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Sends data on a connection.
Syntax
IPCSEND ( vcdesc, data, dlen [,flags] [,opt], result )
Parameters
- vcdesc (input)
- 32-bit integer, by value. The VC socket descriptor, a number
identifying the VC socket belonging to this process through which the
data will be sent.
- data (input)
- Record or byte array, by reference. Contains the data to be sent
or a list of data descriptors (maximum of two) indicating the locations
from which the data will be gathered. If data descriptors are used,
flags [31] must be set to indicate vectored sends. For programming in
"C" language, see Appendix E "C Program Language
Considerations"
- dlen (input)
- 32-bit integer, by value. The byte length of the data parameter:
that is, the amount of actual data (maximum of 30,000) or the combined
length of the data descriptors. The data descriptor length is 8 for
compatibility mode and 12 for native mode. The combined length is 16 for
compatibility mode and 24 for native mode.
- flags (input)
- 32 bits, by reference. A bit representation of various options.
The only flag defined is:
- flags [31] — vectored input. Indicates that the data
to be sent are to be gathered from the addresses specified in the
data parameter. (The parameter will not contain actual data.)
- opt (input)
- Record or byte array, by reference. A list of options, with
associated information. Refer to "Common Parameters" for more
information on the structure of this parameter. The following options
are defined:
- data offset (code=8, length=2; 2-byte integer) (input).
Compatibility mode (CM) only. An offset in bytes from the data
parameter's address indicating the actual beginning of the data.
HP recommends that you do not use data offset if data descriptors
are used to point to another location from which data should be
obtained.
- protocol flags (code=144, length=4; 4-byte buffer) (input).
This option contains 32 bits of protocol-specific flags. The
following flag is currently defined:
- end-to-end acknowledgment (bit 18, input). (X.25
only.) D bit will be set in the last X.25 data packet
corresponding to this message. When this flag is set,
IPCSEND waits to complete until acknowledgment from
the remote that the complete message has been received. When
the connection is between two HP 3000's running NS X.25, the
acknowledgment is made when the remote IPC user has received
the data.
- qualifier bit (bit 19, input). (X.25 only.) This flag
indicates to X.25 to set the Q bit in the packets that
contain this message.
- urgent data (bit 27, input). (TCP only). If set, this
bit will cause the data sent to be marked urgent.
- result (output)
- 32-bit integer, by reference. The error code returned; zero if no
error.
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NOTE: When nowait I/O is used, the result parameter
is not updated upon completion of IOWAIT. Therefore, the value of
result will indicate only whether the call was successfully
initiated. To determine whether the call completed successfully, you can use
the IPCCHECK intrinsic after IOWAIT completes.
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Description
The IPCSEND intrinsic is used to send data on a connection. The only
required parameters are vcdesc, data, and
dlen (option variable).
A set of addresses in the data parameter allows vectored data
to be gathered from multiple locations.
The value specified for the data offset option (compatibility mode only) is
relative to the data array. If data descriptors are used, specifying this
option will cause a portion of the descriptor to be passed over (the offset is
NOT applied to the pointer in the descriptor). This may lead to unexpected
results.
If this intrinsic is called in nowait mode, the address of the data is passed
to the TCP protocol module. The contents of the data buffer will have been
read when IOWAIT completes. As many as 7 nowait sends may be
outstanding on a connection.
Condition codes returned by IPCSEND and IOWAIT are:
- CCE — Succeeded.
- CCL — Failed.
- CCG — Not returned.
This intrinsic can be called in split stack mode.
Protocol-Specific Considerations
The following Table 3-10 "IPCSEND Protocol
Specific Parameters" outlines parameters that are specific to the
particular protocol you are accessing.
Table 3-10 IPCSEND Protocol Specific Parameters
| Parameters |
TCP |
X.25 |
| opt | | |
| 144 | Bit 27: urgent data |
Bit 18: state of D bit in X.25 packets |
| | Bit 19: state of Q bit in X.25 packets |
X.25 Considerations
Setting the Q bit flag causes X.25 to set the Q bit (qualifier bit) in X.25
data packets.
Setting the D bit flag causes X.25 to specify end-to-end acknowledgment of
data packets. IPCSEND does not complete until it receives
acknowledgment that the message has been received.
Common errors returned by IPCSHUTDOWN in result are:
SOCKERR 0 Request completed successfully.
SOCKERR 50 Invalid data length.
SOCKERR 65 Connection aborted by local protocol module.
SOCKERR 67 Connection failure detected.
SOCKERR 107 Transport is going down.
SOCKERR 159 Invalid X.25 D-bit setting.
SOCKERR 160 Incompatible with protocol state.
A complete table of SOCKERRs is included in
Appendix C "Error Messages"
TCP
The urgent data bit of the protocol flags option (opt
parameter) is used to inform TCP that the data to be sent should be marked
urgent. This will not cause the data to be delivered out of band, and the
receiver of this data will not know of urgent data that is pending until a
receive is posted.
Cross-System Considerations For TCP
The following are cross-system programming considerations for this intrinsic:
HP 3000 to HP 1000:
Send size — The HP 3000 send size range is 1 to 30,000 bytes. The
HP 1000 send size is 1 to 32,767 bytes. Although the ranges are different,
cross-system communication is not affected. If you specify a send or receive
size, be sure it is within the correct range for the respective system.
Note that the urgent data bit is not supported on the HP 1000; however,
if this bit is set by the HP 3000 program, it will be ignored by the receiving
process on the HP 1000.
HP 3000 to HP 9000:
Send size — The HP 3000 send size range is 1 to 30,000 bytes. The
HP 9000 send size is 1 to 32,767 bytes. Although the ranges are different,
cross-system communication is not affected. If you specify a send or receive
size, be sure it is within the correct range for the respective system.
Note that the urgent data bit is not supported on the HP 9000; however,
if this bit is set by the HP 3000 program, it will be ignored by the receiving
process on the HP 9000. For differences in send and receive sizes see the
discussion for IPCRECVCN.
HP 3000 to PC NetIPC:
Send size — The PC send and receive size range is 1 to 65,535
bytes. Although the ranges are different, cross-system communication is not
affected. If you specify a send or receive size, be sure it is within the
correct range for the respective system.
On the PC, you can specify the maximum receive size of the data buffer through
the got array in the IPCCONNECT call. This determines
what the maximum value for dlen can be for any IPCRECV
call. PC NetIPC has no option array defined for IPCCONNECT. This does
not affect cross-system communication. The maximum receive size of the data in
the buffer on the HP 3000 will determine the receive size buffer on the PC.
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