Pathway/iTS TCP and Terminal Programming Guide

TCP SETMODE Functions and CONTROL
Operations
Compaq NonStop™ Pathway/iTS TCP and Terminal Programming Guide—426751-001
9-7
Testing TERMINATION Codes
Unsolicited Message Completions
When a CONTROL 26 call is issued as the result of an escape on unsolicited message,
th TERMINATION-STATUS register contains an index pointing to the location of
ESCAPE ON UNSOLICITED MESSAGE clause in the SEND MESSAGE statement.
Table 9-4
summarizes the various TERMINATION-SUBSTATUS values that should
then be tested for. The action in the Meaning column is only suggested; the action taken
depemds on the FEP itself.
Timeout and Error Completions
When a CONTROL 26 call is issued as the result of a timeout, control passes to the ON
ERROR code associated with the SEND MESSAGE statement. Table 9-5 summarizes
the various TERMINATION-SUBSTATUS values that your ON ERROR clauses
should test for.
Table 9-4. ESCAPE ON UNSOLICITED MESSAGE Completions
Terminatio
nStatus
Terminatio
nSubstatus Meaning
* 187 The FEP assisted in terminating the outstanding read. No
data was returned or lost by the FEP and the context is intact.
Process the unsolicited message and start another normal
SEND MESSAGE statement.
* 188 The FEP assisted in terminating the outstanding read. The
FEP might have lost some data, or the integrity of the context
might have been compromised.
After processing the unsolicited message, terminate the
session with the FEP and try to start a new one.
* 189 The FEP assisted in terminating the outstanding read;
however, the operation is still in progress within the domain
of the FEP. The data will be queued and you can retrieve it at
a later time with a subsequent read operation. No data was
lost by the FEP and the context is intact.
Process the unsolicited message and then issue a SEND
MESSAGE statement that causes only a read operation to be
posted. This allows for the retrieval of the outstanding read
when it completes.
* Index of the user's ESCAPE ON UNSOLICITED MESSAGE clause in the SEND MESSAGE statement.
Note: When the TCP issues a CONTROL 26 and the FEP replies to the original I/O request with data and error 0
instead of with data and one of the above errors, the ESCAPE ON UNSOLICTED clause is not processed
even though a UMP message arrived. Instead, the SEND MESSAGE statement completes normally, using
the returned data, and the UMP message is queued for processing at a later time. To detect the arrival of
an unsolicited message, poll the PW-UNSOLICITED-MESSAGE-QUEUED register for a YES value.