Q139114: SNA Server Support for ASCII-EBCDIC Character Conversion
Article: Q139114
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11,3.0,4.0
Operating System(s):
Keyword(s): kbnetwork kbprogramming sna4
Last Modified: 12-JUN-2001
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The information in this article applies to:
- Microsoft SNA Server, versions 2.0, 2.1, 2.11, 3.0, 4.0
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SUMMARY
=======
Because IBM host systems and SNA-capable systems use the EBCDIC character set,
an application programmer using the APPC, CPIC or LUA API interfaces on Windows,
Windows 95, Windows NT, MS-DOS, or OS/2 must be able to convert these characters
to/from the ASCII character set. SNA Server supports this capability using
either:
- the Common Service Verb (CSV) CONVERT and GET_CP_CONVERT_TABLE functions
-or-
- the SNANLS API function, for Windows NT 4.0 (or later) and Windows 95 clients
When using the CSV functions for ASCII-EBCDIC character conversion, various host
and PC code page translation tables can be generated and used to accomodate the
language-specific configuration differences of host and PC systems. For more
information about these function calls, see the SNA Server APPC Programmer's
Guide, Chapter 8 "Common Service Verbs". For 2.1/2.11, the APPC Programmer's
Guide is included in helpfile format in <CDROM>\DOCS\HELP\SNA.HLP. For
3.0, it is included in C:\SNA30gld\SDK\infoview.exe SNA.MVB.
When using the SNANLS API on Windows NT 4.0 (or later versions), SNANLS uses the
EBCDIC Win32 NLS files delivered as part of the Windows NT 4.0 Language Pack
(see the \LANGPACK subdirectory on the Windows NT 4.0 CD-ROM). On Windows 95
clients, the NLS files included with the SNA Server Windows 95 client are used
by the SNANLS API. For more information on the SNANLS API and requirements, see
the SNA National Language Support section within the SNA Server 3.0 "SDK
Documentation" online help. Microsoft recommends using the SNANLS API for Win32
applications that will be run on Windows NT and Windows 95 client machines.
The remainder of this article describes how to use the Common Service Verb
functions. While the Common Service Verb functions are documented in the APPC
Programmer's Guide, they can also be used from a CPIC or LUA application.
MORE INFORMATION
================
The following steps should be used to determine what SNA Server Common Service
Verb (CSV) calls should be used by the application programmer:
1. Determine conversion requirements
The CONVERT API call supports ASCII-to-EBCDIC and EBCDIC-to-ASCII conversion
of characters. The following character set (char_set) table options are
supported by the CONVERT call:
char_set Description
-------- -----------------------------------------------------
SV_A Only the following characters are converted:
$ # @ A-Z 0-9
SV_AE Only the following characters are converted:
. $ # @ a-z A-Z 0-9
SV_G SNA Server uses a user-defined type G conversion
table for character conversion. See below for more
information about type G conversion table.
See Appendix A of the IBM SNA Formats Guide (IBM doc #GA27-3136) for a
description of the A and AE character sets. For SV_A and SV_AE conversions,
trailing blanks (that is, blanks at the end of the source string) are
converted to blanks in either direction. In contrast, embedded blanks are
converted to 0x00 (NULL). If any source character is converted to 0x00, the
CONVERSION_ERROR secondary return_code is returned, though the conversion
will still be completed.
Type G conversion table
-----------------------
The Type G conversion table is user-defined. SNA Server ships with a default
type G conversion table called COMTBLG.DAT. This conversion table is
automatically installed on SNA Server Windows NT and SNA Server Windows 95
client machines, to <snaroot>\SYSTEM\COMTBLG.DAT. Here is how to enable
the this type G conversion table on the other client platforms:
On Windows 3.x, copy the COMTBLG.DAT file to the client machine and add a
COMTBLG entry to the [wnap] section of WIN.INI to point to this file. For
example:
"COMTBLG=C:\SNA.WIN\COMTBLG.DAT" (without the quotation marks)
The COMTBLG.DAT conversion table is composed of 32 lines of 32 characters
each. Each line represents 16 printable hexadecimal characters followed by a
carriage return and line feed. The first 16 lines provide ASCII-to-EBCDIC
conversion information while the second 16 lines provide EBCDIC-to-ASCII
conversion information.
When SNA Server performs the conversion, it uses the numeric equivalent of
each incoming character as a 0-origin index into the conversion table. This
index specifies the table location containing the hexadecimal value of the
converted character. For example, assume that the 32nd position in the table
contained 0x40. SNA Server would convert an incoming character with a value
of 32 to a value of 64 (0x40).
2. If the above conversion tables are insufficient, a custom conversion table
must be generated.
The GET_CP_CONVERT_TABLE function supports the generation of a custom
conversion table which can then be used to create a custom conversion table
to replace the COMTBLG.DAT file shipped with SNA Server. The application
programmer passes the desired source code page (source_cp) and target code
page (target_cp), and receives the desired 256-byte conversion table. These
conversion tables can be concatenated together to form a custom
<snaroot>\system\COMTBLG.DAT file to replace the version included with
SNA Server. This conversion table can then be used when calling the CONVERT
function when the SV_G conversion table option is specified. The
GET_CP_CONVERT_TABLE function supports the following source and target code
pages:
ASCII code pages (also referred to as PC Character Sets)
--------------------------------------------------------
437 - English. US IBM PC. Includes characters for English and most
other European languages. Countries using this code page include
those from Latin America, the United States and Australia.
850 - Multilingual (Latin I). Includes characters for most of the
languages that use the Latin alphabet. This includes Belgium,
Canada(French), Denmark, Finland, France, Germany, Italy,
Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and
United Kingdom. Latin America, the United States and Australia
may also use this code page.
860 - Portuguese. Includes specific character support for the
Portuguese of Portugal.
863 - Canadian-French. Includes characters for English and
Canadian-French
865 - Slavic/Nordic (Latin II). Includes characters for the Slavic
languages that use the Latin alphabet.</ITEM></STEPS>
EBCDIC code pages (also referred to as host code pages)
-------------------------------------------------------
037 - United States, Australia, Belgium, Canada(English and,
French), Netherlands, Portugal
273 - Germany
277 - Denmark, Norway
278 - Sweden, Finland
280 - Italy
284 - Latin America, Spain
285 - United Kingdom
297 - France
500 - International, Switzerland (German and French)
NOTE: User defined code pages range from 65280 - 65534
3. If the GET_CP_CONVERT_TABLE is not sufficient:
If the above conversion tables are not sufficient, a user-written conversion
table must be defined, or a custom character conversion routine must be
implemented by the application programmer.
Additional query words: prodsna
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Keywords : kbnetwork kbprogramming sna4
Technology : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ200 kbSNAServ211 kbSNAServ400 kbSNAServ210
Version : WINDOWS:2.0,2.1,2.11,3.0,4.0
Issue type : kbhowto
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