TN3270e Server Manual

CRT Communication Protocol

TN3270e Server Manual—422923-003

5-3

SNAX/XF Mode

You can configure the TN3270e server process to emulate the SNAX/XF application

interface by specifying the -s switch on the command line. The TN3270e server runs in

AM3270 mode by default.

The following file system procedures are recognized by the ETN32SRV/CRT protocol

when it is operating in SNAX/XF mode:

Two-Step READ Requests

The TN3270 CRT protocol for SNAX provides a two-step READ capability that helps

your application processes make the most efficient use of the available buffer space. A

two-step READ involves two separate READ operations.



The first READ operation, initialized by a WRITEREAD call (that had a write count

of 0 and a read count of 2), returns an integer to the first word of the buffer,

indicating how many bytes of data are in the incoming data block.



The second READ operation, initialized by a READ call, accepts the incoming data

block.

SNAX/XF CRT SETMODE Procedure

Applications use SETMODE calls to control an TN3270e server session and to obtain

information about it. The CRT SETMODEs that have special significance to the

TN3270e server when it is in SNAF/XF mode are described next.

SETMODE Function 144 Procedure

The SETMODE function 144 procedure is used in a SNAX environment to find the

single-byte character set and double-byte character set (if any) that is defined for the

logical unit (LU). In a TN3270e server environment, a SETMODE function 144

procedure returns hard-coded values for the Katakana (single-byte) and Kanji (double-

byte) character set codes. If the -k command line option is not selected, the single-byte

character set code returned is 9 for EBCDIC. The double-byte character set code is 0,

indicating no double-byte character set is used. If the -k option is selected, the single-

byte character set code returned is 14 for Katakana EBCDIC. The double-byte

character set code is 3 for IBM MIXED.

AWAITIO CONTROL OPEN SETMODE WRITEREAD[x]

CANCEL DEVICEINFO READ[x] SETPARAM

CLOSE FILEINFO SETMODE WRITE [x]