Add note explaining that NoticeResponse messages can

arrive even while idle.

diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index 3f87d58f171466024904dd4c4792823220345e70..582b0b1208f2652f5118c429c8783b74e4327f63 100644 (file)
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -4,7 +4,7 @@
 Phil
 Thompson
 
-1998-07-13
+1998-08-08
 
 Frontend/Backend Protocol
 
@@ -389,9 +389,19 @@ The possible response messages from the backend are:
 
 
 A frontend must be prepared to accept ErrorResponse and NoticeResponse
-messages whenever it is expecting any other type of message.  Also,
-if it issues any listen(l) commands then it must be prepared to accept
-NotificationResponse messages at any time; see below.
+messages whenever it is expecting any other type of message.
+
+
+Actually, it is possible for NoticeResponse to arrive even when the frontend
+is not expecting any kind of message, that is, the backend is nominally idle.
+(In particular, the backend can be commanded to terminate by its postmaster.
+In that case it will send a NoticeResponse before closing the connection.)
+It is recommended that the frontend check for such asynchronous notices just
+before issuing any new command.
+
+
+Also, if the frontend issues any listen(l) commands then it must be prepared
+to accept NotificationResponse messages at any time; see below.