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DCS 300 User’s Manual
C-18
Note: If an application sends a Inter system transaction instead of an acknowledgment
to the message handler, the message handler retransmits the last transaction it sent to
that application.
Nonactive Applications
A nonactive application has failed to complete the handshake with the DCS 300 for a
transaction. An application becomes nonactive in these two situations:
•
If the Hot Standby timeout expires before the DCS 300 received an ACK from the
application, the DCS 300 places the application in a nonactive state. Also, the
DCS 300 writes all subsequent transactions for the application in a Hot Standby
file.
•
If the number of transactions in the application’s
AUX_Q
reaches its limit, the
DCS 300 places the application in a nonactive state. Also, the DCS 300 writes the
contents of
AUX_Q
and all new transactions for the application into the Hot
Standby file.
Sending Hot Standby Messages
When the DCS 300 receives a transaction for a nonactive application, it can send a
user-defined response to the device that sent the transacaction. This user-defined
response is the Hot Standby message. You can use the local interface to configure a Hot
Standby message for each transaction ID. The Hot Standby message can serve as a
positive response to a device by indicating that the transaction was saved on disk.
Note: If the DCS 300 does not recognize the transaction ID, the DCS 300 sends a bad
ID response to the source of the invalid transaction. You configure this bad transaction
ID response in the System Parameters dialog box.
Also, if the application receives a transaction from a bar code reader that is operating in
computer response required mode (
CRRM
), the reader remains locked until a response
is received or the reader times out. The DCS 300 should reply with the Hot Standby
message when it cannot deliver a transaction to the application.
If the Hot Standby message field is empty, the DCS 300 sends nothing to the device
when it saves a transaction on disk. It becomes the application’s responsibility to return
a response to a device when it receives the transaction. In some cases, a response may
not even be required, such as when the application is receiving status transactions from
printers.
Because transactions can have multiple routes, the DCS 300 appends a comma to the
end of a Hot Standby message followed by the name of the destination where the Hot
Standby response is being sent.