Virtual file-sharing network

• US 20040255048A1
• Filed: 07/28/2004
• Published: 12/16/2004
• Est. Priority Date: 08/01/2001
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Actona Technologies Limited (Cisco Systems, Inc.)
• Inventors: Kaminsky, Daniel, Ben Shaul, Israel Z, Cidon, Israel, Zach, Idan, Glixman, Shahar, Bortnikov, Vita, Ben Kiki, Danit, Lev Ran, Etai
• Granted Patent: US 7,139,811 B2
• Time in Patent Office: Days
• US Class Current: 709/249
• CPC Class Codes: G06F 16/1774 Locking methods, e.g. locking methods for file systems allowing shared and concurrent access to files
• CPC Class Codes: G06F 16/192 Implementing virtual folder structures
• CPC Class Codes: G06F 16/9574 of access to content, e.g. by caching
• CPC Class Codes: G06F 9/546 Message passing systems or structures, e.g. queues
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/06 specially adapted for file transfer, e.g. file transfer protocol [FTP]
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04L 67/133 Protocols for remote procedure calls [RPC]
• CPC Class Codes: H04L 67/2876 Pairs of inter-processing entities at each side of the network, e.g. split proxies
• CPC Class Codes: H04L 67/563 Data redirection of data network streams
• CPC Class Codes: H04L 67/565 Conversion or adaptation of application format or content adding application control or application functional data H04L67/561
• CPC Class Codes: H04L 67/5651 Reducing the amount or size of exchanged application data
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users

Abstract

A method for enabling access to a data resource, which is held on a file server (25) on a first local area network (LAN) (21a), by a client (28) on a second LAN (21b). A proxy receiver (48) on the second LAN (21b) intercepts a request for the data resource submitted by the client (28) and transmits a message via a wide area network (WAN) (29) to a proxy transmitter (52) on the first LAN (21a), requesting the data resource. The proxy transmitter (52) retrieves a replica of the data resource from the file server (25) and conveys the replica of the data resource over the WAN (29) to the proxy receiver (48), which serves the replica of the data resource from the proxy receiver (48) to the client (28) over the second LAN (21b).

Claims

1-76. -76. (Canceled)

77. A method for enabling access to a data resource, which is held on a file server on a first local area network (LAN), by a client on a second LAN, the method comprising:

conveying a replica of the data resource over a wide area network (WAN) from the file server to a cache held by a proxy receiver on the second LAN;

intercepting at the proxy receiver a file system request for the data resource submitted by the client over the second LAN;

checking the cache to determine whether the replica of the data resource is present in the cache and valid; and

responsive to the file system request and to determining that the replica is present and valid, serving the replica of the data resource from the cache of the proxy receiver to the client over the second LAN.

78. A method according to claim 77, wherein the data resource comprises at least one of a file, a block of a file, a page of content encoded in a markup language, and a file system directory.

82. A method according to claim 77, wherein conveying the replica of the data resource comprises conveying at least one of metadata, an access list applicable to the data resource, and a permission applicable to the data resource.

85. A method according to claim 77, wherein the request for the data resource is submitted by the client using a call to a native network file system used by the file server.

87. A method according to claim 77, wherein conveying the replica comprises monitoring the file server using a watchdog agent to detect a change made to the data resource by a native client on the first LAN, and conveying the replica of the data resource from the file server to the proxy receiver again responsive to the change.

88. A method according to claim 77, wherein the data resource is a file comprising a plurality of file blocks, and wherein conveying the replica comprises analyzing a pattern of access by the client to the file blocks, and conveying replicas of a portion of the file blocks not yet requested by the client, responsive to the pattern.

90. A method according to claim 77, wherein serving the replica comprises periodically checking at the proxy receiver whether the replica of the data resource in the cache of the proxy receiver is consistent with the data resource held by the file server, and deleting the replica from the cache upon determining that the replica is not consistent.

91. A method according to claim 77, and comprising deleting the replica from the cache responsive to a predetermined cache removal policy.

92. A method according to claim 77, and comprising conveying to the proxy receiver metadata regarding the data resource on the file server and, responsive to the metadata, presenting to the client a virtual directory of the file server.

93. A method according to claim 77, wherein intercepting the request comprises intercepting a lock request submitted by the client for a lock on the data resource, and wherein conveying the replica over the WAN comprises transmitting a lock message via the WAN from the proxy receiver to the file server, requesting the lock, and comprising:

responsive to the lock message, issuing the lock at the file server;

conveying the lock over the WAN from the file server to the proxy receiver; and

serving the lock from the proxy receiver to the client.

94. A method according to claim 77, wherein conveying the replica of the data resource from the file server to the cache held by the proxy receiver comprises determining whether the data resource is held by the file server, and conveying a negative response relating to the data resource from the file server to the proxy receiver when it is determined that the data resource is not held by the file server, and comprising caching the negative response at the proxy receiver for a certain period.

95. A method according to claim 94, wherein serving the replica of the data resource from the cache of the proxy receiver to the client comprises checking whether the negative response relating to the requested data resource is present and not expired, and, responsive to determining that the negative response is present and not expired, serving the negative response from the proxy receiver to the client over the second LAN.

96. A method according to claim 77, wherein intercepting the request comprises intercepting a file system request submitted by the client for an operation on the data resource, and wherein transmitting the message comprises transmitting the file system request and a request for a lock via the WAN from the proxy receiver to the file server, and comprising, responsive to the request for the lock, obtaining the lock from the file server at the proxy receiver.

97. A method according to claim 96, and comprising, if the proxy receiver intercepts no more file system requests from the client with respect to the data resource for a certain period, issuing an unlock request from the proxy receiver to the file server with respect to the data resource.

98. A method according to claim 77, wherein intercepting the request comprises intercepting the request for the data resource submitted in accordance with a first native network file system of the client, and wherein conveying the replica comprises:

translating the request for the data resource from the first native network file system to a second native network file system used by the file server,

requesting the resource from the file server using the translated request, and

conveying the replica of the data source to the proxy receiver over the WAN.

99. A method according to claim 77, wherein conveying the replica of the data resource over the WAN comprises ascertaining an available bandwidth of the WAN, and conveying the replica using a portion of the bandwidth that is less than a total available bandwidth, responsive to a management directive downloaded to the proxy receiver over the WAN.

100. A method according to claim 77, and comprising, upon determining that the replica is not present or not valid, requesting that the replica be conveyed again from the file server to the proxy receiver.

105. A method according to claim 77, and comprising performing an operation on the replica of the data resource in the cache responsive to a management directive downloaded to the proxy receiver over the WAN.

107. A method according to claim 77, wherein intercepting the request comprises intercepting a group of one or more requests for first data resources on the file server, and comprising analyzing a pattern of the group of requests, and retrieving replicas of one or more second data resources from the file server to the cache of the proxy receiver, responsive to the pattern.

108. A method according to claim 107, wherein retrieving the replicas of the one or more second data resources comprises retrieving the second data resources before the client requests the second data resources.

109. A method according to claim 107, wherein analyzing the pattern comprises calculating for each of the second data resources on the file server a relation of an expected usage of the replicas of the second data resources at the proxy receiver to an expected modification rate of the second data resources at the file server.

110. A method according to claim 107, wherein retrieving the replicas of the one or more second data resources comprises analyzing a relation of an available bandwidth of the WAN to an expected usage of the replicas of the second data resources at the proxy receiver, and determining, responsive to the relation, when to retrieve a replica of the second data resource.

112. A method according to claim 107, wherein retrieving replicas of the one or more second data resources comprises determining an order of retrieval of the second data resources responsive to a predetermined retrieval policy, and conveying the replicas over the WAN in the determined order.

113. A method according to claim 112, wherein in accordance with the retrieval policy, the first data resources requested by the client are retrieved with a higher priority than the second data resources.

114. A method according to claim 77, and comprising intercepting at the proxy receiver a write request submitted by the client for application to the data resource, and passing the write request over the WAN from the proxy receiver to the file server.

79-81. -81. (Canceled)

83-84. -84. (Canceled)

86. (Canceled)

89. (Canceled)

101-104. -104. (Canceled)

106. (Canceled)

111. (Canceled)

115-116. -116. (Canceled)

117. A method for enabling access to data resources held on a file server on a first local area network (LAN) by a client on a second LAN, the method comprising:

reading metadata from the file server using a proxy transmitter on the first LAN;

transmitting the metadata via a wide area network (WAN) from the proxy transmitter to a proxy receiver on the second LAN; and

based on the metadata, constructing at the proxy receiver a directory of the data resources on the file server, for use by the client in accessing the data resources.

119. A method according to claim 117, wherein the metadata includes file attributes of the data resources, which file attributes are stored in a directory object on the file server, and wherein reading the metadata comprises reading the file attributes from the directory object.

120. A method according to claim 117, wherein the data resources comprise files, and wherein the metadata includes file attributes that are stored in the files, and wherein reading the metadata comprises reading the file attributes from the files.

121. A method according to claim 117, and comprising intercepting at the proxy receiver a file system request with respect to one of the data resources in the directory submitted by the client over the second LAN, and, responsive to the file system request, serving data from the one of the data resources from the proxy receiver to the client over the second LAN.

118. (Canceled)

122-200. -200. (Canceled)

201. Apparatus for enabling access to a data resource, which is held on a file server on a first local area network (LAN), by a client on a second LAN, the apparatus comprising a proxy receiver, which is located on the second LAN and comprises a cache, and which is adapted to retrieve a replica of the data resource from the file server over a wide area network (WAN) to the cache, to intercept a file system request for the data resource submitted by the client over the second LAN, to check the cache to determine whether the replica of the data resource is present in the cache and valid, and, responsive to the file system request and to determining that the replica is present and valid, to serve the replica of the data resource from the cache to the client over the second LAN.

202. Apparatus according to claim 201, wherein the data resource comprises at least one of a file, a block of a file, a page of content encoded in a markup language, and a directory.

206. Apparatus according to claim 201, wherein the proxy receiver is adapted to retrieve from the file server at least one of metadata, an access list applicable to the data resource, and a permission applicable to the data resource.

209. Apparatus according to claim 201, wherein the request for the data resource is submitted by the client using a call to a native network file system used by the file server.

211. Apparatus according to claim 201, and comprising a watchdog agent, which is adapted to monitor the file server to detect a change made to the data resource by a native client on the first LAN, wherein the proxy receiver is adapted to retrieve the replica of the data resource again from the file server responsive to the change.

212. Apparatus according to claim 201, wherein the data resource is a file comprising a plurality of file blocks, and wherein the proxy receiver is adapted to analyze a pattern of access by the client to the file blocks, and to retrieve from the file server replicas of a portion of the file blocks not yet requested by the client, responsive to the pattern.

214. Apparatus according to claim 201, wherein the proxy receiver is adapted to periodically check whether the replica of the data resource in the cache is consistent with the data resource held by the file server, and to delete the replica from the cache upon determining that the replica is not consistent.

215. Apparatus according to claim 201, wherein the proxy receiver is adapted to delete the replica from the cache responsive to a predetermined cache removal policy.

216. Apparatus according to claim 201, wherein the proxy receiver is adapted to retrieve from the file server metadata regarding the data resource on the file server, and to present to the client a virtual directory of the file server, responsive to the metadata.

217. Apparatus according to claim 201, wherein the proxy receiver is adapted to intercept a request submitted by the client for a lock on the data resource, to transmit a lock message via the WAN to the file server, requesting the lock, to receive over the WAN a lock issued by the file server, and to serve the lock to the client.

218. Apparatus according to claim 201, wherein the proxy receiver is adapted to determine whether the data resource is held by the file server, and to cache a negative response relating to the data resource for a certain period, when it is determined that the data resource is not held by the file server.

219. Apparatus according to claim 218, wherein the proxy receiver is adapted to check whether the negative response relating to the requested data resource is present and not expired, and, responsive to determining that the negative response is present and not expired, to serve the negative response to the client over the second LAN.

220. Apparatus according to claim 201, wherein the proxy receiver is adapted to intercept a file system request submitted by the client for an operation on the data resource, and to send the file system request and a request for a lock via the WAN to the file server, and wherein the proxy receiver is adapted to obtain the lock from the file server, responsive to the request for the lock.

221. Apparatus according to claim 220, wherein the proxy receiver is adapted to issue an unlock request to the file server with respect to the data resource, if the proxy receiver intercepts no more file system requests from the client with respect to the data resource for a certain period.

222. Apparatus according to claim 201, wherein the proxy receiver is adapted to intercept the request for the data resource submitted in accordance with a first native network file system of the client, to translate the request for the data resource from the first native network file system to a second native network file system used by the file server, to request the resource from the file server using the translated request, and to retrieve from the file server the replica of the data source over the WAN.

223. Apparatus according to claim 201, wherein the proxy receiver is adapted to ascertain an available bandwidth of the WAN, and to retrieve from the file server the replica using a portion of the bandwidth that is less than a total available bandwidth, response to a management directive downloaded to the proxy receiver over the WAN.

224. Apparatus according to claim 201, wherein the proxy receiver is adapted to request that the replica be conveyed again from the file server to the proxy receiver, upon determining that the replica is not present or not valid.

229. Apparatus according to claim 201, wherein the proxy receiver is adapted to perform an operation on the replica of the data resource in the cache responsive to a management directive downloaded to the proxy receiver over the WAN.

231. Apparatus according to claim 201, wherein the proxy receiver is adapted to intercept a group of one or more requests for first data resources on the file server, to analyze a pattern of the group of requests, and to retrieve replicas of one or more second data resources from the file server to the cache, responsive to the pattern.

232. Apparatus according to claim 231, wherein the proxy receiver is adapted to retrieve the replicas of the one or more second data resources before the client requests the second data resources.

233. Apparatus according to claim 231, wherein the proxy receiver is adapted to calculate for each of the second data resources on the file server a relation of an expected usage of the replicas of the second data resources at the proxy receiver to an expected modification rate of the second data resources at the file server, and to retrieve the replicas from the file server to the cache, responsive to the calculation.

234. Apparatus according to claim 231, wherein the proxy receiver is adapted to analyze a relation of an available bandwidth of the WAN to an expected usage of the replicas of the second data resources at the proxy receiver, and to determine, responsive to the relation, when to retrieve a replica of the second data resource.

236. Apparatus according to claim 231, wherein the proxy receiver is adapted to determine an order of retrieval of the second data resources responsive to a predetermined retrieval policy, and to retrieve, the replicas from the file server over the WAN in the determined order.

237. Apparatus according to claim 236, wherein the proxy receiver is adapted to retrieve the first data resources requested by the client with a higher priority than the second data resources, in accordance with the retrieval policy.

238. Apparatus according to claim 201, wherein the proxy receiver is adapted to intercept a write request submitted by the client for application to the data resource, and to pass the write request over the WAN to the file server.

203-205. -205. (Canceled)

207-208. -208. (Canceled)

210. (Canceled)

213. (Canceled)

225-228. -228. (Canceled)

230. (Canceled)

235. (Canceled)

239-240. -240. (Canceled)

241. Apparatus for enabling access to data resources held on a file server on a first local area network (LAN) by a client on a second LAN, the apparatus comprising:

a proxy transmitter, located on the first LAN and adapted to read metadata from the file server, to transmit the metadata via a wide area network (WAN) to the second LAN; and

a proxy receiver, located on the second LAN, which is adapted to construct a directory, based on the metadata, of the data resources on the file server, for use by the client in accessing the data resources.

243. Apparatus according to claim 241, wherein the metadata includes file attributes of the data resources, which file attributes are stored in a directory object on the file server, and wherein the proxy transmitter is adapted to read the file attributes from the directory object.

244. Apparatus according to claim 241, wherein the data resources comprise files, and wherein the metadata includes file attributes that are stored in the files, and wherein the proxy transmitter is adapted to read the file attributes from the files.

245. Apparatus according to claim 241, wherein the proxy receiver is adapted to intercept a file system request with respect to one of the data resources in the directory submitted by the client over the second LAN, and, responsive to the file system request, to serve data from the one of the data resources to the client over the second LAN.

242. (Canceled)

246-324. -324. (Canceled)

325. A computer software product for enabling access to a data resource, which is held on a file server on a first local area network (LAN), by a client on a second LAN, the product comprising a computer-readable medium, in which program instructions are stored, which instructions, when read by a computer on the second LAN, cause the computer to operate as a proxy receiver having a cache, so as to retrieve a replica of the data resource from the file server over a wide area network (WAN) to the cache, to intercept a file system request for the data resource submitted by the client over the second LAN, to check the cache to determine whether the replica of the data resource is present in the cache and valid, and, responsive to the file system request and to determining that the replica is present and valid, to serve the replica of the data resource from the cache to the client over the second LAN.

326-364. -364. (Canceled)

365. A computer software product for enabling access to data resources held on a file server on a first local area network (LAN) by a client on a second LAN, the product comprising a computer-readable medium, in which program instructions are stored, which instructions, when read by a first computer on the first LAN, cause the first computer to operate as a proxy transmitter, so as to read metadata from the file server, and to transmit the metadata via a wide area network (WAN) to the second LAN, and which instructions, when read by a second computer on the second LAN, cause the second computer to operate as a proxy receiver, and to construct a directory, based on the metadata, of the data resources on the file server, for use by the client in accessing the data resources.

366-372. -372. (Canceled)