Patent ID: 12238189

DETAILED DESCRIPTION

In accordance with various embodiments, a service is provided for caching of applications that utilize multiple sessions for retrieval of same content object (e.g., file or stream).

The multi-session applications supported by the caching service can include:(a) applications that utilize one or more sessions to discover information about a content object (hereinafter “content object meta-data”), that identifies the content sources that the application contacts to retrieve the content object, data protocols used to do so, and data queries used to retrieve the object.(b) applications that utilize multiple sessions to retrieve the content object, passing information necessary for object identification only in some of the sessions.
(a) Multi-Session Applications Utilizing Content Object Meta-Data for Content Object Retrieval

FIG.1illustrates an exemplary network architecture illustrating use of a caching service In accordance with one or more embodiments. Client A1establishes multiple sessions to one or more meta-data services M on a network, sends data queries to retrieve content object meta-data for content object Z1, and receives one or more responses from the meta-data services M.

The content object meta-data includes at least one variable, selected from the following:(i) addresses of content source(s);(ii) protocols supported by an individual content source;(iii) encryption keys, per object or per individual content source; and(iv) content object structure.

The content source address can be identified through an IP address, e.g., using IPv4 IP address 1.1.1.1 or IPv6 address fe80::200:f8ff:fe21:67cf, or using a domain name, e.g., cache12.bos.us.cdn.net, that can be resolved to IP address using Domain Name System (DNS).

The content source address can use either implicitly named port number for applications using well-known protocol ports (e.g., port tcp/80 used by HTTP protocol) or name ports explicitly.

The content source address can be identified in conjunction with protocols supported by it, including, but not limited to, using universal resource locators (URL), as defined in RFC1738, that specifies protocol, content source address, port and remote path to the object.

The content object structure information includes information allowing client A1to form data queries for parts of the object and to verify correctness of data responses received in response to such queries.

The content object structure information includes information pertaining to parts comprising the objects, e.g., “pieces” used by Bittorrent protocol, “parts” used by eDonkey P2P protocol or “playback levels” used in adaptive bitrate streaming protocols, such as Microsoft Silverlight Smooth Streaming, Adobe HTTP Dynamic Streaming, Apple HTTP Live Streaming, among others.

The information about content objects parts includes at least one of the following: enumeration of parts of the content object, length of each part, data checksum of each part, availability of parts at a specific content source, where the content source is identified using content source addresses as defined in [0023-0025] above.

The meta-data including all or some of the above information can be stored in a separate file with a pre-defined structure, e.g. a torrent file for Bittorrent or a manifest file used by Microsoft Silverlight smooth streaming.

The meta-data services M offering content object meta-data may include dedicated network servers designed to support delivery of a specific application or one or more content objects (e.g., Bittorrent trackers, ED2K servers, etc.), generic search engines (Google, Microsoft Bing, or others), a network of computer nodes that collectively stores the meta-data (e.g. distributed hash table networks used by P2P applications), or other clients that participate in distributed content source discovery networks (e.g., distributed hash table networks), or other clients that are downloading and/or serving the content object Z1and maintain meta-data related to it.

Client A1may use multiple meta-data services M to discover content object meta-data, where one service M1can provide part of the content object meta-data and optionally point to another service M2to provide another part.

Thus, for example, client A1may retrieve a torrent file from a Bittorrent search engine that includes the content object data structure information as well as URL of a Bittorrent tracker that provides the information of currently active content source addresses.

Client A1may continue to send data queries to meta-data services M during download of content object Z1or portions of it, for purposes of identification of new content sources and/or content object structure information (for example, in case of object Z1being a live stream, of which new parts become continuously available).

In accordance with one or more embodiments, the caching service C receives and stores data queries and/or responses exchanged between client A1and one or more meta-data services M.

In accordance with one or more embodiments, the caching service C intercepts the sessions between A1and M, either by being in data path between A1and B, or through use of one or more dedicated redirection devices (e.g., a load balancer, a router, a DPI device, etc.) that sit in data path and redirect specific data sessions to the caching service C, and relays the data queries and responses between A1and M.

In accordance with one or more embodiments, the caching service C modifies at least one of the meta-data responses provided by the meta-data service M, e.g., to indicate the caching service C as a content source or as a meta-data service for the content object Z1.

In accordance with one or more embodiments, the caching service C receives a copy of communications between the client A1and the meta-data services M, using an optical tap, mirror port or other device replicating network traffic.

In accordance with one or more embodiments, the caching service C receives the data queries related to content object Z1from client A1by virtue of offering at least one of the meta-data services M.

In accordance with one or more embodiments, the caching service C subsequently queries the meta-data services M itself for meta-data related to content object Z1, and receives and stores the responses.

In accordance with one or more embodiments, the caching service C continuously analyzes the queries and responses exchanged between at least one client A1and the meta-data services M, as well as the responses received by the caching service C directly from the meta-data services M, as described above.

As a result, the caching service C maintains content object meta-data MZfor at least one content object Z1that client A1is retrieving.

In accordance with one or more embodiments, the caching service C stores meta-data responses as part of meta-data Mzin conjunction with the most recent time the response was received by C.

The caching service C subsequently periodically discards any responses that were received more than some time ago based on time-out.

In accordance with one or more embodiments, the caching service monitors meta-data requests and responses and discards any stored responses that contradict meta-data responses received later.

Following retrieval of meta-data pertaining to the content object Z1, the client A1and at least one of content sources B1discovered by the client A1using the meta-data services M, start establishing data sessions with each other, for purpose of retrieving content object Z1or part of it by A1.

In accordance with one or more embodiments, the caching service C intercepts the data sessions S1established between the client A1and the content sources B1.

In accordance with one or more embodiments, the caching service C intercepts the data sessions either by being in a data path between A1and B1, or through use of one or more dedicated redirection devices (e.g., load balancer, router, DPI device, etc.) that sit in data path and redirect specific data sessions to the caching service C.

In accordance with one or more embodiments, the caching service C intercepts only such sessions that have been established between A1and such content sources B1′, that match the meta-data Mz stored for the object Z1by the caching service C.

In accordance with one or more embodiments, the client A1establishes at least one session S2with the caching service C, which is identified by the client Alas one of the content sources for the content object Z1.

In accordance with one or more embodiments, the caching service C utilizes at least one of the following protocols to interpret data queries and data responses in the session S1between the client A1and content source S1:(i) data protocols associated with the client A1, as part of meta-data Mz, as described above;(ii) data protocols associated with the session S1, as part of meta-data Mz, as described above; and(iii) data protocols identified by the caching service C when analyzing the data queries and responses received in the session S1, using signature-based or other generic protocol identification technique.

In accordance with one or more embodiments, the caching service C utilizes similar approach for session S2.

In accordance with one or more embodiments, when failing to identify data protocol of session S1and S2, using method described in [0048], the caching service C may apply at least one of encryption keys K, stored by C as part of the meta-data Mz, to establish an encrypted session with either client A1, or content source B1, or both.

The encryption keys K may be associated with the content object Z (e.g., in Bittorrent the hash identifier of object Z is used for encryption of sessions between Bittorrent peers), or specific content sources.

In accordance with one or more embodiments, following establishment of data session with client A1and identification of the protocol used in this session, the caching service C receives data query Q1for object Z1or portion of it from the client A1.

In accordance with one or more embodiments, the caching service C identifies a response matching the query, using the meta-data Mz associated with the content object Z1as described above.

For example, if the client A1requests a chunk of 500 Kbps playback level of content object Z1, available over Microsoft Silverlight smooth streaming protocol, that starts at offset 0, without identification of the end offset, the caching service C may use the meta-data Mz describing the object Z1, to identify the end offset.

In accordance with one or more embodiments, if the matching response R1to the query Q1is stored by the caching service C, C delivers the response to the end client A1.

In accordance with one or more embodiments, the caching service C may use the stored meta-data Mz associated with the content object Z to verify the validity of the data response R1, before sending it to the client A1.

In accordance with one or more embodiments, when a matching response to the query Q1is not available at the caching service C and the query Q1has been sent as part of session S1between the client A1and the content source B1, the caching service C forwards the query to retrieve such response from the content source B1, receives and optionally stores the response and relays the response to the client A1.

In accordance with one or more embodiments, when a matching response to the query Q1is not found at the caching service C, the caching service C sends data query Q1′ allowing it to respond to the data query Q1to at least one of content sources B, identified by C as carrying the content object Z, based on the meta-data Mz stored by C.

Subsequently, the caching service C receives the responses R1′ for these queries, stores them and optionally verifies their validity against the meta-data Mz, and delivers response to the query Q1to the client A1.

In accordance with one or more embodiments, when a matching response to the query Q1is not found at the caching service C, C may redirect the client A1to one of content sources B for the content object Z, as stored by the caching service in the meta-data Mz.

(b) Multi-Session Applications Allowing Identification of Content Object Only in Some Sessions

Client A2establishes multiple sessions S2to one or more destinations B2to retrieve content object Z2, in parallel or in series. The client A2sends data queries for portions of the content object Z2in each such session.

Depending on the naming convention for the content object Z and/or its parts, used by client A2and destination(s) B2, the caching service C, intercepting or receiving sessions S2, may not be able to identify the content object and/or portions of it requested by client A2in each session, or identify data responses matching those queries.

The client A2and content source(s) B2may use dynamic URL (so-called “hashed URLs”) to identify object Z2that is assigned uniquely for each download of the content object Z2. In this case caching service C cannot rely on the data in the data query alone to identify a matching response, but rather analyzes data responses to identify the requested object and match it to the previously stored data responses.

According to one or more embodiments, when receiving such data queries and/or responses in one or more sessions S2that allow identification of the content object Z, C stores the content object Z2identification together with the IP address of client A2, the IP address of content source B2, and the dynamic content identification (e.g. URL) used by client A2, in a list L2.

According to one or more embodiments, when caching service C receives a data query and/or data response that does not allow it to identify the content object Z referenced in the query and/or response, caching service C establishes whether the IP address of client A2, dynamic content identification URL, and IP address of content source B2are stored in list L2.

According to one or more embodiments, in case of applications that utilize multiple content sources, the caching service C may disregard the IP address of content source B2.

According to one or more embodiments, caching service C removes entries from list L4based on the timeout since last activity seen by client A2, related to content object Z2.

The processes of the caching service described above may be implemented in software, hardware, firmware, or any combination thereof. The processes are preferably implemented in one or more computer programs executing on a programmable device including a processor, a storage medium readable by the processor (including, e.g., volatile and non-volatile memory and/or storage elements), and input and output devices. Each computer program can be a set of instructions (program code) in a code module resident in the random access memory of the device. Until required by the device, the set of instructions may be stored in another computer memory (e.g., in a hard disk drive, or in a removable memory such as an optical disk, external hard drive, memory card, or flash drive) or stored on another computer system and downloaded via the Internet or other network.

Having thus described several illustrative embodiments, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to form a part of this disclosure, and are intended to be within the spirit and scope of this disclosure. While some examples presented herein involve specific combinations of functions or structural elements, it should be understood that those functions and elements may be combined in other ways according to the present disclosure to accomplish the same or different objectives. In particular, acts, elements, and features discussed in connection with one embodiment are not intended to be excluded from similar or other roles in other embodiments.

Additionally, elements and components described herein may be further divided into additional components or joined together to form fewer components for performing the same functions. For example, the caching service may comprise one or more physical machines, or virtual machines running on one or more physical machines. In addition, the caching service may comprise a cluster of computers or numerous distributed computers that are connected by the Internet or another network.

Accordingly, the foregoing description and attached drawings are by way of example only, and are not intended to be limiting.