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Accessing Network Files using Local Disk Operating System File Handles

IP.com Disclosure Number: IPCOM000108811D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 4 page(s) / 128K

Publishing Venue

IBM

Related People

Nguyen, CD: AUTHOR [+3]

Abstract

In the Disk Operating System (DOS), each open file is assigned with a file identification number. The applications use this file identification number to specify the open file that they want to do the file IO request, such as reading or writing data. When a computer running with DOS is connected to a network with many types of file servers, access to files on each type of file server is provided by a specific network file system software that usually runs on top of DOS. These network file systems typically work independently from each other and from DOS as well. Since they all work independently, there is a problem with coexistence among network file system softwares, and even with DOS, as two or more open files are assigned with the same file identification number.

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This is the abbreviated version, containing approximately 52% of the total text.

Accessing Network Files using Local Disk Operating System File Handles

       In the Disk Operating System (DOS), each open file is
assigned with a file identification number.  The applications use
this file identification number to specify the open file that they
want to do the file IO request, such as reading or writing data.
When a computer running with DOS is connected to a network with many
types of file servers, access to files on each type of file server is
provided by a specific network file system software that usually runs
on top of DOS.  These network file systems typically work
independently from each other and from DOS as well.  Since they all
work independently, there is a problem with coexistence among network
file system softwares, and even with DOS, as two or more open files
are assigned with the same file identification number.  The reason
for this file identification collision is that network file system
softwares use different schemes of assigning the file identification
number for their network files.  As a result, the uniqueness of file
identification numbers for each open file are not guaranteed across
all network file system softwares or even between any network file
system software and DOS.  This can result in data corruption among
the open files that have the same file identification number.

      This article details a simple solution to this problem without
requiring all network file system softwares to follow a common
scheme, thus allowing them to still work independently.  Each network
file system software will no longer do the task of assigning the file
identification number each time it opens a network file.  Instead, it
will obtain a file identification number from DOS and use it for each
open file on its network file servers.  By requiring all network file
system softwares to get the file identification number from DOS, the
problem of file identification collision is eliminated.

      Accessing files in DOS consists of three basic operations.
First, the applications must issue an open file request to obtain a
file identification number.  With the file identi...