Previewing File Information Over a Network

Abstract

An example embodiment of the present invention provides a process for opening and reading a file over a network, including a WAN. In the example embodiment, an edge file gateway appliance (or server) receives a request from an application such as a tile manager to open a file cached with the edge file gateway appliance at one point on a network and stored on a file server connected to a central server appliance (or server) at another point on the network. The edge file gateway appliance then forwards the request to open the file to the central server appliance, along with any offsets and lengths stored from any previous requests to read the file. The central server appliance responds by sending any file data described in the stored offsets and lengths to the edge file gateway appliance. Then when the edge file gateway appliance receives a read request from an application, the edge file gateway appliance stores the offset and length for the request, if a predefined storage limit is not exceeded, and attempts to satisfy the request from cached file data. The edge file gateway appliance fetches the entire file from the CS appliance if a predefined file limit is exceeded.

1 - 20 . (canceled) 
     
     
         21 . A computer-implemented method, comprising:
 initiating a cache cleanup upon a determination that a predefined limit is exceeded by file data stored in a cache connected to a network device;   determining whether there are stored offset positions and lengths from previous read requests from a client for a least recently used file in the cache, wherein the stored offset positions and lengths describe one or more data segments of the file;   based on a determination of whether there are stored offset positions and lengths from previous read requests from the client for the least recently used file in the cache, selecting a manner of reducing size of the least recently used file from a plurality of manners of reducing size of the least recently used file; and   creating a sparse file using the selected manner of reducing size of the least recently used file.   
     
     
         22 . The method of  claim 21 , further comprising:
 determining that that there are stored offset positions and lengths from previous read requests from the client for the least recently used file in the cache; and   based on the determination, creating the sparse file by selecting to reduce size of the least recently used file by conditionally making space available in the cache by zeroing out the parts of the least recently used file that are not described in the stored offset positions and lengths from previous read requests.   
     
     
         23 . The method of  claim 21 , further comprising:
 determining that there are no stored offset positions and lengths from previous read requests from the client for the least recently used file in the cache; and   based on the determination, creating the sparse file by selecting to reduce size of the least recently used file by conditionally making space available in the cache by truncating the least recently used file to zero bytes.   
     
     
         24 . The method of  claim 21 , wherein the predefined limit comprises a specified percentage of available storage space in the cache. 
     
     
         25 . The method of  claim 21 , wherein the network is a wide area network. 
     
     
         26 . The method of  claim 21 , further comprising maintaining any parts of the least recently used file described in the stored offset positions and lengths in the cache. 
     
     
         27 . An apparatus comprising:
 a processor; and   a machine-readable, non-transitory medium comprising instructions, the instructions, when loaded and executed by the processor, configure the processor to:
 initiate a cache cleanup upon a determination that a predefined limit is exceeded by file data stored in a cache connected to a network device; 
 determine whether there are stored offset positions and lengths from previous read requests from a client for a least recently used file in the cache, wherein the stored offset positions and lengths describe one or more data segments of the file; 
 based on a determination of whether there are stored offset positions and lengths from previous read requests from the client for the least recently used file in the cache, select a manner of reducing size of the least recently used file from a plurality of manners of reducing size of the least recently used file; and 
 create a sparse file using the selected manner of reducing size of the least recently used file. 
   
     
     
         28 . The apparatus of  claim 27 , wherein the medium further comprises instructions for causing the processor to:
 determine that that there are stored offset positions and lengths from previous read requests from the client for the least recently used file in the cache; and   based on the determination, create the sparse file by selecting to reduce size of the least recently used file by conditionally making space available in the cache by zeroing out the parts of the least recently used file that are not described in the stored offset positions and lengths from previous read requests.   
     
     
         29 . The apparatus of  claim 27 , wherein the medium further comprises instructions for causing the processor to:
 determine that there are no stored offset positions and lengths from previous read requests from the client for the least recently used file in the cache; and   based on the determination, create the sparse file by selecting to reduce size of the least recently used file by conditionally making space available in the cache by truncating the least recently used file to zero bytes.   
     
     
         30 . The apparatus of  claim 27 , wherein the predefined limit comprises a specified percentage of available storage space in the cache. 
     
     
         31 . The apparatus of  claim 27 , wherein the network is a wide area network. 
     
     
         32 . The apparatus of  claim 27 , wherein the medium further comprises instructions for causing the processor to maintain any parts of the least recently used file described in the stored offset positions and lengths in the cache. 
     
     
         33 . A non-transitory, computer-readable medium comprising instructions, the instructions, when loaded and executed by a processor, configure the processor to:
 initiate a cache cleanup upon a determination that a predefined limit is exceeded by file data stored in a cache connected to a network device;   determine whether there are stored offset positions and lengths from previous read requests from a client for a least recently used file in the cache, wherein the stored offset positions and lengths describe one or more data segments of the file;   based on a determination of whether there are stored offset positions and lengths from previous read requests from the client for the least recently used file in the cache, select a manner of reducing size of the least recently used file from a plurality of manners of reducing size of the least recently used file; and   create a sparse file using the selected manner of reducing size of the least recently used file.   
     
     
         34 . The medium of  claim 33 , further comprising instructions for causing the processor to:
 determine that that there are stored offset positions and lengths from previous read requests from the client for the least recently used file in the cache; and   based on the determination, create the sparse file by selecting to reduce size of the least recently used file by conditionally making space available in the cache by zeroing out the parts of the least recently used file that are not described in the stored offset positions and lengths from previous read requests.   
     
     
         35 . The medium of  claim 33 , further comprising instructions for causing the processor to:
 determine that there are no stored offset positions and lengths from previous read requests from the client for the least recently used file in the cache; and   based on the determination, create the sparse file by selecting to reduce size of the least recently used file by conditionally making space available in the cache by truncating the least recently used file to zero bytes.   
     
     
         36 . The medium of  claim 33 , wherein the predefined limit comprises a specified percentage of available storage space in the cache. 
     
     
         37 . The medium of  claim 33 , wherein the network is a wide area network. 
     
     
         38 . The medium of  claim 33 , further comprising instructions for causing the processor to maintain any parts of the least recently used file described in the stored offset positions and lengths in the cache.