HP 3000 Manuals

COMMUNICATOR 3000/XL - REL. 2.0 (A.30.00)

Introducing SNA DHCF/XL 

by Bruce Weiler 
Business Networks Division 

PRODUCT OVERVIEW 

You can now access HP 3000 systems from your IBM 3270 terminal with the
HP SNA Distributed Host Command Facility (DHCF)/XL software product.  SNA
DHCF/XL provides IBM 3270 users with access to HP 3000 systems and
applications from their existing SNA networks.  Together with the IBM
Host Command Facility (HCF Version 2) product on the IBM mainframe, SNA
DHCF/XL gives the IBM 3270 terminal user the ability to logon to the
remote HP 3000 and appear as a Virtual Terminal.

SNA DHCF/XL is an HP to IBM networking service product that uses SNA
LINK/XL (HP 30291A) to communicate with HCF on the IBM mainframe running
MVS. SNA LINK/XL is a combination of software and hardware that
implements the lower four layers of the SNA architecture.  It
communicates with the Network Control Program (NCP) running in the IBM
37x5 communications controller to which it is connected and appears to
the NCP as a remote Physical Unit Type 2 controller.  The SNA LINK/XL
product supports multiple links with up to 64 concurrent sessions per
link.  These sessions can be divided among other HP to IBM products
allowing more than one service to share the same link.


          SNA DHCF in a Typical Network Environment 

Each SNA DHCF/XL session appears as a Virtual Terminal (VT) session.  SNA
DHCF/XL currently will support up to 120 simultaneous sessions depending
on the number of VT sessions being used by other products.

SNA DHCF/XL provides 3270 terminal users with all the MPE XL capabilities
and security of a locally attached terminal.  Once logged on, the 3270
user can run HP applications, in-house applications, and third party
applications provided that the applications conform to the SNA DHCF/XL
requirements.  The applications that SNA DHCF/XL supports can be
classified into two categories:  TTY applications and VPLUS applications.

TTY Applications 

TTY applications are characterized by their minimum use of terminal
control characters.  Typically, TTY applications use Carriage Return,
Tab, and Line Feed to control output to a terminal.  HP applications
supported in this mode include the MPE XL commands, TDP running in line
mode, and HPDesk running in TTY mode.

TTY applications can reside on any system in the HP network.  For TTY
mode applications, SNA DHCF/XL performs the data conversion on data sent
to and received from the 3270 terminal.  The conversion is limited to the
basic TTY control characters such as Carriage Return, Line Feed, and Tab.
TTY mode applications require no modifications to work with SNA DHCF/XL
and function the same whether the terminal is an HP terminal or an IBM
terminal.  However, as a result of the conversion, TTY applications may
appear differently on an IBM terminal because of the inherent differences
between the terminals.

VPLUS Applications 

VPLUS has been enhanced to support IBM 3270 terminals.  VPLUS is a forms
development tool that manages forms for data entry.  Application
programmers create VPLUS forms using the forms development tools and then
compile them into a forms file.  VPLUS applications use VPLUS intrinsics
to send the compiled forms to the terminal and to send and receive data
to and from the terminal.

VPLUS applications must reside on the HP system where SNA DHCF/XL is
installed.  For VPLUS applications, the data conversion is managed by
VPLUS and not SNA DHCF/XL. Applications that will be used from a 3270
terminal must have all their forms recompiled using the VPLUS 3270
compile option before the application can be used with an IBM 3270
terminal.  Compiling screens for use with an IBM terminal is similar to
compiling screens for use with HP terminals, only a different terminal
option is selected.  By compiling screens for use with IBM terminals, the
overhead of translating the screen image at run-time is eliminated
resulting in improved performance.

ADDITIONAL INFORMATION 

For a more in-depth description of the application features supported by
SNA DHCF/XL, order the SNA DHCF/XL Application Programmer's Manual (P/N
36935-61003).

MPE/iX Communicators