Envoy Application Programming Manual

BISYNC Centralized Multipoint Supervisor Protocol
Envoy Application Programming Manual—427159-001
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WRITEREAD Procedure (Conversational Exchange)
WRITEREAD Procedure (Conversational Exchange)
This subsection describes how use of the WRITEREAD procedure is affected by the line
state.
Initial WRITEREAD (Line in CONTROL State)
This operation is not permitted.
Initial WRITEREAD (Line in READ State and Last State is
CONTROL or WRITE)
A WRITEREAD while the line is in the READ state is used to acknowledge a message
from the tributary by returning a message instead of the normal acknowledgment (ACK0
or ACK1). The action of an initial WRITEREAD (Example 4-12
) while the line is in the
READ state is the same action as that for a call to WRITEREAD while the line is in the
WRITE state.
The file-system errors for an initial WRITEREAD while the line is in the READ state
are the same as the errors for a continuation READ.
177 Text overrun on selection. The length of the
response received exceeds two characters (text was
received rather than a control character). The selec-
tion or transmission was attempted the number of
times specified by the retry value.
CONTROL
Example 4-12. Initial WRITEREAD (Line in READ State and Last State is
CONTROL or WRITE)
Supervisor (Local) Tributary (Remote)
line state = READ
CALL WRITEREAD (...)
| reply message -->
|
| <-- message n or
| ACK0 or
(WRITE completes) EOT
Table 4-13. WRITE File-System Errors (page 2 of 2)
Error State Description Resultant Line State