System and method for streaming media objects

• US 20070266169A1
• Filed: 05/10/2006
• Published: 11/15/2007
• Est. Priority Date: 05/10/2006
• Status: Active Grant

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Xiao, Zhen, Zhang, Xiaodong, Chen, Songqing, Guo, Lei
• Granted Patent: US 8,230,098 B2
• Time in Patent Office: Days
• US Class Current: 709/231
• CPC Class Codes: H04L 65/612 for unicast
• CPC Class Codes: H04L 67/06 specially adapted for file transfer, e.g. file transfer protocol [FTP]
• CPC Class Codes: H04L 67/104 Peer-to-peer [P2P] networks
• CPC Class Codes: H04L 67/1065 Discovery involving distributed pre-established resource-based relationships among peers, e.g. based on distributed hash tables [DHT] pre-configuration of logical or physical connections H04L67/1053
• CPC Class Codes: H04L 67/108 characterised by resources being split in blocks or fragments
• CPC Class Codes: H04L 67/1091 Interfacing with client-server systems or between P2P systems
• CPC Class Codes: H04L 67/1093 Some peer nodes performing special functions
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching

Abstract

A method and system for streaming media objects. A streaming system includes a group of end nodes and at least one core node connected via an overlay network. The end nodes cache segments of media objects and stream the media objects to a client segment by segment. Each end node stores segment indices for locating segments cached on end nodes or a core node in the system. The core node is a dedicated proxy which fetches media objects from a remote media server and streams the media objects to a client when the media objects are unavailable from the end nodes.

Claims

1. A method of streaming a segment of a media object requested by a client in a system having a plurality of end nodes and at least one core node, the method comprising:

determining whether the segment is stored on any of the nodes;

if the segment is not stored on any of the nodes, retrieving the segment from a remote media server via the core node, storing the segment at the core node, and streaming the segment to the client from the core node; and

if the segment is stored on one or more of the nodes, streaming the segment to the client from one of the nodes at which the segment is stored.

2. The method of claim 1, wherein said determining step comprises:

routing a request for the segment to a target end node assigned to a key space zone corresponding to the segment;

if a segment index exists at the target node, determining whether the segment is stored at any of the nodes in the system based on a location list of the segment index; and

if a segment index does not exist at the target node, determining that the segment is not stored at any of the nodes in the system.

3. The method of claim 2, wherein said step of determining whether the segment is stored at any of the nodes in the system based on a location list of the segment index comprises:

if the location list is empty, determining that the segment is not stored at any of the nodes in the system;

if the location list is not empty, determining that the segment is stored at at least one location listed in the location list of the segment index.

4. The method of claim 2, wherein said retrieving step comprises:

connecting to the remote media server via the core node to fetch the segment;

storing the segment at the core node;

if the segment index does not exist at the target node, creating a segment index for the segment and storing the segment index at the target node assigned to key space zone corresponding to the segment identifier of the segment; and

if the segment index does exist at the target node, storing location information of the core node in the location list of the segment index.

5. The method of claim 1, wherein the client is one of the end nodes.

6. The method of claim 5, wherein said determining step comprises:

searching a local cache on the client for the segment;

if the segment is not in the local cache, routing a request for the segment from the client to another end node based on a segment identifier of the segment and searching for a segment index corresponding to the segment identifier on the other end node to determine whether the segment is stored at any of the end nodes and the core node based on a location list included in the segment index.

7. The method of claim 5, further comprising:

storing the streamed segment at the client when the segment is streamed to the client.

8. The method of claim 7, further comprising:

publishing the segment stored on the client in a location list of a corresponding segment index stored on one of the end nodes.

9. The method of claim 1, wherein said retrieving step further comprises:

publishing the segment stored at the core node in a location list of a corresponding segment index stored at one of the end nodes.

10. The method of claim 9, wherein said publishing step comprises:

sending an IP address and a port number of the core node to the one of the end nodes storing the corresponding segment index to include the IP address and the port number of the core node in the location list of the corresponding segment index.

11. The method of claim 1, wherein said streaming step comprises:

selecting a node at which the segment has been stored to serve as a serving node;

sending a location of the selected serving node to the client; and

streaming the segment from the serving node to the client.

12. The method of claim 11, wherein said selecting step comprises:

retrieving a segment index corresponding to the segment and stored at one of the end nodes; and

choosing an end node or the core node from a list of locations included in the segment index.

13. The method of claim 12, wherein said choosing step comprises:

choosing the end node or the core node in the list of locations with the most available bandwidth.

14. The method of claim 1, further comprising:

playing a current segment of the requested media object at the client when receiving the streaming segment from an end node or the core node; and

buffering a next segment of the requested media object at the client when playing the current segment.

21. The streaming system of claim 1, wherein each segment index has a corresponding segment identifier.

22. The streaming system of claim 21, wherein each end node is assigned a key space zone and stores the segment indices of the segments having segment identifiers corresponding to the key space zone.

23. The streaming system of claim 22, wherein each end node further comprises:

means for routing a request for a segment not stored at that end node to a target end node, which is an end node assigned to the key space zone corresponding to the segment identifier of the requested segment.

15. A streaming system, comprising:

a plurality of end nodes, each comprising;

a memory comprising segments of media objects and segment indices for locating segments of media objects, and

means for streaming the stored segments to a client; and

at least one core node comprising;

means for fetching segments of media objects from a remote server when the segments are not available from any of the end nodes, and

means for streaming the fetched segments to the client.

16. The streaming system of claim 15, wherein said end nodes and said at least one core node communicate via an overlay network.

17. The streaming system of claim 15, wherein said memory further comprises a subset of a distributed hash table for storing the segment indices having location information of the stored segments of media objects.

18. The streaming system of claim 17, wherein each segment index comprises a location list which lists each end node or core node in the system at which the corresponding segment is stored.

19. The streaming system of claim 18, wherein the location list comprises an IP address and a port number for each end node or core node in the system at which the corresponding segment is stored.

20. The streaming system of claim 15, wherein each end node further comprises:

means for searching the memory for a segment index corresponding to a requested segment of a media object; and

means for selecting an end node or a core node listed in the location list of the corresponding segment to be used to stream the requested segment to the client; and

means for routing a location of the selected end node or core node to the client.