KR101112572B1 - System and Method for Multimedia Streaming of Distributed Contents Using Node Switching Based on Cache Segment Quantity - Google Patents

Abstract

The present invention relates to a content distributed storage multimedia streaming system and method using node fragments based on cache fragment storage. The present invention distributes and stores the fragmented cache fragments in a cache server of several nodes, and the node receiving the client's streaming request checks the cache fragment storage amount of each node and switches the streaming node to the node having the largest storage capacity, thereby performing streaming. By reducing the time it takes a node to collect cache fragments from other nodes, it can provide the most efficient streaming service in terms of overall performance and quality of service of the network.

Streaming, CDN, Multimedia Content, Nodes, Cache Servers, Cache Fragments, Storage, Node Switching

Description

System and Method for Multimedia Streaming of Distributed Contents Using Node Switching Based on Cache Segment Quantity}

The present invention relates to a multimedia streaming service. More specifically, the multimedia content to provide a streaming service is divided into multiple cache pieces, distributed and stored in a cache server of multiple nodes, and a node receiving a client's streaming request is cached by each node. The present invention relates to a streaming system and method for checking fragment storage and switching streaming nodes to the largest storage nodes.

With the development of internet technology, a streaming service that receives multimedia content such as video or animation through the internet in real time is being activated. Streaming refers to a technique of playing in real time while buffering a certain amount of the entire file, unlike a download method of playing after receiving all multimedia content files. Since the rest is continuously transmitted while playing back the buffered part, it is called 'streaming' because the transmitted data is treated like a continuous, continuous stream of water. Such streaming services include real time broadcast services or video on demand services.

Meanwhile, with the explosive increase in video content including user created contents (UCC), Internet traffic has been increasing rapidly in recent years. The growth rate of Internet bandwidth (supply) is not able to keep pace with the growth rate of Internet traffic (demand). In 2007 alone, global Internet traffic grew 75 percent, but Internet bandwidth grew only 44 percent.

As a way to solve the shortage of Internet bandwidth, CDN (content delivery network) technology is attracting attention. CDN technology is a technology that can utilize the internet network more efficiently by using active traffic distribution to increase average network utilization and lower peak traffic. According to the CDN technology, the content provider replicates the content to be provided to the client to a plurality of locally distributed servers, and when requested by the client, the content provider can receive the content from the optimal server.

In addition, one of the technologies widely used to increase the data transmission speed of the subscriber end in a data service such as streaming is a cache technology. In a typical cache implementation, an object to be cached is composed of data units of various sizes, and based on this, the cache server generates various statistics for managing data.

However, this method does not cover various types of resources of the cache server (RAM size, storage space, total content capacity of the original content provider server, etc.), instability of the internet transmission speed, and various behavioral characteristics of the user's use of the content (during downloading or streaming). , Etc.), and various sizes of data to be cached, the following problems occur when the object unit handled by the cache server depends on the content size.

1. Inefficiencies due to inconsistent utilization of computing resources when dealing with large and small files

2. Inconsistent quality of service (QoS) for users who requested files of different sizes

3. Splitting that occurs when a user's request for a file is not terminated normally (that is, if the user's request saves the entire file to a cache server or memory but is interrupted in the middle), the overall efficiency is reduced.

As a solution to this problem, a technique for dividing large-capacity multimedia contents of various sizes into a plurality of fixed size cache segments and distributing them in a cache server of several nodes is known. This allows you to load balance the entire system through distributed data storage, and to make the physical performance (RAM, CPU, network bandwidth, etc.) of a single server hardware behave as if it is more than one cache server, for example a hardware barrier of a single server (e.g., Maximum memory size).

However, the conventional content distributed streaming technology focuses only on distributed storage of data, and how and from which node it is most efficient to collect and stream cache fragments of adjacent nodes when a client requests streaming. There is a lack of research.

Accordingly, the present invention is to solve the conventional problem, when the streaming request from the client in the content distributed multimedia streaming service to collect the cache fragments and perform streaming in the most efficient manner in terms of overall performance and quality of service of the network It is to provide a multimedia streaming system and method.

In order to achieve this object, the present invention provides a content distributed storage multimedia streaming system and method using node fragments based on cache fragment storage.

Contents distributed storage multimedia streaming system according to the present invention includes a content providing server for providing multimedia content, each provided in a plurality of nodes distributed locally distributed between the content providing server and a plurality of clients, And a cache server for storing the cache fragment into which the multimedia content is divided. In particular, the cache server of the client access node that receives the streaming request from the client of the nodes includes a cache fragment storage confirmation unit for determining the cache fragment storage of the nodes to determine the node with the largest cache fragment storage as the streaming node The cache server of the streaming node includes an inter-node communication unit for obtaining the cache fragments from other nodes, and a streaming control unit for streaming the content to the client.

The distributed content streaming multimedia streaming system of the present invention may further include an index server provided in each of the nodes to store information on the cache fragment storage amount of the nodes, wherein the client access node is connected to the cache server. It may be provided with the index server for providing information on the cache fragment storage amount.

The cache server of the client access node may include the inter-node communication unit that transmits a node switch message to the streaming node when the streaming node is determined.

In addition, when there are two or more nodes having the largest cache fragment storage amount, the cache server of the client access node may determine the streaming node among the nodes having the largest cache fragment storage amount by using a secondary parameter.

In addition, each of the cache fragments may be redundantly stored in at least two or more of the nodes.

On the other hand, according to the present invention, the content distributed storage multimedia streaming method is distributed locally and distributed between a content providing server providing a multimedia content and a plurality of clients, and each cache fragment in which the multimedia content is divided is distributed and stored in a cache server. When the client accesses a specific node among a plurality of nodes to request streaming, receiving the streaming request of the client at the specific node, and the cache server of the specific node stores the cache fragment storage amount of the nodes. Checking and determining a node having the largest cache fragment storage amount as a streaming node, and the cache server of the streaming node obtaining the cache fragments from other nodes and streaming the content to the client.

In the content distributed storage multimedia streaming method of the present invention, each of the nodes may further include an index server for storing information on the cache fragment storage amount of the nodes, wherein the cache server of the client access node is Information about the cache fragment storage amount may be requested from an index server and provided.

The cache server of the client access node may transmit a node switch message to the streaming node when the streaming node is determined.

In addition, when there are two or more nodes having the largest cache fragment storage amount, the cache server of the client access node may determine the streaming node among the nodes having the largest cache fragment storage amount by using a secondary parameter.

In addition, each of the cache fragments may be redundantly stored in at least two or more of the nodes.

The present invention distributes and stores the fragmented cache fragments in a cache server of several nodes, and the node receiving the client's streaming request checks the cache fragment storage amount of each node and switches the streaming node to the node having the largest storage capacity, thereby performing streaming. By reducing the time taken for a node to collect cache fragments from other nodes, it is possible to provide the most efficient streaming service in terms of overall performance and quality of service of the network.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention. In describing the embodiments, descriptions of technical contents that are well known in the art to which the present invention pertains and are not directly related to the present invention will be omitted. This is to more clearly communicate without obscure the core of the present invention by omitting unnecessary description. In addition, like reference numerals designate like or corresponding elements throughout the accompanying drawings.

1 is a view schematically showing the configuration of a multimedia streaming system according to the present invention, Figure 2 is a view showing the configuration of the multimedia streaming system and the content distribution storage method according to an embodiment of the present invention.

Referring to FIG. 1, the multimedia streaming system of the present invention includes a plurality of nodes distributed locally distributed between a content providing server CP and a plurality of clients C1, C2, C3, C4, C5,. node; N1, N2, N3, ..., Nn).

Content providing server (CP) is a server that stores the original of the multimedia content to provide a streaming service, also called an origin server (origin server), multimedia server, content server. The content providing server CP distributes and stores a copy of the multimedia content in each node N1, N2, N3, ..., Nn according to a predetermined content distribution storage policy. The multimedia contents include UCC and other video contents, online education, mass media contents such as movies, broadcasting, and music, and recording and live broadcasting contents.

As illustrated in FIG. 2, each node N1, N2, N3, N4 has a cache server CS1, CS2, CS3, CS4. The cache server supports the real-time streaming protocol (RTSP) of the international standard IETF RFC2326 and the real-time transport protocol (RTP) / RTP control protocol (RTCP) of the IETF RFC3550 to perform streaming.

The multimedia content MC is divided into several cache segments S1 to S10 and distributed in cache servers of various nodes. In this case, all cache fragments of the multimedia content are distributed and stored in at least two nodes, and at least one cache fragment is stored in the cache server of the node in charge of storage. In the example of FIG. 2, the multimedia content MC is divided into ten cache fragments S1 to S10 and distributed to four nodes N1 to N4, where each cache server CS1 to CS4 is one. (S1), two (S2 to S3), four (S4 to S7), and three (S8 to S10) cache fragments.

The cache fragmentation of the multimedia content MC is performed according to a predetermined predetermined rule, and the content fragmentation rule may be determined in various ways such as a frame unit, a time unit, a capacity unit, and the like. In addition, the content division rule may be determined differently for each content type or may be determined collectively regardless of the content type. In addition, the content partitioning rule may be determined in proportion to the storage capacity of each node or may be determined regardless of the node storage capacity.

Each node N1, N2, N3, N4 further has an index server IS1, IS2, IS3, IS4. The index server stores cache fragment storage information of how much cache fragments S1 to S10 of the multimedia content MC are stored in which node. In addition, the index server may further store node state information such as transmission delay time between nodes as described below.

Meanwhile, the client C1 includes one or more buffers B1 that receive streaming data and temporarily store the streaming data. The client C1 encompasses various electronic devices capable of receiving, decoding and playing streaming data. For example, the client C1 may be a computer, a set top box, a personal digital assistant (PDA), a mobile phone, a game machine, an MP3 player, or the like.

The cache server will be described in more detail with reference to FIG. 3 showing the detailed configuration of the cache server. Each cache server CS1 may include a streaming controller 11, a content cache fragment storage unit 12, a cache fragment storage amount confirming unit 13, and an inter-node communication unit 14.

The streaming control unit 11 receives a streaming request from the client C1 and transmits the requested content to the client in a streaming manner. The content cache fragment storage unit 12 stores a cache fragment allocated to its own node among the cache fragments in which the content is divided, and transmits the cache fragment to the client C1 through the streaming control unit 11. When the streaming control unit 11 receives the streaming request from the client C1, the cache fragment storage checking unit 13 accesses the index server IS1 to check the cache fragment storage amount of each node, and the node with the largest cache fragment storage amount. Is determined as the streaming node. The inter-node communication unit 14 obtains cache fragments from other nodes N2 to N4 if its node is a streaming node, and transmits the cache fragments to the client C1 through the streaming control unit 11, and if not, the content cache fragment. The cache fragment stored in the storage unit 12 is transmitted to the cache server of the streaming node.

Next, a multimedia streaming system and method according to an embodiment of the present invention will be described in more detail with reference to FIG. 4. 4 is a flowchart illustrating a multimedia streaming method according to an embodiment of the present invention.

When the client C1 connects to a specific node and makes a streaming request, the cache server CS1 of the node N1 receives the streaming request of the client C1 (step S11). Hereinafter, the specific node N1 receiving the streaming request of the client C1 will be referred to as a 'client access node' to distinguish it from other nodes. As will be described later, a node that actually performs streaming may be a node other than a client access node, and a node that actually performs streaming will be referred to as a 'streaming node'.

The cache server CS1 of the client access node N1 requests the index server IS1 for cache fragment storage information of the content that has received the streaming request (step S12). Cache fragment storage information includes a list of cache fragments stored by each node and information on cache fragment storage. The cache fragment storage amount is, for example, the number of cache fragments, and may also be the total capacity of the cache fragments or the total reproduction time. Table 1 below is an example of cache fragment storage information.

Node Cache fragment Count Full capacity Total duration N1 S1 One 150 MB 12 minutes N2 S2, S3 2 300 MB 24 minutes N3 S4, S5, S6, S7 Four 600 MB 48 minutes N4 S8, S9, S10 Three 450 MB 36 minutes

The index server I1 provides the cache fragment storage information of the corresponding content to the cache server CS1 (step S13).

The cache server CS1 which has received the cache fragment storage information from the index server IS1 checks the cache fragment storage amount of each node and determines the node having the largest cache fragment storage amount (step S14). In the example of Table 1 above, the node with the largest cache fragment storage is the third node (N3).

When the node N3 having the largest cache fragment storage amount is determined, the client connection node N1 switches the streaming node to the node N3 having the largest cache fragment storage amount (step S15). Node switching is performed by the cache server CS1 of the client connection node N1 sending a node switching message and the cache server CS3 of the opposite node N3 receiving it. When transmitting the node switch message, the client access node N1 provides the client information and the content information requested for streaming together.

The cache server CS3 of the streaming node N3 requests cache fragments from the remaining nodes N1, N2, and N4, respectively, which store the cache fragments (steps S16, S17, and S18). At this time, the cache server CS3 of the streaming node N3 may obtain cache fragment storage information from its index server IS3 or may be provided from the client access node N1 to request cache fragments.

Receiving a cache fragment request from the streaming node N3, the cache servers CS1, CS2, and CS4 of the nodes N1, N2, and N4 respectively transmit the cache fragments they store to the streaming node N3 (step). S19, S20, S21).

The cache server CS3 of the streaming node N3, which has obtained cache fragments from the other nodes N1, N2, and N4, streams the content to the client C1 who has requested the streaming (step S22).

The client C1, which has started to receive the streaming data from the streaming node N3, decodes and streams the streaming data into the buffer B1 to play the content.

As described above, the client access node N1 receiving the streaming request from the client C1 does not perform the streaming but the node N3 having the largest cache fragment storage performs the streaming as follows. In order for a particular node to perform streaming, it needs to acquire cache fragments stored in other nodes, which takes time to receive cache fragments from other nodes. Therefore, the smaller the amount of cache fragments received from other nodes, that is, the more cache fragments they have, the shorter the acquisition time of the cache fragments. Thus, the most efficient streaming service in terms of overall network performance and quality of service. Can be made.

On the other hand, when the client access node (N1) checks the cache fragment storage amount of the other nodes (N2, N3, N4) and determines the node with the largest cache fragment storage amount, if there is more than one node with the largest cache fragment storage amount, the secondary The streaming node may be determined using the parameter. For example, as described above, the index server of each node may store node state information such as transmission delay time between nodes, and when such node state information is used, one of the nodes having the largest cache fragment storage capacity may be used. Can be determined.

Table 2 below is an example of determining a streaming node by using a secondary parameter. In this case, the nodes with the largest cache fragment storage are N2 and N4, and considering the secondary parameter (maximum transmission delay time between nodes), the streaming is performed. The node is determined to be N4.

Node Cache fragment Count Maximum transmission delay time between nodes Streaming node N1 S1, S2 2 3.2 seconds X N2 S3, S4, S5 Three 4.7 seconds X N3 S6, S7 2 1.9 seconds X N4 S8, S9, S10 Three 3.5 seconds O

In addition, each cache fragment of the multimedia content MC may be duplicated and stored in at least two different nodes. In this case, the client connection node may check the cache fragment storage of the other nodes regardless of whether it is redundantly stored or not. This largest node is determined as the streaming node.

Table 3 below is an example of such a case, and the multimedia content is divided into 10 cache fragments S1 to S10 and distributed to four nodes N1 to N4, and each cache fragment is duplicated by two different nodes. Are stored in. In the example of Table 3, the streaming node becomes node N2 with the largest cache fragment storage.

Node Cache fragment Count Streaming node N1 S1, S2, S9, S5 Four X N2 S3, S10, S1, S6, S7, S8 6 O N3 S4, S5, S6, S2, S9 5 X N4 S7, S8, S3, S4, S10 5 X

As described above, the present specification and drawings have been described with respect to preferred embodiments of the present invention, although specific terms are used, it is only used in a general sense to easily explain the technical contents of the present invention and to help the understanding of the present invention. It is not intended to limit the scope of the present invention. It is to be understood by those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

The present invention can be usefully used for a variety of multimedia streaming services that appear in a variety of forms, such as video content, online education, mass media content such as movies, broadcasts, music, recording and live broadcast, IPTV, including UCC.

1 is a view schematically showing the configuration of a multimedia streaming system according to the present invention.

2 is a diagram illustrating a configuration of a multimedia streaming system and a distributed content storage method according to an embodiment of the present invention.

3 is a diagram illustrating a detailed configuration of the cache server of FIG. 2.

4 is a flowchart illustrating a multimedia streaming method according to an embodiment of the present invention.

<Description of main parts of drawing>

CP: Content Delivery Server

N1, N2, N3, N4,... , Nn: node

C1, C2, C3, C4, C5,... , Cn: Client

MC: Multimedia Content

S1, S2, S3, S4, S5, S6, S7, S8, S9, S10: Content Cache Fragment

CS1, CS2, CS3, CS4: Cache Server

IS1, IS2, IS3, IS4: Index Server

B1: buffer

11: streaming control

12: content cache fragment storage

13: Cache fragment storage confirmation unit

14: inter-node communication unit

Claims (10)

A content providing server providing multimedia content; A cache server, each of which is provided in a plurality of nodes that are distributed and distributed locally between the content providing server and a plurality of clients, and stores a cache fragment in which the multimedia content is divided; Including; The cache server of the client access node receiving the streaming request from the client of the nodes includes a cache fragment storage amount confirming unit for determining the cache fragment storage of the nodes to determine the node having the largest cache fragment storage as the streaming node, The cache server of the streaming node includes an inter-node communication unit for obtaining the cache pieces from other nodes, and a streaming control unit for streaming the content to the client. The method according to claim 1, An index server provided at each node to store information on the cache fragment storage amount of the nodes; More, And said client access node comprises said index server for providing said cache server with information about said cache fragment storage amount. The method according to claim 1, And the cache server of the client access node includes the inter-node communication unit which transmits a node switching message to the streaming node when the streaming node is determined. The method according to claim 1, If there is more than one node having the largest amount of cache fragment storage, the cache server of the client access node determines the streaming node among the nodes having the largest amount of cache fragment storage by using a secondary parameter. Distributed storage multimedia streaming system. The method according to claim 1, Wherein each said cache fragment is redundantly stored in at least two of said nodes. The client accesses and streams a specific node among a plurality of nodes distributed and distributed locally among a plurality of clients and a content providing server that provides multimedia contents, and each cache fragment in which the multimedia contents are divided. Receiving a streaming request from the client at the specific node; Determining, by the cache server of the specific node, a cache node storage amount of the nodes to determine a node having the largest cache fragment storage amount as a streaming node; The cache server of the streaming node obtaining the cache fragments from other nodes and streaming the content to the client; Content distributed storage multimedia streaming method comprising a. The method according to claim 6, Each said node further comprises an index server for storing information about said cache fragment storage of said nodes, And the cache server of the client access node requests and receives information on the cache fragment storage amount from the index server. The method according to claim 6, And the cache server of the client access node transmits a node switch message to the streaming node when the streaming node is determined. The method according to claim 6, If there is more than one node having the largest amount of cache fragment storage, the cache server of the client access node determines the streaming node among the nodes having the largest amount of cache fragment storage by using a secondary parameter. Distributed storage multimedia streaming method. The method according to claim 6, Wherein each cache fragment is redundantly stored in at least two of said nodes.

Images