FLUSH

The FLUSH verb sends the contents of the local LU's send buffer to the partner LU (and TP). If the send buffer is empty, no action takes place.

For the Microsoft® Windows® version 3.x system, it is recommended that you use WinAsyncAPPC rather than the blocking version of this call.

The following structure describes the verb control block used by the FLUSH verb.

struct flush {
    unsigned short   opcode;
    unsigned char    opext;
    unsigned char    reserv2;
    unsigned short   primary_rc;
    unsigned long    secondary_rc;
    unsigned char    tp_id[8];
    unsigned long    conv_id;
}; 
 

Members

opcode

Supplied parameter. Specifies the verb operation code, AP_B_FLUSH.

opext

Supplied parameter. Specifies the verb operation extension, AP_BASIC_CONVERSATION.

primary_rc

Returned parameter. Specifies the primary return code set by APPC at the completion of the verb. The valid return codes vary depending on the APPC verb issued. See Return Codes for valid error codes for this verb.

secondary_rc

Returned parameter. Specifies the secondary return code set by APPC at the completion of the verb. The valid return codes vary depending on the APPC verb issued. See Return Codes for valid error codes for this verb.

tp_id

Supplied parameter. Identifies the local TP. The value of this parameter is returned by TP_STARTED in the invoking TP or by RECEIVE_ALLOCATE in the invoked TP.

conv_id

Supplied parameter. Provides the conversation identifier. The value of this parameter is returned by ALLOCATE in the invoking TP or by RECEIVE_ALLOCATE in the invoked TP.

Return Codes

ap_ok

Primary return code; the verb executed successfully.

ap_parameter_check

Primary return code; the verb did not execute because of a parameter error.

ap_bad_conv_id

Secondary return code; the value of conv_id did not match a conversation identifier assigned by APPC.

ap_bad_tp_id

Secondary return code; the value of tp_id did not match a TP identifier assigned by APPC.

ap_state_check

Primary return code; the verb did not execute because it was issued in an invalid state.

ap_flush_not_send_state

Secondary return code; the conversation was not in SEND state.

ap_comm_subsystem_abended

Primary return code; indicates one of the following conditions:

• The node used by this conversation encountered an ABEND.
• The connection between the TP and the PU 2.1 node has been broken (a LAN error).
• The SnaBase at the TP's computer encountered an ABEND.

The system administrator should examine the error log to determine the reason for the ABEND.

ap_conversation_type_mixed

Primary return code; the TP has issued both basic and mapped conversation verbs. Only one type can be issued in a single conversation.

ap_invalid_verb_segment

Primary return code; the VCB extended beyond the end of the data segment.

ap_stack_too_small

Primary return code; the stack size of the application is too small to execute the verb. Increase the stack size of your application.

ap_conv_busy

Primary return code; there can only be one outstanding conversation verb at a time on any conversation. This can occur if the local TP has multiple threads, and more than one thread is issuing APPC calls using the same conv_id.

ap_unexpected_dos_error

Primary return code; the operating system has returned an error to APPC while processing an APPC call from the local TP. The operating system return code is returned through the secondary_rc. It appears in Intel byte-swapped order. If the problem persists, consult the system administrator.

Remarks

Data processed by SEND_DATA accumulates in the local LU's send buffer until one of the following happens:

• The local TP issues FLUSH (or other verb that flushes the LU's send buffer).
• The buffer is full.

The request generated by ALLOCATE is also buffered.

The conversation must be in SEND state when the TP issues this verb.

There is no state change.