart of the prior art multi-level cdn caching method;

[0029] Figure 2 is a flow chart of a multi-level CDN caching method according to an embodiment of the present application;

[0030] Figure 3 is a data access flow chart of a multi-level CDN caching method according to an embodiment of the present application;

[0031] Figure 4 is a flow chart of nginx configuration acl;

[0032] Figure 5 is a schematic diagram of a central configuration module issuing a configuration file to a CDN node;

[0033] Figure 6 is a structural schematic diagram of a multi-level CDN caching system according to an embodiment of the present application;

[0034] Figure 7 is a structural schematic diagram of a computer readable storage medium according to an embodiment of the present application;

[0035] Figure 8 is a structural schematic diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0036] The present application will be described in more detail by the following specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in the specification. The present application can also be implemented or applied by different specific embodiments, and each detail in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0037] Embodiment one:

[0038] Multi-level caching is the most commonly used way for CDN at present, and nodes with similar resource quantities are classified as nodes of the same level, and the load capacity of CDN is improved through multi-level way. However, this limits that a node can only play the role of a certain level of cache, which can be referred to as shown in Figure 1 that is, the resources are planned at the beginning, and then the configuration of the corresponding level is issued. However, in the edge scene, the resources of the edge nodes are not all uniform, and the number of the most can reach more than 10, and the number of the least may be 1-3 machines. If all are uniformly used as edge nodes, this will lead to that the resource load of large edge nodes is not full, and the load of small edge nodes is very busy. In the process of using the current multi-level caching method, the following problems are found:

[0039] In both on-demand and live streaming scenarios, the origin nodes are overloaded, while the edge nodes experience uneven resource distribution. This is because, firstly, all edge nodes converge on the origin nodes, and secondly, the resources of the edge nodes are unevenly distributed.

[0040] Because clients require that the same file should only be retrieved from the origin server once, typically only one origin server node can be used. This makes the node lack high availability. If it is shut down due to unforeseen circumstances, that node becomes unusable.

[0041] A node can only play a role at one level. Edge nodes can actually act as parent nodes to share the load pressure of the back-to-source nodes.

[0042] Therefore, refer to Figure 2 , Figure 3 As shown, this embodiment provides a multi-level CDN caching method, including the following steps:

[0043] S1. The initial CDN node receives a data request. The initial CDN node processes the request using the first layer ACL in the ACL multi-level configuration file and sends the processed request to the Ats of the initial CDN node. The Ats accesses the next CDN node according to the pre-configured load balancing strategy to send the processed request to the next CDN node. The next CDN node is at the same level or adjacent to the initial CDN node.

[0044] It should be noted that, Figure 3 The diagram is presented in three tiers: the first tier is the county-level CDN node, of which one is shown in the diagram; the second tier is the city-level CDN node, of which two are shown in the diagram; and the third tier is the provincial-level CDN node, of which two are shown in the diagram.

[0045] S2. The current CDN node uses the next-level ACL in the ACL multi-level configuration file to process the request and sends the processed request to the Ats of the current CDN node. The Ats accesses the next CDN node according to the pre-configured load balancing strategy to send the processed request to the next CDN node. The next CDN node is at the same level or adjacent to the previous CDN node.

[0046] S3. Repeat step S2 until Ats accesses the origin server according to the pre-configured load balancing strategy. The origin server will then distribute and cache the data to the CDN nodes that the previous access route passed through.

[0047] The CDN node in the application can access CDN nodes in the same level or adjacent levels, so the same CDN node can play the role of different cache levels, ensuring high availability of each CDN node and greatly improving the load efficiency of the CDN node. Moreover, each CDN node can use the same set of ACL multi-level configuration files, and only needs to use different layers of acl in the ACL multi-level configuration to process the request in sequence, without the need to issue different configurations for each level, reducing the complexity of operation and configuration management, and facilitating the central configuration system to issue configurations.

[0048] Specifically,

[0049] The step S1 includes the following steps:

[0050] The acl multi-level configuration file and the load balancing strategy configuration file of each CDN node are set, and the acl multi-level configuration file and the corresponding load balancing strategy configuration file are issued to each CDN node. The load balancing strategy configuration file includes the inquiry strategy of the CDN node and the accessible CDN node.

[0051] The Ats selects a CDN node as the next CDN node for access from the accessible CDN nodes according to the pre-configured inquiry strategy.

[0052] Referring to Figure 3 As shown in the figure, for example, the first layer CDN node can access the second layer CDN1 node, and can also access the second layer CDN2 node. The second layer CDN node 1 can access the second layer CDN2 node in the same level or the top layer CDN1 node and the top layer CDN2 node. It should be noted that Figure 3 In the application, a maximum of 2 CDN nodes are displayed in one level. When there are more CDN nodes, the accessible nodes can be configured according to the cache capacity of each CDN node. The CDN node with strong cache capacity can be accessed by more CDN nodes. The mechanism of accessing other nodes is similar, which will not be described in detail here.

[0053] The specific inquiry strategy is described as follows:

[0054] Among them, the top layer CDN node closest to the source station adopts the master-backup inquiry strategy. The master-backup inquiry strategy is that all top layer CDN nodes can directly access the source station, but only when all top layer CDN nodes accessible by the top layer CDN node fail, or when the top layer CDN node has no configured accessible CDN node, the source station is directly accessed.

[0055] Taking the top-level CDN1 node as an example, it is configured to access the top-level CDN2 node. It can access the origin server through CDN2 or directly, but it prioritizes accessing the origin server through CDN2. Direct access to the origin server only occurs when CDN2 fails. The top-level CDN2 node is not configured to access any top-level CDN node, therefore it directly accesses the origin server. This master-slave query strategy ensures high node availability while data is only routed to the origin server once.

[0056] Except for the top-level CDN node, all other CDN nodes employ a round-robin query strategy. This strategy involves a CDN node randomly selecting either a CDN node of the same level or a higher-level CDN node from its accessible CDN nodes for access.

[0057] by Figure 3 Taking the first-layer CDN node as an example, it is configured to access the second-layer CDN1 node and the second-layer CDN2 node. Therefore, it randomly selects one of these two nodes for access. It should be noted that if the second-layer CDN1 node fails, it will select the second-layer CDN2 node for access, and vice versa. Similarly, for the second-layer CDN node 1, it is configured to access the second-layer CDN2 node, the top-layer CDN1 node, and the top-layer CDN2 node, and therefore randomly selects one node for access.

[0058] It should be noted that when using a round-robin query strategy for access, it is not necessary to use a random selection mechanism. A weighted mechanism can also be used, or the appropriate CDN node can be selected for access based on the client's request.

[0059] The following describes the prerequisite technologies required to implement the solution of this invention:

[0060] 1. Nginx + OpenResty technology, which supports loading a formatted file (JSON) as an ACL (Access Control List) configuration file. (See also...) Figure 4 As shown. This technology is based on a CDN node framework, and multi-layered configurations are implemented on top of this framework.

[0061] 2. Nginx + OpenResty technology is responsible for handling the caching logic, such as request processing, hotlinking prevention, and blacklists / whitelists.

[0062] 3、Ats (apache traffic server) is responsible for processing actual cache files, and can index files according to the sticky header of nginx. It can be understood as a real cache server.

[0063] 4、The center configuration module can divide the back source node and the edge node. It should be noted that the back source node can be understood as the top-level CDN node in the Figure 3 , that is, the provincial CDN node, and the edge node can be understood as the first layer and the second layer CDN nodes in the Figure 3 , that is, the county-level and city-level CDN nodes. The acl multi-level configuration file and the load balancing strategy configuration file of each CDN node can be set, and the acl multi-level configuration file and the corresponding load balancing strategy configuration file are distributed to each CDN node. The load balancing strategy configuration file includes the inquiry strategy of the CDN node and the accessible CDN node. The edge node sets the back source strategy of the ats to the polling inquiry strategy when setting. The back source node sets the back source node to the master-backup inquiry strategy.

[0064] The present application improves the following in the existing framework in combination with the capacity of the edge CDN node in view of the original CDN multi-level cache scheme:

[0065] 1、Each node can set multiple levels of configuration (use the configuration file of ACL), so each node can be used as any level of cache (because the cache is indexed according to the value of the key), and the overall back source flow can refer to Figure 3 . A prerequisite is that if a node is down, the back source will use the node that is not down, which ensures that the service does not interrupt.

[0066] 2、Set high-availability nodes in the center node, which can share the load of the center node and also guarantee the requirement of only one back source for the same file (this depends on the dynamic back source module provided by openresty).

[0067] 3、The center side only needs to distribute the same configuration to each node, and does not need to distribute different configurations to each level. The bottom principle can be referred to in Figure 4 , and the interaction between the center configuration module and the CDN node can be referred to in Figure 5 .

[0068] The following describes the processing flow of the client sending a data request under various conditions to further explain the scheme of the present application:

[0069] Case 1, first normal data flow processing:

[0070] When the request (www.test.com / test.txt) reaches the first-level CDN node, the CDN checks if the request header contains nginx_level. Since this is an initial request, there is no nginx_level header. The CDN will then use the previously configured first-level ACL to process the request. Figure 5 (www.test.com in the URL). And set nginx_level +1, and configure the cached request glue header:

[0071] Send cache_key:www.test.com / test.txt cache_time:maxAge=1800 to ATS.

[0072] After receiving the request, ATS uses the cache_key to retrieve the cached block data. If the file is not found, it queries the corresponding CDN node according to the query strategy. The strategy here is set to round-robin, so a node will be randomly selected to return to the origin. For example, the second-level CDN1 node was selected here.

[0073] The second-layer CDN1 node, based on nginx_level, discovers that it needs to read the second-layer configuration. Figure 5 Then, it reads the configuration and repeats the same actions as the first-level CDN node (up_1_www.test.com).

[0074] Finally, the traffic reaches the top-level CDN1 node, which repeats the same logic. After reaching the ATS, because the load balancing strategy uses a primary / backup approach (primary is the top-level CDN2 node, and backup is the origin server), all traffic will eventually reach the top-level CDN2 node and then the origin server.

[0075] The top-level CDN2 node pulls the data, and ATS caches the data based on the cache_key: www.test.com / test.txt. Then it sends the data to the top-level CDN1, and so on down to the first-level CDN node, completing the caching process.

[0076] Scenario 2: The client accesses the CDN node again:

[0077] Upon reaching the first-level CDN node, the first-level configuration (www.test.com) is read. Then, the cache_key:www.test.com is used to access ATS. If the file exists, it is returned directly.

[0078] Arrive at the second layer cdn2 node, because there is no cache, according to the round robin load strategy, access the top layer cdn1 node, and then the top layer cdn1 node exists the file before, directly return the node. Of course, the round robin strategy, can also access the top layer cdn2 node, and because of the cache in case one, can also access the file.

[0079] Case three: the second layer cdn1 node failure:

[0080] The request arrives at the first layer cdn node, and the ats uses the health probe to exclude the second layer cdn1 node, and uses the second layer cdn2 node as the source. Then repeat the logic of case one, set cache_key, cache_time request header, and then return to the source station.

[0081] Case four: the top layer cdn1 node failure:

[0082] The second layer cdn node selects the top layer cdn2 node as the source according to the round robin strategy, and repeats the logic of case one, sets cache_key, cache_time request header, and returns to the source station.

[0083] Case five: the top layer cdn2 node failure:

[0084] The second layer cdn node accesses the top layer cdn1 node according to the round robin strategy, and the top layer cdn node adopts the master-slave strategy. Since the top layer cdn2 node fails, only the standby node, that is, the source station, can be accessed. Pull the file from the source station, cache the file according to cache_key and cache_time, and return it to the client.

[0085] Embodiment two:

[0086] Referring to Figure 6 The embodiment provides an expression syntax analysis system based on the expression syntax analysis method in embodiment one, which comprises a center configuration module, a cdn node group and a source station.

[0087] The center configuration module is used for setting acl multi-level configuration files and load balancing strategy configuration files of each cdn node, and delivering the acl multi-level configuration files and the corresponding load balancing strategy configuration files to each cdn node.

[0088] The cdn node is used for receiving data requests sent by a client, and performing access and data caching according to the configured acl multi-level configuration files and load balancing strategy configuration files.

[0089] The source station is used for delivering the requested data to the corresponding cdn node.

[0090] It should be noted that the expression syntax analysis system provided in this embodiment is similar to that in Embodiment 1, and will not be described in detail here.

[0091] Example 3:

[0092] Reference Figure 7 As shown, this embodiment of the invention also provides a storage medium storing a computer program 601. When executed by a processor, this program implements the steps of a multi-level CDN caching method described in the above embodiments. Those skilled in the art will understand that all or part of the processes in the methods described in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes described in Embodiment 1 above.

[0093] The storage medium may be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium may also include combinations of the above types of memory.

[0094] Example 4:

[0095] Reference Figure 8 As shown, this embodiment of the invention also provides an electronic device, which may include a processor 51 and a memory 52, wherein the processor 51 and the memory 52 can be connected via a bus or other means. Figure 8 Taking the example of a connection between China and Israel via a bus.

[0096] Processor 51 can be a central processing unit (CPU). Processor 51 can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations of the above types of chips.

[0097] The memory 52, as a non-transitory computer readable storage medium, can be used to store non-transitory software programs, non-transitory computer executable programs and modules, such as corresponding program instructions / modules in the embodiments of the present application. The processor 51 performs various functional applications and data processing of the processor by running the non-transitory software programs, instructions and modules stored in the memory 52, that is, implements the multi-level CDN cache method in the above-mentioned embodiment one.

[0098] The memory 52 can include a program storage area and a data storage area, wherein the program storage area can store application programs required by the operation of the device and at least one function; and the data storage area can store data created by the processor 51 and the like. In addition, the memory 52 can include a high-speed random access memory, and can also include a non-transitory memory, such as at least one disk storage device, a flash memory device, or other non-transitory solid-state memory device. In some embodiments, the memory 52 can optionally include a memory remotely arranged with respect to the processor 51, and these remote memories can be connected to the processor 51 through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0099] The one or more modules are stored in the memory 52, and when executed by the processor 51, perform the multi-level CDN cache method described in embodiment one.

[0100] The above-mentioned electronic device specific details can be understood in correspondence with the corresponding related description and effects in embodiment one, which will not be repeated here.

[0101] The above-mentioned embodiments only describe the preferred embodiments of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements of the technical solutions of the present application made by those skilled in the art shall fall within the protection scope of the present application.

Claims

1. A multi-tiered CDN caching method, characterized by, The method comprises the steps of: S1, an initial CDN node receives a data request, the initial CDN node processes the request using a first layer ACL in an ACL multi-layer configuration file, and sends the processed request to an Ats of the initial CDN node, the Ats accesses a next CDN node according to a pre-configured load balancing strategy to send the processed request to the next CDN node, the next CDN node is in the same layer or adjacent layer as the initial CDN node; S2, a current CDN node processes the request using a next layer ACL in the ACL multi-layer configuration file, and sends the processed request to an Ats of the current CDN node, the Ats accesses a next CDN node according to a pre-configured load balancing strategy to send the processed request to the next CDN node, the next CDN node is in the same layer or adjacent layer as the previous CDN node; S3, repeating step S2 until the Ats accesses a source station according to the pre-configured load balancing strategy, the source station sends data and caches the data to the CDN nodes on the previous access route.

2. The multi-tiered CDN caching method of claim 1, wherein, Before step S1, the method comprises the steps of: setting an ACL multi-layer configuration file and a load balancing strategy configuration file of each CDN node, and sending the ACL multi-layer configuration file and the corresponding load balancing strategy configuration file to each CDN node, the load balancing strategy configuration file comprises an inquiry strategy and accessible CDN nodes of the CDN node; the Ats selects an accessible CDN node as a next CDN node for access according to the pre-configured inquiry strategy.

3. The multi-tiered CDN caching method of claim 2, wherein, The top-layer CDN nodes closest to the source station all adopt a master-backup inquiry strategy.

4. The multi-tiered CDN caching method of claim 3, wherein, The master-backup inquiry strategy is that all top-layer CDN nodes can directly access the source station, but only when all top-layer CDN nodes accessible by the top-layer CDN node all fail, or when the top-layer CDN node has no configured accessible CDN node, the top-layer CDN node directly accesses the source station.

5. The multi-tiered CDN caching method of claim 3, wherein, The CDN nodes in layers other than the top layer all adopt a polling inquiry strategy.

6. The multi-tiered CDN caching method of claim 5, wherein, The polling inquiry strategy is that a CDN node randomly selects a CDN node in the same layer or an upper CDN node in an adjacent layer from the accessible CDN nodes of the CDN node for access.

7. The multi-tiered CDN caching method of claim 2, wherein, The accessible CDN nodes of the CDN node are configured according to the cache capabilities of the CDN nodes.

8. A multi-tiered CDN caching system based on the multi-tiered CDN caching method of any of claims 1-7, characterized in that, The method comprises a central configuration module, a CDN node group, and a source station. The central configuration module is configured to set an ACL multi-layer configuration file and a load balancing strategy configuration file of each CDN node, and send the ACL multi-layer configuration file and the corresponding load balancing strategy configuration file to each CDN node. The CDN node is configured to receive a data request, and access and cache data according to the configured ACL multi-layer configuration file and load balancing strategy configuration file. The source station is configured to send requested data to a corresponding CDN node.

9. A computer-readable storage medium, characterized in that, The computer readable storage medium stores computer instructions for causing the computer to perform the multi-layer CDN caching method of any one of claims 1-7.

10. An electronic device, comprising: The method comprises: A memory and a processor, which are connected with each other in communication, the memory stores computer instructions, and the processor executes the computer instructions to perform the method of claim 1-7.

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