Method and apparatus for recovering aborted file (or data) transmission

• US 5,752,251 A
• Filed: 08/18/1997
• Issued: 05/12/1998
• Est. Priority Date: 08/07/1995
• Status: Expired

• Current Assignee: Teledata Sound LLC (Intellectual Ventures LLC)
• Original Assignee: NCR Corporation
• Inventors: Cripps, Michael J.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): RONES, CHARLES
• Application Number:
  US08/912,457
• Time in Patent Office: 267 Days
• Field of Search: 371/53, 371/32, 380/49, 395/500, 707/100, 707/104, 707/202
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1443 Transmit or communication errors

Abstract

A system for transmitting files includes a transmitting terminal and receiving terminal. After a file transmission has aborted, the receiving terminal generates a size and checksum for the portion of the file received by the receiving terminal. The transmitting terminal generates the checksum based on the corresponding portion of the file stored in the transmitting terminal in reference to the size. The transmitting terminal re-starts the file transmission process if the checksum generated at the receiving terminal does not match that generated at the transmitting terminal. The transmitting terminal transmits the rest of the file that has not received by the receiving terminal if the checksum generated at the receiving terminal matches that generated at the transmitting terminal.

Claims

1. A system for performing a file transmitting process from a transmitting terminal to a receiving terminal, comprising:

the receiving terminal including;

a processor circuitry for generating a first value for a portion of a file received at the receiving terminal, and for generating a size for the portion of the file received at the received terminal, said portion of the file containing a plurality of data blocks, said first value being calculated based on contents of said portion of said received file;

a transmitting circuitry for sending said first value and size from the receiving terminal to the transmitting terminal;

the transmitting terminal including;

a processor circuitry for generating a second value for a corresponding portion of a corresponding file stored at the transmitting terminal, said corresponding portion of said corresponding file at the transmitting terminal containing a plurality of data blocks and being indicated by said size from the receiving terminal, said second value being calculated based on contents of said corresponding portion of said corresponding file;

a processor circuitry for comparing said first value generated at the receiving terminal with said second value generated at the transmitting terminal; and

a transmitting circuitry for transmitting said corresponding file from the transmitting terminal to the receiving terminal if said first value generated at the receiving terminal does not match said second value generated at the transmitting terminal, and transmitting remaining portion of said corresponding file from the transmitting terminal to the receiving terminal if said first value generated at the receiving terminal matches said second value generated at the transmitting terminal.

2. The system of claim 1,

wherein said first and second values are checksums for the portion received at the receiving terminal and the corresponding portion at the transmitting terminal respectively.

8. The method of claim 1,

wherein said first and second values are checksums for the portion received at the receiving terminal and the corresponding portion stored at the transmitting terminal respectively.

3. An apparatus for performing a file transmitting process from a transmitting terminal to a receiving terminal, comprising:

the transmitting terminal including;

a receiving circuitry for receiving from the receiving terminal a first value for a portion of a file received at the receiving terminal and for receiving from the receiving terminal a size for the portion of the file received at the received terminal, said portion of the file containing a plurality of data blocks, said first value being calculated based on contents of said portion of received file;

a processor circuitry for generating a second value for a corresponding portion of a corresponding file stored at the transmitting terminal, said corresponding portion of said corresponding file at the transmitting terminal containing a plurality of data blocks and being indicated by said size from the receiving terminal, said second value being calculated based on contents of said corresponding portion of said corresponding file;

a processor circuitry for comparing said first value generated at the receiving terminal with said second value generated at the transmitting terminal; and

a transmitting circuitry for transmitting said corresponding file from the transmitting terminal to the receiving terminal if said first value generated at the receiving terminal does not match said second value generated at the transmitting terminal, and transmitting remaining portion of said corresponding file from the transmitting terminal to the receiving terminal if said first number generated at the receiving terminal matches said second value generated at the transmitting terminal.

4. The apparatus of claim 3, wherein said first and second values are checksums for the portion of the file at the receiving terminal and the corresponding portion of the corresponding file stored at the transmitting terminal respectively.

5. A method for performing a file transmitting process from a transmitting terminal to a receiving terminal, comprising the steps of:

(a) at the transmitting terminal, receiving, from the receiving terminal, a first value for a portion of a file received at the receiving terminal and a size for the portion of the file received at the receiving terminal, said portion of the file containing a plurality of data blocks, said first value being calculated based on contents of said portion of said received file;

(b) at the transmitting signal, generating a second value for a corresponding portion of a corresponding file stored at the transmitting terminal, said corresponding portion of said corresponding file at the transmitting terminal containing a plurality of data blocks and being indicated by said size from the receiving terminal, said first value being calculated based on contents of said corresponding portion of said corresponding file;

(c) at the transmitting signal, comparing said first value generated at the receiving terminal with said second value generated at the transmitting terminal; and

(d) at the transmitting terminal, transmitting said corresponding file to the receiving terminal if said first value generated at the receiving terminal does not match said second value generated at the transmitting terminal, and transmitting remaining portion of said corresponding file from the transmitting terminal to the receiving terminal if said first value generated at the receiving terminal matches said second value generated at the transmitting terminal.

6. The method of claim 5, wherein said first and second values are checksums for the portion of the file at the receiving terminal and the corresponding portion of the corresponding file stored at the transmitting terminal respectively.

7. A method for performing a file transmitting process from a transmitting terminal to a receiving terminal, comprising the steps of;

at the receiving terminal;

(a) generating a first value for a portion of a file received at the receiving terminal, said portion of the file containing a plurality of data blocks, said first value being calculated based on contents of said portion of said received file;

(b) generating a size for the portion of the file received at the receiving terminal;

(c) sending said first value and size from the receiving terminal to the transmitting terminal;

at the transmitting terminal;

(d) generating a second value for a corresponding portion of a corresponding file stored at the transmitting terminal, said corresponding portion of said corresponding file at the transmitting terminal containing a plurality of data blocks and being indicated by said size from the receiving terminal, said second value being calculated based on contents of said corresponding portion of said corresponding file;

(e) comparing said first value generated at the receiving terminal with said second value generated at the transmitting terminal; and

(f) transmitting said corresponding file from the transmitting terminal to the receiving terminal if first value generated at the receiving terminal does not match said second value generated at the transmitting terminal, and transmitting remaining portion of said corresponding file from the transmitting terminal to the receiving terminal if said first value generated at the receiving terminal matches said second value generated at the transmitting terminal.

9. A system for performing a file transmitting process from a source terminal to a destination terminal, comprising:

a processor circuitry, located at the source terminal, for selecting at least one file from a plurality of files at the source terminal;

a processor circuitry, located at the destination terminal, for generating a first value for a respective file corresponding to said selected file at the destination terminal and a size for said respective file, said respective file containing a plurality of data blocks, said first value being calculated based on contents of said respective file;

a transmitting circuitry, located at the destination terminal, for sending said first value and size to the source terminal;

a processor circuitry, located at the source terminal, for generating a second value for a corresponding portion of said selected file stored at the source terminal, said corresponding portion being indicated by said size, said second value being calculated based on contents of said corresponding portion of said selected file;

a processor circuitry, located at the source terminal, for comparing said first value generated at said destination terminal with said second value generated at said source terminal; and

a transmitting circuitry, located at the source terminal, for transmitting said selected file from the source terminal to the destination terminal, in response to a comparing result by said comparing circuitry;

wherein said transmitting circuitry at the source terminal transmits a remaining portion of said selected file that is not present in the destination terminal if said second value generated from said selected file at the source terminal matches said first value generated from the respective file at the destination terminal;

wherein said transmitting circuitry at the source terminal transmits said selected file if said second value generated from selected file at the source terminal does not match said first value generated for said respective file at the destination terminal.

10. The system of claim 9,

wherein said first and second values are checksums for the respective file stored at the destination terminal and the corresponding portion stored at the source terminal respectively.

11. A method for performing a file transmitting process from a source terminal to a destination terminal, comprising the steps of:

(a) at the source terminal, selecting at least one file from a plurality of files to be transmitted to the destination terminal;

(b) at the destination terminal, generating a first value for a respective file corresponding to said selected file and a size for said respective file, said respective file containing a plurality of data blocks, said first value being calculated based on contents of said respective file;

(c) at the destination terminal, transmitting said first value generated at the destination terminal and size to the source terminal;

(d) at the source terminal, generating a second value for a portion of said selected file stored at the source terminal, said portion being indicated by said size, said second value being calculated based on contents of said portion of said selected file;

(e) at the source terminal, comparing said first value generated from said respective file at the destination terminal with said second value generated from said selected file at the source terminal; and

(f) at the source terminal, transmitting said selected file from the source terminal to the destination terminal;

wherein said step (f) transmits a portion of said selected file that is not present in the destination terminal if said second value generated from said selected file at the source terminal matches said first value generated from the respective file at the destination terminal;

wherein said step (f) transmits said selected file if said second value generated from selected file at the source terminal does not match said first value generated for said respective file at the destination terminal.

12. The method of claim 11,

wherein said first and second values are checksums for the respective file at the destination terminal and the corresponding portion stared at the source terminal respectively.