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Status-Acknowledge(Nack-1)

  • Article

The Status-Acknowledge(Nack-1) message flows from the node to the application and from the application to the node. It is used with both system services control point (SSCP) and primary logical unit (PLU) connections.

Syntax

  
struct Status-Acknowledge(Nack-1) {  
    PTRBFHDR  nxtqptr;  
    PTRBFELT  hdreptr;  
    CHAR      numelts;  
    CHAR      msgtype;  
    CHAR      srcl;  
    CHAR      srcp;  
    INTEGER   srci;  
    CHAR      destl;  
    CHAR      destp;  
    INTEGER   desti;  
    CHAR      sfhdr.stackhdr.akstat;  
    CHAR      sfhdr.stackhdr.akqual;  
    INTEGER   sfhdr.stackhdr.akmsgkey;  
    CHAR      sfhdr.stackhdr.akflags1;  
    CHAR      sfhdr.stackhdr.akflags2;  
    INTEGER   sfhdr.stackhdr.aknumb1;  
    INTEGER   sfhdr.stackhdr.aknumb2;  
    INTEGER   sfhdr.stackhdr.akseqno;  
};   
struct Status-Acknowledge(Nack-1) {  
    PTRBFELT   hdreptr->elteptr;  
    INTEGER    hdreptr->startd;  
    INTEGER    hdreptr->endd;  
    CHAR       hdreptr->trpad;  
    CHAR[268]  hdreptr->dataru;  
};

Members

nxtqptr
Pointer to next buffer header.

hdreptr
Pointer to buffer element (NIL if not using LUA).

numelts
Number of buffer elements (0x00 if not using LUA).

msgtype
Message type STATFMI (0x21).

srcl
Source locality.

srcp
Source partner.

srci
Source index.

destl
Destination locality.

destp
Destination partner.

desti
Destination index.

sfhdr.stackhdr.akstat
Status type ACK (0x01).

sfhdr.stackhdr.akqual
Acknowledgment type ACKNEG1 (0x03).

sfhdr.stackhdr.akmsgkey
Message key.

sfhdr.stackhdr.akflags1
Application flag 1.

sfhdr.stackhdr.akflags2
Application flag 2.

sfhdr.stackhdr.aknumb1
Sense data 1.

sfhdr.stackhdr.aknumb2
Sense data 2.

sfhdr.stackhdr.akseqno
SNA sequence number.

LUA only (see Remarks):
Element

hdreptr–>elteptr
Pointer to buffer element (NIL).

hdreptr–>startd
Start of data in this buffer element.

13 or 10 for second and subsequent segments of outbound segmented request/response units (RUs)

hdreptr–>endd
End of data in this buffer element.

hdreptr–>trpad
Reserved.

hdreptr–>dataru
Data RU.

Remarks

  • The message key and application flags reflect the message key and application flags of the data message to which this is a negative acknowledgment. (For more information, see the note about LUA that follows.)

  • For Status-Acknowledge(Nack-1) messages from the local node to the application, the sense data reflects the sense data in the SNA negative response.

  • For Status-Acknowledge(Nack-1) messages from the application to the local node, the sense data fields are those intended for the SNA negative response to the host.

  • For outbound Status-Acknowledge(Nack-1) messages from the local node to the application, the SNA sequence number gives the sequence number of the inbound data message to which this is a negative acknowledgment. (For more information, see the note about LUA that follows.)

  • For inbound Status-Acknowledge(Nack-1) messages from the application to the local node, the SNA sequence number reflects the sequence number of the outbound data message to which this is a negative acknowledgment.

  • If the application is using the LUA variant of the function management interface (FMI), the transmission header (TH) and (if appropriate) response header (RH) are included in the data, and the startd field points to the TH. The akmsgkey, akflags1, and akflags2 fields are undefined and should not be used. The corresponding data from the element should be used instead. The akseqno field is similarly undefined on messages from the local node to the application. It must be set on messages from the application to the local node. (For more information about FMI, see FMI Concepts.)

  • If the application is not using the LUA variant of the FMI, the message consists of a buffer header only. There is no buffer element.