File transfer method and apparatus utilizing delimiters

• US 6,076,084 A
• Filed: 04/30/1996
• Issued: 06/13/2000
• Est. Priority Date: 01/03/1994
• Status: Expired due to Fees

• Current Assignee: Norton-Lambert Corp.
• Original Assignee: Norton-Lambert Corp.
• Inventors: Harlan, Jim
• Primary Examiner(s): Fetting, Anton W.
• Assistant Examiner(s): LEWIS, CHERYL RENEA
• Application Number:
  US08/766,785
• Time in Patent Office: 1,505 Days
• Field of Search: 395/614, 395/613, 364/200, 364/900, 707/1, 707/2
• US Class Current: 715/748
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing

Abstract

The present invention facilitates the transmission of a file to a computer where the receiving computer has a file (called the old file) that is related to the file being transmitted (called the new file) but where the sending computer does not know the status or content of the old file. As a preliminary step, one of the computers generates a Delimiter Selection Profile Table (DSPT). The DSPT is generated by first determining the number of times each delimiter in a set of delimiters appears in the file and the distance between the locations of the delimiters in the file. Next using the information in the DSPT one of the delimiters is chosen as the delimiter which will be used and this delimiter is transmitted to the computer which did not generate the DSPT. The receiving computer next generates a Segment Profile (SPT) of the old file and the sending computer generates an SPT the new file. The SPT is generated by calculating a hash code (such as a CRC) for each segment which is defined by the selected delimiter. The hash codes from the old file are transmitted to the sending computer. The sending computer then sends to the receiving computers those segments in the new file that do not have a hash code number which matches one of the hash code numbers from the old file. The sending computer also sends an indication of where segments from the old file should be inserted into the new file. The receiving computer then constructs the new file from the segments received from the appropriate old segments.

Claims

1. A method of transferring a first file from a first computer to a second computer, where a second file is stored on said second computer comprising the steps of:

a) analyzing one of said files to generate a Delimiter Selection Profile Table (DSPT),

b) selecting a delimiter based on said DSPT,

c) analyzing both the first and the second files to generate a first Segment Profile Table (first SPT) and a second Segment Profile Table (second SPT) for segments defined by the selected delimiter for both the first and the second files,

d) sending to the first computer the second SPT,

e) sending from the first computer to the second computer a first set of segments of said first file which do not have a matching entry of the first and second SPT, and

f) combining at the second computer the segments in said first set of segments, with a second set of segments from the second file which have corresponding entries in said first and second SPT,

whereby said first file is quickly transferred to said second computer.

2. The method recited in claim 1 wherein said files consist of a series of bytes and where said delimiter is two bytes long.

3. The method recited in claim 1 wherein said second file is analyzed to generate said DSPT.

4. A system for transferring a first file a first computer to a second computer, where a second file is stored on said second computer comprising:

a) means for analyzing one of said files to generate a Delimiter Selection Profile Table (DSPT),

b) means for selecting a delimiter based on said DSPT,

c) means for analyzing both the first and the second files to generate a first Segment Profile Table (first SPT) and a second Segment Profile Table (second SPT) for segments defined by the selected delimiter for both the first and the second files,

d) means for sending to the first computer the second SPT,

e) means for sending from the first computer to the second computer a first set of segments of said first file which do not have a matching entry of the first and second SPT, and

f) means for combining at the second computer the segments in said first set of segments, with a second set of segments from the second file which have corresponding entries in said and second SPT.

whereby said first file is quickly transferred to said second computer.

5. A method of transferring a first file from a first computer to a second computer, where a second file is stored on said second computer comprising the steps of:

a) analyzing one of said files to generate a Delimiter Selection Profile Table (DSPT),

b) selecting a delimiter based on said DSPT,

c) analyzing both the first and the second files to generate a first Segment Profile Table (first SPT) and a second Segment Profile Table (second SPT) for segments defined by the selected delimiter for both the first and the second files,

d) sending to the first computer the second SPT,

e) sending from the first computer to the second computer a first set of segments of said first file which do not have a matching entry of the first and second SPT, and

f) combining at the second computer the segments in said first set of segments, with a second set of segments from the second file which have corresponding entries in said first and second SPT,

whereby said first file is quickly transferred to said second computer; and

wherein said files consist of a series of bytes and where said delimiter is two bytes long.

6. The method recited in claim 5 wherein said second file is analyzed to generate said DSPT.

7. A system for transferring a first file on a first computer to a second computer,

where a second file is stored on said second computer comprising

a) means for analyzing one of said files to generate a Delimiter Selection Profile Table (DSPT),

b) means for selecting a delimiter of at least two bytes based on said DSPT,

c) means for analyzing both the first and the second files to generate a first Segment Profile Table (first SPT) and a second Segment Profile Table (second SPT) for segments defined by the selected delimiter for both the first and the second files,

d) means for sending to the first computer the second SPT,

e) means for sending from the first computer to the second computer a first set of segments of said first file which do not have a matching entry of the first and second SPT, and

f) means for combining at the second computer the segments in said first set of segments, with a second set of segments from the second file which have corresponding entries in said first and second SPT,

whereby said first file is quickly transferred to said second computer.