Use Of Directory Paths to Solve File Handling Problems in a CMS Multitasking Environment
Original Publication Date: 1995-Apr-01
Included in the Prior Art Database: 2005-Mar-30
Disclosed is the use of the CMS Shared File System and directory pathing to solve two problems associated with executing a current CMS program in a CMS multitasking environment.
Use Of Directory Paths to Solve File Handling Problems in
a CMS Multitasking
the use of the CMS Shared File System and
directory pathing to solve two problems associated with executing a
current CMS program in a CMS multitasking environment.
as, for example, in the CMS Shared File System
(SFS), is a user-defined entity containing a set of files. A
directory path is a sequence of directories such that programs can
read and write to a directory path and not know about the individual
directories or minidisks which make up the directory path.
have the following rules:
1. If an application writes to a file which does not currently
exist, the file will be created in the first
Read/Write directory or minidisk in the directory path.
For example, using Fig. 1, files created in the directory
path would be placed in directory 1.
2. If an application reads or writes a file which does exist in a
directory in the directory path, the file is read or written
the directory in which it exists. For example, using Fig. 1,
a program using that path wrote to file X, file X in directory
would be modified.
which are designed for a single tasking system,
such as CMS, make certain assumptions about their environment. One
assumption made by CMS applications is that no other program is
sharing its Read/Write DASD space. This assumption is based in the
CMS minidisk file system which has the rule that only one user (and
therefore only one application) has "write authorization" to a
minidisk at a time.
assumption is that it can read and write to a minidisk
named "A". Traditionally each user has a private read/write "A"
minidisk to which applications read input files and write work files
and output files. This "A-disk" may be either a minidisk or an SFS
One result of
these assumptions is the use of standard, or
fixed, file names by applications. Each time the program is
executed, it creates a file of the same name. Because no other user
can execute a program writing to the same minidisk at the same time,
there was no danger of colliding on the file name. A collision is
defined as writing successively to the same file name. T...