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T_DATA_REQ(D7tpi)


T_DATA_REQ -- Data Request

Synopsis

This message consists of one M_PROTO message block followed by zero or more M_DATA message blocks where each M_DATA message block contains zero or more bytes of data. The format of the M_PROTO message block is as follows:
   struct T_data_req {
   	long PRIM_type;	 /* always T_DATA_REQ */
   	long MORE_flag;	 /* indicates more data in TSDU */
   }

Description

This primitive indicates to the transport provider that this message contains a transport interface data unit. One or more transport interface data units form a transport service data unit (TSDU).

This primitive has a mechanism which indicates the beginning and end of a transport service data unit. However, not all transport providers support the concept of a transport service data unit.

Parameters


PRIM_type
identifies the primitive type.

MORE_flag
when greater than zero, indicates that the next T_DATA_REQ primitive is also part of this transport service data unit.

Rules

The transport provider must also recognize a message of one or more M_DATA message blocks without the leading M_PROTO message block as a T_DATA_REQ primitive. This message type will be initiated from the write operating system service routine.

This primitive does not require any acknowledgments, although it may generate a fatal error. This is indicated via a M_ERROR message type which results in the failure of all operating system service routines on the stream.

Errors

The allowable errors are as follows:

EPROTO
This indicates one of the following unrecoverable protocol conditions:

Modes

Only connection-mode.

Originator

Transport user.

Notices

Hardware constraints

None

Applicability

N/A

Backward compatibility

UnixWare-specific TPI Message Formats

Forward compatibility

N/A
19 June 2005
© 2005 The SCO Group, Inc. All rights reserved.
OpenServer 6 and UnixWare (SVR5) HDK - June 2005