Browse Prior Art Database

Fast Host Application Access to Local Area Network Server Files

IP.com Disclosure Number: IPCOM000110771D
Original Publication Date: 1994-Jan-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 6 page(s) / 170K

Publishing Venue

IBM

Related People

Beausoleil, WF: AUTHOR [+6]

Abstract

A program is disclosed that provides direct application access to Local Area Network (LAN) file server data from System/370 (S/370) host programs. This access path provides faster access to the data than existing methods that involve complete file transfer. It also reduces programmer development time and S/370 host system utilization.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 45% of the total text.

Fast Host Application Access to Local Area Network Server Files

      A program is disclosed that provides direct application access
to Local Area Network (LAN) file server data from System/370 (S/370)
host programs.  This access path provides faster access to the data
than existing methods that involve complete file transfer.  It also
reduces programmer development time and S/370 host system
utilization.

      Many programs have been written to send data from a Personal
Computer (PC) to a host mainframe application.  TCP/IP provides a
program called File Transfer Protocol (FTP) to accomplish data
transfers to heterogeneous computers.  Many other programs exist to
accomplish similar tasks.  3270 terminal emulation programs, for
example, provide utilities to transfer files to and from a host.

      All "file transfer" methods involve extra I/O overhead because
the data is first moved as a complete file from the PC disk to the
S/370 host disks, and then the host application accesses the actual
portions of the file which are needed.  Fig. 1 is an illustration of
this "slow" mechanism.  The original data, residing on the PC disk,
is transferred through the controller to the S/370 host, where it is
written out to host disk.  The only way an application can avoid this
extra disk I/O and S/370 processor overhead is by writing a
special-purpose program on both computers, using an
application-to-application interface.  All major protocols provide
such a programming interface.  SNA has APPC, TCP/IP has Sockets and
3270 has SRPI.  Since the programming time associated with these
interfaces is far from trivial, designers will opt for the slow file
transfer method.

      This article describes how IBM LAN Resource Extension and
Services/VM (LANRES/VM), IBM Program Number 5684-142, provides Fast
Host Application Access (FHAA) to Lan Server files.  FHAA is a
programming interface that can be used by S/370 VM application
programs for reading and writing LAN data files using a
channel-attached NetWare* file server.  This interface allows host
applications to read and write PC files directly, as if the files
were on their native system (e.g., using assembler calls that are
similar to the CMS file system interfaces FSREAD and FSWRITE).  It
provides optimum performance with minimum program development effort.

      Fig. 2 shows the FHAA mechanism.  The PC's data resides in
files on the NetWare file server's disk.  Any LAN file server could
be used (e.g., OS/2** LAN Server).  The S/370 VM application uses the
FHAA read and write interfaces to access the files directly as if the
files resided on that host.

This new method results in:

o   High performance direct access to LAN files.  The host
    application does not have to stage the data on a host disk.  Data
    transfer occurs directly between S/370 memory and the LAN file
    server disk.

o   Reduced development time to achieve optimization.  A simple
 ...