KR101825841B1 - Apparatus and method for allcating time-to-live - Google Patents

Abstract

Disclosed are an apparatus and a method to allocate a time-to-live (TTL), capable of reducing load of an origin server and a cache server. According to the present invention, the origin server to provide a personal broadcasting service comprises: at least one processor; and at least one memory to store instructions executed by the processor. When being executed by the processor, the instructions are configured to execute an operation of allowing the processor to receive a transmission request for video data from the cache server when the cache server does not include the video data requested by a client; an operation of calculating a TTL of the video data based on information related to the video data corresponding to the transmission request for the video data; and an operation of transmitting the video data and the TTL to the cache server.

Description

[0001] APPARATUS AND METHOD FOR ALLCATING TIME-TO-LIVE [0002]

The following description relates to a technology for allocating a TTL to video data, and relates to a technique for allocating a TTL to video data stored in a cache server in real time broadcasting.

Recently, the number of one-person media has increased. For example, personal television service African TV appeared, and services such as YouTube or Facebook also launched real-time personal broadcasting services. Especially, in the case of YouTube, a viewer is provided with a function of selectively reverting the past video when the viewer wants to watch the past video even while the personal broadcasting is in progress.

The present invention provides an apparatus and a method for reducing load on a root server and a cache server by allocating a survival time based on information related to image data to image data transmitted to a cache server.

A source server that provides a personal broadcasting service according to one embodiment includes at least one processor and at least one memory for storing instructions to be executed by the processor, the instructions being executable by the processor Receiving, by the processor, a request for transmission of the image data from the cache server when the cache server does not include the image data requested by the client; Calculating a time to live (TTL) of the image data based on information related to the data, and transmitting the image data and the lifetime to the cache server.

The information related to the image data may include an audience rating of the image data.

The information related to the image data may include an amount of conversation of the chat room associated with the image data.

The information related to the image data may include a number of times the image data is requested.

The information related to the image data may include the number of feedbacks to the image data.

According to an embodiment, the load of the root server and the cache server can be reduced by allocating the survival time based on the image data related to the image data to be transmitted to the cache server.

1 is a block diagram of a system for providing a personal broadcasting service according to an exemplary embodiment of the present invention.
2 is a flowchart illustrating a method of providing a personal broadcasting service according to an exemplary embodiment of the present invention.
3 is a flowchart illustrating a process of providing a personal broadcasting service according to an exemplary embodiment of the present invention.
FIG. 4 illustrates an example of a time-based display of information related to image data as data for determining priority of image data according to an exemplary embodiment.
5A is a flowchart illustrating a process of transmitting image data in which priority is determined based on information related to image data corresponding to # 1 in FIG. 4 according to an exemplary embodiment.
FIG. 5B is a flowchart illustrating a process of transmitting image data whose priority is determined based on information related to image data corresponding to # 2 in FIG. 4 according to an exemplary embodiment.
5C is a flowchart illustrating a process of transmitting image data whose priority is determined based on information related to image data corresponding to # 3 of FIG. 4 according to an exemplary embodiment.
5D is a flowchart illustrating a process of transmitting image data in which priority is determined based on information related to image data corresponding to # 4 in FIG. 4 according to an exemplary embodiment.

Specific structural or functional descriptions of embodiments are set forth for illustration purposes only and may be embodied with various changes and modifications. Accordingly, the embodiments are not intended to be limited to the specific forms disclosed, and the scope of the disclosure includes changes, equivalents, or alternatives included in the technical idea.

The terms first or second, etc. may be used to describe various elements, but such terms should be interpreted solely for the purpose of distinguishing one element from another. For example, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" to another element, it may be directly connected or connected to the other element, although other elements may be present in between.

The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises ", or" having ", and the like, are used to specify one or more of the described features, numbers, steps, operations, elements, But do not preclude the presence or addition of steps, operations, elements, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning of the context in the relevant art and, unless explicitly defined herein, are to be interpreted as ideal or overly formal Do not.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention with reference to the accompanying drawings, the same components are denoted by the same reference numerals regardless of the reference numerals, and a duplicate description thereof will be omitted.

1 is a block diagram of a system for providing a personal broadcasting service according to an exemplary embodiment of the present invention.

According to one embodiment, the system may provide personal broadcasting services. For example, the system can be applied to personal broadcasting of media such as African TV, YouTube or Facebook. According to one embodiment, the system can provide broadcast services in real time. The system can store the past image data in the source server 110 and transmit the image data corresponding to the transmission request of the client 140, 141 or 142 to the image data.

For example, the video data may include segments of MPEG-DASH. When the client 140, 141, or 142 transmits a transmission request for a segment at a specific point in time, the origin server 110 may transmit the segment corresponding to the point in time. Accordingly, the system can provide the client 140, 141, or 142 with the image at the time when the system has already passed the client during the real-time personal broadcasting.

According to one embodiment, the system may temporarily store image data in the cache server 120 or 123 closer to the client 140, 141 or 142 than the origin server 110. [ The client 140, 141, or 142 may first transmit the transmission request to the cache server 120 or 123 to receive the image data. When the cache server 120 or 123 does not store the corresponding image data, the cache server 120 or 123 requests the image data required by the source server 110 and receives the image data and transmits the image data to the client 140, 141 or 142 Lt; / RTI >

According to one embodiment, the system may allocate time-to-live (TTL) to video data transmitted from the source server 110 to the cache server 120 or 123. Thus, the load of the source server 110 and the cache server 120 or 123 can be reduced together. In the case of the origin server 110, a load corresponding to a transmission request may be reduced, and a load may be imposed on the storage space in the case of the cache server 120 or 123.

According to one embodiment, the system allocates a longer lifetime to the image data having higher priority by the source server, thereby efficiently utilizing the storage space of the cache server in which the image data is stored. Here, the image data having high priority can be referred to as highlight image data. The highlight video data may mean video data having high viewer preference. As such, the system can guarantee a better quality of service (QoS) by allocating a longer lifetime to highlight image data.

To this end, the system may include a source server 110, a cache server 120 or 123 and a client 140, 141 or 142. For example, the origin server 110 may include a Content Delivery Network (CDN) server. Here, the cache server may be one or a plurality of cache servers. For example, the cache server may include cache server 1 120, ..., cache server N 123. Here, N may be an arbitrary integer. The client may be either one or plural.

The origin server 110, the cache server 120 or 123, and the client 140, 141 or 142 may be networked. For example, a wide area network (WAN) 130 may be used. However, the network refers to a connection structure in which information can be exchanged between each node such as terminals and servers. An example of such a network is an Internet, a LAN (Local Area Network), a Wireless LAN Local Area Network), WAN, Personal Area Network (PAN), 3G, 4G, LTE and Wi-Fi.

The system may further include a multicast router 124. The cache server 120 or 123 may transmit data to the client 140, 141 or 142 using the multicast router 124. [ Alternatively, the cache server 120 or 123 may send data directly to the client 140, 141 or 142. [

The system may further include a camera 111 or an encoder 112. The system may encode the image data photographed through the camera 111 through the encoder 112 and transmit the encoded image data to the source server 110. Alternatively, the system does not include the camera 111 or the encoder 112, but may receive the image data encoded by the external camera and encoder and transmit the image data to the origin server.

According to one embodiment, the origin server 110 may store image data captured by the camera 111 and encoded by the encoder 112. In one embodiment, The encoding method may be a suitable technique for a real-time broadcast or streaming service. For example, the encoder 112 may use technologies such as MPEG's Dynamic Adaptive Streaming over HTTP (DASH), Apple's HLS, Microsoft's Smooth Streaming, or Adobe's HDS.

Here, the DASH of MPEG is a streaming standard in which moving pictures are divided into segments and transmitted through HTTP. MPEG DASH stores segments of compressed video data at various bit rates, allowing a user to select segments of different bit rates for the same video according to the state of the network. For example, using DASH of MPEG, an adaptive service suitable for a network environment is set up by setting a small segment of a mobile and real-time broadcast service where a network performance is prioritized and a segment size of a non-real-time video- It is possible.

The system can store the image data stored in the source server 110 in one or more cache servers 120 or 123 since it is inefficient when transmission requests for all of the image data are transmitted to the source server 110. [ The cache server 120 or 123 is located close to the client 140, 141 or 142 and caches the content of the origin server 110 and transmits the content to the client 140, 141 or 142 on behalf of the origin server 110. [ As shown in FIG. As described above, since the cache server 120 or 123 has a small round-trip time (RTT) due to a short distance, it is possible to perform a fast transmission.

When the content stored in the source server 110 is updated, the content cached in the cache server 120 or 123 may not be valid any more. The cache server 120 or 123 may periodically validate the freshness of the cached content from the origin server 110. If it is determined that the content has been updated, the cache server 120 or 123 may receive the content again from the origin server 110. [

Referring to FIG. 1, one or more clients 140, 141, or 142 may transmit a request for transmission of image data to the cache server 120 or 123. When the cache server 120 or 123 stores image data corresponding to a transmission request, the cache server 120 or 123 can transmit the image data to the client 140, 141 or 142.

If the cache server 120 or 123 does not store the image data corresponding to the transfer request, the cache server 120 or 123 may transmit the transfer request to the origin server 110. [ The source server 110 may receive a transmission request for video data from the cache server 120 or 123. [

The source server 110 may allocate a longer lifetime to the higher priority video data and transmit it to the cache server 120 or 123. [ To this end, the origin server 110 may include one or more processors and one or more memories. The memory may store instructions to be executed by the processor. The image data may be stored in the memory.

The processor may determine the priority of the image data based on information related to the image data in response to the transmission request for the image data. The processor can assign priority to the image data. The processor may send the image data and the lifetime to the cache server 120 or 123.

According to another embodiment, the processor may allocate the lifetime of the image data based on information related to the image data in response to a transmission request for the image data. As such, the processor may assign the survival time immediately without determining the priority.

The cache server 120 or 123 may transmit the image data and the lifetime received from the origin server 110 to the client 140, 141 or 142 in response to the transmission request of the client 140, 141 or 142. As described above, the source server 110 can provide the video data to the client 140, 141, or 142 through the cache server 120 or 123.

2 is a flowchart illustrating a method of providing a personal broadcasting service according to an exemplary embodiment of the present invention.

According to one embodiment, in step 210, when the cache server 120 or 123 does not store image data corresponding to a transfer request, it may transmit a transfer request to the origin server 110. [ The source server 110 may receive a transmission request for video data from the cache server 120 or 123. [

According to one embodiment, in step 230, the source server 110 may determine the priority of the image data based on information related to image data in response to a transmission request for image data.

For example, the information related to the image data may include the viewing rate of the image data, the amount of conversation of the chat room related to the image data, the number of requests for the image data, and the number of times of feedback on the image data. For example, feedback can include Facebook's likes or African TV's 'star balloon' clicks.

For example, the source server 110 may calculate the audience rating of the video data in a preset manner. When the audience rating is high, it can mean that the viewer's preference with respect to the video data is high. Likewise, when there is a large amount of the dialog volume or the number of requests for the image data related to the image data, it may mean that the viewer's preference for the image data is high. As described above, it is possible to determine whether the information related to the image data is highlight image data based on the image data.

For example, the source server 110 may determine the priority based on the number of feedbacks to the image data. The source server 110 may determine the priority of the video data based on the content of the feedback. If the contents of the feedback include a preset word or sentence, the priority can be determined by adding the predetermined score to the word or sentence.

The above description is only an example, and the information related to the image data is not limited thereto.

According to one embodiment, in step 250, the origin server 110 may assign a priority lifetime to the image data. For example, a longer lifetime may be assigned to image data with higher priority. As a result, the load corresponding to the transmission request can be reduced for the source server 110, and the load on the storage space can be reduced for the cache server 120 or 123.

According to one embodiment, in step 270, the origin server 110 may transmit image data and a lifetime to the cache server 120 or 123. [ The cache server 120 or 123 may store the received image data for a corresponding lifetime. If the lifetime is exceeded, the cache server 120 or 123 may delete the received image data.

3 is a flowchart illustrating a process of providing a personal broadcasting service according to an exemplary embodiment of the present invention.

Referring to FIG. 3, during the real-time broadcasting, the client transmits a transmission request (HTTP GET) to the cache server with respect to the past video data seg # 1 having the host address "www.example.com" .

The cache server can determine that the image data seg # 1 is not stored in the memory after confirming that the image data seg # 1 is stored in the memory. The cache server can send a transfer request for the image data (seg # 1) to the origin server.

The source server can retrieve the image data (seg # 1) stored in the memory in response to the transfer request. The source server checks the last modification time of the video data seg # 1 and then reads the information (Analysis Results) related to the video data seg # 1 and loads the priority of the video data seg # You can decide. For example, the origin server can set the lifetime of the image data (seg # 1) to be stored in the cache server to 3000 seconds based on the determined priority through the command "Cache Control.Max age = 3000".

The source server may transmit the information on the survival time together with the image data (seg # 1) to the cache server. The cache server may store the image data (seg # 1) and set the survival time to 3000 seconds in the cache control table. The cache server may transmit the image data seg # 1 to the client.

After 1800 seconds, the client can again send a transmission request for the image data (seg # 1) to the cache server. The cache server can confirm that the lifetime of the cache control table is 1200 seconds. Since the video data seg # 1 is stored in the cache server, the cache server is in a cache hit state, and the cache server can transmit the video data seg # 1 to the client.

FIG. 4 illustrates an example of a time-based display of information related to image data as data for determining priority of image data according to an exemplary embodiment.

Referring to FIG. 4, an image may be composed of a plurality of image data. Here, the image data may be referred to as a segment. For example, the image data may be a DASH segment. For example, the image may be composed of segments of # 1 to # 4, which are four segments. Each segment can be divided into time units.

The information related to the video data may include the viewing rate of the video data, the amount of conversation of the chat room related to the video data, the number of requests for the video data, and the number of times of feedback on the video data. For example, referring to FIG. 4, the information related to the image data includes 'number of viewers (total_viewer)' included in the audience rating, 'number of likes clicks (num_like)' included in the number of feedbacks, quot; num_balloon " and " chat room num_chat. "

5A is a flowchart illustrating a process of transmitting image data in which priority is determined based on information related to image data corresponding to # 1 in FIG. 4 according to an exemplary embodiment.

Referring to FIG. 5A, during the real-time broadcasting, the client transmits a transmission request (HTTP GET) to the cache server with respect to the past video data seg # 1 having the host address "www.example.com" .

The cache server can determine that the image data seg # 1 is not stored in the memory after confirming that the image data seg # 1 is stored in the memory. In this way, when a cache miss occurs, the cache server can transmit a transfer request for the image data seg # 1 to the source server.

The source server can retrieve the image data (seg # 1) stored in the memory in response to the transfer request. The source server reads the information (Analysis Results) related to the image data seg # 1 after confirming the last modification time of the image data seg # 1 and then calculates the lifetime of the image data seg # Can be determined.

For example, if the 'total_viewer' of the image data seg # 1 is 100, the number of 'liked clicks num_like' is 7, the number of star balloons 'num_balloon' is 2, Quot; num_chat " of the chat room may be 207. [

The source server may add 300 seconds to the survival time 0 second based on the 'total_viewer' 100. The source server calculates a chat rate (chat_rate) 2.07 based on the 'chat_rate_20' of the chat room, and based on this, it can add 600 seconds to the lifetime 300 seconds. The origin server can add 0 seconds to the lifetime 900 seconds based on the 'likelihood clicks (num_like)' 7. The origin server may add 0 seconds to the 900 second survival time based on the number of star balloons (num_balloon) 2. For example, the origin server can set the lifetime of the image data (seg # 1) to be stored in the cache server to 900 seconds through the command "Cache Control.Max age = 900 ".

The source server may transmit information (900 seconds) about the survival time together with the image data (seg # 1) to the cache server. The cache server may store the image data seg # 1 and set the lifetime to 900 seconds in the cache control table. The cache server may transmit the image data seg # 1 to the client.

FIG. 5B is a flowchart illustrating a process of transmitting image data whose priority is determined based on information related to image data corresponding to # 2 in FIG. 4 according to an exemplary embodiment.

Referring to FIG. 5B, during the real-time broadcasting, the client transmits a transmission request (HTTP GET) to the cache server with respect to the past video data seg # 2 having the host address "www.example.com" .

The cache server can determine that the image data seg # 2 is not stored in the memory after confirming that the image data seg # 2 is stored in the memory. In this way, when a cache miss occurs, the cache server can transmit a transmission request for the image data seg # 2 to the source server.

The source server can retrieve the image data (seg # 2) stored in the memory in response to the transmission request. The source server reads the information (Analysis Results) related to the image data seg # 2 after confirming the last modification time of the image data seg # 2 and loads the survival time of the image data seg # Can be determined.

For example, if the number of viewers (total_viewer) of the image data seg # 2 is 100, the number of thumbnails is 39, the number of balloons is 57, Quot; num_chat " of the chat room may be 399. [

The source server may add 300 seconds to the default lifetime 0 seconds based on the 'total_viewer' 100. The source server calculates a chat rate (chat_rate) 3.99 based on the 'chat_battery' (num_chat) '399, and based on this, it can add 900 seconds to the lifetime 300 seconds. The origin server may add 900 seconds to the lifetime 1200 seconds based on the 'likes click (num_like)' 39. The source server may add 600 seconds to the lifetime of 2100 seconds based on the number of balloons (num_balloon) '57. For example, through the command "Cache Control.Max age = 2700", the source server can set the lifetime of the image data (seg # 2) to be stored in the cache server to 2700 seconds.

The source server can transmit the information on the survival time (2700 seconds) to the cache server together with the image data (seg # 2). The cache server may store the image data (seg # 2) and set the lifetime to 2700 seconds in the cache control table. The cache server may transmit the image data seg # 2 to the client.

5C is a flowchart illustrating a process of transmitting image data whose priority is determined based on information related to image data corresponding to # 3 of FIG. 4 according to an exemplary embodiment.

Referring to FIG. 5C, during the real-time broadcast transmission, the client transmits a transmission request (HTTP GET) to the cache server with respect to the past video data seg # 3 having the host address "www.example.com" .

The cache server can determine that the image data seg # 3 is not stored in the memory after confirming that the image data seg # 3 is stored in the memory. In this way, when a cache miss occurs, the cache server can transmit a transmission request for the image data seg # 3 to the source server.

The source server can retrieve the image data (seg # 3) stored in the memory in response to the transmission request. The source server reads the information (Analysis Results) related to the image data seg # 3 after confirming the last modification time of the image data seg # 3 and calculates the lifetime of the image data seg # Can be determined.

For example, if the total number of viewers of the image data seg # 3 is 100, the number of likes clicks is 12, the number of balloons is 23, (Num_chat) of the chat room may be 371.

The source server may add 300 seconds to the default lifetime 0 seconds based on the 'total_viewer' 100. The source server calculates a chat rate (chat_rate) 3.71 based on the 'chat_rate_number' 371, and based on this, it can add 900 seconds to the lifetime 300 seconds. The origin server may add 300 seconds to the lifetime 1200 seconds based on the 'likelihood clicks (num_like)' 12. The origin server may add 300 seconds to the survival time of 1500 seconds based on the number of star balloons (num_balloon). For example, through the command "Cache Control.Max age = 1800", the origin server can set the lifetime of the image data (seg # 3) to be stored in the cache server to 1800 seconds.

The source server may transmit information (1800 seconds) about the survival time together with the image data (seg # 3) to the cache server. The cache server may store the image data (seg # 3) and set the lifetime to 1800 seconds in the cache control table. The cache server can transmit the image data seg # 3 to the client.

5D is a flowchart illustrating a process of transmitting image data in which priority is determined based on information related to image data corresponding to # 4 in FIG. 4 according to an exemplary embodiment.

Referring to FIG. 5D, during the real-time broadcasting, the client transmits a transmission request (HTTP GET) to the cache server with respect to the past video data (seg # 4) having the host address "www.example.com" .

The cache server may determine whether the image data seg # 4 is stored in the memory, and then determine that the image data seg # 4 is not stored. In this way, when a cache miss occurs, the cache server can transmit a transfer request for the image data seg # 4 to the source server.

The source server can retrieve the image data (seg # 4) stored in the memory in response to the transmission request. The source server reads the information (Analysis Results) related to the image data seg # 4 after confirming the last modification time of the image data seg # 4 and calculates the lifetime of the image data seg # Can be determined.

For example, if the number of viewers (total_viewer) of the image data seg # 4 is 100, the number of thumbnails is 13, the number of balloons is 15, Quot; num_chat " of the chat room may be 295.

The source server may add 300 seconds to the default lifetime 0 seconds based on the 'total_viewer' 100. The source server calculates a chat rate (chat_rate) of 2.95 based on the 'chat_battery' (num_chat) '295, and based on this, it can add 300 seconds to the life time of 900 seconds. The source server may add 300 seconds to the life time 900 seconds based on the 'likes click (num_like)' 13. The origin server can add 300 seconds to the lifetime 1200 seconds based on the number of balloons (num_balloon) 15. For example, the origin server can set the lifetime of the image data (seg # 4) to be stored in the cache server to 1500 seconds through the command "Cache Control. Max age = 1500 ".

The source server may transmit the survival time information (1500 seconds) to the cache server together with the image data (seg # 4). The cache server may store the image data (seg # 4) and set the lifetime to 1,500 seconds in the cache control table. The cache server may transmit the image data seg # 4 to the client.

The embodiments described above may be implemented in hardware components, software components, and / or a combination of hardware components and software components. For example, the devices, methods, and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, such as an array, a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer readable medium may include program instructions, data files, data structures, and the like, alone or in combination. Program instructions to be recorded on a computer-readable medium may be those specially designed and constructed for an embodiment or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

Although the embodiments have been described with reference to the drawings, various technical modifications and variations may be applied to those skilled in the art. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

110: source server
111: camera
112: Encoder
120: cache server 1
121: Storage
122: Splitter
123: cache server N
124: multicast router
130: WAN
140: Client
141: Client
142: Client

Claims (5)

A source server for providing a personal broadcasting service,
The origin server,
At least one processor; And
And at least one memory for storing instructions to be executed by the processor,
The instructions, when executed by the processor, cause the processor to:
Receiving a transmission request for the image data from the cache server when a cache miss occurs because the cache server does not include image data encoded in a dynamic adaptive streaming over HTTP (DASH) scheme requested by the client;
Calculating a time to live (TTL) of the image data based on information related to the image data after confirming a last modification time of the image data in response to a transmission request for the image data; And
And transmitting the video data and the lifetime to the cache server
, ≪ / RTI >
Wherein the image data is a DASH segment,
Wherein the information related to the image data includes an audience rating of the image data, a talk volume of a chat room related to the image data, a request frequency for the image data, and a feedback frequency for the image data,
Wherein when the feedback includes one or more words or one or more sentences, a survival time of the video data is calculated by summing predetermined scores corresponding to the words or the sentences, respectively, .


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