HP 3000 Manuals HP 3000 Manuals
Additional Application Considerations
Besides the primary tasks of understanding terminal differences and
preparing an application, the following additional application
considerations are important to understand:
* Application Support File.
* Error handling.
* VPLUS/Windows security.
* Native language support.
Application Support File
VPLUS/Windows starts an application on the HP 3000 by using the RUN
command options. Many interactive applications require more external
control information than the RUN command provides. For example, an
application may need to use FILE statements or JCWs to prepare for actual
application execution.
VPLUS/Windows enables you to use the Application Support File (ASF) to
prepare the supporting environment. The ASF consists of a simple,
unnumbered ASCII file in which each record is used as input for the
COMMAND intrinsic. VPLUS/Windows does not edit the ASF contents. The
application definition includes the name of the ASF. (Refer to "Define
Application" in Chapter 3 for a description of the ASF interface to
VPLUS/Windows.)
Processing and Errors. VPLUS/Windows processes the ASF just before
initiating the application process. The application startup terminates
if the COMMAND intrinsic detects errors. The VPLUS/Windows presentation
server notifies the PC end user of an application startup failure by
displaying the ASF record that the COMMAND intrinsic rejects.
Content Restrictions. The COMMAND intrinsic and VPLUS/Windows both have
certain restrictions that apply to the contents of an ASF.
COMMAND Intrinsic Restrictions. The commands in the ASF must be
programatically executable, as described in the COMMAND intrinsic. The
COMMAND intrinsic does not support user-definable commands. Refer to the
MPE Intrinsics Reference Manual (32650-90028) for information about the
COMMAND intrinsic.
VPLUS/Windows Restrictions. The VPLUS/Windows presentation server
manages the user device (the PC); consequently, no session device exists.
Therefore, commands that use $STDIN or $STDLIST cannot interact with a
user. When VPLUS/Windows activates the defined application, it
automatically redirects both $STDIN and $STDLIST to $NULL. You can
override the automatic redirections by supplying your own redirection in
the PROG options of the application definition.
Error Handling
Network or PC catastrophic errors that VPLUS/Windows detects on the HP
3000 are passed to VPLUS and reflected as standard VPLUS errors.
Additionally, VPLUS returns the value of -500 in the filerrnum variable
within the COMAREA parameter to signal these errors. Your application
should handle these errors by properly closing all data files and
immediately shutting down the application. Improper handling of these
error conditions can cause unexpected looping conditions or useless
remnants of the application process.
Table 2-6 lists the corresponding error number and error message for each
VPLUS intrinsic impacted by PC or network errors.
Table 2-6. Network and PC Errors that Affect VPLUS Intrinsics
----------------------------------------------------------------------------------------------
| | | |
| Intrinsic | Error Number | Error Message |
| | | |
----------------------------------------------------------------------------------------------
| | | |
| VOPENFORMF | 50 | Forms file open failed. (FSERR -500) |
| | | |
----------------------------------------------------------------------------------------------
| | | |
| VCLOSEFORMF | 63 | Failure to close forms file. (FSERR -500) |
| | | |
----------------------------------------------------------------------------------------------
| | | |
| VCHANGEFIELD | 856 | Invalid VCHANGEFIELD specification type. |
| | | |
----------------------------------------------------------------------------------------------
| | | |
| VPLACECURSOR | 501 | The field number supplied is out of range. |
| | | |
----------------------------------------------------------------------------------------------
| | | |
| VGETNEXTFORM | 100 | Can't find the next form. |
| | | |
----------------------------------------------------------------------------------------------
| | | |
| VSHOWFORM | 130 | Internal error: Terminal write failed. (FSERR |
| | | -500) |
| | | |
----------------------------------------------------------------------------------------------
| | | |
| VREADFIELDS | 160 | Internal error: Terminal read failed. (FSERR |
| | | -500) |
| | | |
----------------------------------------------------------------------------------------------
| | | |
| VOPENTERM | 9 | The terminal open failed. (FSERR -500) |
| | | |
----------------------------------------------------------------------------------------------
| | | |
| VCLOSETERM | 10 | The terminal close failed. (FSERR -500) |
| | | |
----------------------------------------------------------------------------------------------
You can provide a JCW in the Application Support File that enables
VPLUS/Windows to immediately terminate your application process and
session after detecting catastrophic errors on the network or PC. You
have the following choices for setting the JCW, depending on the type of
termination desired:
SETJCW VWTERMINATE=0 Return the error number to the application
(default).
SETJCW VWTERMINATE=1 Terminate the application immediately.
Note that if you enable VPLUS/Windows to control application termination,
your application cannot finish as it ordinarily would, and cannot undo
transaction work that may have been in progress.
Refer to Chapter 6 for information about manually recovering from
unexpected interruptions or failures.
VPLUS/Windows Security
Other than the administrator password, VPLUS/Windows does not provide
additional PC security support to prevent users from viewing or altering
application definitions. To prevent users from starting applications,
use the PC physical security lock.
You may have created logon UDCs on the HP 3000 to produce additional
security prompts and menus for user application selection. However,
VPLUS/Windows does not provide a facility enabling a user to respond to
these prompts before running the VPLUS application. VPLUS/Windows only
supports the basic MPE security measures of account, user, and group
passwords. Consequently, if a program run under a logon UDC requires a
user to respond to a prompt before the user can continue, you must remove
the program or response requirement in order for VPLUS/Windows to
establish a programmatic session.
Native Language Support
VPLUS/Windows supports the HP 3000 ROMAN8 character set and the terminal
Line Drawing character set. VPLUS/Windows supports all languages that
use ROMAN8. Other character sets, including 2-byte characters, are
currently unsupported.
The character set definition on the PC is not the same as the character
set definition on the HP 3000 in the upper half of the character set
table. VPLUS/Windows automatically converts the characters of the ROMAN8
table used on the HP 3000 to the ANSI table used in Microsoft Windows.
Refer to the Native Language Programmer's Guide (32650-90022) for
information about the ROMAN8 table on the HP 3000. Refer to
the Microsoft Windows Software Development Kit-Reference
(SY0302a-300-R00-1089) for information about the ANSI table in Microsoft
Windows.